Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)

[Spencerleehorton]

Hi Guys,

this may have been covered but need clarification, the schematic for the M49b version says 300k for R7, i have been told by dany that i should use a 2M trimmer?
with the 2M in i get 6.1v on the cathode and i cant seem to lower it with the timmer?
need to clean it all up and check for errors and will try a 300k resistor in there.
for the 150M resistors ive had to use 160M but thought this wouldnt make much difference?

regards

Spence.

 

[poctop]

Hi Guys,

this may have been covered but need clarification, the schematic for the M49b version says 300k for R7, i have been told by dany that i should use a 2M trimmer?
with the 2M in i get 6.1v on the cathode and i cant seem to lower it with the timmer?
need to clean it all up and check for errors and will try a 300k resistor in there.
for the 150M resistors ive had to use 160M but thought this wouldnt make much difference?

regards

Spence.

Waht is your plate Voltage ,  with the B version it is not very obvious to measure the Bias Voltage direclty as there are High M resistor up to the grid from this point on,

if your plate voltage reads between 47-50V for 120VB+ you are probably fine ,  Trimming with the 2M should affect the plate voltage.
one can use the substraction method to have a ball park number for the grid bias.  what you read is the filament voltage unchanged at this node

Best,
Dan,

 

[Spencerleehorton]

sorted the issue on one, was my fault wiring in the transformer!!, the M49c one still buzzes a little so will look at next week!!!

regards

Spence.

 

[poctop]

Kit in stock,

http://www.groupdiy.com/index.php?topic=49675.480

Best,
Dan,

 

[bruce0]

Looking for sources for capsules as I pull together the BOM and I could not find a consolidated list.  I pulled this together, but am I missing some names?  Not sure if the MFG/Distributor labels are correct. I have just listed "names" rather than links because the links go bad fast (just look at the meta).

MFG
Dale
Campbell Transmitter
Peluso
Beezneez
Tskguy
Theirsch

Distributors
Alctron (and other China based sources)
Microphoneparts
Canadian Audio Distributors

Other
Andreas Grosser?

Original commercial

Neumann
Sennheiser
Etc

 

[HellfireStudios]

Thiersch and Sennheiser/Neumann sell capsules too.

-James-

 

[tskguy]

Hey all,

Here is a clip of my M49b proto that Wave and I did. They are of some ACG and Vocal. They line up if you want to add to a session. This is also a bit of a shameless plug mainly because the mic also has my k47 style capsule in it.

For some reason I was getting a little noise from the tube (I think) ??? so please forgive that.

Now don’t just listen and not say anything.. I want honest opinions!!! Everyone has been so quit when anyone posts clips.

The recording chain was 9098 pre amp in to pro tools at 16bit 44.1


https://www.dropbox.com/s/hfnvasqfz17rrby/M49%20ACG.wav
https://www.dropbox.com/s/mkkbsoi6odzs9in/M49%20Vox.wav

 

[poctop]

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 ,


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.



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 ,

Best,
Dan,
 
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


Cabling connection From PsU https://cdn.groupbuilder.com/groupdiy/u/39511/58d0281993e53.jpg

 

[Spencerleehorton]

this is a bit confusing, ive read this several times and im still not exactly clear what you mean?

do you mean:

M49 b + c version:

the psu pcb is wired to the 7 pin connector normally 1-8?
on the 7 pin connector on the mic you do the following:
pin 3 goes to 7 on the mic pcb
pin 7 goes to 3 on the mic pcb

pin 8 on the psu goes to chassis

is this what you ment?

regards

Spence.

 

[poctop]

this is a bit confusing, ive read this several times and im still not exactly clear what you mean?

do you mean:

M49 b + c version:

the psu pcb is wired to the 7 pin connector normally 1-8?

pin 8 do not connect from psu it is a calibration input on the mic only

on the 7 pin connector on the mic you do the following:

pin 3 goes to 7 on the mic pcb
yes
pin 7 goes to 3 on the mic pcb
yes

pin 8 on the psu goes to chassis
no pin 8 do not connect on psu it is just on the mic and it is a calibration input at the mic only

is this what you ment?

regards

Spence.

yes it is the same for Both M49b and c,

basically the pin 3 from the psu will connect to (pad 7 (Chassis) on original schemo) at the mic pcb  and the pin 7 from the psu will connect at pad 3 at the mic  ( Circuit ground from original schematic) 

if you look at the schematic , pad 3 and pad 7 are both ground so it does not realy mattter , but if you have a ground loop or issue you will be able to tell that the chassis and shield return is tied to psu with a jumper for a gnd lift but not the circuit ground wich must not have a jumper ,

So they are the same level on the pcb but on the psu only pin 3 has a ground lift for the shield or chassis.
it is just to avoid confusion to actually wired the circuit ground to a jumperable connection

hope this helps ,
Best,
Dan,

 

[Spencerleehorton]

HI Dany,

Ok i think i get it all now:

on mic connector in mic, swap pins 7 and 3
on psu dont use pin 8 on pcb

Onto the other issue of noisey psu for these, i have changed over the cheap 20v transformer for the same one in the good psu which doesnt have any noise and there still seems to be a little noise.
I was wondering whether the caps in the psu could be the culprits as ive used another cheaper type in the two that are noisy and in the quiet one i have the white versions as specified in the BOM, i do have more of these so could change one psu to see if there is any improvement? but would it be these?

regards

Spence.

 

[Spencerleehorton]

Hi Dany/everyone,

have changed the 0.1uf 400v caps to the white ones from mouser in the BOM and buzz gone, PSU now sounds pretty much exactly the same as the good one now, slight difference but minimal, btw i am testing this as very high gains and have recorded all the noise floors to compare in protools.
I also used some wire that i wasnt completely happy with which i have changed for brand new good quality stuff, a must for everyone dont scrimp on anything or you'll get noise stuff!!!

much happier now!!!

regards

Spence.

 

[Edward]

Sorry if i missed it somewhere, but what transformer options are there on this M49 puck style build?

All pics of builds shows the AMI T49... what about Kirchers BV.11?

 

[poctop]

Sorry if i missed it somewhere, but what transformer options are there on this M49 puck style build?

All pics of builds shows the AMI T49... what about Kirchers BV.11?

The Current Kit Supports the amazing work of Max BV11,  the AMIT49 and any other transformer that will fit the bill

Best,
DAn,

 

[gary o]

Re OP transformers what are soud differences between Max BV11 & AMIT49 ..........also should any 10:1 transformer work, I currently use a Hauf original T14/1 .... sounds good but wondering about the sound differences as I may usr my T14 for a C12

thanks chaps

 

[Phrazemaster]

OK I just joined this club! Dan I sent you $$ for a round board set!! Can't wait to get this going!

Any word on the Latch Lake mounts? Sounded really really good!

Excited!

Mike

 

[Phrazemaster]

Just bought a few 5840 JANs off ebay:

http://www.ebay.com/itm/5-NOS-Raytheon-JAN-5840W-Subminiture-Audio-Radio-Microphone-Vacuum-Tubes-NIB-/290897652222?pt=Vintage_Electronics_R2&hash=item43bad9e9fe

I was a little concerned these are the JAN versions - in one thread I read that the JAN's were Joint Army Navy stock and could be very harsh unless specifically made for audio. But it seems like folks are using these here and Poctop's samples sounded smooth and great so...dunno. I usually try to get premium parts so mebbe I'm slipping heheh...

Anyway, anyone have any thoughts on the JAN versions?

Thanks,

Mike

 

[Edward]

What transformer are you planning to use Phrazemaster?

I'm also giving this project a try and just ordered the AMI BV11R to use with a 5840 tube.

Haven't decided on what 5840 tube to use yet.

 

[Phrazemaster]

Hi Edward, I'm going with Max (ioaudio)'s BV11. I realize it may not be mated for a 5840 as well from what I've read, but I think the guy does a bang-up job on his stuff and I'd like to support him. I bought a BV12 from him, and although I still have to test it, looks amazing!

Plus, the 11r is a lot more than I want to spend right now; Max's Bv11 is sitting pretty right in the middle.

I pulled the trigger and bought some JAN 5840's; reading suggests they could be harsh for audio use, however, I noticed that Dany (poctop) is using them and in his build his mic sounded velvety smooth so...I'm going to try the "generic" route and just ordered 5 NOS JAN 5840's for only 25 bucks. I'm usually the guy that gets super premium everything so...must be slipping lol! Or maybe the spirit of DIY and experimentation is getting to me.

Edward are you going to build the b or c version of the M49? I'm on the fence; not sure. Haven't found enough info on the differences to decide yet. Anyone have any info on sonic diff's betw the two builds?

 

[Edward]

I first was thinking about ioaudios BV11 as well, but the audiophile in me forced me to get the BV11R...

I think I'll learn from you and get a bunch of fairly inexpensive tubes and see if I get this thing working. Then "upgrade" later if needed.

I thought I would build the b version but I'm unsure of the differences sound wise. Would like to read comments on that as well.