GroupDIY

Project Specific Discussions => Microphones => Topic started by: poctop on December 23, 2012, 02:43:34 PM

Title: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on December 23, 2012, 02:43:34 PM
D-M49c and D-M49b Build Thread .

M49 Round Body version thread here :   http://groupdiy.com/index.php?topic=60108.0
M49 mic body available here : http://www.groupdiy.com/index.php?topic=52563.0

All the info Here : http://www.groupdiy.com/index.php?topic=49675.0 (http://www.groupdiy.com/index.php?topic=49675.0)


The Safety Manual and Considerations.
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0357d.pdf

IMPORTANT:
You Should always have the SHLF Jumper in position in the PSU PCB ,  this will ensure that your cable shield is tied at both end of the cable and connect to 0V
you Should Also have the 0V star grounded to your case and then from there to you IEC earth ground ,


For More Information on Grounding
https://www.dropbox.com/s/6y121dasm3iw4ba/Sound_System_Interconnection.pdf?dl=0

Best,
Dan,


BOM 
Note:
missing from the BOM Styroflex Capacitor   C1  1000pf, C6  560pf  / 630V

PSU 2469 passive
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=532017ac2f

M49 C or B Mic Parts
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=f556c18411

Schematic:  M49C   https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a040b7.bmp (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a040aa.bmp)

Schematic:  M49B   https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a040c4.pdf

M49 Schematic Poctop PCBS 49b and 49c

https://www.dropbox.com/s/ym5f8tur4y0rgw8/49c-round.jpg?dl=0
https://www.dropbox.com/s/wcym8uf65ov84vi/49b-round.jpg?dl=0

Best,
Dan,

PSU Schematic : https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a040e7.pdf (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a040e7.pdf)
Note : the Toroidal tranformer secondary is wired in parrallel to get 120V at the input of the psu

Cabling connection From PsU https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0410e.jpg (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0410e.jpg)

The 20Vac traffo for Europe will not fit as per the current BOM please replace it with this one or an equivalent ,
http://www.mouser.com/ProductDetail/Hammond-Manufacturing/186B20/?qs=sGAEpiMZZMvwUzoUXIIvyQPvPmwnNFGyR%2fQB%252b1BzrOY%3d
also The fuse will be 0.1A instead of 0.2 for America



M49B Overall Connection and Silk Screen https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04129.jpeg

M49C Overall Connection and Silk Screen https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0413b.jpeg


The Safety Manual and Considerations.https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04147 (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04147)


Quote
Connection For AMI T49 to PcB
TRFO to Mic PCB
A- 4
B-3
C-1
D-2

Quote
For Converting the 5840 Tube to a Triode Tie pin 7-5 Togheter Do not use Pin 4 or Pin 8

5840 Tube Datasheet https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0415d.pdf (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0415d.pdf)


D-M49c

install the floating pin First.  ( cut the other end of the pin on back of pcb but leave full lenght the one from Fgrid
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04176.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04188.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04194.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041a1.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041ae.jpg)


Note:  To Operate S2 Cardiod only Switch
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041bb.jpg)



(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041c7.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041d4.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041e1.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041ee.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a041fb.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04208.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993a04.jpg)




Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: micaddict on December 23, 2012, 04:47:43 PM
Never a dull moment with Dan.
Might as well tell us what's the next one on the list.  :P
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: Scrappersa on December 23, 2012, 05:07:13 PM
Hey Dan. Sounds like a great idea. I would love to be one of the people to put together one of the sample pcbs. With all of your boards, one could have the ultimate mic locker.
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: bernbrue on December 23, 2012, 05:56:29 PM
Hi Dan,
me and my buddy are in for two 60mm round pcbs.
regards
Bernd
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: lotus on December 23, 2012, 06:15:16 PM
I'm in for one pcb.Eric
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: bernbrue on December 24, 2012, 06:42:06 AM
Dan,
just an idea. Would it be possible to make two round versions? One with the diameter of the M49 body (60mm) and another smaller one with the diameter of the Alctron GT-2B, short U47 type body (50mm).
regards
Bernd
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: 0dbfs on December 24, 2012, 05:24:05 PM
Hi Dan, I'd like to get in on two each of the proto's for the B and C versions if possible.

Cheers,
jonathan
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: baadc0de on December 25, 2012, 04:19:48 AM
Not sure if these are proto or debugged versions, but I'm all for one b and two c when these are debugged (if there is need for that, otherwise put me down immediately). Fitting in a 60mm round body.
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 26, 2012, 02:39:55 PM
Dan,
just an idea. Would it be possible to make two round versions? One with the diameter of the M49 body (60mm) and another smaller one with the diameter of the Alctron GT-2B, short U47 type body (50mm).
regards
Bernd

The 2 version above should fit the GT2B type as they are the same size as the FET pcb i am currently working on a circular version i will start with the 60mm version ,  the 2 version above will be mounted in verticaly in the gt2b style body with the tube on one side and the component on the other side ,
i am on it at the moment ,  :)

Dan,
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: bernbrue on December 26, 2012, 03:29:22 PM
great, edited my post
regards
Bernd
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: riggler on December 30, 2012, 10:55:51 AM
Hey Dan,

I am making progress as far as getting the bodies to come in at a reasonable price! The one thing to watch out for on the 60mm round PCBs is that there are three holes for where the standoffs go up to the top cap. I will send you a drawing on what I am doing for my bodies if that would help, if you are interested in incorporating that.

Damian
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 30, 2012, 11:28:34 AM
Hey Dan,

I am making progress as far as getting the bodies to come in at a reasonable price! The one thing to watch out for on the 60mm round PCBs is that there are three holes for where the standoffs go up to the top cap. I will send you a drawing on what I am doing for my bodies if that would help, if you are interested in incorporating that.

Damian

PM sent ,
Dan,
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 30, 2012, 06:38:30 PM
That might look like this ,  Needs some polish and the square version is redone to miniaturize again for proper railing clearance and better connection scheme


this square version should fit the GT2B body 44*48mm and the aMI t49 just on the touch, will post picture soon.
and this one sould go in your mic body. :)

Let me know the Coordinate of the mounting hole. 

(http://dl.dropbox.com/u/43869772/rb.gif)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993a17.gif)

DAn,
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: tubestation on December 31, 2012, 05:34:20 AM
Hello!! This  is a nice Project!! Witch Tubes are you using? 5840,5702,5703,Ec 71? Threre is no real substitute Tube for the Ac701 but I wrote in the Prosoundweb Forum that IO audio uses Ec 71 Tubes in an Ac701 circuit with good results.The Kathoderesistor needs to be aligned .Somewhere i wrote also that the EC 1000(Electrometertube) can be used as well (if you have one )how about the Tube Cj uses in his new cascade u47 mic?Did anybody design a Transistor Circuit like the Andreas Grosser Vf 14 Replacement , for the Ac 701Tube?(With a different Powersupply)A few Days ago I saw a MXL G  Trac usb Mic witch Headbascet looks very similar to a M49!!
Thank You very much!!!
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 31, 2012, 01:32:28 PM
So these are the final Version , the square version (44mm * 48mm) should fit the gt-2b style , and the round version is 60mm diameter should fit upcoming riggler mic body 
i have been able to fit 2 mounting hole as per riggler drawing of 5.05mm mouting , i am to produce gerber at the moment so i will probably run a very small batch of those , so if any interest let me know ,  this will be an experiment for sure ,  there is 2 versions of each to accomodate the M49b and M49c version.

Stay tuned ,

M49b mini driver round   Note : the Bypass cap will go underneath the first plate as it is not show here only connection point ,
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04297.gif)

M49b mini driver round
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a042a3.gif)

M49c mini driver square
(http://dl.dropbox.com/u/43869772/D-M49BC/mbs.gif)

M49c mini driver square
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993a27.gif)
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: 3nity on December 31, 2012, 02:03:39 PM
you waisting no time huh!
Im running out of place to store mics Dan.

Happy hollidays.
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 31, 2012, 02:08:35 PM
you waisting no time huh!
Im running out of place to store mics Dan.

Happy hollidays.

Yeah Thanks Trinity , I said to myself i'd give my maximum in 2012 and then i could get super lazy in 2013  ;D
Best,
DAn,
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 31, 2012, 02:16:57 PM
here is a preliminary BOM ,

it does not include the presume C6 600pf styro and Selectable Styro C4 and also the C1 1000pf styro I presume,
Best,

Stuff for both version for 1 mic , note there is a 22K and a 2.2K as i could not be sure of the value of R7 in the C version

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=f556c18411  (http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=f556c18411)

Let see what happens next  ;D

Dan,
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: poctop on December 31, 2012, 05:35:44 PM
A quote from Oliver A,

Quote
Hello Guys,

there are a bunch of tubes that will work and pass signal to call it close enough to an AC701, but there is virtually no tube that will sound the same. 
There is the AC761 made by RFT an east german copy, that looks and feels the same but the noise figures are pretty bad compared to an real one.
The EC1000 looks pretty similar and gets close to the sound, but the lifetime is pretty short and noise can be an issue.
That far I used the 5840 as general replacement, it give an in the direction feel....

Best regards,

Oliver
Title: Re: (Feeler) PCB support M49b and M49c tube microphone headamp driver,
Post by: bernbrue on January 07, 2013, 01:53:27 PM
Stuff for both version for 1 mic , note there is a 22K and a 2.2K as i could not be sure of the value of R7 in the C version

It´s a 2,2K. Let me know when the round 49c proto pcbs are there.

regards
Bernd
Title: (Feeler) PCB support M49c tube microphone ( It's Alive)
Post by: poctop on January 07, 2013, 03:58:34 PM
Stuff for both version for 1 mic , note there is a 22K and a 2.2K as i could not be sure of the value of R7 in the C version

It´s a 2,2K. Let me know when the round 49c proto pcbs are there.

regards
Bernd

thanks for the info Bernd , i should some by next week.
Best,

Dan, :)
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: micaddict on January 08, 2013, 04:06:10 AM
 ;D

 ;)
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: Winetree on January 08, 2013, 12:15:22 PM
I was told years ago to upgrade my Neumann M49 B's to the C versions.
It was just a resistor change or something. Never did. Left them orginal.
What's the "sound" difference between versions B and C?
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: poctop on January 08, 2013, 03:30:36 PM
I was told years ago to upgrade my Neumann M49 B's to the C versions.
It was just a resistor change or something. Never did. Left them orginal.
What's the "sound" difference between versions B and C?

I have no idea of what the sound difference is but i can tell b , c are not biased the same way , the self bias  on the c version isolate the heater from Katode,
it seems to give it another kind of sound but i hope i will find out soon.  :)
Best,
Dan,
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: 0dbfs on January 08, 2013, 03:47:49 PM
The B version develops the cathode voltage ref'd to the h+ which is often referred to as fixed or stiffened bias. H+ needs to be well filtered or "stiffened" so as not to introduce any ac noise signal present in the h+ into the Vgk which would show up in the audio. The C version uses the 2k2 to elevate the cathode from ground and make the grid then negative wrt cathode. The C version also has the bypass cap from cathode to ground which shorts audio frequencies to gnd and therefore prevents NFB in that path. So the B version has NFB due to no bypass cap and thus lower output.

The 2k2 cathode resistor can be tweaked for "optimal" symmetrical bias although there is a wide range which "works fine" and the specific grid bias point can be tuned for desired results. That 2k2 also sets the current through the tube.

10uf cathode bypass cap is recommended with the 5840 instead of stock 20uf but experimentation and tuning is recommended.

5840 has a 6.3V heater and I used a 5.7V heater supply to slightly under heat.

Really looking forward to checking these out and experimenting a little. Thanks Dan!

Cheers,
jb
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: poctop on January 08, 2013, 04:01:00 PM
The B version develops the cathode voltage ref'd to the h+ which is often referred to as fixed or stiffened bias. H+ needs to be well filtered or "stiffened" so as not to introduce any ac noise signal present in the h+ into the Vgk which would show up in the audio. The C version uses the 2k2 to elevate the cathode from ground and make the grid then negative wrt cathode. The C version also has the bypass cap from cathode to ground which shorts audio frequencies to gnd and therefore prevents NFB in that path. So the B version has NFB due to no bypass cap and thus lower output.

The 2k2 cathode resistor can be tweaked for "optimal" symmetrical bias although there is a wide range which "works fine" and the specific grid bias point can be tuned for desired results. That 2k2 also sets the current through the tube.

10uf cathode bypass cap is recommended with the 5840 instead of stock 20uf but experimentation and tuning is recommended.

5840 has a 6.3V heater and I used a 5.7V heater supply to slightly under heat.

Really looking forward to checking these out and experimenting a little. Thanks Dan!

Cheers,
jb

Thanks JB, this is very well explained indeed ,
stay in touch,
Best ,
Dan,
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: 0dbfs on January 08, 2013, 04:45:37 PM
Just a couple more notes here:

AMI Has a couple different BV11 "M49/50" style transformers:

------------ AMI TRAFO's ---------------
BV11A: Direct replacement for M49/50, historically correct -> AC701, AC701K -> $450
BV11R: BV11A with extended low and low-mid frequency response -> EC92, EF732, 5840, 6072a and 12AY7WA -> $450
T49: Similar to BV11, same ratio, can be used instead of T14, PCB mounted -> AC701, ECC81, EC92, 6072, 12AT7 and 12AY7 -> $85
------------ AMI TRAFO's ---------------

I have used the BV11R and T49 in this circuit (Olivers M49c conversion with some sections added back in from the original that are not in the AMI conversion) and I prefer the BV11r with 5840's although the T49 is also quite nice. I'm planning to use the BV11r's for this set so will need to wait for funds availability.

I may spring for a pair of AC701's one day but am completely happy with the results when pairing a 5840 with a BV11r.

The cool thing about the C version is that you can use a stock chinese PSU if you want (for example from a GT2B kit) and mod that with a couple zeners to drop B+ (and P+) from about 150V to 120V and insert a series standard diode into the heater supply (just before the connector) to drop the 6.3V heater down to about 5.6V.

This makes the mic pretty affordable to put together depending on your doner-body, capsule, and transformer choices. My other pair uses Tim Campbell CT12's and I've got a BV11r in one with a T49 in the other. They are slightly different circuit-wise too (really hard to keep stuff stock when tweak options also sound "good"). In any case these with M7's ought to provide some more sonic-options for my dirty little red-light-habit :)

Cheers,
jb

PS: I haven't used any of the other BV11 style trafo's from other sources but would certainly like to and maybe paired with some RK47/7/12 capsules could be very affordable.
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: poctop on January 23, 2013, 06:01:06 PM
D-M49c is Alive , sneek peek.  I will have few pcb left for sale, round and square version will post some pic soon there are minor silk error but thats it,  PSU, D-M49C- T49 Adator board all of this is in a gt-2B from Chunger ,  :) :)
i am leaving the M49b option as of now, i will be offering the 49C version.  PM Me if interested i have about 15 set of each left ,

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04389.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a04397.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a043a4.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a043b1.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a043c2.jpg)


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a043cf.jpg)

(https://dl.dropbox.com/u/43869772/M49c%20build%20picture/Terrebonne-20130123-00721.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993a9a.jpg)
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: dandeurloo on January 23, 2013, 08:14:39 PM
I can't wait!
Title: Re: [Feeler] PCB kit support M49B and M49C tube microphone and M269 tube
Post by: wave on January 23, 2013, 10:06:26 PM
Dany,
Once again you are proving yourself to be the Godfather of German microphone cloning! Looks great!

Dave
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: micaddict on January 24, 2013, 04:08:49 AM
Me likey!

Just in case, you never know etc.; would it fit in a gutted TLM49 (short and fat/wide, just like the M49)?
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: poctop on January 24, 2013, 01:51:17 PM
Me likey!

Just in case, you never know etc.; would it fit in a gutted TLM49 (short and fat/wide, just like the M49)?

the round pcb is 60mm diameter and should fit upcoming Riggler's M49 body or any other body that will accept this diamter ,  the square versions is the same size as fet47 pcb and they make it fantastic in the gt2b body , i will be installing an M7 in there tonight  :)
Let me know.
dany,
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: micaddict on January 24, 2013, 02:22:27 PM
Quote
the round pcb is 60mm diameter and should fit upcoming Riggler's M49

Yes, of course, there's the feeler thread about those.
Dany, so much has been happening here lately, sometimes I just forget things.  :-[
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: poctop on January 24, 2013, 04:10:25 PM
PCB D-49c added to online Store only 12 set left
Best,  :)
dan,
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: riggler on January 24, 2013, 09:34:35 PM
I have read a lot of opinion on B/C - fixed bias, etc. If you do a search on hear about it, there was a very good thread a few pages long about this. Klaus says that B is the way to go for the "real" sound. Who knows. I bet either way is going to sound great. C is certainly a safer, easier path.

Anyway, guy finally got back to me. Actively working on a price. We are going to make a couple test bodies in aluminum. Your 60mm boards will fit and holes are accounted for. Good times!!!!!!!!!!

 ::)
Title: Re: [Feeler] PCB kit support for M49C tube microphone (it's Alive)
Post by: poctop on January 24, 2013, 09:44:00 PM
I have read a lot of opinion on B/C - fixed bias, etc. If you do a search on hear about it, there was a very good thread a few pages long about this. Klaus says that B is the way to go for the "real" sound. Who knows. I bet either way is going to sound great. C is certainly a safer, easier path.

Anyway, guy finally got back to me. Actively working on a price. We are going to make a couple test bodies in aluminum. Your 60mm boards will fit and holes are accounted for. Good times!!!!!!!!!!

 ::)

Dont worry i have all the version For the Round Body B, C just ask for it, even the M50B round, that it is just too much pcb  ;), I have both B, C square also , the issue is that the psu pcb is only working for the C version wich is not very picky about hummy-Supply not even sure about LM supply style either  , i am working on making another one specially for Filament Bias B version all passive.    Last Thing i need to work out as the coming M269 is fixed bias and the supply will work for both.

Best,
in developpment

Title: Re: D-M49c tube microphone Build Thread
Post by: bkbirge on January 25, 2013, 01:47:39 PM
What are capsule sources for this build? Anyone tuning for this circuit?
Title: Re: D-M49c tube microphone Build Thread
Post by: poctop on January 25, 2013, 01:55:14 PM
What are capsule sources for this build? Anyone tuning for this circuit?

the capsule are K47-M7 type as for tuning the stock value K bias 2.2K, and 100K plate  of the self biased c version get very very close to the spot as 52V for the plate and 1.55V for grid Bias for the 5840 ,  I also built a B version but i need to redo the power supply for this one as for the M269 wich will be a b version it did not work hum free ,
both installing a 1M pot i was able to tune the bias on spot .   
Let me know,
 
Best,
Title: Re: D-M49c tube microphone Build Thread
Post by: micaddict on January 25, 2013, 05:04:49 PM
Quote
What are capsule sources for this build?

M7 was in earlier M49; not in -c (which had K47/49). Regarding -b, it depends whom you ask.
But I wouldn't worry about that. Just get a nice M7 or K47 capsule (whichever is preferred).
For those who can't make up their minds (or regardless), there's the BeesnNeez K7 which is a crossbreed of the two.
Usual suspects for M7 are Thiersch (also in PVC), Dale Ulan, Beesneez again, Max/ioaudio (soon). Gefell (PVC) only as part of a microphone.
K47 can be had from quite a few more makers/suppliers.

Quote
Anyone tuning for this circuit?

Good question. A maker might chime in.
Of course, if necessary, tuning can also be done the other way around, if that makes sense.
And then there's personal taste.
Title: Re: D-M49c tube microphone Build Thread
Post by: poctop on January 25, 2013, 05:27:42 PM
All version are available so please do ask ,  the only thing is that the current pcb supply will support the c version.

I am not even sure if LM317 Style regulation will be enough in this b version.

This is going to be called Choke Time  :),

Dany,
Title: Re: D-M49c tube microphone Build Thread
Post by: poctop on January 27, 2013, 05:24:49 PM
The Solution For filament Bias Mic PsU version M49b and M269b,  All passive split choke design ,  should be cleanest available option.

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993ab9.jpg)

To follow up,  :)
Best,
Dan,
Title: Re: D-M49c tube microphone Build Thread
Post by: poctop on February 07, 2013, 10:22:13 PM
Just finished testing the new power supply,  I have built up an M49b this time and tested with this one ,  I am Super happy with the results ,
the 49b filament bias version mic is  Extra quiet and the sound is just awesome ,  I guess this was a very good day , when finishing the power supply i did not even have to touch the POt 8) it was 120V-6V  after warmup.  I installed a 1M ohm pot for the bias and i set it to (4.4V-6 ) = 1.6V bias with 52V plate as results
 
Now i will have the M269 running soon enough and no worry about the psu beeing noisy , it is just plain whole passive choke filtering full recitfied B+ and heater with a nice array of Big smoother. So Happy now. ;D ;D

I will be replacing the c only version psu with this one and it will also work for the M269b mic coming soon, the M49b version will also be available soon.


(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0447e.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0448c.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a0449d.jpg)

(https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/Terrebonne-20130207-00745.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993adb.jpg)
Title: Re: D-M49c tube microphone Build Thread (D-M49b tested fantastic with new psu)
Post by: poctop on February 07, 2013, 11:08:02 PM
Here is a simple sample of the D49b,  you can hear very well  that i fall of my chair at the end   ;D

Enjoy :
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993aeb.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993aeb.wav)

PS: Do Save target as

Best,
Dan,
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: micaddict on February 08, 2013, 07:24:56 AM
Sounding good, Dany.  :)

So, how are you liking the Raytheon 5840?
And have you tried other brands?

Raytheon also has (or had) the 5702 which is very similar but "the only major difference is that that grid 3 (suppressor) comes out on a separate lead this can be tied to the cathode lead on the base". BeesNeez uses that one in some models. Any thoughts about this?



Henk
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: Tommy Radonicus on February 08, 2013, 08:01:17 AM
That sounds very impressive Dan. Lots of proximity effect .. By the sound of it you were close to the capsule, but the bottom and top end are both lovely nonetheless. So this is with a 5840 ??
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: poctop on February 08, 2013, 08:28:39 AM
That sounds very impressive Dan. Lots of proximity effect .. By the sound of it you were close to the capsule, but the bottom and top end are both lovely nonetheless. So this is with a 5840 ??

thanks I really dig the sound od this mic as well ,   i was close but had a pop filter in the way i know this willl not change that much the proximity much, but this mic has beef to it ,  and yes it is with the Raytheon 5840 tube ,  I was really concerns about the psu for this filament type bias and it sounds quiet big time ,

Best,
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: micaddict on February 08, 2013, 09:09:11 AM
Is it the regular or WB version?
(And did you read reply #43? :) )

Quote
it sounds quiet big time
The Brauner Valvet X has a 5840, too.
Noise floor of that mic is below 9 dbA.  8)
Despite "old fashioned" tube and tranny.
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: Melodeath00 on February 08, 2013, 10:57:38 AM
The mic/clip sounds very good! Lots of proximity, but I dig it.

Are you using an angled headbasket like the 49?

You're planning to do a 269? Will this be very similar to the D67, but use a 5840 instead of EF86?

Thanks
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: 0dbfs on February 08, 2013, 11:21:46 AM
Dan, This is most exceptional. Looking forward to stuffing some 49b's and c's since the double-choke'd-smoothed-and-stiffened psu will work with either.

Great thing is that you can stuff both a b and c rev fairly economically and use them in the same body/capsule/trafo/psu combo. So stuffing boards with some different tubes (5840/5702) and/or perhaps output caps or whatever allows some adaptability to the record task at hand.

I'm thinking the 269's will be cool too. Especially to open up the options on sourcing tubes.

I haven't looked at the 5702 docs yet but will be checking them out too. I've got about 15x 5840's in stock and the 86 family stuff starts to add up quickly so however you look at it options are always nice :)

Cheers,
jb
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: poctop on February 08, 2013, 11:26:56 PM
Sounding good, Dany.  :)

So, how are you liking the Raytheon 5840?
And have you tried other brands?

Raytheon also has (or had) the 5702 which is very similar but "the only major difference is that that grid 3 (suppressor) comes out on a separate lead this can be tied to the cathode lead on the base". BeesNeez uses that one in some models. Any thoughts about this?



Henk

Yep That is the standard Raytheon in there i should check out the other model too  :) the mic will be open to option  :),  i did not have time to try much yet but i am pretty happy with that old plain 5840 from Raytheon nOS for now, have heard of 5748WB or somthing similar as well,
this will be fun experiment with those minis  :)
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: poctop on February 08, 2013, 11:28:10 PM

You're planning to do a 269? Will this be very similar to the D67, but use a 5840 instead of EF86?

Thanks

Yes it is in process already see the other thread .
Best,
dan,
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: micaddict on February 09, 2013, 05:30:00 AM
Quote
have heard of 5748WB or somthing similar as well,

Yes, there are several, like the 5702, CV4501 and CV4502, that are very similar though not the same.

BTW the military grade (JAN, WA, WB and such) is an interesting matter. Some say these are the same as the standard versions, only more rugged. Others don't agree.
Here's what Oliver Archut wrote about it in 2002 on the Neumann forum:

Quote
JAN tubes, Join Army Navy tube key, specialty tubes made for military use. Most of them were upgraded industrial tubes, with the one purpose to insure function under very heavy-duty circumstances. Their construction was designed to insure the minimal function over a long period of time. To put it into better terms, there were pre tested on the edge of their rating to sort out early failing ones. It doesn't mean that they were tested for audio, and most of those tubes are very noisy, not microphonic but a lot of random and white noise. In circuits like the U67 most of it is suppressed because of the HF cut off feedback as you pointed out. The higher noise relates to the cathode construction, some of them used sintered ones others a double layer coating design, the first layer is fast activated at the factory, the second one starts activating over a long period of time. *This process was patented by Sylvania and use for most JAN tubes after 1963* That is what generates the higher noise floor if used for audio. Sure they nearly live forever with hardly no microphonics, but gain structure is quite different, most of them sound quite harsh. In the last few years so many JAN tubes were decommissioned and entered the audio market, but for my personal taste a standard RADIO GRADE or some industrial tubes are more desirable. Of course there are some exception, like the JAN tubes than were special made for audio use.

For those who don't know, Oliver Archut is the same guy who makes the T49 tranny as used for this here M49 project. And yes, he does know a thing or two about tubes, too.

Of course, highly regarded mic builders like Dirk Brauner, the earlier mentioned Ben Sneesby and others do use military grade tubes with great success. Perhaps these tubes are the exception Oliver talks about in the last sentence of the quote. (?)

Here's a discussion that took place on another forum in 2005:
http://www.diyaudio.com/forums/tubes-valves/53836-difference-between-5687-5687wa-5687wb-tubes.html (http://www.diyaudio.com/forums/tubes-valves/53836-difference-between-5687-5687wa-5687wb-tubes.html)
It's just one discussion and simply the first that popped up.
For more in depth discussions about this (like Oliver Archut's story), one's best bet IMO would be to search in the archives of Klaus Heyne's excellent REP forum.
Come to think of it, our own forum may hold some useful ones, too.

Oh and as a rule the standard version tubes are cheaper.

Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: poctop on February 10, 2013, 04:22:39 PM
Is it the regular or WB version?
(And did you read reply #43? :) )

Quote
it sounds quiet big time
The Brauner Valvet X has a 5840, too.
Noise floor of that mic is below 9 dbA.  8)
Despite "old fashioned" tube and tranny.

I double checked and it seems i have the Raytheon 5840W series, i will use the same one for now in the M269 Build  :)

Best,
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: micaddict on February 10, 2013, 04:40:04 PM
Thanks, Dany.
The 5840 in the Brauner is a Philips JAN, BTW. The tranny a custom Lundahl.
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: poctop on February 10, 2013, 04:41:55 PM
Thanks, Dany.
The 5840 in the Brauner is a Philips JAN, BTW.

thanks,  good to know, once this is all working and tested i will have some fun with other tubes and i will keep that one in mind , I will be orering different flavor and bias those and see  :)

Best,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: gary o on March 04, 2013, 09:24:42 PM
http://proel.com/category/products/ldf410

Any use
Title: Re: D-M49c tube microphone Build Thread D-M49B in testing.
Post by: 0dbfs on March 04, 2013, 09:40:58 PM
Thanks, Dany.
The 5840 in the Brauner is a Philips JAN, BTW.

thanks,  good to know, once this is all working and tested i will have some fun with other tubes and i will keep that one in mind , I will be orering different flavor and bias those and see  :)

Best,
Dan,

I'll try out some other tube options too.

Cheers,
jb
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: gary o on March 05, 2013, 06:30:19 AM
http://www.thomann.de/gb/media_bdbviewer_AR_165293.html?image=4

very cheap maybr good for a body
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: poctop on March 19, 2013, 04:32:17 PM
http://www.thomann.de/gb/media_bdbviewer_AR_165293.html?image=4

very cheap maybr good for a body

not sure this one will fit the aMI T49 is one piece of iron to fit in amic body for sure,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: poctop on April 03, 2013, 05:06:04 PM
Here the first Sample ,   it looks sweet just looking at the wav form in the DAW  :)

AMI T49-ChuckD M7

let me know what you think,

Best,
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c83.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c83.wav)

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 03, 2013, 05:45:13 PM
Wait, is this the earlier mic that had the Peluso capsule, but now with the ChuckD/Dale M7?
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 05:46:49 PM
I have done so many mics i cant even remmeber that is why i guess i describe the sample in words  :),

wich sample would that be again ,

Best,
Dan,
 
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 03, 2013, 05:50:12 PM
The one in reply #42 of this thread.
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 05:52:28 PM
Yes,
the same mic,   but this one is biased properly also  ;) and have the Chuckd M7 i dont have a C anymore need another body  ;D

i guess it will update during this tuning process,

Best,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 05:53:32 PM
Sample 1 peluso K47 AMI T-49  Bias ?
https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/d49b.wav (https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/d49b.wav)


Sample 2
AMI T49-ChuckD M7

let me know what you think,

Best,
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c93.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c93.wav)

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 03, 2013, 05:56:04 PM
That was the -b version, too, wasn't it? (And it was after you updated the PSU.)

Quote
Here is a simple sample of the D49b,  you can hear very well  that i fall of my chair at the end   ;D

Enjoy :
https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/d49b.wav

BTW please don't remove the older sample.  :)
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 05:57:15 PM
Just put them both above,

Both B version ,

BEst,
D
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 05:57:56 PM
Sample 1 peluso K47 AMI T-49  Bias ?  gain on pre ?
https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/d49b.wav (https://dl.dropbox.com/u/43869772/D-M49BC/Build%20Folder%20M49c/d49b.wav)


Sample 2
AMI T49-ChuckD M7

let me know what you think,

Best,
https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c9d.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993c9d.wav)
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 03, 2013, 06:00:39 PM
Great to have 'em both, Dany!

Tomorrow I'll give them a proper listen. I'm off to bed now.
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2013, 06:40:49 PM
here is some quick ACG,  with config #2 ChuckD M7- AMIT49

https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993cac.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993cac.wav)

Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 04, 2013, 04:20:53 AM
OK, I listened.

Those two new samples (speech and guitar) are very nice indeed.

But ...

... that earlier sample with the Peluso capsule (who'd have thunk it) really rocks my boat. I'm floored every time I play it. Yes, you were probably closer on the mic (proximity). And yes, I know it's only one sample. But it has that sound. Big, full, intimate. Clarity too, but nowhere harsh. Clear sibilants but oh so smooth. Etc.
Wrong bias? Then I want wrong bias.  :P Do you keep notes?
It strongly reminds me of the Horch RM2J in red (pure cardioid) mode. No coincidence maybe since that mic was inspired by the M49 (although it has a U47-style body). That is a 6000 dollar microphone BTW.

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 04, 2013, 06:38:34 AM
Careful, Dan is going to raise his rates. Just kidding. Sounds to me like the proximity is different. I've got a couple different m7 and 47 capsules to listen to for those specific differences in proximity between the two styles.

I really like the sound of the b being as you describe "smooth yet still with nice sibilance" type of thing. Will be cool to compare to the c too.

These tools are awesome to say the least.

Cheers,
j
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: MagnetoSound on April 05, 2013, 07:58:30 AM
http://proel.com/category/products/ldf410

Any use

Very cheap. Anyone looked inside?

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread.
Post by: HellfireStudios on April 05, 2013, 10:17:33 AM
http://proel.com/category/products/ldf410

Any use

Very cheap. Anyone looked inside?

It looks a lot like the KAM Crystal LDC. If it is the same internally, it has SMT parts and less room than a MXL 990. A google images search of "kam crystal mic" brought up internal pics of the PCB and capsule (34mm K67-type). I hope that helps.

-James-
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: MagnetoSound on April 05, 2013, 10:29:19 AM
James, thanks. It doesn't look to me like a contender.
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 05, 2013, 04:23:07 PM
Is 600pf C6 a high frequecy roll off cap or is it for RF....... thanks
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 06, 2013, 12:37:37 PM
OK, I listened.

Those two new samples (speech and guitar) are very nice indeed.

But ...

... that earlier sample with the Peluso capsule (who'd have thunk it) really rocks my boat. I'm floored every time I play it. Yes, you were probably closer on the mic (proximity). And yes, I know it's only one sample. But it has that sound. Big, full, intimate. Clarity too, but nowhere harsh. Clear sibilants but oh so smooth. Etc.
Wrong bias? Then I want wrong bias.  :P Do you keep notes?
It strongly reminds me of the Horch RM2J in red (pure cardioid) mode. No coincidence maybe since that mic was inspired by the M49 (although it has a U47-style body). That is a 6000 dollar microphone BTW.

I beleive the Bias was set just a tad to low in plate current from my calculation it ran at 0.6ma instead of the 0.7ma as per the spec ,  the peluso capsule gave excellent results indeed, and finally compared figured of gain with the mic and everthing is perfect on this stage require between 40-50 db for a full operation signal , i was to reinstall the peluso in there but i had a infortunate accident with it and it died  :(, 

Overall can't be happier with this one,   as soon as i have another micbody i will restick the M49c circuit in it and have a more comparable results between the 2
will keep you posted, for sure,

Best,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 06, 2013, 01:08:26 PM
Quote
i was to reinstall the peluso in there but i had a infortunate accident with it and it died

Ouch.  :o
Re-skin?

What mic pre do you use BTW?

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 06, 2013, 01:14:14 PM
Quote
i was to reinstall the peluso in there but i had a infortunate accident with it and it died

Ouch.  :o
Re-skin?

What mic pre do you use BTW?

The Famous Martin EZ1073 Pre.  Just love em,  all sample i take are from those,
Best,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on April 07, 2013, 05:09:33 PM
Hi guys !

I'm starting a 49b build, but I still have to sort out a few things...

1/ what kind of wiring should I do to run the PSU on the European 240 V main ?

2/ just checking my combo will do : 49b + cinemag 2480 + 5840W + RK47 or RK7 (from parts) ? Anything looking wrong from there ?

Thanks !
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 07, 2013, 06:14:25 PM
Hi guys !

I'm starting a 49b build, but I still have to sort out a few things...

1/ what kind of wiring should I do to run the PSU on the European 240 V main ?

2/ just checking my combo will do : 49b + cinemag 2480 + 5840W + RK47 or RK7 (from parts) ? Anything looking wrong from there ?

Thanks !

Looks fine for the combo ,   what version are you building the round or sqaure version   ?

you main toroid transformer will be wired in series for 230 at the primary and then in parralle at the secondary for 120V out ,

will you be using the hammond 20V traffo dual primary for the heater ?

Best,
Dan,
 
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on April 08, 2013, 04:23:24 AM
what version are you building the round or sqaure version   ?

Square, to fit a Thomann SCT-700 body.

will you be using the hammond 20V traffo dual primary for the heater ?

Well, it's in the PSU BOM, so i guess so... Are you worried about the space it requires ?
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 08, 2013, 08:22:51 AM
what version are you building the round or sqaure version   ?

Square, to fit a Thomann SCT-700 body.

will you be using the hammond 20V traffo dual primary for the heater ?

Well, it's in the PSU BOM, so i guess so... Are you worried about the space it requires ?



Well, it's in the PSU BOM, so i guess so... Are you worried about the space it requires ?


Have you replaced it with the dual primary 20V traffo as per the note on the first page of the build thread,
Let me know ,  you will need the dual primary version of this traffo for europe.

Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on April 08, 2013, 12:03:01 PM
Ok so is this BOM correct ? http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8508A2A30F

I changed to 0.3 A fuse to 0.1 A. Should i go for 0.15 A instead ?
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Winetree on April 08, 2013, 01:06:31 PM
The P.S. BOM shows Rotary Switches SP3T SHRTNG 1.5" ACT
for the pattern select switch only allowing 3 choices.
Can another pot  be used for variable pattern select like the orginal M49? What value?
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 08, 2013, 02:44:33 PM
Ok so is this BOM correct ? http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8508A2A30F

I changed to 0.3 A fuse to 0.1 A. Should i go for 0.15 A instead ?

Yes you have the corrected traffo for europe,   sometime the fuse is not slow blow enough for the draw considering having some tad higher rated Fuse is a good advice indeed.

best,
dAn,


Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 08, 2013, 03:57:00 PM
Here is some  alternatives for the 5*11mm caps needed specifically for the M49bc square and round,  also in the U67 and 269c mic,


http://www.alliedelec.com/search/searchresults.aspx?dsNav=Ntk:Primary|MKT1813310405|3|,Ny:True,Ro:0&dsDimensionSearch=D:MKT1813310405,Dxm:All,Dxp:3&SearchType=0 (http://www.alliedelec.com/search/searchresults.aspx?dsNav=Ntk:Primary|MKT1813310405|3|,Ny:True,Ro:0&dsDimensionSearch=D:MKT1813310405,Dxm:All,Dxp:3&SearchType=0)


http://canada.newark.com/vishay-roederstein/mkt1813310405g/capacitor-film-0-01uf-400v-axial/dp/26M1636?Ntt=MKT1813310405

http://canada.newark.com/vishay-roederstein/mkt1813-310404/capacitor-poly-film-0-01uf-400v/dp/18M2494?Ntt=MKT1813310404

http://fr.farnell.com/vishay-roederstein/mkt1813310405g/condensateur-0-01uf-400v/dp/1166851?Ntt=MKT1813310405

Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 08, 2013, 05:17:38 PM
The P.S. BOM shows Rotary Switches SP3T SHRTNG 1.5" ACT
for the pattern select switch only allowing 3 choices.
Can another pot  be used for variable pattern select like the orginal M49? What value?


https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993cfa.pdf (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993cfa.pdf)

you absolutely can,   if you look at the schematic attached,  all you have to do  is :

use a 100K lin pot ,

and connect the wiper of the pot to the COM pad ,   one side of the pot to OM and the other side of the pot to F8 pad,  this way the pot will act as a voltage divider from 0V omni  to 120V figure 8 ,


I did that this way to avoid having to solder resistor on the 3 pole switch   I used a 3 pol switch cause i am not a very big user of the infinite pattern possiblity
of the mic ,  i am just using fig 8 , omni and cardiod ,  but this will not prevent you of doing this that way , that is why i like DIY , you can make it the way you like , but in this case it is very easy to modify,

Best,
Dan,
 
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on April 13, 2013, 09:18:25 AM
HI Guys,

need a bit of help making sure this ac107 is wired in correctly.

pin1 = go through the board from the underside and attach to the fgrid, is this ok?
pin2 =  connect to K turret
pin3 = connect to HG turret
pin 4 cut
pin 5 + 7 = connect to A turret
pin 6 = connect to H+ turret
pin 8 cut off

please advise as I know im not understand this.

regards

Spence.
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 13, 2013, 03:45:11 PM
HI Guys,

need a bit of help making sure this ac107 is wired in correctly.

pin1 = go through the board from the underside and attach to the fgrid, is this ok?
pin2 =  connect to K turret
pin3 = connect to HG turret
pin 4 cut
pin 5 + 7 = connect to A turret
pin 6 = connect to H+ turret
pin 8 cut off

please advise as I know im not understand this.

regards

Spence.

That is exactely correct, 
Best
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 13, 2013, 03:52:54 PM
Good news ,

For those that will be building the mic project that needs the 0.01uf  capacitor in the package 5*11mm  i have been able to change mouser minds to offer a 10% variation at a minimum qty of 1  ;),

here is a link for it ,
http://ca.mouser.com/ProductDetail/Vishay-Roederstein/MKT1813310405/?qs=N5kmjX/bzE4Fjs7uA0EePA==

i aslo went over my BOM and added in the customer part number cell some nice subsitution for the parts that went back order , should be all good now ,

Best,
Dan,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 15, 2013, 08:52:44 AM
What plate & Cathode voltages are you guys getting at what is optimal voltages  ...... thanks

All the best
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 15, 2013, 09:39:49 AM
What plate & Cathode voltages are you guys getting at what is optimal voltages  ...... thanks

All the best

I trimed to pot to get the proper bias wich is about 1.6V in self bias (c) or  it was easier to get the plate current in filament biased (b) where it is supposed to sit in this circuit so adjusting the plate voltage to about 50V with the B+ operated at 120V and a 100K plate resistor, would give the 0.7ma as per the original circuit.

Best,
Dan.,


Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 15, 2013, 10:14:51 AM
Thanks Dan Im just messing with similar to C version circuit as experiment I have my own supply giving 118V ht 5.7V filiment & I get 52V plate & 1.3V cathode I guess Im in the ball park

Thanks
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 15, 2013, 10:18:20 AM
Thanks Dan Im just messing with similar to C version circuit as experiment I have my own supply giving 118V ht 5.7V filiment & I get 52V plate & 1.3V cathode I guess Im in the ball park

Thanks

the calculation of your plate current is the most important thing , are you using a 100K plate resistor ?

Dany,
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 15, 2013, 11:19:16 AM
Thanks Dany yes 100K plate resistor
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 15, 2013, 11:22:22 AM
Thanks Dany yes 100K plate resistor

you are indeed very close then ,
D
Title: Re: D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 15, 2013, 11:25:41 AM
May add a pot on cathode then, to achieve 1.6V on cathode voltage

Thanks
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 08:27:17 AM
Added trim pot trimmed to 1.6V mic sound great and very very quiet , love it
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 17, 2013, 10:14:51 AM
Gary, How does that adjustment affect your voltage drop across the 100k plate resistor (ie; operating current closer to 0.7ma?) as well as b+, and Vplate values?

Thx,
jonathan
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 10:30:13 AM
Hi Johnathan not sure how to measure/ calculate what your asking .... sadly I lack lots of basic electronics knowledge but would like to learn ..... I can measure B+ plate voltage  & then need to calculate is that right ......

Edit ..... Ok I now have B+ 115.7 plate 53.1V  I think polar voltage is 53.3V if measuring from correct node

thanks
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 17, 2013, 01:16:01 PM
Easy thing about having a 100k in that position is that you can do the math in your head.

B+ = 115V
Plate = 53V

Drop across 100k = 115-53 = 62V Voltage drop across 100k and that means the tube is running at .62ma

We would want about 45V on the plate to get to the specified 0.7ma

Some tubes will differ and heater voltage can also effect this so worth experimenting with the tweaker positions and such to see how your tube is working and adjusting accordingly.

Are you using a 5840?

Thx,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 17, 2013, 02:28:15 PM
Hi Johnathan not sure how to measure/ calculate what your asking .... sadly I lack lots of basic electronics knowledge but would like to learn ..... I can measure B+ plate voltage  & then need to calculate is that right ......

Edit ..... Ok I now have B+ 115.7 plate 53.1V  I think polar voltage is 53.3V if measuring from correct node

thanks
Hi Gary,

Normally the polarization voltage in cardiod should be exactely half the B+ voltage minus a hair for current limiting resistor inside the psu , so 53.5V would be on the low side should be more like , 58V,   also the heater operating voltage will affect those conditions a little where the plate voltage may vary a tad,
did you built the PSU with the pcb i supply or it is home brew,  Wich capsule did you ended up doing ,  if you have a chance you might want to post a quick Krooner sample of yours  :), 

did you make the c or the b version of the circuit, 

LEt me know,

Good Job,

Best ,
Dany,


Let me ko

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 04:11:12 PM
Hi Jb Dany & anyone thanks for help ....how do I change plate voltage...... change plate resitor value ?...... Yes using 5840 tube Jb thanks

My PSU is a homebrew I made years ago before internet day made it for a C28A really didnt know what I was doing then (still dont now) Ashley Styles Sarurn sound help me out over the phone its based on AKG C28A PSU really work great with C28, 120V B+ adjustable LT adjusted to 5.7V for my 5840 ....Capsule Im testing with is Tim Cambel & Violet Vin67, the circuit im messing with is the Oliver A TLM149 conversion wich I think is most like the M49C

Yes I can do a quick youtube trashy croon with the mic ....

thanks for help fellas very interested to learn  :)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 07:46:54 PM
So I need a 70V drop across plate resistor .........doI raise my B+ to 123V to achieve the .7ma ....
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 17, 2013, 08:04:32 PM
So I need a 70V drop across plate resistor .........doI raise my B+ to 123V to achieve the .7ma ....

Try this , put B+ to 120V and then adjust the plate voltage to 50 this will give you 0.7ma plate current ,  this is the most important aspect of the circuit.
the bias is the results of this operation and will be dependant of the heater voltage used and tube type and also the final plate voltage set for this circuit ,
the bias with the 5840 tube might not be exactely 1.6V but should be pretty much nearby this value the plate current has predominance over the bias,
what is actually calibrated is the plate current not the bias try it out and let me know what is the final value of your bias , and make sure you do have 58-59V on  the R6-R7 node.  and then try the mic out and let me know, with only one trimmer the bias and plate current will be a compromise over the best results  :)

if you want to vary the range of both condtition you may want to tweak the plate resistor value  ;)  this will get you exactely where you want to be on the tube curve

Best,
DAn,

 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 17, 2013, 08:16:22 PM
What Dan says and the CT12 doesn't want to see more than 60V.

Which transformer are you using? Sorry if I missed that :)

I did two of Oliver's 5840 circuits with ct12's and those are great. I'll try to measure my voltages and post but I think I had about 43V or so on the plate with 120V b+. Slightly different on both mic's but close.

Cheers,
-jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 17, 2013, 08:36:16 PM

if you want to vary the range of both condtition you may want to tweak the plate resistor value  ;)  this will get you exactely where you want to be on the tube curve  :)

Best,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 17, 2013, 09:12:53 PM
Based on a B+ at 120V ,    Exactely 47V at the plate would give the calibration plate current 0.73ma,  ;)
Hope this helps,
D

 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 10:03:36 PM
Thanks Dan I have been tweeking I now have 130K plate resistor B+ is now 122V plate is now 52V I have -1.6V cathode & cathode resistor is 2K8 instead of 2K2 I have 56.5V at R5 6 7 node for capsule ?......

Soooo 122V B= 52V plate = 70V drop = .7ma is that right ...... edit Im just thinking Noooo cant be right cant it coz my plate res is 130K.......my brain hurts it late well early sleeeeeeep now

jb Im using T14/1 from a AKG C28
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 17, 2013, 10:49:11 PM
Cant sleep.... trying to do maths so 70V drop divided by 130k is .538ma Im further away now ......can I put DMM in series with plate & plate resistor ......
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 18, 2013, 10:23:53 AM
Cant sleep.... trying to do maths so 70V drop divided by 130k is .538ma Im further away now ......can I put DMM in series with plate & plate resistor ......

to measure the plate current the easiest way is to measure the voltage drop acrosss the plate resistor and divide it by the plate resistor ,
U/R = I

Try a lower Value of plate resistor like 80K and it will probably get you statifiy both condition at once while trimming for the bias value,   :)

Let us know what you end up with

Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 18, 2013, 01:29:03 PM
Just tried 91K plate res volts across 59.6/91000R = 0.00062A is that right 62ma Im still down my B+ went down to 114.3V Plate was 54.V ....._1.6V cathode

I think I need more power captain !! PSU Im using was designed for a AKG C28A  doesnt wanna give me 120V when I use 100K plate res with this mic, will see if i can get more power.....
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 18, 2013, 01:44:27 PM
Adjusting the cathode resistor in a self bias should set the current through the tube. Try adjusting that one and see how it affects current.

Cheers,
j
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 18, 2013, 03:11:36 PM
I have canged some resistors in my homebrew PSU .... I now have more power .....
Adjusting the cathode resistor in a self bias should set the current through the tube. Try adjusting that one and see how it affects current.

Cheers,
j

Sorry J I didnt answer this earlier ..... here are some results

with 100K plate res B+ measured 124V plate 56.8v drop across plate res 67.3V cathode was at -1.653V capsule 58.1V
I adjusted cathode pot to -1.6V & that changed the B+ 123.2V plate 55.1V drop across plate res 67.8V capsule 57.5V     sooooo 67.8 ma not far off .....

I tried 91K plate res next cathode was at -1.65V  B+ went to 121V plate 56.9V drop across plate 64V ( 70.3MA ?) capsule 56.6V
I adjusted cathode to 1.6V B+ went to 120.2V plate 55.6V drop across plate res 64.5V ( 70.8MA ?) capsule 55.5V

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 18, 2013, 03:40:20 PM
That looks pretty close with the 91k & -1.6V cathode.

The DMM readings at the backplate polarization divider may be off due to higher impedance so best to calculate the resistor values With 120V b+ the polarization should be 60V if you have matched the resistors pretty close in that divider section.

Cheers!
-j
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 18, 2013, 06:46:53 PM
Quote
I tried 91K plate res next cathode was at -1.65V  B+ went to 121V plate 56.9V drop across plate 64V ( 70.3MA ?) capsule 56.6V
I adjusted cathode to 1.6V B+ went to 120.2V plate 55.6V drop across plate res 64.5V ( 70.8MA ?) capsule 55.5V


Yes Go For it  :),

Best,
dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 18, 2013, 08:39:51 PM
So with 91K plate resistor I will tweak cathode pot to get 63.7V/91000R = .00070A ..... BUT the cathode voltage wont be bang on _1.6V BUT close & plate current more important right
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 18, 2013, 10:08:05 PM
So with 91K plate resistor I will tweak cathode pot to get 63.7V/91000R = .00070A ..... BUT the cathode voltage wont be bang on _1.6V BUT close & plate current more important right

Correct , Since we are not using the exact same tube the resulting plate current adjustment at 0.73ma will results in a slighlty different bias condition it should be close but will not be necessarly be 1.6V precisely,  since we are using a fixed plate resistor change in cathode resistor ( trimmer)  will have an effect on the final bias value,   all you have to do after this is try the mic out and let me know.   

After you inital test with the mic :
a nice addon experiment would be to replace the plate resistor with a 250K pot and tweak the value of the bias trimmer from 1.6V to 1.9V and then variying the plate resistor trimmer to get about 0.8-0.9ma while readjusting the B+ at the end at 120V and tweak back untill both conditions are met. and see how the mic react in this zone, if you have time to perform this i would be really curious to see what you can end up withas final plate resistor Value and cathode resistor value , I was to make the experiment myself but the studio wont let me take my mic back  ;),   as soon as i have another body to put the my other 49c in i will keep you posted as well.

Let me know, :)
Best,




Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Winetree on April 19, 2013, 12:12:25 AM
M49 Power Supply Round transformer hook-up to main P.S.B.
Yellow & Red
Black & Orange
To P.S.B.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 19, 2013, 06:32:08 AM
Ok Dan I can add the pot & tweak after weekend got some gigs to do first,it will be interesting, I bought a little scope at second hand market today maybe it can help......
 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 19, 2013, 08:49:30 AM
M49 Power Supply Round transformer hook-up to main P.S.B.
Yellow & Red
Black & Orange
To P.S.B.

That is correct, the Traffo secondary output is wired in parrallele to the Main PCB, 

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 19, 2013, 08:54:42 AM
Had quick go added 100K to my 91K but proving difficult to tweak because I have to desolder the 100K pot to measure then do the sums...... can I connect my DMM as Ma meter and tweak for 00070A ....... Where will I need to connect meter in series ? thanks
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 19, 2013, 10:08:26 AM
You can temporarily connect it in series between the 100k (91k) and the plate. This should give you the accurate MA reading..

You can also calculate the current by measuring the cathode voltage and calculating current through the cathode resistor.

For instance:

Cathode = 1.6V
Rk=2k2

I=V/R
I=1.6/2200
I=0.00072727
or
0.73mA

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 19, 2013, 10:31:11 AM
JB thanks, I was gonna ask if I could measure between plate & plate res & I thought I would try anyway

so now I have 120V B+ I tweaked the plate resistor with 47K & 100K ( will measure final plate resistance) to 0.70ma tweaked cathode resistor for -1.6V again will measure final cathode resistance plate voltage is 53.3V drop across plate resistor is 68.3V

my capsule voltage has gone right down to 42.4 not sure why....... I am using a different DMM to measure voltages now as other meter is measuring the Ma ......they both cheap meters ..... Im measuring at junction of R6 R7 both 1M so should read 60V I guess .......

As I say my circuit different slightly to what you guys are building

http://www.tab-funkenwerk.com/id89.html

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 19, 2013, 11:38:47 AM
Hmm both my DMM s read slightly different voltages on B+ plate & capsule voltages...... thats what I get for buying cheap ones I guess ......cathode voltage read same & milli ampage reads the same tho ........

my plate resistor ended up 103.5K and cathode resistance ended up 2279R

hope this help you builders....

One other thing I  read somewhere to lower cathode resistor to 10uf for the 5840 tube I notice its 22uf on your BOM

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 19, 2013, 11:43:16 AM
Oliver mentioned to me to lower the cathode bypass cap to 10uf (in his ckt with a 5840) but you can try either 22(25)uf or down to 10uf to see. I think it's worth experimenting a little to see how these fine-tuning or voicing details affect performance.

Good info here!

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 19, 2013, 11:50:26 AM
One thing Im still not sure about is the 0.7ma thru tube & -1.6v cathode is for Ac701 tube right ? do we need to look at graphs wich I wont be able to read to find 5840 current & voltage.....

Re 25/22/10uf cathode cap that can be another experiment for me....

Also I would like to change my circuit to more like original with feedback to hear the difference that should be fun too
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on April 19, 2013, 12:15:56 PM
I did that w/Oliver's and CT12's (added feedback bits on one of two mic's). The output is a bit lower but it still sounds good either way :)

The current remains constant through the plate resistor, tube, and cathode resistor so you can measure it in series anywhere in that chain or via the voltage drop I=V/R maths.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: gary o on April 20, 2013, 07:25:42 AM
Ah Jb I did read thru your posts then very interesting I might add the feedback part with a switch Im also interested in the AKG ElaM251 that is very similar to M49C
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on April 20, 2013, 07:56:46 AM
Yep, plenty similarities there. And of course both originally had the AC701 tube.
Matador designed the C12 PCB and next will be the Ela M251 twist (perhaps even on the same board). Well, the Ela M251E (export version) actually, since it will be for the 6072a tube. I suggested he'd do a subminiature tube (original, non -E) version, too, that could work with Dany's PSU.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: pH on April 24, 2013, 02:55:09 PM
Looking at this build I'm a bit unclear on a couple of things...
Where is the switch for the capacitor across the capsule? (S2). It seems like you leave it unconnected on your build...and what does this cap do?
Also, what happens with pin 8? (calibration input on the Neumann schematic)

Thanks,
Paul
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 26, 2013, 09:09:38 AM
Looking at this build I'm a bit unclear on a couple of things...
Where is the switch for the capacitor across the capsule? (S2). It seems like you leave it unconnected on your build...and what does this cap do?
Also, what happens with pin 8? (calibration input on the Neumann schematic)

Thanks,
Paul

Thanks For the Note Pip , it has been anticipated as they are one leg of the cap that is mounted on a teflon turret as depicted in the picture,
as for the pin 8 it is also as the original schematic on the pcb, it is used to inject a signal and calibrate later C4,  C4 is a balancing capacitor for the low end and high end ,  it is usually 8 pf but can be tweaked it can range from 8-12 pf IIRC.
Hope this helps,  I am adding it to the build thread at the moment.

All M49 models after 1957 had a “cardioid only” switch built in, to achieve a 4dB s/n improvement [as compared to setting the pattern] remotely, from the power supply.



Note:  To Operate S2 Cardiod only Switch
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993d2b.jpg)


Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 26, 2013, 09:39:46 AM
Adjusting your PsU for AC701K tube operation  using the PSU pcb of this project.

So For B+ the idea at this point is to stick the 150K resistor between pin 5-7 of your Psu connector and adjust the voltage to 116V on the psu,
Make sure you actually read a voltage drop acrross this resistor for 116V  , so at 116V/150K = 0.77ma at 116V the neumann spec,
in theory you would need here a 0.25W resistor  cause 0.77ma *116V = about 0.1W

Same thing for the heater 4V at 100ma  this would be the equivalent of plugging a 40 ohm resistor between pin 4-7
So 4V/40ohm = 100ma  ,   this way you can ball park adjust the psu before you connect it to the mic,
in theory you would need here a 0.5W resistor  cause 100ma *4V = about 0.4 W if you make the adjustment pretty quick it should not overheat too much at 0.25W,

once the mic is connected fine tune the adjustments while the mic is warming up and the psu also.
Hope this helps,  :)
BEst,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bernbrue on April 27, 2013, 01:03:55 PM
Hi,
pictures of our work in progress.
regards
Bernd & Reiner

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 27, 2013, 01:45:36 PM
Hi,
pictures of our work in progress.
regards
Bernd & Reiner

Nice doing Bernd and Reiner ,  I hope everything is going well with your prototype version PCB,  ;)

Will stay tune and prepare some popcorn as well,

Best,

Dan,

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on April 27, 2013, 07:13:50 PM
Hi Dany,

so this

Adjusting your PsU for AC701K tube operation  using the PSU pcb of this project.

So For B+ the idea at this point is to stick the 150K resistor between pin 5-7 of your Psu connector and adjust the voltage to 116V on the psu,
Make sure you actually read a voltage drop acrross this resistor for 116V  , so at 116V/150K = 0.77ma at 116V the neumann spec,
in theory you would need here a 0.25W resistor  cause 0.77ma *116V = about 0.1W

Same thing for the heater 4V at 100ma  this would be the equivalent of plugging a 40 ohm resistor between pin 4-7
So 4V/40ohm = 100ma  ,   this way you can ball park adjust the psu before you connect it to the mic,
in theory you would need here a 0.5W resistor  cause 100ma *4V = about 0.4 W if you make the adjustment pretty quick it should not overheat too much at 0.25W,

once the mic is connected fine tune the adjustments while the mic is warming up and the psu also.
Hope this helps, 
BEst,
DAn,


will this setup work for the M269c as well?

regards

Spence.

p.s dont know if ive got a 40ohm resistor!!! :)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 28, 2013, 02:20:01 PM
Quote
will this setup work for the M269c as well?

the principle is the same but the calculation number diefferent but the same results the adjusted voltage will be diefferent for this tube only for the heater

For the 5840 tube , 

B+ is a 120V  at 0.8ma approximately  so ,    U= RI    then U/I = R = 150K ish resistor will act as a loading,
for the  Heater , 150ma at 6V  ------>   40 ohm ish,      

Wattage = P=VI   ------>   for B+ 120V*0.0008A  =  0.1W
                                ------->  for the Heater 6V*.150A = 0.9W = 1W

hope this helps,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 16, 2013, 03:01:56 PM
HI all,

need some help a. getting my brain around all this!!!! b. getting the correct voltages on the cathode.
First of all im using the 5840W tube.
PSU seems to check out with the correct voltages and everything seems to work well without blowing up!!!!
Once the mic is plugged in and after a minute to heat up im getting the following voltages:

PSU at pint 4 = 6.5v
PSU at pin 5 = 120v
PSU at pin 6 = 56.4v

at H+ on mic = 6.3v
at K on mic = 1.0v
at HG on mic = 0v
at A on mic = 39.5v

I cant seem to get the cathode up any higher, Dany says it should be 1.6v, but other than crank the voltage on the psu up to raise the cathode I dont know what else i can do!!!!
I have cleaned the pcb with 99% IA so it is clean, but is there i can back trace to getting the correct voltages?
or can anyone spot my mistake?

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on May 16, 2013, 03:14:18 PM
Try a small 5k tweaker in the Rk position and tweak till you've got between 1.6V and 1.8V on the cathode.. Then swap a resistor in that matches the value.. Or try some different value R's in the Rk around that 2k2 range..... you know, 1k, 2k, 2k5, 3k, etc.....

If you have a different tube try that too and you may want to tweak the heater down to 5.7V or so.

Look forward to hearing your impressions on this and which capsules/trafo's you used.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 16, 2013, 03:50:49 PM
Hi,

Ah so if i use lower resistors this should give me higher cathode voltage as i understand it?
Im using the RK47 capsule and a sowter 9610 at the moment but have a few other choices transformer wise.
will give it some tweaks tomorrow and see if i can get a higher cathode voltage.

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on May 16, 2013, 04:06:17 PM
Higher Rk makes higher voltage @ K..

That is a string of resistors from B+ to GND with the tube being a "variable-resistor" depending on operating points. Like this:

B+ -> Rp -> anode-5840-cathode -> Rk -> GND

So, measuring a Voltage at each node is exactly the same as measuring at points in a voltage divider / resistor string.

B+ is 120V.. Across a 100k Rp then 39V @ anode.... Means we drop 81 volts across the 100k or in other words, 0.81ma of current from B+ through tube anode/cathode to GND...

2k2 Rk dropping 1V shows .45ma though. Do you have a 200k plate resistor?

M49B or C?

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 17, 2013, 12:24:11 AM
Hi,

its a M49c, i have tried it with a 5k pot at R7 but will try a 2k2 to see if i can get higher cathode.
where are you meaning to use the 200k? i dont see that on the m49c schematic?

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 17, 2013, 05:35:05 AM
Hi,

Have tried as you've suggested changing R7, and ive tried 560ohm right through to 2.2M and i get 1.1v with 2.2M!!!
Dont know what you mean about the 200k resistor as this is only in the m49b version, i am doing the M49c version.
This is really buggin me now!!!

regards
Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 17, 2013, 09:01:56 AM
Hi,

Just put together the puck version of the M49c and exactly the same thing happens with the Cathode low voltage? 0.8v
The tube im using is a Philips 5840W and i have changed it for another one and get same result!!
only one change i have made from before and used a 470pf polystyrene rather than a 560pf.
Everything else is correct as per schematic!!!
Help its driving me insain!!!

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on May 17, 2013, 09:48:16 AM
Hope checking those picture will help finding your issue , this is what i have here , works like a charm  :)

What is the ratio of your transformer ?  .....  Where do you actually Measure the Kathode voltage against what reference ?

B+ was readjusted to 120V afterwards hence the 50V  on the plate wich is about 4-5V higher than the cal point at (116V-120) = 50-4= 46Vplate.

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05a9b.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05aa8.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05ab9.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05aca.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05adb.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d1402a05ae8.jpg)

(https://dl.dropboxusercontent.com/u/43869772/D-M49BC/M49C%20Measurement/7_7.jpg)

(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993d65.jpg)

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 17, 2013, 10:35:19 AM
Hi Dany,

the transformer is a 9610 sowter which is 10:1 ratio

http://www.sowter.co.uk/specs/9610.htm

dont really understand what you saying about:

B+ was readjusted to 120V afterwards hence the 50V  on the plate wich is about 4-5V higher than the cal point at (116V-120) = 50-4= 46Vplate

could you be more specific in laymens terms please.

I am measuring it with black multi meter lead on earth and using other red lead to check voltages with multi meter set to V- 200.

Im more confused now than ever!!! perhaps im having a bad week!!!

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 21, 2013, 04:40:45 AM
Hi All,

found my problem, leaky C9 cap, top tip always check the caps!!!
headache over now!!! onto building some!!!!

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Spencerleehorton on May 22, 2013, 09:19:01 AM
Hi All,

got my M49c working, done a little sample, recorded about 6 foot away from the drums.

http://www.filedropper.com/m49cdrums

regards

Spence.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on July 22, 2013, 08:15:12 PM
Kit in Stock,

http://www.groupdiy.com/index.php?topic=49675.480
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on August 11, 2013, 11:41:49 AM
important Information For All M49 and 269c builder

the psu pinout  connection shows that pin 3 is the cable shield lift channel with the jumper that should be by default installed on the psu , unless a specific cableshield scheme is used  and that pin 7 is the Audio Ground ,

on the M49 Mic pcb as per the original numbering the pin 7 is actually the shield from chassis and the pin 3 is the audio ground ,
since the 2 points are linked on the pcb they are basically the same but special attention must be taken to actually take into account for this properly grounding the mic and cableshield as the number are reversed on the mic end ,

take special attention to ground loop while grounding the shield of the mic cable ,


the same PSU can be used for the M269C build but note that the difference is that pin 3 is the calibration input on the mic pcb not the shield ,
there is a pad on the 269 pcb labeled Cal on the mic pcb. Always have the original schematic of the mic when building as all the numbering on the mic pcb always follow the original numbering on the schematic as opposed to the psu that will always stay te same for both mics 49bc-269c ,
the remote pattern on the M269c is like the original as well that is you have to switch on the mic pattern and then on the psu to get the poper pattern , ( see schematic)  the use of a linear pot can be used in both configuration for the pattern ,

I went to update the PsU schematic with proper labeling of the output pin of the psu and also did this little table that will help explain

Best,
Dan,

Cabling connection From PsU https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993e71.jpg (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281993e71.jpg)

Side Note: For those having a polarity that is reversed for a known or unknow reason , remember that you can swap the wire inside the psu at the xlr output connector swapping wire pin 2 and wire pin 3 will reverse the polarity of the ouput.

 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: terry setter on November 17, 2013, 11:25:23 PM
Hello Dan,

Terry Setter here.  I design tube mics for Chameleon Labs, Cascade Mics, and custom builds.  I've been studying the M49 series of designs and it appears that you've already gotten WAY into them.  Could you characterize the sonic difference between the M49b and M49c bias schemes?  I read your post that said you were very happy with the sound of the M49b model you had built, but I'd LOVE more specific comments about what is different between them. 

I realize that Neumann made changes to lower noise and raise RF rejection, but there are always sonic costs, etc., and I know of people who are having their M49c models stripped of the feedback circuitry.  I don't know of anyone who has reverted the bias system (and this might be due to sloppy heater voltage smoothing).

Any comments about the differences between these two mic models would be MOST appreciated.

Regards,

Terry
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on November 18, 2013, 11:16:41 AM
Hello Dan,

Terry Setter here.  I design tube mics for Chameleon Labs, Cascade Mics, and custom builds.  I've been studying the M49 series of designs and it appears that you've already gotten WAY into them.  Could you characterize the sonic difference between the M49b and M49c bias schemes?  I read your post that said you were very happy with the sound of the M49b model you had built, but I'd LOVE more specific comments about what is different between them. 

I realize that Neumann made changes to lower noise and raise RF rejection, but there are always sonic costs, etc., and I know of people who are having their M49c models stripped of the feedback circuitry.  I don't know of anyone who has reverted the bias system (and this might be due to sloppy heater voltage smoothing).

Any comments about the differences between these two mic models would be MOST appreciated.

Regards,

Terry

Hi Terry , i have not been able so far to have a (b) and (c) built up at the same time , the first one was a prototype in a different mic body , and the second one is about to be built in the proper mic body here: http://groupdiy.com/index.php?topic=52563.0
i will be more than happy when those are finalized to let you knowhow it feels

as a primer i have also found this that explains the difference between the 2.

http://repforums.prosoundweb.com/index.php?topic=5534.0

Stay tuned,

Best,
dAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on November 18, 2013, 12:04:21 PM
Terry, good to see you around these parts. The "C's" (original) seem to generally be "preferred" by users out in the field. There are a couple feedback paths and filters in there. The b has all that but uses the different bias scheme.

I've been so busy I haven't had time to finish these yet but when I do I'm going to stuff both the b and c boards so I can swap accordingly. Not an "in the field" swap but if I've got an iron...

Cheers,
Jonathan
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: scott_humphrey on November 18, 2013, 01:38:13 PM
Hi Terry,

You can read about cathode bias versus fixed here:

http://www.foxaudioresearch.ca/the12.htm

According to the Brian Fox on his site: "…the fixed grid bias voltage   ...removes the low frequency response limits and phase distortions that occurr when you use the resistor/capacitor network in the more commonly used "cathode bias" configuration. And because the cathode is connected directly to ground, fixed bias also maximizes the gain of the tube."

I've experimented with this quite a bit. To my ear, bass response is better with fixed bias, and the microphone just sounds better. Of course, the Tele ELA M 251 has a cathode bias and it is considered a classic   …but when I changed my "clone" to fixed bias I liked it even better. It's all subjective, of course….

The downside is that you need a very clean power supply, so it might be more expensive to make a fixed bias mic and do it right.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on November 24, 2013, 12:46:30 PM
Hi everyone !

I can't find R1 and R10 on the M49b BOM... Is it supposed to be sourced somewhere else ?

Hugo.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on November 24, 2013, 01:35:37 PM
Quote
The "C's" (original) seem to generally be "preferred" by users out in the field.

Not so sure about that one. Depends on the purpose.
Also, there's the M7 vs. K47/49 capsule to take into account.

Of course, addicts want 'em all.  :P

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on November 25, 2013, 08:25:34 AM
Hi everyone !

I can't find R1 and R10 on the M49b BOM... Is it supposed to be sourced somewhere else ?

Hugo.

only C1 and C6 are sourced or ordered on the online store as Styro cap kit for D-M49B and C 

Both the 100K and the 150M are in the BOM here :

M49 C or B Mic Parts
http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=f556c18411

Let me know if you have an issue with the BOM
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on November 25, 2013, 06:11:13 PM
Hi Dan,

Ok for the 150 M, I misread the MOX component.

But as for the 100 k, I get confused. The BOM says it is both R5 and R9, but on the schematics, these resistors are supposed to be 1 M and 150 M... :o

Am I reading it wrong ?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on November 25, 2013, 07:21:47 PM
Hi Dan,

Ok for the 150 M, I misread the MOX component.

But as for the 100 k, I get confused. The BOM says it is both R5 and R9, but on the schematics, these resistors are supposed to be 1 M and 150 M... :o

Am I reading it wrong ?

Please do not refer to the Customer part number in the mouser BOM cause the part number is associated with other projects,
i will remove them all when i have a little time to avoid further confusion ,
Best,
DAN,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 03, 2013, 04:19:26 PM
Dear vintage-tube-microphone Brain Trust:

I am wondering what your guys thoughts are regarding using these mic's in a 24/7 installed environment, system-longevity, and what parts may fail first.

In particular the m49c version but any comments are appreciated.

Best regards,
jonathan
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 08, 2013, 07:58:49 AM
Just curious, any thoughts on using PIO caps in the puck? I know the MKT caps are pretty decent, but would PIOs give a nice sound as well? Assuming I can make them fit?

Thx gang,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 10, 2013, 11:43:49 AM
I used these in a couple of my m49's and like them.

(http://i.ebayimg.com/t/1uF-250V-PIO-Capacitors-K42Y-2-Lot-of-8-/00/s/NjAwWDYwMA==/z/ztMAAOxyn~pR4Tds/$(KGrHqJHJBwFG+FW-2YRBR4TdsGLKw~~60_3.JPG)

Russian PIO K42 1uf 250V

http://www.ebay.com/itm/1uF-250V-PIO-Capacitors-K42Y-2-Lot-of-8-/400469129881?pt=Vintage_Electronics_R2&hash=item5d3dd1fa99



I have one left and am putting a Puck together so I'll be using that one to start off with. I'll probably need to rig it up a little to get it to fit but I'll be rigging a couple other items as well so....

I've also got a couple of these:
http://www.ebay.com/itm/1-uF-630-V-LOT-OF-2-RUSSIAN-PAPIR-IN-OIL-PIO-AUDIO-CAPACITORS-MBGP-1-/281208432237?pt=Vintage_Electronics_R2&hash=item417954266d
(http://i.ebayimg.com/t/1-uF-630-V-LOT-OF-2-RUSSIAN-PAPIR-IN-OIL-PIO-AUDIO-CAPACITORS-MBGP-1-/00/s/MTYwMFgxMjAw/z/U4cAAOxyTjNSimLA/$_57.JPG)

I think that one is too big to fit into this body though (also appears to be too big for this post!) so am saving for a different mic.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 10, 2013, 11:47:38 AM
Just curious, any thoughts on using PIO caps in the puck? I know the MKT caps are pretty decent, but would PIOs give a nice sound as well? Assuming I can make them fit?

Thx gang,

Mike

I've also got some 15uf PIO's that I might try as a cathode bypass cap (should have an "affect" since they cancel nfb components of the cathode portion of the ckt). If I can fit-it.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 11, 2013, 07:21:40 AM
Just curious, any thoughts on using PIO caps in the puck? I know the MKT caps are pretty decent, but would PIOs give a nice sound as well? Assuming I can make them fit?

Thx gang,

Mike

I've also got some 15uf PIO's that I might try as a cathode bypass cap (should have an "affect" since they cancel nfb components of the cathode portion of the ckt). If I can fit-it.

Cheers,
jb
Thanks for the feedback jb. Just curious if you could tell me where different types of caps would make sense to go; I don't understand the theory well enough to know where a PIO would make sense vs a styroflex etc. Any thoughts?

Thanks for the links as well; I can't imagine how I could fit such a huge cap into the puck but then again I don't have the body yet to really suss it all out.

Thanks,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 11, 2013, 10:09:28 AM
Hey Mike,

The 1uF output DC-blocking cap between plate and output-transformer would be the main one to try different PIO's and other types for color. It might be a little tight if you're using Riggler's bodies but other capacitor types in that position will also sound "different".

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 11, 2013, 06:54:26 PM
Thanks jb, makes sense.

I spent a couple hours googling different cap types; I couldn't find any PIO's that look like they will fit.

You are not using riggler's body then I take it, to fit that cap you posted a link to?

Fun stuff.

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 12, 2013, 01:43:42 AM
Hey Mike, I do have three of Riggler's bodies on-order in this run but the puck49-mic i'm putting together now uses a Chameleon Labs TS2 body which has more space.... I think it certainly has enough room for one of the green PIO's and that's the only 1uF i've got on hand so if it doesn't fit I'll probably go with a poly or what Dany's BOM specifies to get it going not to mention consistency in future builds in that body/platform.

I'm hoping I can fit the PIO in there just because....

I think PIO's are pretty much sorta big compared to more modern equiv's of the same values. The output cap should be rated for about 2x or 3x the plate voltage which should be about 50V @ that node.... Say .7 -to- .8mA across a 100k plate-R with 120VDC-B+ means a static ~40-50VDC on the cap PLUS the audio signal wiggling above and below that (which is hopefully more-often-than-not).... So near 0V -to- near 120V max @ the cap x2= about a 250VDC rated cap... That's the green one which is sorta big.

You might be able to fit something like that into a Riggler body if you change up the standoff size and capsule-mount height to squeeze some room.... Forget the trafo PCB, mount the trafo down as low as possible, and wire directly to the "driver/head-ampPCB.... Maybe shorten the capsule-mount.

On the other hand... DO-NO-HARM and use the "cleanest" sounding cap at that critical point and the signal from the capsule is less... "Adulterated"... More like the source than some gooey-tar-wrapped-in-foil-and-paper... And your mic is less like an FX-BOX.....

All very subtle at the end of the day but x10 stacked overdubs... ?

I like the romance and mystery of it all the more :) Until the very end.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 12, 2013, 02:42:07 AM
Hi jb, makes sense! Yeah I spend way more time researching parts than I do building...but...I like it that way!

Thanks for the input. Hope rig's bodies come through soon.

Best,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 12, 2013, 03:54:47 AM

The output cap should be rated for about 2x or 3x the plate voltage which should be about 50V @ that node.... Say .7 -to- .8mA across a 100k plate-R with 120VDC-B+ means a static ~40-50VDC on the cap PLUS the audio signal wiggling above and below that (which is hopefully more-often-than-not).... So near 0V -to- near 120V max @ the cap x2= about a 250VDC rated cap...
Cheers,
jb
Hi jb, would I be able to get away with a 200v cap here? I noticed the russian K40y's are only available in 200v versions, and supposedly they are better than the K42y's...any thoughts? I don't want to put my build at risk, but it would be nice to use the K40y's if possible.

Thanks in advance,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on December 12, 2013, 09:01:09 AM
200V should be fine.

With a plate voltage of 45V I don't think that cap would be exposed to more than 2x that @ 90V which would be AC not DC and those would be transients/peaks so typically not "sustained". The RMS average would be lower. Since B+ is 120V you wouldn't get higher than that in any case.

At start-up of the tube the linear PSU B+ will be "unloaded" until the heater warms the cathode up enough to make the path-to-gnd and load the PSU down so there are a couple seconds where that B+ voltage may "climb" before settling down to 120V.

Sometimes you will see a standby switch on tube circuits which disconnects B+ and in those cases they recommend turning it on in "standby" where B+ is disconnected and the power switch sends power to the heater. That way when you take it out of "standby" the heater is already warm, the cathode has then created it's "electron-cloud" which then allows current to flow from B+ through cathode to gnd.....

That's usually in guitar amps and things where the voltage and current is much higher even under load. No load and those become much more dangerous to the components... And us....

All parts will eventually fail. Even under the best operating conditions. That output cap does connect up to the output transformer primary too so 100V or so through the PRI to GND would probably let the smoke out. I forget what the DCR is of that coil is but let's say 1k5 or something...

I wouldn't expect a 200V rated part in that position to fail any time soon and it's within the recommended 2x-3x de-rating guidelines....

Anyone know whether PIO's fail open or closed and/or what type of life expectancy these older parts may have?

Might be sorta fun to stress-test some of these and see what happens and at which points.

Cheers,
jonathan




EDIT:
Here is an article on failure-modes and calculating life expectancy:
http://my.execpc.com/~endlr/reliability.html
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on December 12, 2013, 12:08:32 PM
Jonathon, thanks for a most excellent, thorough, and informative post. It's content like this that makes this forum worthwhile.

I don't know the answer to your question, but I hope some genius will chime in.

Best,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: trans4funks1 on December 15, 2013, 09:26:35 AM
Hi,
 I'm looking at the PSU249P.pdf schematic and I have a couple questions.

1) What is happening at X-1-2 and X-1-1?

2) What is happening at X-5-1 and X-5-2?

3) Are the two points 0V-1 and 0V-2 simply for testing and measurement purposes?



I see a choke and a 1/2watt trim pot on the B.O.M.

???


Thank You.

best regards,
mike

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on December 15, 2013, 11:15:41 AM
Hi,
 I'm looking at the PSU249P.pdf schematic and I have a couple questions.

1) What is happening at X-1-2 and X-1-1?

2) What is happening at X-5-1 and X-5-2?

3) Are the two points 0V-1 and 0V-2 simply for testing and measurement purposes?



I see a choke and a 1/2watt trim pot on the B.O.M.

???


Thank You.

best regards,
mike

1) What is happening at X-1-2 and X-1-1?

this is where the Choke Goes,

2) What is happening at X-5-1 and X-5-2?

this is where the heater trimpot goes

hope this helps,
Best,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on January 08, 2014, 03:35:27 AM
Hi DAn,

Hopefully Mike asked a related question before I do so I don't too stupid... I'm having a hard time figuring out how to connect all the transformers, and more important maybe I don't get what they are meant to do  :o besides the 230 to 20 as the PSU seems to feed on 20 VAC.

Could you enlighten me ?  ;D

PS: I'm from France, so it's 230 over there.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on January 08, 2014, 08:39:58 AM
Hi DAn,

Hopefully Mike asked a related question before I do so I don't too stupid... I'm having a hard time figuring out how to connect all the transformers, and more important maybe I don't get what they are meant to do  :o besides the 230 to 20 as the PSU seems to feed on 20 VAC.

Could you enlighten me ?  ;D

PS: I'm from France, so it's 230 over there.

the toroid transformer (main)  is for B+ and the small (20VAC is for the heater),
if you are in europe the primary of the toroid transformer needs to be in series and the secondary in parralelle for 120V to B+

the 20VAC traffo wich would be a dual tap if you got the correct part number (notice ion the first page of the thread) or equivalent will be tapped in series for the primary for 230V operation and then the ouput is configured for 20VAC
hope this helps,
Dan,


 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 13, 2014, 04:15:09 PM
...just curious if any of those who have completed a D-M49b or D-M49c have had an opportunity to compare with a vintage M49...also, how would you describe the sound of your completed mic?...do you find it to be particularly dark?...any characterizations, comparisons or descriptions would be appreciated...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 13, 2014, 04:26:25 PM
...just curious if any of those who have completed a D-M49b or D-M49c have had an opportunity to compare with a vintage M49...also, how would you describe the sound of your completed mic?...do you find it to be particularly dark?...any characterizations, comparisons or descriptions would be appreciated...

Do you find yours dark now it has the Dale M7 in it? The sample I remember wasn't dark IMO, but at that point it was wearing a Peluso K47.



Henk
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 13, 2014, 04:34:53 PM
...just curious if any of those who have completed a D-M49b or D-M49c have had an opportunity to compare with a vintage M49...also, how would you describe the sound of your completed mic?...do you find it to be particularly dark?...any characterizations, comparisons or descriptions would be appreciated...

Do you find yours dark now it has the Dale M7 in it? The sample I remember wasn't dark IMO, but at that point it was wearing a Peluso K47.

Henk

...well, how would you classify the sample Dan posted with the Dale M7?...to me, both clips sound dark (lets say, compared to my Pearlman TM-1), but the Peluso capsule is clearly less dark...I'm not saying this is a bad thing, just curious how it compares to the classic M49 sound...I have no particular reference to an original other than some old recordings...



Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 13, 2014, 04:50:29 PM
I'd have to retrieve them both and listen again.

Unfortunately I haven't tried a vintage one, yet, so I can't help you there.  :-\
You know I would if I could.
Let's hope others chime in.

What I can add, based on many earlier times we've "met" in places like these  :)  is that you're probably slightly tuned to the brighter side (more than I am, that is). So that could play a part here.
Also, keep in mind that proximity will tilt the balance towards the lows. But you already knew that.

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 13, 2014, 05:45:58 PM
What I can add, based on many earlier times we've "met" in places like these  :)  is that you're probably slightly tuned to the brighter side (more than I am, that is). So that could play a part here.

...yes, exactly my thoughts...you do know me  ;)

Also, keep in mind that proximity will tilt the balance towards the lows. But you already knew that.

...bingo!
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 20, 2014, 11:52:41 AM
...OK, I thought I'd chime in to update the status of the M49b I purchased from Dany a week ago...since the mic had no power supply (and I'm not gifted in the DIY skillset) I had Dany forward the mic to Brian Fox (Foxaudioresearch.ca) who is also in Canada...I've admired Brian's work, and his exceptionally informative website, so I thought this might be a good opportunity to establish a dialog and commission him to modify a PSU to service the M49b...

...Brian has carefully researched the build options (both b and c) and the specific needs in reference to modifying a standard OEM Chinese power supply...he asked me from the get-go if I was locked in to keeping the mic true to Dany's B build specs, or if I would be open to some minor tweaks that might benefit the mic's performance, as per my particular needs...I told him to feel free to suggest options and we would go from there...

...Brian's initial testing focused on the mic's filament bias circuit...noting that in the revised C version, Neumann converted to a cathode bias, he suggested making that modification, to limit the amount of filter capacitance needed in the power supply...he noted the only thing special about the kit supply was that it had enormous amounts for filament power filtering just so the filament bias method would not inject hum into the mic (this was not needed with an indirect heated tube like the 5840)....with my approval, he made the adjustment to generate the bias in cathode as in the C, but it with a fixed voltage of 1.6 like the B...Brian does this by using a red LED in the cathode circuit instead of a resistor, which creates a fixed 1.6 volts with perfect low end response, but with much lower hum and noise than using a filament based bias voltage...

...with that he could re-wire the M49 7pin XLR so that the mic will work with any Chinese supply that is voltage adjusted to 120 volts or less...he modded the OEM chinese supply to produce 116 V volt B+...measurements showed the preamp has a net gain of +1 dB and can produce -10 dBu output before hitting 1% 2nd Harmonic distortion, and distortion is pretty even from 100Hz to 20KHz....

...I hope I have detailed Brian's approach properly (as I'm no "tech" by any measure)...this morning he sent some graphs and a sound file...he offered me the opportunity to further "sculpt" the mic's sonic character, by implementing an EQ cap (270 pF and 470 pF)...but I'm pretty satisfied with what I hear, and would prefer to stay as close to Dany's build, other than the biasing modification...so here is the response graph and sound file...any input or comments are welcomed...

Soundfile: https://soundcloud.com/kidvybes/bouchard-m49-sample-converted

*** Brian assured me that the preamp section of the mic was very flat in it's response, so that the dips in the mic's frequency response chart (from 2K-8K) may be a direct result of this particular M7 capsule's tuned response...

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 20, 2014, 12:32:30 PM
Great, detailed post, Dennis!

Thanks for sharing.

Just a little sad that it's no longer a true -b, but hey.  ;)



Henk
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 20, 2014, 12:37:51 PM
Great, detailed post, Dennis!

Thanks for sharing.

Just a little sad that it's no longer a true -b, but hey.  ;)



Henk

...revision aside, Henk, how does it sound?...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 20, 2014, 01:14:14 PM
Man, you're fast.

OK, I did a quick listen. Cool of Brian to do that BTW.

Yeah, it certainly sounds good. Very hard to compare, though. Did Brian do a before recording, too?
Dany's first sample still haunts me in my dreams, but that was a different voice, different pre, different distance maybe etc. etc.
And not only was it still a -b then, it also wore a K47 rather than an M7. So apples to oranges really.
 
I don't know if Brian still has it, but it could be a nice experiment to try a K47(49) in there now. Historically, that would make more sense than a K47 in the -b version BTW, not that it bothered me then.
If you keep the mic, I have a feeling that that is what you'll end up with eventually. Not that it's better than an M7, mind. Just a matter of taste (if I indeed do know you just a little).
On the other hand it's a cool flavor that should complement your other mics pretty well.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 20, 2014, 01:38:28 PM
Oh, and that chart does look interesting.

There's a subtle, long and very gradual "bass" roll off. Despite proximity effect (was it in cardioid?), coming in a little closer than three inches could be a good idea. Kinda like you would on a Gefell UM70 (which also wears an M7, with PVC no less).

Then there's the long mid to high scoop which you'd sooner expect from a CK12. The good news is that the valley is at 6-7k which will attenuate sibilance.

And then there's a rise (or back to 0 more or less) around 10k. So dark it is not.

The plot looks very nice actually.
And it has the true mids somewhat stronger than the high mids and lower trebles.

Also keep in mind that the headbasket on the GT-2B body is very much like the one on a U47.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 21, 2014, 01:36:41 PM
I don't know if Brian still has it, but it could be a nice experiment to try a K47(49) in there now. Historically, that would make more sense than a K47 in the -b version BTW, not that it bothered me then.
If you keep the mic, I have a feeling that that is what you'll end up with eventually. Not that it's better than an M7, mind. Just a matter of taste (if I indeed do know you just a little).
On the other hand it's a cool flavor that should complement your other mics pretty well.

...actually Brian offered to try one of his Thiersch M7 capsules, but since my budget is limited, I thought it best to avoid placing any further temptation in my path...and considering that I already have both Dave Pearlman's and Ben Sneesby's take on the K47 coupled to a 47/49 circuit, I thought Dany's 49, as it now stands, might be a nice contrast to those two...

Also keep in mind that the headbasket on the GT-2B body is very much like the one on a U47.

...I've also considered swapping the headbasket for an angled style, but for now I think I will test this mic, once it arrives, on the singers I'm working with before making any more changes or unnecessary purchases...I already commited to selling another of my mics to offset the expense of this new purchase (house rules)...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 21, 2014, 01:58:54 PM
Quote
...I've also considered swapping the headbasket for an angled style, but for now I think I will test this mic, once it arrives, on the singers I'm working with before making any more changes or unnecessary purchases...I already commited to selling another of my mics to offset the expense of this new purchase (house rules)...

I didn't mean to suggest you'd swap it. Just that the frequency plot seems to echo some (!) of the typical U47 treats. And that ain't necessarily a bad thing.  :)
http://mixguides.com/microphones/vintage_products/audio_vintage_microphones_part/ (http://mixguides.com/microphones/vintage_products/audio_vintage_microphones_part/)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Melodeath00 on February 24, 2014, 10:44:38 AM
I apologize if I missed it, but what M7 is in it right now? Dale?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 24, 2014, 12:39:06 PM
Yup.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 27, 2014, 09:32:05 PM
...just as a point of reference, Brian Fox just compared the Dale M7 to a Thiersch M7 in the same mic...the Dale M7 displayed more bass (proximity effect?) and less pronounced upper-mids than the Thiersch capsule, which shares some similarity to the response of Dany's M49 (w/Dale M7) that I purchased...response graph attached:
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 28, 2014, 04:43:44 AM
Just for my proper understanding, was this your Dale M7 or another one?



Henk
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 28, 2014, 09:44:26 AM
Just for my proper understanding, was this your Dale M7 or another one?



Henk

...this was Brian's own Dale M7 and a Thiersch Red M7 capsule...(my capsule is lost somewhere in the US Custom's labyrinth for the time being)...

Soundfiles:
https://soundcloud.com/fox-audio-research/far-47-long-body-with
https://soundcloud.com/fox-audio-research/far-47-long-body-with-dale-m7
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 28, 2014, 12:07:01 PM
Thanks. I asked because, from what I understand, Dale M7s can vary a bit from one to the other. Like the old ones, probably.

Does the Thiersch have Mylar, too (red line)?

Interesting samples. Thiersch sounds more bassy and trebly to me. In other words, Dale is more middy.
In the graph, the lifted treble from the Thiersch shows, but the lifted low end does not. You would expect Dale to be bassier. No?

I like both BTW.
Thiersch somewhat modern and finished. Bigger. Good voice over sound. Perhaps just a little essy.
Dale somewhat olden and smooth. Might suit some singers better.

I'm only on cans now, mind!
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on February 28, 2014, 01:10:51 PM
Does the Thiersch have Mylar, too (red line)?

...yes, Mylar...here's Brian's own comments:
"Now these recordings were made on different days. I tried to maintain the same distance to both mics. Nevertheless the Dale is warmer than the Thiersch as confirmed by the plots. Both are good, but the Thiersch catches some of that crunch in the high end."
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on February 28, 2014, 01:43:22 PM
I think he was in somewhat closer proximity to the Thiersch.   ;)

Anyway, good stuff.
We need more graphs and more samples, folks.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 06, 2014, 10:14:07 AM
Anyway, good stuff.
We need more graphs and more samples, folks.

...I thought I would post further documentation that Brian Fox provided for the D-M49b he modified for me, for those that might be interested...

Here's page 1:
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 06, 2014, 10:15:45 AM
Page 2:
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 06, 2014, 10:16:36 AM
Page 3:
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 06, 2014, 10:22:08 AM
Page 4:
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on March 06, 2014, 10:30:20 AM
Super, Dennis!



Henk
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 12, 2014, 05:54:14 PM
...here's a quick sample of the Bouchard/Fox M49 (documented above) on a very dynamic female vocalist I'm working with...she was working about 6-8" from mic with Pearlman metal "Beatle" style pop-filter...

Chain: M49b > Great River ME-1NV > DAW

...thoughts are welcomed...

https://soundcloud.com/kidvybes/bouchard-fox-m49b-on-dynamic
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on March 15, 2014, 12:08:17 PM
Thanks for the sample.

This singer has a loud and very edgy voice to my ears. I can imagine she cuts like a hot knife through butter.
Differently put, there's much energy squeezed into a relatively narrow band. You hear that kind of thing a lot lately.
Obviously, this won't show what the mic can do in the lower regions.
But it does hold up well to this lady's singing which is not as obvious as it may seem.

You say she's a dynamic vocalist. By definition that would mean not just loud.
I'd love to hear her do some quieter stuff, too.  :)
On this mic, of course!  :P
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on March 15, 2014, 05:28:11 PM
You say she's a dynamic vocalist. By definition that would mean not just loud.
I'd love to hear her do some quieter stuff, too.  :)
On this mic, of course!  :P

...yes, I plan on continuing to use this mic for future tracking sessions on this vocalist...more importantly, she loves what she's hearing in her headphones when tracking with this mic, and I find that the vocalist's comfort with a particular mic is often critical in getting the most from a session...we will definately be doing some softer tracks...just as a point of reference, here are some other tracks from the same vocalist:

http://www.reverbnation.com/michellesongbirdgordon
Title: Help me with the M49(b) PCB Kit
Post by: fredbasement on March 20, 2014, 05:16:11 PM
Hey fellow forum-members,

I'm in need of some help from people that have built or have experience with the the M49-B-Version:

So how do I start without being boring  ;D

First some info about my build and how I got around some bugs:

1) Heater Voltage business: I didn't have a 1G-Ohm-Pot at hand so I installed a DC/DC step-down (buck) converter to get the 5,7V Heater Voltage, which seems to works fine

2) Plate current business: With b+ at 120V when R10 was still a fixed 100k I had only 37V on the plate (so 120V-38V/100k =0,83mA and I thought pretty close) But everybody in the thread said it had to be around 50V.  so I installed a variable Resistor to get the 50V, but it doesn't do me any good, because when I have 50V on the Plate i have only 30k on R10 which would result in 120V-50V/30k = 2,3mA which seems a little too high. So how did you guys balance this out?

3) Capsule: I bought a k47 replica of micandmod but it doesn't spit out any signal... If I measure the three terminals where the capsule is supposed to be connected against ground I have 5V on the Front Diaphragm, 5V on the Back-Plate and (depending on the polarization) 0V/2.5V/4.5V on the Back Diaphragm. Dany said the values look fine, but how can a condenser work without any electric potential between diaphragm and back-plate... i don't get this... and how do I find out what voltages actually end up on the membranes? I know everyone talks about the 120V/60V/0V- Polarization Voltage not taking into account the giant resistors in between the supply and the capsule.... so what voltages need to be on the membranes and looking at the m49b schematic: from where does the capsule get its ground?

thanks in advance for your time and input... I really want to use this mic and it seems i'm pretty close....
hope someone can help me... you can also send a pm at: [email protected]


thanks again,
Frederik
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 20, 2014, 06:12:00 PM
you cant measure DC polarisation direct on the capsule or backplate because of the High Meg Resistance will fool most meter, you have to measure it before those resistor and since there is virtually no current you should be able to read the full voltage there and regarding the data you sent everything is corect the backplate a 57V is fine B+ heater and such , Check your tube also ,
did you wire it in triode mode ? 

if you have constructed the Square version of the M49 Actually verify that the grid ( casule front) point near the bypass cap is not shorting
you need special attention to this place,  might also a picture of your build help as well, did you check out your transformer too

if all the voltage looks right you really must be just a tiny detail away from the success,

if you remove the capsule can you inject a sine tone and verify the amp portion of the mic check out,

beware also of the cardiod only switch that needs to be set for the pattern to work might have you connected the wrong side of the capsule with the cardiod only switch not jumpered ?.....

Keep us posted when you find it because i beleive the oh My God is imminent :)

Hope this helps
Best,
dAN

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 24, 2014, 08:23:37 AM
I should be getting a Little Run of the square versions D-M49 b-c
very soon,
Best,
Dan,
 
Title: Re: Help me with the M49(b) PCB Kit
Post by: poctop on March 24, 2014, 02:50:13 PM
Hey fellow forum-members,

I'm in need of some help from people that have built or have experience with the the M49-B-Version:

So how do I start without being boring  ;D

First some info about my build and how I got around some bugs:

1) Heater Voltage business: I didn't have a 1G-Ohm-Pot at hand so I installed a DC/DC step-down (buck) converter to get the 5,7V Heater Voltage, which seems to works fine

2) Plate current business: With b+ at 120V when R10 was still a fixed 100k I had only 37V on the plate (so 120V-38V/100k =0,83mA and I thought pretty close) But everybody in the thread said it had to be around 50V.  so I installed a variable Resistor to get the 50V, but it doesn't do me any good, because when I have 50V on the Plate i have only 30k on R10 which would result in 120V-50V/30k = 2,3mA which seems a little too high. So how did you guys balance this out?

3) Capsule: I bought a k47 replica of micandmod but it doesn't spit out any signal... If I measure the three terminals where the capsule is supposed to be connected against ground I have 5V on the Front Diaphragm, 5V on the Back-Plate and (depending on the polarization) 0V/2.5V/4.5V on the Back Diaphragm. Dany said the values look fine, but how can a condenser work without any electric potential between diaphragm and back-plate... i don't get this... and how do I find out what voltages actually end up on the membranes? I know everyone talks about the 120V/60V/0V- Polarization Voltage not taking into account the giant resistors in between the supply and the capsule.... so what voltages need to be on the membranes and looking at the m49b schematic: from where does the capsule get its ground?

thanks in advance for your time and input... I really want to use this mic and it seems i'm pretty close....
hope someone can help me... you can also send a pm at: [email protected]


thanks again,
Frederik

Where is you post , ?
I remember seeing somthing and its gone ,
is the OMG moment yet,  ;)
Best,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: fredbasement on March 26, 2014, 01:29:23 PM
hey dan, you're right - it disapeared. I made such a foolish mistake, that i was too embarressed to keep the post up there for everyone to see. ;D  I'll post again, when I figured out where I'm at... greetz, Frederik 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 26, 2014, 02:13:10 PM
hey dan, you're right - it disapeared. I made such a foolish mistake, that i was too embarressed to keep the post up there for everyone to see. ;D  I'll post again, when I figured out where I'm at... greetz, Frederik 

There is no Problem with mistakes , this is actually helpfull for others Group Member as well,

if you dont do mistakes you dont learn  :),

Well keep us posted then ,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 27, 2014, 07:12:31 PM
hey dan, you're right - it disapeared. I made such a foolish mistake, that i was too embarressed to keep the post up there for everyone to see. ;D  I'll post again, when I figured out where I'm at... greetz, Frederik 

Keep Us in the Loop of your findings,
Best,
daN,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2014, 09:33:25 AM
I should have some of the square version back in stock as of tommorow ,
Best,  :)
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 03, 2014, 08:50:38 PM
I have a little run available for the square M49 Style,
Best,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on April 06, 2014, 03:55:37 PM
...I had the opportunity to use the M49b (with Fox Audio tweaks) on a male reggae vocalist this weekend...sounded real nice on his voice (he commented he loved how he sounded in the headphones)...

...here's a snippet of a ruffmix I did this morning...I can also post clips of raw vocals if requested...these are obviously treated in the mix...both lead and BGVs were tracked on Dany's M49:

https://soundcloud.com/kidvybes/stamina-allstars-ft-adam-1
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: fredbasement on April 11, 2014, 10:00:35 AM
OMG Dany!  ;D

it was quite a journey but I have a working Mic now!

but it's not the M49(b). after fixing my initial misktake of wiring the fgrid to the cathode/gnd floating pin instead of the s2a pin my voltages were all over the place and didn't look nearly as nice as before. I have literally spent hours of trial and error getting it right but the filament bias is a real pain to put it nicely.  maybe I should have been a little worried when you wrote something about "required creative bending". I guess my creativeness wasn't up to the task... anyway after being all frustrated I went back here to find the foxresearch m49(b) update and I thought hey that's great I'll do the modification. well after this the pcb just shorted out and I didn't even have a solid B+ anymore. so with the b-version all screwed up I went to a local electronics shop, got some new parts for stuffing the M49(c) and literally before the last resistor my soldering station died.... but even with that short delay (I go an awesome new soldering station) the c-Version was done that evening:

B+ = 120V
Polarization = 118V / 58V / 0V
H+ = 5,8V
Plate = 48V
Cathode = 1,4V
with R7 @ 2262k (0,707mA)

(dany: how could I get up to 0,73mA?)

it works without hum or noise or anything and sounds rich and tasty. :D I will be able to really say something about the sound when I get to the studio in a couple of days, because I cannot really hear much at the bench. but I'll keep you updated about the sound.

but to end the little tale about non-professional soldering-enthusiasts wanting to build the M49(b): "JUST DON'T!". the M49(c) gives you much less headaches and you'll have a functioning mic much sooner. It is the safer route!

alright you guys. thanks so much for reading.

PS: Dany, any of those 47-FET pcbs lying around??? :D :D

have a great day...

(http://imagizer.imageshack.us/v2/800x600q90/203/iep8.jpg)

oh and here are some building notes i destilled, so to anybody that does not want to read the whole thread.

hope it helps.

Frederik

-------------
-------------

build notes:

-------------
-------------

Connection For AMI T49 to PcB
TRFO to Mic PCB
A- 4
B-3
C-1
D-2

--------------------

5840 tube:

For Converting the 5840 Tube to a Triode:
Tie pin 7-5 Togheter.
Do not use Pin 4 or Pin 8.

B+ = 115V
Plate = 53V
Drop across 100k (plate resistor)
= 115-53 = 62V Voltage drop across 100k
that means the tube running at .62ma
We want about 45V on the plate to get to
the specified 0.7ma then

--------------------

R7 = 2.2K (m49c)
R7 = 22K? (m49b)

--------------------

m49C:

self bias / heater isolated from cathode

R7 (cathode resistor) = 2.2K elevating cathode from gnd

bypass cap to prevent negative    feedback (NFB) 

10uf (20uF / 25uF) cathode bypass cap is recommended with the 5840 tube.

(series standard diode for heater supply (just before the connector to drop the 6.3V heater down to about 5.6V for underheating)

proper bias = 1.6V (cathode voltage)

plate resistance: 103.5K / cathode resistance: 2.279K

--------------------


m49B:

fixed bias / cathode voltage ref'd to h+

H+ needs filtering to prevent ac in grid voltagen (Vgk)

With 1M ohm pot in power supply
set it to (4.4V-6 ) = 1.6V bias with 52V plate as results

adjusting plate voltage to 50V with B+ at 120V
plus 100K plate resistor leads to 0.7ma plate current in filament biased (b)


--------------------

Power supply:

passive choke filtering.
full recitfied B+ and heater.
120V-6V after warmup.

polarization voltage in cardiod should be exactely half the B+ voltage
minus a hair for current limiting resistor inside the psu. (ca. 58V)

B+ to 120V then adjust plate voltage to 50V to get 0.7ma plate current
calibrate plate current not the bias. 58-59V on the R6-R7 node.

M49 Power Supply transformer hook-up to main P.S.B.
Yellow & Red / Black & Orange To P.S.B.

X-1-2 and X-1-1 = where the Choke Goes

X-5-1 and X-5-2 = where the heater trimpot goes

--------------------

5840 correct wiring:

pin 1 = through the board to fgrid
pin 2 =  connect to K turret
pin 3 = connect to HG turret
pin 4 =cut
pin 5 + 7 = connect to A turret
pin 6 = connect to H+ turret
pin 8 = cut off

--------------------
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on April 11, 2014, 11:02:58 AM
OMG Dany!  ;D

it was quite a journey but I have a working Mic now!

but it's not the M49(b). after fixing my initial misktake of wiring the fgrid to the cathode/gnd floating pin instead of the s2a pin my voltages were all over the place and didn't look nearly as nice as before. I have literally spent hours of trial and error getting it right but the filament bias is a real pain to put it nicely.  maybe I should have been a little worried when you wrote something about "required creative bending". I guess my creativeness wasn't up to the task... anyway after being all frustrated I went back here to find the foxresearch m49(b) update and I thought hey that's great I'll do the modification. well after this the pcb just shorted out and I didn't even have a solid B+ anymore. so with the b-version all screwed up I went to a local electronics shop, got some new parts for stuffing the M49(c) and literally before the last resistor my soldering station died.... but even with that short delay (I go an awesome new soldering station) the c-Version was done that evening:

B+ = 120V
Polarization = 118V / 58V / 0V
H+ = 5,8V
Plate = 48V
Cathode = 1,4V
with R7 @ 2262k (0,707mA)

(dany: how could I get up to 0,73mA?)

it works without hum or noise or anything and sounds rich and tasty. :D I will be able to really say something about the sound when I get to the studio in a couple of days, because I cannot really hear much at the bench. but I'll keep you updated about the sound.

but to end the little tale about non-professional soldering-enthusiasts wanting to build the M49(b): "JUST DON'T!". the M49(c) gives you much less headaches and you'll have a functioning mic much sooner. It is the safer route!

alright you guys. thanks so much for reading.

PS: Dany, any of those 47-FET pcbs lying around??? :D :D

have a great day...

(http://imagizer.imageshack.us/v2/800x600q90/203/iep8.jpg)

oh and here are some building notes i destilled, so to anybody that does not want to read the whole thread.

hope it helps.

Frederik

-------------
-------------

build notes:

-------------
-------------

Connection For AMI T49 to PcB
TRFO to Mic PCB
A- 4
B-3
C-1
D-2

--------------------

5840 tube:

For Converting the 5840 Tube to a Triode:
Tie pin 7-5 Togheter.
Do not use Pin 4 or Pin 8.

B+ = 115V
Plate = 53V
Drop across 100k (plate resistor)
= 115-53 = 62V Voltage drop across 100k
that means the tube running at .62ma
We want about 45V on the plate to get to
the specified 0.7ma then

--------------------

R7 = 2.2K (m49c)
R7 = 22K? (m49b)

--------------------

m49C:

self bias / heater isolated from cathode

R7 (cathode resistor) = 2.2K elevating cathode from gnd

bypass cap to prevent negative    feedback (NFB) 

10uf (20uF / 25uF) cathode bypass cap is recommended with the 5840 tube.

(series standard diode for heater supply (just before the connector to drop the 6.3V heater down to about 5.6V for underheating)

proper bias = 1.6V (cathode voltage)

plate resistance: 103.5K / cathode resistance: 2.279K

--------------------


m49B:

fixed bias / cathode voltage ref'd to h+

H+ needs filtering to prevent ac in grid voltagen (Vgk)

With 1M ohm pot in power supply
set it to (4.4V-6 ) = 1.6V bias with 52V plate as results

adjusting plate voltage to 50V with B+ at 120V
plus 100K plate resistor leads to 0.7ma plate current in filament biased (b)


--------------------

Power supply:

passive choke filtering.
full recitfied B+ and heater.
120V-6V after warmup.

polarization voltage in cardiod should be exactely half the B+ voltage
minus a hair for current limiting resistor inside the psu. (ca. 58V)

B+ to 120V then adjust plate voltage to 50V to get 0.7ma plate current
calibrate plate current not the bias. 58-59V on the R6-R7 node.

M49 Power Supply transformer hook-up to main P.S.B.
Yellow & Red / Black & Orange To P.S.B.

X-1-2 and X-1-1 = where the Choke Goes

X-5-1 and X-5-2 = where the heater trimpot goes

--------------------

5840 correct wiring:

pin 1 = through the board to fgrid
pin 2 =  connect to K turret
pin 3 = connect to HG turret
pin 4 =cut
pin 5 + 7 = connect to A turret
pin 6 = connect to H+ turret
pin 8 = cut off

--------------------


thanks Fred for the OMG moment reat work , you should have been using the 0.01uf/400V I had in my BOM , i just cant figure out how you did it with those fat bastard Capacitor you have there but you made it  :),  congrats  Thanks for the nice documentation note also , the plate current you have is very well close enough to be on the benchmark, since you have a different tube the bias can also be a bit different so it is not a mandatory to end up a perfectly 0.73ma as this is related to the ending plate voltage and the cathode bias this is more like a guideline since your are using a another tube. you can actually bias it to your taste, you should not only look at the schematic perfect value since another tube will give slighltly different results this shall and will not be exactely the same depending on the tube used in those condition. but more if it make sense and it sounds right also, dont forget that the cathode bias and plate final voltage are related as well

 I have built both b and c in the square format and i could not really see that much of a difference in the build difficulty could you explain further on this that would greatly be appreciated.

PS: if you need the U47Fet all the pcb are in stock on the webstore at the moment.

Again Thanks for your post,
Best,
DAN,



Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: fredbasement on April 11, 2014, 01:50:15 PM
thank you for your help dan. I know the 0,01uF in your bom would have been much easier to fit, but after my shorting out things I wasn't sure if they were still good and I have no meter to test capacitors (next thing I'm gonna get) so I bought those big boys because the electronic shop didn't have those 400V caps and I wasn't patient enough to wait for another order. about the building difficulty: It probably was just my inexperience but I couldn't get the balance between plate voltage and plate resistance. i tried a trimpot on the plate resistor becayse the voltage drop was never right. either I had 50v plate but 22ohm on the plate resistor or I hat 100k on the resistor but 32ish volts on the plate I tried to crank the b+ but there wasn't enough juice. and as I read the plate current was the most important thing in filament bias I had no idea how to get the values right. anyway im glad it works now and I'm super psyched to try it out. you can send me the paypal money request for the 47fet because my omg-moment triggered an instant "I want more"-feeling. love your work, keep it up and I'll post some samples when I recorded something. have a great day dan. fred.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on July 23, 2014, 09:59:59 AM
Finished my build tonight. Came up great. This is a quick soundclip. I have not set the bias on the scope yet. I'm certain I can milk a bit more creamy goodness from this mic yet.  :)

https://www.dropbox.com/s/cq4nek1f452r0lj/Dale%20M7%20M49B.wav (https://www.dropbox.com/s/cq4nek1f452r0lj/Dale%20M7%20M49B.wav)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on July 29, 2014, 06:46:54 AM
Hey guys. Have had a bit more time to muck around with this build. I have added a 100K lin pot for a fully variable pattern (removed the 3 position switch). I have also been mucking around with the bias both by ear, scope and using my multimeter. Simply dialling in 120V,50V exactly and exactly 1.6v bias gave the best results both sonically and headroom wise. I have ordered a bunch of different 5840 tubes to find the quietest and nicest sounding option. At the moment I'm running a Sylvania USA made 5840w. It's a bit noisy, but sounds okay.
I'd love to get a AC701K for it but they are stupid money.  Last but not least I removed C6. This opened the mic up added more air and seemed to balance the whole shooting match a bit better.

Clip

https://www.dropbox.com/s/aqvujev9x27qdt6/M49B%20bias%20and%20C6%20removed.wav (https://www.dropbox.com/s/aqvujev9x27qdt6/M49B%20bias%20and%20C6%20removed.wav) 
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on July 29, 2014, 12:49:10 PM
Hey guys. Have had a bit more time to muck around with this build. I have added a 100K lin pot for a fully variable pattern (removed the 3 position switch). I have also been mucking around with the bias both by ear, scope and using my multimeter. Simply dialling in 120V,50V exactly and exactly 1.6v bias gave the best results both sonically and headroom wise. I have ordered a bunch of different 5840 tubes to find the quietest and nicest sounding option. At the moment I'm running a Sylvania USA made 5840w. It's a bit noisy, but sounds okay.
I'd love to get a AC701K for it but they are stupid money.  Last but not least I removed C6. This opened the mic up added more air and seemed to balance the whole shooting match a bit better.

Clip

https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199430b.wav (https://io.groupdiy.com/file/gdiy-2017/u/39511/58d028199430b.wav)

Thanks for taking the time to report on your findings,
 :) :) :),
Best,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on August 13, 2014, 11:38:29 AM
...separated at birth...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on August 13, 2014, 11:43:01 AM
...solo...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mgronroos on August 13, 2014, 08:46:51 PM
Really nice!

I like that you are using the same colour on all Mics.
It looks really good and professional.

Something tells me that Santa is coming early this year, and that he may have a powder coating gun with him..  8)

//Michael
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: kidvybes on August 13, 2014, 09:31:44 PM
Really nice!

I like that you are using the same colour on all Mics.
It looks really good and professional.

Something tells me that Santa is coming early this year, and that he may have a powder coating gun with him..  8)

//Michael

Thanks Michael!...actually, each time i bring mics to the powder-coater, I'm limited to what color they are spraying that particular day (or just come back another day) since they allow me to just add my mics to the existing work order to avoid paying any setup fees...

...the MataChung C12 was coated in a "cream" tone, and this Poctop duo are more like the "seamist" that Bock uses on his 251 (a kinda "greige", grey-beige)...these shades definately have an old-school vibe, and give the mics a more "boutique" look...and at these prices (about $20 a mic) I couldn't resist...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on August 19, 2014, 04:30:25 AM
I have nailed this mic. Have spent quiet a bit of time trying a few different ideas provided by an old tech mate of mine.

So after going through a few more tubes I have one! A Jan 5840 USA NOS tube. Burnt in for 2 days and it come up nice a quiet.
I have also removed R3. This is a common mod on original M49's. It opens the low end up all the way down to 20hz.
Also another common mod to these mics is to swap out C4 (8pf) with a 2pf 300v mica cap. This gives lower noise and higher gain (about 3db)
Last but not least I swapped C5 with a 1uf oil in paper cap. This made a huge difference and really gives the mic that smooth and creamy sound like the original.

My studio is currently on a location recording job so I'll have to wait until I've finished that project until I post a new sample.


Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on August 19, 2014, 07:56:37 AM
I have nailed this mic. Have spent quiet a bit of time trying a few different ideas provided by an old tech mate of mine.

So after going through a few more tubes I have one! A Jan 5840 USA NOS tube. Burnt in for 2 days and it come up nice a quiet.
I have also removed R3. This is a common mod on original M49's. It opens the low end up all the way down to 20hz.
Also another common mod to these mics is to swap out C4 (8pf) with a 2pf 300v mica cap. This gives lower noise and higher gain (about 3db)
Last but not least I swapped C5 with a 1uf oil in paper cap. This made a huge difference and really gives the mic that smooth and creamy sound like the original.

My studio is currently on a location recording job so I'll have to wait until I've finished that project until I post a new sample.

Thanks For your post , this makes all sense, R3 will indeed affect the feedback to transformer Primary.
C4 is actually tweakable in the M49 , from 2-8 pf depending on what you want to balance out , it is a Flex point in the response curve ,
C5 is the Flavour-Spice Cap ,  PIO is always a good choice :)

I do Like the 5840 JAN this is what i used as well in my builds, LOve em ,

Thanks again for taking the time to expose your observation and feedback looking forward to listen to your sample.
Wich capsule are you using.

Best,
DAn,



Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on August 19, 2014, 08:22:19 AM
Cathedral Pipes(Dale) M7 Capsule  :)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on September 04, 2014, 09:43:38 AM
Hi Guys. Final sample uploaded. Check it out https://www.dropbox.com/s/3ssfesucttd3doy/M49B%20Final%20sample.wav?dl=0 (https://www.dropbox.com/s/3ssfesucttd3doy/M49B%20Final%20sample.wav?dl=0)

Cheers!
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mgronroos on September 04, 2014, 07:59:21 PM
Sounds great!

I think I may also make the R3-mod and use a green Russian PIO for C5.
Really looking forward to finish this one!

Best,
Michael
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on September 30, 2014, 04:38:48 PM
Hi Guys !

I got back to my M49b build, and finished to check the PSU. Before I plug it into the mic, I'd like to clear something out : I can't figure how to measure plate current once your PSU is all soldered up. To me, current can only be measured by putting the multimeter across (instead of) the path it is supposed to follow... that seems pretty impossible when everything is soldered. I know it must be a very noob question though !

The only things i could measure (after playing with both pots) were :

Is it possible to tell anything from these voltage alone ?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on September 30, 2014, 06:05:14 PM
Measure on each side of the plate resistor to calculate voltage drop across the resistor. Then use ohms law to calculate current.

Cheers!
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on September 30, 2014, 06:59:07 PM
That makes sense, yet I'm not sure wich one is the plate resistor. Everyone give very variable values for it...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on September 30, 2014, 07:28:27 PM
In the 49b schematic it's R10, 100k.

For the most accurate reading you should also measure the value of R10 and use that to compute current because it's not likely to be exactly 100k. Probably close enough for rock and roll tho.

Different tubes will draw slightly different current and you can modify/control the amount to an extent by adjusting the resistor ladder connected to the cathode, and the heater voltage. All those points affect eachother to a certain extent including the grid bias which is also derived from the heater voltage.

How does the mic sound?

Cheers!
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on September 30, 2014, 07:35:05 PM
Nice, thanks for the full answer !

I'll post some vocals as soon as it works -- Don't expect much though, i'll sing myself 8)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on October 01, 2014, 08:05:54 AM
I'm definitely getting closer ! Here's what I have so far :

bias = 0.747 V
plate = 75.2 V
pola = 56 V
B+ = 120 V

Ain't that a weird bias voltage ? In case I measure it wrong, here's where I put the voltmeter probes :
(http://i62.tinypic.com/2dhz71f.png)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on October 01, 2014, 03:53:52 PM
It's aliiiiiiiive ! It's freakin alive ! after a 2 years lazy wait, I finally nailed it !

I don't know if my voltage tuning is optimum -- I hardly can tell as I'm recording in my bedroom, and its acoustic sucks.

## disclaimer ## I'm no audio engineer, no guitarist, no singer. Just regular hobbyist, so don't expect perfect pitch, nor inspired mix ## disclaimer ##

I have recorded over the last hour a song (guitar + vocals, both m49b, + drum loop to keep the beat). Path is m49b in SCT-700 body --> Soundskulptor MP73 --> M-audio Fast track ultra 8R. Guitar is a 150 € folk from Thomann :

My opinion so far :

It may not be the end of the tweaking, but I still would like to thank you guys for your help and making it possible !

Cheers !  :)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on October 01, 2014, 04:24:08 PM
I'm definitely getting closer ! Here's what I have so far :

bias = 0.747 V
plate = 75.2 V
pola = 56 V
B+ = 120 V

Ain't that a weird bias voltage ? In case I measure it wrong, here's where I put the voltmeter probes :
(http://i62.tinypic.com/2dhz71f.png)

Thanks For your post , 8)
Did you try to adjust the bias pot ? ,  you should be able to aim at a lower Plate voltage measure on A ,
you should be able to get it down in the 50V range , try that and let me know if it improves your recording, sometime measuring bias can be tricky when a high Megohm resistor is invlolved it will fool your meter,  (R5)
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on October 01, 2014, 05:31:36 PM
Well, doesn't a 50 V plate voltage across a 100 k R10 would lead to a weak plate current (~50 mA) ?

A what kind of improvement should I expect ? Do you hear something odd -- apart from the playing -- in the files I've posted ?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on October 01, 2014, 05:52:18 PM
No necessarily. You need to measure the voltage drop. ie; the difference between V on each side of the 100k resistor. So if B+ is 120V on the B+ side of the plate resistor and you measure 50V at the plate then you get 70V of drop. I=E/R or 70mA=70/100k.

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on October 01, 2014, 05:57:29 PM
OK my bad, I thought "plate voltage" stood for "R10 voltage".
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on October 02, 2014, 08:23:15 AM
No necessarily. You need to measure the voltage drop. ie; the difference between V on each side of the 100k resistor. So if B+ is 120V on the B+ side of the plate resistor and you measure 50V at the plate then you get 70V of drop. I=E/R or 70mA=70/100k.

Cheers,
jb

that would be more something like 0.7ma not 70ma  ;),
if you measure the voltage at the anode (A) or plate directly you should have somthing like in the 50V range,
or measuring drop at R10 will give you the relationship demonstrated above by JB,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: OneRoomStudios on October 15, 2014, 03:42:29 PM
I'm thinking about trying to build up a 49b using a 5718 rather than a 5480. (5718 datasheet: http://frank.pocnet.net/sheets/079/5/5718.pdf)

Apparently the 5718 was a favorite AC701k replacement tube of Oliver Archut's (see here: http://medias.audiofanzine.com/files/archive-ac701-substitute-471341.pdf), and others have confirmed that it sounds great. I have a GE and an RCA 5718 lying around, a Dale M7, and a donor body. Seems like a no-brainer. Anyone have any experience with a 5718 in this design?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Melodeath00 on October 15, 2014, 07:40:59 PM
Nice find, OneRoomStudios! Thanks for posting
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: adrian on January 05, 2015, 07:24:37 AM
I'm Currently finishing  2  PSU and cables for this nice project, 8)
I have sommercable SC-OCTAVE TUBE wire, it have 5 AWG 26 (for audio and control) and 2 AWG 20 conductors,
I used the 2 AWG20 conductors for B+ and 0V,
is that OK?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on January 06, 2015, 06:08:57 PM
I'm Currently finishing  2  PSU and cables for this nice project, 8)
I have sommercable SC-OCTAVE TUBE wire, it have 5 AWG 26 (for audio and control) and 2 AWG 20 conductors,
I used the 2 AWG20 conductors for B+ and 0V,
is that OK?

Use the larger wires for heater connections since they have the most current.
Cheers,
j

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: adrian on January 06, 2015, 06:11:28 PM
OK!
so between 0V (7) and H+ (4),

thanks a lot!!
Title: M49 B/C MODS
Post by: Phrazemaster on January 08, 2015, 12:43:48 AM
Hey gang, I've run across several suggested mods to the M49 that supposedly improve bass/high freq response as well as correcting phase shift issues.

Here they are summarized; note they apply equally to B and C versions:


Here are some (but not all) relevant links:

Remove R3 or make it much higher:

http://www.neumann.com/forums/view.php?bn=neumann_archive&key=990963033&v=f (http://www.neumann.com/forums/view.php?bn=neumann_archive&key=990963033&v=f) (plus search this forum)

"...R3 can be gradually increased in convenient stages: first, leave R3 at 5 meg Ohms, and put a 1 meg resistor in series with it, for a total feeback resistance of 6 meg. Then increase the added resistor's value to 2, 3, and 4 meg. You will notice that at around 7 meg total resistance it becomes increasingly hard to hear a difference in the mic's low end response between this very slight feedback and no feedback at all (which would be resistors disconnected altogether) Kind regards, Klaus Heyne
P.S.: I would always try to run the mic as wide open as possible, i.e. R3 out or only minimally engaged; that's when phase shift is at its lowest."

Remove C6:

... Last but not least I removed C6. This opened the mic up added more air and seemed to balance the whole shooting match a bit better.

https://groups.google.com/forum/#!topic/rec.audio.pro/jQC3wLhKWo0 (https://groups.google.com/forum/#!topic/rec.audio.pro/jQC3wLhKWo0)

"3.  Neumann M49, cap. C6.
In this case cap. C6 together with the output impedance of the amplifying
stage (it can be considered as an an active resistance) establish first
order LP (low pass) filter that reduces signal at high frequencies.
Measuring the circuitry, we got the following results:
     2 kHz  - 0.04 dB
     4 kHz  - 0.12 dB
     8 kHz  - 0.43 dB
   10 kHz  - 0.65 dB
   16 kHz  - 1.48 dB
   20 kHz   -2.14 dB
31.5 kHz  -4.08 dB

Capacitance C6 brings the following phase distortion:
     2 kHz +   4.1 Deg.
     4 kHz +   8.2 Deg.
     8 kHz + 15.9 Deg.
   10 kHz + 19.5 Deg.
   16 kHz + 29.1 Deg.
   20 kHz + 34.3 Deg.
31.5 kHz + 44.5 Deg.

It is preferable to remove this capacitance."


Reduce or Remove C4:

http://prorecordingworkshop.lefora.com/reply/46983815/Anybody-have-a-BLUE-M49-schematic#.VKz5hMaoXbg  (http://prorecordingworkshop.lefora.com/reply/46983815/Anybody-have-a-BLUE-M49-schematic#.VKz5hMaoXbg) (plus search this forum)

"@ryan the 8pF value is from the m49b, b for broadcast, so there's a filter as well as higher amount of NFB. You could go as low as 2pF or up to 4pF, I think 8 is ridiculous as the AC701 barely has enough gain to start with." (David Bock)

https://groups.google.com/forum/#!topic/rec.audio.pro/jQC3wLhKWo0 (https://groups.google.com/forum/#!topic/rec.audio.pro/jQC3wLhKWo0)

"2. Neumann M49, cap. C4. Cap. C4 (8 pF) is placed between tube's AC 701 plate and grid. So it is parallel to the tube's own capacitance Cag. This capacitance according to the tube's manufacturer's literature is 2.2 pF. As a result we get 10.2 pF. At stage's gain (20 dB) - in other words ? 10 times (it is a typical volume) we get 102 pF (10.2 pF x 10 = 102 pF) known as Miller's capacitance that is connected between tube's grid and cathode. This is a parasitical capacitance that causes attenuation of signal in cases of capacitive acoustical transducer (condenser mic capsule). It will reduce the signal dynamic range. So it is preferable to remove this capacitance."

These sound like no-brainers to me; what do you think?

Also, as a true newbie, is it really ok to simply omit these components from the PCB altogether? Or would a jumper be necessary in any case? As far as I can tell, I can simply omit them all with no problem, with the exception of C4 which I'm uncertain what would happen.

What say you?

Many thanks,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on January 08, 2015, 06:05:38 AM
Thanks, Mike.

Although a guy like Klaus does have a reputation, I'm not convinced his mods improve on what the original builders (talk about reputation) had in mind. E.g. from what I understand, there is some deliberate negative feedback going on.
Also, making it "better" can in fact compromize the character of the mic. There is a reason most prefer it over a TLM49.

But yes, at some points the original builders were forced (e.g. by the big broadcast clients) to implement things they rather didn't.
Even this could have added character we are now used to, but it may be an area to explore. Experimenting and discussing hurts nobody.

BTW, did you also find (in numbers that is) what Klaus does to U67s? Filtering, NFB and phase shift a-plenty in that one. Question is, do we want to miss that?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on January 08, 2015, 09:59:17 AM
If you haven't already you guys should check out, build, and compare olivers m49 conversion ckt here (which eliminates the items mentioned or you can add them back in as needed/desired):
http://www.tab-funkenwerk.com/sitebuildercontent/sitebuilderpictures/TLM49ArchutModschematic.jpg

What I appreciate about the M49 approach is that there are several points that allow for fine tuning of the systems to more specific situations / needs / clients. In Oli's conversion ckt it's a pretty standard self-bias plate-out setup with no additional feedback (other than the self-bias) or RF filtering. Look at Max's MK7 to see how you may want to implement a fixed bias scenario into Oliver's M49 conversion ckt.

Neumann manufactured and delivered a consistent product across a global client base and this microphone system was able to be put into service in a wide range of environments in the field without "getting under the hood". The various RF and other filtering components allowed for a more consistent product in a wider range of environments (not necessarily optimizing a capsule/tube/trafo in a specific environment/application). When they went to the self-bias version they were also able to deliver a more consistent product because the bias implementation in the B version exposes more of the tube fingerprint.

If you want to deliver a more consistent product then perhaps sticking with the C version and including the FB/filtering will help with some consistency. For more individual, unique, or special needs however there are options. Who wants the same mic as everyone else anyway (we've already got essentially the same DAW/plugins)?

To summarize, tuning of the original mic/ckt "system" may include items like:
- Capsule selection (M7, pvc, mylar, kk47, c12, mfgr, other)
- Transformer & tube selection-and-setup (ratio, materials, etc)
- Output cap selection & value
- Fixed/Self bias implementation
- passive/regulated PSU implementation
- Grid bias point spec
- Grid/backplate/rear-diaphragm resistor value
- Heater voltage (ie; under-heating and to which degree)
- Cathode bypass cap value/selection
- 5M neg feedback/HPF selection/omission
- 2-8pf plate to grid cap spec
- 400-600pf Plate to gnd cap value/selection/omission
- Head basket geometry

Hope this provides some food for thought and don't forget to make more microphones!

Cheers,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 01:03:24 PM
Thanks for the thoughtful replies guys.

Can anyone explain how the NFB works in this circuit?

Also if I wanted to leave out C4, can I just omit it entirely from the PCB?

Thanks!

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on January 08, 2015, 01:18:45 PM
If you haven't already you guys should check out, build, and compare olivers m49 conversion ckt here (which eliminates the items mentioned or you can add them back in as needed/desired):
http://www.tab-funkenwerk.com/sitebuildercontent/sitebuilderpictures/TLM49ArchutModschematic.jpg

What I appreciate about the M49 approach is that there are several points that allow for fine tuning of the systems to more specific situations / needs / clients. In Oli's conversion ckt it's a pretty standard self-bias plate-out setup with no additional feedback (other than the self-bias) or RF filtering. Look at Max's MK7 to see how you may want to implement a fixed bias scenario into Oliver's M49 conversion ckt.

Neumann manufactured and delivered a consistent product across a global client base and this microphone system was able to be put into service in a wide range of environments in the field without "getting under the hood". The various RF and other filtering components allowed for a more consistent product in a wider range of environments (not necessarily optimizing a capsule/tube/trafo in a specific environment/application). When they went to the self-bias version they were also able to deliver a more consistent product because the bias implementation in the B version exposes more of the tube fingerprint.

If you want to deliver a more consistent product then perhaps sticking with the C version and including the FB/filtering will help with some consistency. For more individual, unique, or special needs however there are options. Who wants the same mic as everyone else anyway (we've already got essentially the same DAW/plugins)?

To summarize, tuning of the original mic/ckt "system" may include items like:
- Capsule selection (M7, pvc, mylar, kk47, c12, mfgr, other)
- Transformer & tube selection-and-setup (ratio, materials, etc)
- Output cap selection & value
- Fixed/Self bias implementation
- passive/regulated PSU implementation
- Grid bias point spec
- Grid/backplate/rear-diaphragm resistor value
- Heater voltage (ie; under-heating and to which degree)
- Cathode bypass cap value/selection
- 5M neg feedback/HPF selection/omission
- 2-8pf plate to grid cap spec
- 400-600pf Plate to gnd cap value/selection/omission
- Head basket geometry

Hope this provides some food for thought and don't forget to make more microphones!

Cheers,
jb

I kinda like that post.  ^
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 02:04:31 PM
Just FYI FleA uses (b) version.

http://www.flea-microphones.com/fdq.html (http://www.flea-microphones.com/fdq.html)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on January 08, 2015, 02:09:36 PM
They do -c, too, upon request.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 03:57:49 PM
Thanks Henk.

Can anyone explain the function of c4??

If leaving out would I just wire jumper across the PCB?

Thanks
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on January 08, 2015, 04:27:17 PM
I believe C4 is an RF neg feedback path, 4-8pf plate to grid. Plate signal is opposite polarity to grid so it filters and cancels out RF as well as increasing miller C which acts as a C divider (ie; pad) WRT the capsule capacitance. Since the value is labeled as "selected" is anyone aware of what the selection criteria or "factory test setup" is or may be?

Thx,
jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 09:14:01 PM
JB are you saying that C4 is needed to eliminate radio frequencies? (RF)?

Also any one know what David Bock meant about reducing C4 because it affected the tube gain?

Finally, if I want to leave it out it looks like I'll need to just jumper it, since other parts of the circuit still need to connect...right?

Thanks gents
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 11:15:07 PM
OK JB, found a post from Neumann (with a correction; he talks about "R4" but mistakes it for C4):

"R4, the feedback capacitor on the tube, is typically 8 pF in the M49b, typically 0..2pF in the M50b.

Selected to obtain the correct amplification.

That's it."

From: http://www.neumann.com/forums/view.php?site=neumann&bn=neumann_archive&key=897298159 (http://www.neumann.com/forums/view.php?site=neumann&bn=neumann_archive&key=897298159)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on January 08, 2015, 11:26:21 PM
I used a 2pf on my 49B build. It increased gain and reduced the noise floor a few dB.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on January 08, 2015, 11:31:26 PM
I would like to like to post but there Is no Like button ?
D
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 08, 2015, 11:43:11 PM
I thought something was wrong with my MIND! I've tried to like a couple posts lately from my iPhone but no button; it's not here on my mac now either!  :o

Thanks Nyqvist and JB and Henk!
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on January 09, 2015, 06:58:37 AM
Simply say you like it, guys.
That's what I do.
I guess I'm too old for them buttons.   ;)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: 0dbfs on January 09, 2015, 10:34:32 AM
Hey Phraze, Re: C4 omission

Don't jumper it, just leave it out.

Jumpering would connect plate directly to grid.... Applying the 43V plate voltage to the front capsule diaphragm and the grid as well as the full bandwidth plate signal.

I was tinkering with some different tube mic setups some time ago and when I removed this cap I got tons of distortion and an un-useable signal. May have been some other issue combined with removing that because I eventually scrapped that experiment and did something else.

Makes sense about tuning in an accurate gain stage but from a purist (do no harm to the signal) standpoint I agree with leaving it out to minimize phase issues that may be associated with capacitive pads. How often is the pad on the mic used anyway?

On the other hand I also don't mind stuffing it at all to have a more circuit accurate M49.

Cheers!
-jb
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 09, 2015, 01:45:18 PM
Thanks JB!

Informative and thoughtful as usual.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on January 10, 2015, 01:30:19 AM
Here's a question.

I'm going to build a "load" switch into my PSU along with a digital multimeter so I can test voltages at various locations when I use the M49. I'm going to use a real AC701 and don't want any mishaps due to variances in wall line voltages since the PSU is a passive design with no regulators.

I want to add a load to both the heater and the B+, even though I know the heater is the more critical.

My issue is that most switches are not rated for 120v DC! I know in general switches don't handle DC very well compared to their AC counterparts.

My thinking is, since the current is only .8mA this shouldn't matter, and I can go ahead and use a switch that is rated only 20-30v DC. I found one at .4A.

What is the wisdom gents; am I courting trouble or is it OK to go ahead with a lower rated DC switch since the current is so tiny?

Thanks for your thoughts.

Best, Mike

**PS I should mention I did find a switch that will handle it but it's $34 and not to my taste! I'd rather use a better looking switch but it's not rated for more than 30V DC.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: adrian on January 10, 2015, 08:19:34 AM
reading this thread I see everybody used Raytheon's 5840W Tubes but it's hard to find here in Europe,
I found Mullard on ebay :
 http://www.ebay.fr/itm/310272371060?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

do you think there will be a huge difference?
should I rather buy directly Raytheons tubes in the US?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Pip on January 10, 2015, 04:49:25 PM
Don't think there is much difference. But buy several as noise is always the problem. You might get lucky but I built mine so I could play with tubes and change them easily. The only tube that I would say is in me experience superior to most is the RCA manufactured 5840. Sadly the rest of the world thinks so as well and has bought em up.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nyquist on January 11, 2015, 01:54:39 AM
Agreed I bought 10 RCA's from Germany. They are much quieter then the Jan tube I had in the mic originally and the top end is a bit smoother as well.  The second RCA I tried was super quiet, low microphonics and sounds great. I have stuck with that tube and now have plenty of spares. I purchased these ones from ebay http://www.ebay.com.au/itm/5x-RCA-CV-3929-EF732-EF-732-Subminiatur-Rohre-NOS-/321105571871?pt=DE_TV_Video_Audio_Elektronenr%C3%B6hren_Valves&hash=item4ac362301f
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: adrian on January 11, 2015, 05:07:25 AM
OK!
I just ordered these RCA, ;)
thanks a lot for the link,
when my mics will be finished I will try RCA and mullard tubes and let you know the differences,

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: jackinthebox on March 17, 2015, 01:45:49 PM
what are people doing with the ground pin on the IEC inlet? i can see one of the 0V terminals connecting the chassis/box but i'm not 100% sure what to do with the IEC ground?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: jackinthebox on March 17, 2015, 01:48:05 PM
what are people doing with the ground pin on the IEC inlet? i can see one of the 0V terminals connecting the chassis/box but i'm not 100% sure what to do with the IEC ground. I'm guessing it will connect to the the other 0V terminal on the PCB?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 17, 2015, 03:19:48 PM
what are people doing with the ground pin on the IEC inlet? i can see one of the 0V terminals connecting the chassis/box but i'm not 100% sure what to do with the IEC ground. I'm guessing it will connect to the the other 0V terminal on the PCB?

OV from PCB pad goes to chassis and from Chassis goes to IEC earth ground.
best,
DAn,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 21, 2015, 02:22:33 PM
Upcoming Soon,
Microphone Body for this Project ,
http://groupdiy.com/index.php?topic=52563.0
Thanks To Riggler and TSKGUY,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Winetree on May 14, 2015, 05:22:56 PM
I want to use the larger transformer for the D-M49 Tr board ( Round Version )
It's indicated The MX BV11 will work.
Will the AMI BV 11r or any other P.S.B.  transformer soldier directly to the board?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on May 14, 2015, 09:27:20 PM
I want to use the larger transformer for the D-M49 Tr board ( Round Version )
It's indicated The MX BV11 will work.
Will the AMI BV 11r or any other P.S.B.  transformer soldier directly to the board?

the transfo pcb pinout (pad correspondance) is one side for Max Bv11 and the other side for the AMI T49 only, you can use about any transformer as long as it fits sterically in the deck, you can then solder directly the wire from the transformer to the second deck,
Let me know if you need help with the second deck connection scheme ,
Hope this helps,
Best,
Dan,


Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on September 23, 2015, 11:54:58 AM
Hello everyone,

While I was perfectly happy with my m49b, I've lend it to a friend who could not use it because of a "buzz". As he gave it back to me, it indeed has a gigantic buzz and muffled sound!

Voltages are very strange, and certainly not as I've set them previously. Just to make sure I got it right, I made a quick picture of what my voltmeter should read -- beware: colors are utterly ugly.

Is that right ?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: bioman666 on October 31, 2015, 07:11:20 PM
Hi guys,

So voltages seem to be OK. I measured them through a 1 GOhms voltage divider and a cheap multimeter.

So if voltages are OK, what can make this buzz/sound (wave file here : https://goo.gl/G0BoqI) ?

Hugo.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Le Roux on March 28, 2016, 10:48:13 AM
Just building up my mic, 49b

For biasing the mic, do I have to have the capsule installed?

Also, the psu I can't adjust the H+ lower than 20V.
Should I just add a larger value pot?

Thanks
Neil
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on March 28, 2016, 12:23:36 PM
Just building up my mic, 49b

For biasing the mic, do I have to have the capsule installed?

Also, the psu I can't adjust the H+ lower than 20V.
Should I just add a larger value pot?

Thanks
Neil

Capsule isn't  needed.
Try much larger.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on March 28, 2016, 12:25:54 PM
Just building up my mic, 49b

For biasing the mic, do I have to have the capsule installed?

Also, the psu I can't adjust the H+ lower than 20V.
Should I just add a larger value pot?

Thanks
Neil

is the PSU Loaded , ( Mic connected)
a Passive psu will need a load for adjustement ,
D.

For the Bias try to aim at the plate voltage ,
Dan,

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on May 14, 2016, 04:22:38 AM
Dan - question for you from the other topic - i'm courious :)

How is connected input in your circuit?
Did you make switchable option for cardioid only - according to original schematic C1 via S2?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on May 14, 2016, 10:18:08 AM
Dan - question for you from the other topic - i'm courious :)

How is connected input in your circuit?
Did you make switchable option for cardioid only - according to original schematic C1 via S2?

Input straight from tube grid and floating Fgrid capsule connection point ,

connect floating switch to those 2 points,  same points available on this round version as well,

Note:  To Operate S2 Cardiod only Switch
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d02819948c0.jpg)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Delta Sigma on May 26, 2016, 11:46:30 PM
For North America, is the only point of the torridial transformer to isolate ground? 120V in, 120V out.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mjproc on June 02, 2016, 12:02:42 PM
Hi

  Been on and off with my build of a m49b, still not working properly, hope someone can help me bringing the mike to full glory ;-)

I use 5840, and the power supply for this project.

PSU: I could not get above approx 3,5 v for the heater (under load), so I had to short both R6 and R11 to get 6,3V.... strange, but it will work ok?  120V output and polarization  are ok.

M49:
I have problem getting to 1,6v bias, I´ve tried to replace R10 several times with other values, still no where nere 1,6V

My voltages:
B+:  120v
A:  47,08v
H+:  6,3v
R8-R9 junction:  57,38v
R2 (against centre of capsule); 5,5 (should be 56v according to Neumann scheme)
Polarisation voltage (pin 6 from pus): 119,6/half/0
Voltage after R11 : 10,92/half/0
R1: 5v
R7-R6-R5 junction: 57,5v
Bias: -0,87v

R10 is 100k and plate voltage adjusted for 0,73mA using R7 pot

Trying to measure Polarization voltage, gives me nowhere near 0/60/120v measured from gnd - capsule

Output is lower than d-U87, and noise is approx the same.   

The mike gives a desent signal, but I´m worried bout the low bias voltage and the low polarization voltage.....

I´ve tried to find a voltage reference sheet on the net, this would be very helpful if someone has taken the time to plot this on a working mike....

Brgds
Ole Peder
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Delta Sigma on June 02, 2016, 03:20:02 PM
Output will be lower (?roughly 5dB?) than U87. U87 switches polar patterns where the M49 has both capsules paralleled, patterns changed by power supply voltage.

Are you sure you building M49b? Are you using a bypass cap on your cathode? If so that would be M49c and you would set your bias by R10, 5840 and R7 voltage divider.

See schematics in first post.

M49b bias voltage comes from the heater supply and the R6 R7 voltage divider.

M49c bias is cathode referenced to ground (grid @ ground potential). M49b bias is referenced from cathode to grid or the junction of R6 and R7.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mjproc on June 02, 2016, 04:42:59 PM
Output will be lower (?roughly 5dB?) than U87. U87 switches polar patterns where the M49 has both capsules paralleled, patterns changed by power supply voltage.

Are you sure you building M49b? Are you using a bypass cap on your cathode? If so that would be M49c and you would set your bias by R10, 5840 and R7 voltage divider.

See schematics in first post.

M49b bias voltage comes from the heater supply and the R6 R7 voltage divider.

M49c bias is cathode referenced to ground (grid @ ground potential). M49b bias is referenced from cathode to grid or the junction of R6 and R7.

I am sure it´s the M49b, but from the schematics I measured bias from grid to heater.   Should I measure grid - (R6-R7 juction)?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on June 02, 2016, 04:59:17 PM
It's been awhile since I built my M49b but as I recall you cannot measure the grid bias directly.  Something about the high Meg resistors messing up the measurement. You have to set the correct voltage across anode resistor R10(?) if memory serves. You've only got 2 pots to play with and don't over turn them or they will break. I ended up rebuilding mine from scratch after a careful first build that even Poctop couldn't help me fix. Rebuild works fine.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on June 02, 2016, 06:51:17 PM
In case like this, good picture of the circuit is usual helpful.

Did you installed C4 - 8pF?

There would be hard to get 1,6V when heater voltage is 6.3V.
Difference is also in heater current where AC701k suck 100mA and 5840 150mA.
That's why it is much more easy to build "C" version using 5840.

Try adjust heaters to 6V (not 6.3V) and use R6  110k

Adjust B+ and back diaphragm polarisation voltage (pin 6) to 116V.

Measure  back diaphragm polarisation on Pin6, before R11
Measure backplate polarisation before R2.

Optional use internal switch S2 for "better" cardioid response.

Give us know is it working properly

P.S don't bend tube leads at the base, leave at least 2mm of straight wire.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mjproc on June 05, 2016, 05:45:59 AM
I will rebuild the mike using the 49c pcb.... As I have no idea how the different versions really sound, I think this is the way to proceed as of now... ;-)

Thnx

OleP
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on June 05, 2016, 07:38:37 AM
Klaus Heyne, Oliver Archut and maybe others described the tone difference on the R/E/P forum.
Some googling will get you there.

To my ears and in my words:
M49b is somewhat meatier, thicker, ballsier etc. Great low mid character. Maybe slightly preferrable for lead vocal.
M49c is a bit airier and has a little less noise (not that the M49b is noisy). Less demanding on tube and PSU. Perhaps slightly preferable as an allrounder.

The late Dennis Stone (kidvybes) bought Dany's M49b prototype and had Brian Fox finetune it. Brian turned it into a cross between the -b and -c version.
You can read more about this on page 10 of this thread, particularly reply #181.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on June 05, 2016, 02:41:43 PM
I will rebuild the mike using the 49c pcb.... As I have no idea how the different versions really sound, I think this is the way to proceed as of now... ;-)

Thnx

OleP

If you build already B version, change it should be simple, use my recipe and check first.
This way should work much more close to the original.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: mjproc on June 06, 2016, 12:38:35 PM
Moved the components to 49c pcb this afternoon.  Took 1 hour of soldering and all is ok.... Bias adjusted to 1,6V, B+ at 116 heater at 5,8V

All is ok technically....will test the audio later......

Feel good now ;-)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: cariocaman85 on June 13, 2016, 07:16:50 AM
Hello Dan,

I wanted to buy your capsule D7 and the square D49 PCB but paypal just told me that you’re out of stock.
When will it be possible to order?
By the way I tried to email you from your site, but the mail came back undelivered, and your Groupdiy box is reported to be full...

Thanks,

Best regards,


Rémi Bourcereau
Ingénieur du son
[email protected]
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: MPM on June 13, 2016, 07:26:48 AM
Hello Dan,

I wanted to buy your capsule D7 and the square D49 PCB but paypal just told me that you’re out of stock.
When will it be possible to order?
By the way I tried to email you from your site, but the mail came back undelivered, and your Groupdiy box is reported to be full...

Thanks,

Best regards,


Rémi Bourcereau
Ingénieur du son
[email protected]

Hello Dan,

I tried to contact you by mail and here in GroupDiy, but got the same reports as the poster above.

Cheers,
Mikko PM
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: micaddict on June 13, 2016, 08:31:51 AM
I believe Dan is busy moving to another place.

So the connecting problems could be a result of that.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on June 13, 2016, 01:40:33 PM
Hello Dan,

I wanted to buy your capsule D7 and the square D49 PCB but paypal just told me that you’re out of stock.
When will it be possible to order?
By the way I tried to email you from your site, but the mail came back undelivered, and your Groupdiy box is reported to be full...

Thanks,


Best regards,


Rémi Bourcereau
Ingénieur du son
[email protected]

Hello Dan,

I tried to contact you by mail and here in GroupDiy, but got the same reports as the poster above.

Cheers,
Mikko PM

yes indeed i am moving to another location ,
i should be resuming business soon ,
Thanks for your patience,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on July 03, 2016, 04:44:11 PM
Hi All, Proudly Presenting the Cinemag BV11 Transformer Many thanks To Dave at Cinemag to take the challenge.
for all  DIY Microphone Requiring a BV11 Style Transformer  8)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

The Cinemag CM-6511 ( BV11 Mic output X-Transformer)
(https://dl.dropboxusercontent.com/u/43869772/Cinemag%20CM-6511%20BV11.JPG)

Connection
(https://io.groupdiy.com/file/gdiy-2017/u/39511/58d0281994912.jpg)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: G-Sun on September 18, 2016, 10:54:45 AM
So, is square for standard bodies
and round for 49-style bodies?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on September 18, 2016, 11:49:37 AM
So, is square for standard bodies
and round for 49-style bodies?

The Square one was initially made for the GT2B style mic
and the round one for Andriejus Style , AMI Style ,And Ben
standard M49 enclosure ,
Best,
Dan,
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: G-Sun on September 18, 2016, 12:36:45 PM
So, is square for standard bodies
and round for 49-style bodies?

The Square one was initially made for the GT2B style mic
and the round one for Andriejus Style , AMI Style ,And Ben
standard M49 enclosure ,
Best,
Dan,
Thank you!
Trying to get an overview of project, main parts, budget and quality-considerations.

The GT2B typical goes along with .. the TPS100 psu?
Any SYT-options that are easy fit?
Transformer and capsule seems expensive.

Beesneez M7 Capsule + body + psuBody = 800-900aud
Edit: That's not for psu enclosure. Mic body only
TAB Funkenwerk AMI T49 Transformer $85
You're selling D7. That's for this project, right?  235usd

Ok, Mouser boom is for all psu. I see
Mic parts are not so expensive.
Nor the 5840 tube.

Many vendors, ++shipping and vat-costs

Hm.. I'll have to see if I can afford this one.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: G-Sun on September 18, 2016, 02:01:54 PM
Looking things over I'm coming to a cost of $990 / 8251nok
shipped to Norway.

Spot any big errors?

Typical Exchange fees adds quite a little.

Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on November 03, 2016, 12:55:17 AM
Hi All, Proudly Presenting the Cinemag BV11 Transformer Many thanks To Dave at Cinemag to take the challenge.
for all  DIY Microphone Requiring a BV11 Style Transformer  8)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php

The Cinemag CM-6511 ( BV11 Mic output X-Transformer)
(https://dl.dropboxusercontent.com/u/43869772/Cinemag%20CM-6511%20BV11.JPG)

Connection
(https://dl.dropboxusercontent.com/u/43869772/Cinemag%206511%20%20%28BV11%20%29%20%20%28M49%20Transformer%29.jpg)

For All information about this transformer and ordering
http://cinemag.biz/contactus/contact_us.php
Tried getting info about this. Contacted Cinemag but haven't heard back. There are no specs or details that I can find on the Cinemag website.

Dany, do you have more information about this? How authentic is this to an original BV11? Do they still offer this?

I am also thinking of going with Haufe. I tried contacting AMI/Tab but so far no response from them either on their BV11, and there is no link for that transformer. I know I can use a T49 but I'd rather a recreation of the original.

Thanks for any thoughts,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: poctop on November 07, 2016, 02:16:29 PM
Give Dave a Call and let me know how it goes ,
Best,
DAn, <
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Phrazemaster on November 07, 2016, 02:25:37 PM
Thx Dan; I've been talking to AMI so at this point I'm probably going to get one of their x-formers. I appreciate your support.

How are you man!!! My M49b "poctop" is still going strong; I just used it yesterday and it sounds warm, full, rich, and awesome! Thanks for helping me troubleshoot it; remember it was the mic with "gremlins" you said!

Best,

Mike
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: muffy1975 on August 22, 2017, 09:07:44 AM
Hi there,

Is there a problem using 100m ohm resistors in place of the 150m ohm resistors in this circuit?

Thanks in advance for any insight with regards to this matter.


Michael
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on August 22, 2017, 09:26:48 AM
No, unless it's 100M (mega) not 100m (mili) ;)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: rmburrow on August 22, 2017, 09:33:10 AM
You're better off with the 150 meg ohm (or higher value) resistors in that capsule circuit.  Go too low on the capsule resistors, the time constant of the capsule and resistors "loading" it falls in the audio range.  If you have a number of the 1/4 watt or smaller 100 meg resistors, try two of them in series in place of the 150 meg resistor.  The original tube in the M49 (the venerable and expensive AC701) liked to be loaded with 150 meg.  There is not a lot of published data about how the 5840, 6072, 5703, 7586, etc. behave when used with high grid impedance.  Those tubes I listed have been used in condenser microphones over the years.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on August 22, 2017, 10:47:05 AM
Bla, bla, bla - theory - bla, bla, bla ;) :D
100M will work very nicely - no problems i guarantee that - most tubes works much worse with too high value resistors like 1G - FET  is  different pair of shoes.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: muffy1975 on August 24, 2017, 12:22:05 PM
Thanks guys. Archut used to use a lot of 1g resistors in his designs. I'll try both ideas. Those 1/4 watt resistors are quite cheap. Hopefully they are no noisier than the 1/2 watt ones in this position in the circuit?

What do you think?

Gonna build a p2p m49 with a bunch of old mica caps and pio 10n caps. Also a massive Ampohm  1 uf 630v oil filled cap and  beezneez  M7 . I have  a long acrylic tube for the body. Gonna shield where appropriate.



I know 1/2 watt resistors are quieter in UA designs etc.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on August 24, 2017, 12:57:59 PM
That's why i wasn't fan of Oliver mods ideas and some circuits implementations - still - missing the guy around us...
Test two values - even direct comparison via switch (100M + 1G in parallel) and you will see - do you hear difference or not - there's no better option ;)
Probably not noisier, much more be carefull with soldering (don't overheat) and clean soldering points after work.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: rmburrow on August 24, 2017, 01:31:17 PM
Bla, bla, bla - theory - bla, bla, bla ;) :D
100M will work very nicely - no problems i guarantee that - most tubes works much worse with too high value resistors like 1G - FET  is  different pair of shoes.

The late Dr. Karl Schoeps used 180 meg ohm resistors in the M221 with the 20 pF capsules...Agree the 100 meg will work but experimentation will find what's best...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: justinheronmusic on September 05, 2017, 02:49:08 PM
Just getting into my M49b build. Can someone please explain to me the floating pins? My pins don't seem to fit my PCB, and from looking at the PCB ground plane, are they absolutely necessary or are they optional?  I am not totally clear as to whether or not I am soldering these in place.

 Also, can anyone post a photo of the front and back of their finished M49b Mini Driver PCB?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: stelin on September 11, 2017, 05:04:15 PM
I’m trying to get my head around what the feedback resistor R3 (5M) does in the M49c circuit.
I understand the basics of RC-filters, but there are too many components involved… 
Is it negative feedback? Is it only affecting the bass? Adding or subtracting?
I’ve tested the AC701 “Electronic tube” from Phaedrus. That “tube” oscillates in an M49c circuit and the fix is to remove the R3 resistor. But how does that affect the rest of the circuit?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: stelin on September 11, 2017, 05:56:14 PM
Never mind, guys.
I've found a good answer here: http://www.neumann.com/forums/view.php?bn=neumann_archive&key=990963033&v=f
The R3 is part of a bass roll off filter.
I suspect that the problem with the AC701 “Electronic tube” is the very hefty phase shift staring at 10 Hz (yes, I've measured it). That turns a negative feedback into a positive feedback at very low frequencies (around 4 Hz).
The size of the R3 determines the amount of bass roll off. If removed, there will be no roll off at all.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: ln76d on September 12, 2017, 06:49:22 AM
Never mind, guys.
I've found a good answer here: http://www.neumann.com/forums/view.php?bn=neumann_archive&key=990963033&v=f
The R3 is part of a bass roll off filter.
I suspect that the problem with the AC701 “Electronic tube” is the very hefty phase shift staring at 10 Hz (yes, I've measured it). That turns a negative feedback into a positive feedback at very low frequencies (around 4 Hz).
The size of the R3 determines the amount of bass roll off. If removed, there will be no roll off at all.

What did you found is not an answer but crap.
Neither R3 or R5 doesn't make "bass roll off".
R3 is feedback resistor, so if you want to get same level and other "artifacts" then don't mess with it.
If you want to increase low end then change C3 for higher value - that's it.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Delta Sigma on September 12, 2017, 11:06:18 PM
I’m trying to get my head around what the feedback resistor R3 (5M) does in the M49c circuit.
I understand the basics of RC-filters, but there are too many components involved… 
Is it negative feedback? Is it only affecting the bass? Adding or subtracting?
I’ve tested the AC701 “Electronic tube” from Phaedrus. That “tube” oscillates in an M49c circuit and the fix is to remove the R3 resistor. But how does that affect the rest of the circuit?

It is a feedback resistor. I assume your goal is to eliminate the oscillations and not to change the circuit. Why not increase the value of R3 until it stops oscillating? Try 8M or 10M.

The negative feedback depends on the feedback path and the amplifying device. You've changed the tube to what I understand is a semiconductor of some sort. Don't think that should mean you have to eliminate the feedback, just change it.

M49 is a great circuit to modify and learn from; R3 is just as good a place as any to start. There's nothing wrong with the denial and error technique as long as you end up with the mic you love.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: stelin on September 13, 2017, 04:15:00 PM
I don’t want to start a discussion about what is “crap” and what is not, so I’m not going to comment on this any further.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Rlucas41 on October 08, 2017, 01:10:09 AM
Could I get some clarification on calabration please?

I measure the B+ and H+ On the PSU Pads/point to calibrate each respectively using the trim resistor and 250k pot... correct?

And then measure at which points in the mic itself to adjust R7 to ?

I am building a b and c version...

I just need a clarification of steps for proper calibration and exact point to measure please ;D

Kindest Regards,
Robert
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 12, 2017, 02:21:13 AM
Initially I didn't put a low pass filter (600pF to ground) into my freshly built m49oid mic. But I'm too close to a GSM tower and I heard low level radio signal, so I installed  a 560pF capacitor with the result of no radio in the signal anymore: success !
Nevertheless, I don't like the sound as much as before, of course this is a better compromise, I guess phase shift contributes to the change of sound.  Nevertheless: Did anybody experiment with that ? How high can I I move the low pass ans still get rid of the GSM signal ?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Ericbazaar on October 12, 2017, 06:35:08 AM
Initially I didn't put a low pass filter (600pF to ground) into my freshly built m49oid mic. But I'm too close to a GSM tower and I heard low level radio signal, so I installed  a 560pF capacitor with the result of no radio in the signal anymore: success !
Nevertheless, I don't like the sound as much as before, of course this is a better compromise, I guess phase shift contributes to the change of sound.  Nevertheless: Did anybody experiment with that ? How high can I I move the low pass ans still get rid of the GSM signal ?

Wich output transformer did you use? Is the Microphone cable shielded correct? Maybe test a shorter one, 5 meters. Is the Transformer Lamination intern connected to the chassi? This is why i use only transformers with static shielding! Important because of the many Wlan Router(wich are sending with 300mW ore more), Mobile Internet ect.
Best
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 12, 2017, 08:02:58 AM
Hi !

it is a samar 1:6.5 tx, it has no shield, anyway if the lowpass works before the tx and removes the GSM signal it must be introduced before ? or did I get that wrong ? btw my 6s6b sound great !


Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: rmburrow on October 12, 2017, 12:45:46 PM
RFI elimination in a condenser microphone may not be a single step solution.  This assumes you are using good quality cable between the mic and power supply, and cable from the power supply audio output to the preamp, with no wiring or grounding errors.

Bypassing with capacitors can affect the sound, especially if applied across a high impedance.  You may want to try a single ferrite bead at the tube grid connection.  This should reduce RFI before the grid.  Make sure the headbasket and other metal components (connector shell, etc.) are  grounded electrically to the mic body.  Check with an ohmmeter.  RF from a poorly grounded headbasket (antenna) will couple to the high impedance capsule.  The 560 pF cap alone may work across the secondary of the output transformer...but a ferrite bead on each side of the output transformer secondary may work better.  Bad RFI cases may require bypassing the output transformer secondary with capacitor(s) and ferrite beads.  Also, make sure the audio from the mic goes straight to the XLR connector with no components to ground.  (Don't need ground loops.)  My $0.02 worth...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 12, 2017, 05:27:00 PM
but why don't you read what I wrote: I said I solved the radio issue, I just don't like the sound  of the lowpass and my question was how high can i put  the lowpass and still get rid of the rf noise
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Murdock on October 12, 2017, 05:53:09 PM
but why don't you read what I wrote: I said I solved the radio issue, I just don't like the sound  of the lowpass and my question was how high can i put  the lowpass and still get rid of the rf noise

yeah, and he gave you some hints on how to solve the radio issue without the lowpass which you said you don't like, right?
And why not try yourself how high you can go? Just experiment with different values until you're satisfied.
Or try the other solution rmburrow offered you.
Or did I also get you wrong?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 13, 2017, 02:12:57 AM
you are right ! I'm sorry, acctually the first time i missed the tone on this forum, my fault.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: RuudNL on October 13, 2017, 06:39:28 AM
e.oelberg Good to read that you are happy with the 6S6B in your microphone.
I used a couple of those tubes and the quality seems very consistent.
Noise is low, which is a good thing. I prefer them over a 5840.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 13, 2017, 11:53:37 AM
Hi Ruud

I'm very happy, I ponder of kicking out an EF86 in another mic and try a 6s6b instead, very quiet, not very microphonic. The  m49oid mic is my favorite mic in my collection. I have no 5840 but ef732 and I think the russian tube is much better, but than again I didn't do a direct comparison and there are always so many things to consider.
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: e.oelberg on October 13, 2017, 12:04:26 PM
Ruud !

did you compare it to a ac701 ? My guts tell me there can't be much of a difference in terms of noise am I right ?
Sound is always difficult to describe..
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: RuudNL on October 13, 2017, 04:06:12 PM
Unfortunately I don't have the M49 with the AC701 here anymore. (It wasn't mine.)
But from what I remember, the self noise of the tubes is in the same order.
That is: at a very low level!
I already replaced the (1/2 used) ECC83 in another tube microphone with a 6S6B.
That made a tremendous difference in self noise. In fact: the microphone is now useable!  :)
I ordered 25 of those 6S6B tubes, and the variations in self noise are in the range of only 1 dB. (I have tested them all!)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: justinheronmusic on October 28, 2017, 07:23:50 PM
First time microphone builder here:

 Can anyone help me out with how to connect the CM-6511 transformer?

 Do I tie red and orange together, and then blue and violet together?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: KrIVIUM2323 on October 29, 2017, 05:20:46 AM
Primary are : Brown , red; orange, yellow,
Secondary are : green, blue; violet, grey.
You should have primary and secondary each serial connected so:
Red and orange tied together, blue and violet tied together.

Primary 'input' is then Brown, yellow go to ground, secondary '+' output is green, '-' is grey.
The dot in cinemag's schematic give you indication about polarity.
Title: 5840 Connection/Pinout
Post by: justinheronmusic on October 30, 2017, 09:13:37 AM
Thank you so much! That is a huge help.

Also, I found the tube pinout connections, I thought I would post them here for future accessibility.

5840 Tube:

Pin 1 to FGRID
Pin 2 to K
Pin 3 to H+
Pin 4 - Cut
Pin 5 and Pin 7 Tied together to A
Pin 6 toHG
Pin 8 - Cut
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Rlucas41 on November 08, 2017, 05:36:17 PM
How do you wire the 6S6B tube? The pins i mean...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: TillM on November 08, 2017, 05:43:36 PM
Pin 1 to A
Pin 2 to H+
Pin 3 to HG
Pin 4 to Fgrid
Pin 5 to K
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Rlucas41 on November 08, 2017, 06:25:27 PM
Thanks TillM,
I have just ordered some 6S6B tubes, I have built two D49c's and both sound great, curious if the 6S6B will be a little quieter tube...
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nele on January 27, 2018, 06:24:17 PM
I'm about to start building an M49 and want to use the 6S6B tube. Is there anything else I need to adjust from the standard schematic besides the heater voltage? Maybe different transformer?
And where did you guys get the tubes?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: RuudNL on January 28, 2018, 03:53:54 AM
Probably only adjust the cathode resistor to get the bias in the 'sweet spot'.
I bought 25 pcs. of the NOS 6S6B tube in Russia. (And they are all excellent, tested them all.)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Nele on January 28, 2018, 06:14:53 AM
Probably only adjust the cathode resistor to get the bias in the 'sweet spot'.
Thanks! Is this done by ear or can I use some kind of formula (sorry for the newbie question..)


I bought 25 pcs. of the NOS 6S6B tube in Russia. (And they are all excellent, tested them all.)
Did you buy them online? The only source I can find is in Bulgaria (https://www.pentod.com/en/)?
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: vinylwall on July 19, 2019, 08:44:47 AM
Just in case anyone is interested, I have one of my D-49's up for sale (fully assembled).
https://www.ebay.com/itm/183889998100 (https://www.ebay.com/itm/183889998100)
Title: Re: Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)
Post by: Rlucas41 on August 07, 2019, 03:20:39 PM
Howdy folks, need some help wiring a 5703wb Raytheon tube in one of my D49’s.
I have the datasheet denoting the lead next to the red dot but its numbered: 1(red dot) 3_4_5_6

help me please :D