Source for C37A /C800 style mic capsules ?

[maxwall]

looking for a alternative capsule for C37 or C800 type.

Cardoid one sided I think.

I did manage to acquire a pair of Tamradio TD1 10K:600K output transformers, PT,  tubes, and resistors.

the mic has one of the simplest layouts I've encountered.

just need  mic capsules to complete it. looking for suggestions

Does Sony sell them direct from spare parts distribution/repair ?

 

[zebra50]

I might have a spare one of Dale's - let me have a look today & get back to you.

Cheers!

Stewart

 

[maxwall]

thanks for the reply,  Stewart,  let me know ....

Dale did suggest a "U##" type of capsule but details were not specific enough for me to
finalize on -experimentation implied. Although,  I might have a go of it if I cannot locate any other suitable donor.

Actually a Rode Classic tube capsule or Audix SCX25 capsule might be decent starting point.

http://www.beesneezmicrophones.com.au/

 

[Rossi]

Afaik the C800G uses a Neumann K67 knock-off capsule with electrical switching between cardioid and omni. The older C800 (without the G) had a different capsule similar to the C37. Dale's capsule was based on the older design.

 

[maxwall]

I was told the older design with the C37 amplifier has a very flat response, while the C800g type capsule gives
a extended high frequency range.

In any case is'nt the older (C37 type) a one sided capsule ?

 

[Rossi]

Dale would know more about these capsules. Afaik the older Sony capsules wer one sided with mechanical switching to omni by closing the holes on the backside. They were true single diaphragm capsules, not dual diaphragm with a passive (non coated) diaphragm on the backside.

The newer C800G supposedly has a K67 knock-off dual capsule with electrical switching between cardioid and omni.

That's what I've read. I dont't have any Sony mics. I do have a DIY mic built around a Dale C37 capsule, though.

 

[mushy]

Sorry for the hijack.

I have the opposite problem. I have a Dale c800 capsule and no mic to put it in. Can someone recommend a circuit?

 

[zebra50]

C800? It's a more challenging build than some.

http://www.xaudia.com/xaudia/Schematics/Pages/Schoeps_Sony.html

 

[rascalseven]

I hope this isn't an invitation to hijack this thread, but just out of curiosity, does this bear any similarity to the capsule used in Sony's C-500?  I had a C-500 several years ago and the sound was huge!  It had issues, and I wasn't into building at the time, so I sold it before it really got bad.  If I could build a mic with a similar size to its sound, I'd be very interested in building one, but so much of the sound is the capsule, and I know nothing about the C-500's capsule.

Does anyone know of a clone of this capsule, or a source for originals, or something similar?

JC

 

[Rossi]

C800? It's a more challenging build than some.

http://www.xaudia.com/xaudia/Schematics/Pages/Schoeps_Sony.html

Do you have the schematics for the older non-G C800 also? Or is it the same circuit (apart from the pattern switch)?

Apart from the peltier element, the circuit doesn't look too difficult or exotic. But the tube equipped PSU would be an additional challenge. Not sure as to how much impact the PSU has on the sound of the C800.

The coutant site has nice pics of the non-G C800 capsule with mechanical switching to omni.

 

[Rossi]

I have the opposite problem. I have a Dale c800 capsule and no mic to put it in. Can someone recommend a circuit?

You could put in any of the Sony FET circuits, they look quite easy to reproduce. But they're source follower / transformer out, so the output level is low. From what I can tell looking at the specs, they're just a little louder than a dynamic mic. Those Sony style capsules are low output. You definitely need 60-70V polarization voltage for decent S/N.

In my DIY mic, there's a transformerless transistor circuit with about 12 dB gain and a DC/DC converter. I don't have a clean schematic or a PCB. I built it on perfboard, and changed quite a few components in the optimization process.

Here's a few pics:
http://www.groupdiy.com/index.php?topic=30630.0

 

[zebra50]

C800? It's a more challenging build than some.

http://www.xaudia.com/xaudia/Schematics/Pages/Schoeps_Sony.html

Apart from the peltier element, the circuit doesn't look too difficult or exotic. But the tube equipped PSU would be an additional challenge. Not sure as to how much impact the PSU has on the sound of the C800.

Well that's it really, plus it's higher voltage, includes the supercaps, and I recall I had to much about with the bias a little to get it to work properly!

 

[Rossi]

The supercaps shouldn't be a problem, they're readily available and not very expensive, either. They certainly don't hurt, but I wonder if they're really necessary as the circuit is self bias...

 

[zebra50]

Here's a thread with the PSU schematics

http://www.groupdiy.com/index.php?topic=23666.0

You're right - there isn't really anything exotic in there. The B+ voltage is much higher than most of the other common tube mic circuits. I didn't bother with the tube PSU. I'd read a bit about these PSUs being a bit unreliable so just did something solid state and regulated. I just recall that this mic took a bit more tweaking before it sounded half good.

It would be nice to see if the C800-non-G is the same. I had assumed that they were, but it was just that - an assumption.

 

[mushy]

What are the voltages for the C37 or the C800 (non G)?  I can't seem to find them. The C37A survived without the peltier thingy, right?

It seems to me this capsule isn't the kind of thing you'd just throw into an MXL mic and expect it to sound good.  I'm not really concerned with staying true to any particular design. Would any CF circuit work with this thing?  I assume Sony stuck with the 6AU6 for a reason given the heat issues.  You gents in this thread seem to be the only ones who've experimented with this capsule here.

 

[zebra50]

Have a look at the thread I linked in my last post. There are some schematics for the PSU there with voltages, and some good links to a thread by Gus. It says the high voltage side is 276V, unloaded.

We'd guess about 60v on the capsule - at the junction of the 180K/47K voltage divider. So B+ ought to be in the region of 290V. Too high!

It may not even be that complicated - it could be 47V on the capsule which makes the maths really easy for the designer. That would give us 227V B+ under load. That sounds about right. I started there and tweaked, if I recall right. It was a couple of years ago.

[Edit - That's for the G. I'm assuming it's the same apart from the peltier, until I hear otherwise!].

I don't have reliable voltages for the C37. Anyone got one?

 

[Rossi]

Holy smoke, I didn't realize it was such high voltage. Hence the peltier element, I guess.

I would assume that the polarization voltage would be at around 60V. For all I know the newer dual capsule is a K67 copy, and that capsule is optimized for 60V. And why go for a lower voltage, if you have such a high psu voltage to draw from. The PSU schematic in the other thread suggests 276V. Afaik the older Sony capsules were 60V as well; in any case the FET Sonys use DC/DC converters for their polarization voltage

 

[Kingston]

C800? It's a more challenging build than some.

http://www.xaudia.com/xaudia/Schematics/Pages/Schoeps_Sony.html

Wow, C37A does the audio step down on the PSU case side! I wonder if it's such a good idea to wire all the high impedance (unbalanced!) audio all the way to the PSU case. I guess the audio transformer was too big to fit inside the mic.

 

[rodabod]

I don't have reliable voltages for the C37. Anyone got one?

I believe MatthewF did this circuit, but adapted for a 5840. However, he calculated the voltages, so hopefully has them somewhere.

 

[maxwall]

No issues with hijacking here , all related and significant to this mic build , I suppose.

I'm going with the traditional 6x4 rectifier , but why did they use a ss bridge for filaments ?
tubes and ss bridge under the PS hood , strange.

noticed filament in PS is 10Vdc ss bridge with 6V tap for pilot, looks like 10Vdc must be for the resistance drop in the
mic cable run

One thing here my primary ac tap on PT must be for 125vac, any lower (115,117,120)then HT/B+ and filaments go elevated. Not good for 6AU6/EF94 plate voltage which should see 250Vdc max when using NOS tube. New production tubes seem to handle more plate volts.

the OT transformer is 60mm x 40mm x 35mm, a bigger mic body would allow fitment , unlike the original. no need
to put the OT in the PS side unless its required by original design.