The B3hr!ng3r C -2 Matched Pair of SDC Mics for $50 - MODS?

[Svart]

ha, beat you Joly!

the MC012 capsules do tend to work without polarization voltage.. for a while. let them discharge overnight without the amp stage hooked up and they'll be dead.

 

[Scodiddly]

[quote author="PRR"]> TSB-160A http://jlielectronics.com/transsound/electrets/tsb-160a.htm

That part says it has the FET inside. Note the suggested schematic and the 0.5mA current requirement. That conflicts with Svart's description of a 470pFd cap and a 680M resistor, which sure suggests external FET. But note that Transsound's own page is self-conflicted: the schematic shows a 3-terminal capsule, but the mechanical drawing sure suggests a 2-terminal capsule? It is possible some idiot webmaster (I been one myself) cut-pasted generic info without knowing that this model is a special. And of course when Uli calls and orders a million, Transsound will be happy to do it his way, and even happier if they can use tooled-up case and terminals from an existing model. (What this may really mean: Uli can buy cheaper FETs than Transsound can....)
[/quote]

It's a confusing diagram - the capsule is the part inside the dotted line, the rest is a suggestion.

 

[Svart]

I assumed that they assume(that's a lot of assuming..) that you would tailor your FET biasing for the FET you are using and that is why they don't show a "complete" schematic.

 

[Svart]

ok I have had a chance to listen to the modified and the unmodified mics.

at the risk of being a heretic.. I like the UNmodified version better.

mods done: 1000pf polyester FET to capsule capacitor, 1G R, removing mesh from front of capsule.

there was a fair difference in sound between the two originally but now the difference is HUGE. like listening to two different mics actually.

The nasal mids are hyped in the mod'd mic. moving the capsule to the other mic does not really change the sound other than the effect of removing the mesh infront of the capsule itself. The unmodded mic does not have a lot of detail and neither does the modded mic. this could be the circuitry. we need to adapt a better circuit to use so that we may evaluate the capsules further but for right now they are decent sounding and the unmodded mic is fairly neutral but rather dull.

:thumb:

 

[Scodiddly]

Actually that's not too surprising - I built one Alice mic with electrolytic coupling caps instead of film, and actually it sounded pretty nice. The loss of HF tended to complement the rather excessive HF from the capsule! Unfortunately it also lost some of the clarity, too.

 

[northsiderap]

Maybe the output stage is the weak point. Is that partially Zener biased? I can't really identify zeners from regular diodes by eye...

I'm still trying to figure out which end is up. (When I have the spare time.)

The thought had occured to me to bypass the entire output stage with a transformer, but hadn't investigated the gain loss... I'm already not happy with the gain on these. Maybe it's just the lack of clarity and 'punch' that makes me keep turning it up...

Maybe I'll tap the output of the FET with a transformer and monitor the levels/clarity on that setup.

"If something breaks, just throw it away and replace it with a transformer." :roll:

I don't know if this is perverse curiousity on my part... Any opinions on how worthy these type of electret capsules are of re-circuiting?

I do have a tube mic I might be able to try it out on too. Might be fun to not have to worry about polarizing the capsule either.

 

[Scodiddly]

Well, if it really is the TSB-165A and doesn't need external bias... then you could just do the Alice (Shoeps-alike) circuit behind it.

 

[Gus]

Has anyone else traced the circuit? IMO modding this microphone might be a big waste of time and money one could build one of Scodiddly or buy a MXL,Nady, B5 etc and have a better microphone.

I spent to much time trying to make the samson C01 like I wanted it was the capsule and not the circuit. Maybe wasting time on a microphone is a good learning experience.

 

[Svart]

for 50$ it's worth it just for the shells and the nifty little bar mounting device. There is probably a bit of deficiency in both the capsule and the circuit. I am sure we can use the Alice circuit and try the capsule with that and see what happens. I am also suspecting the capsule too though the parts in the circuit are bargain basement.

 

[Rossi]

[quote author="Svart"]
mods done: 1000pf polyester FET to capsule capacitor, 1G R, removing mesh from front of capsule.
[/quote]

Hey Svart, polyester is no better in this application than the cheapo ceramics cap you replaced. Polypropylene or Polysterene give a more open, less nasal sound.

 

[Svart]

I'm not so sure. the ceramics were CHEAP. I don't like the polystyrene sound but I'll go ahead and give it a try as I have some laying around.

 

[clintrubber]

[quote author="Michael_Joly"]Northside -

I see an important revision - you show the 470pf coupling cap and 680M resistor tied to the capsule. The 680M is actually on the other side of the 470pf (at least in my mic).

I looked at this thing 10 different times to confirm this: the only connection to the capsule is through the 470pf.

This pic shows the flat high value resisitor tied to the FET and coupling cap. (1000pf replacement polypro). The only connection to the bottom of the retracting capsule contact pin is through this cap.
[/quote]
Arriving late here, and the pic is gone. If it's still relevant could you repost it ?

Thanks,

Peter

 

[majormono]

May I chime in...

 

[clintrubber]

[quote author="majormono"]May I chime in...[/quote]
Sure, thanks ! :thumb:

 

[SSLtech]

So is this guy just observing an electret behaviour?

http://www.youtube.com/watch?v=5iGEsVaIftk

Keith

 

[Rossi]

FET input + PNP Emitter follower, impedance balanced output.

My guesses PNP = 2N5401, FET = 2N5457. Am I right?

Looks like 797 Audio.

 

[clintrubber]

[quote author="Rossi"]FET input + PNP Emitter follower, impedance balanced output.

My guesses PNP = 2N5401, FET = 2N5457. Am I right?[/quote]
Haven't seen the topology when the pics were up, but it sounds like we have a CFP (Sziklai) here again

Looks like 797 Audio.

That's correct, there's 797 on the PCB.

 

[beatpoet]

[quote author="SSLtech"]So is this guy just observing an electret behaviour?

http://www.youtube.com/watch?v=5iGEsVaIftk

Keith[/quote]

'Scalar Waves' ... A tub of worms that I've never been able to find any concrete information about.

 

[majormono]

Picture (on previous page) edited with actual markings.

 

[Gus]

http://www.xs4all.nl/~nhcjv/nvrecording/AudioTechniek/BehringerC2Mods/EN_BehringerC2useAndModification.htm

and

http://www.xs4all.nl/~nhcjv/nvrecording/AudioTechniek/pa0nhcAudioTechniek.htm