Neumann M49 Clone : D-M49c and D-M49b Tube Microphone Build Thread. (+Sample)

[0dbfs]

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

 

[Phrazemaster]

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

 

[0dbfs]

I used these in a couple of my m49's and like them.

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

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

 

[0dbfs]

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

 

[Phrazemaster]

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

 

[0dbfs]

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

 

[Phrazemaster]

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

 

[0dbfs]

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

 

[Phrazemaster]

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

 

[Phrazemaster]

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

 

[0dbfs]

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

 

[Phrazemaster]

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

 

[trans4funks1]

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

 

[poctop]

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,

 

[bioman666]

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  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.

 

[poctop]

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  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,

 

[kidvybes]

...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...

 

[micaddict]

...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

 

[kidvybes]

...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...

 

[micaddict]

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.