T.bone SCT700 transformer ratio and other blah blah + mod schematic

If anyone is interested the ratio is 11.6:1.
Pretty high.
I always was thinking that CCDA circuits have low ratio transformers.
Probably by some buls..t "stories" over the web.
What a surprise...
I had in mind to use low ratio transformer like 3:1, but forget it - there's no way!
I can't say much about original transformer quality, because i throw it away very quickly.
Overall microphone out of the box sound pretty sh.tty.
Why?

CCDA circuit? NO! It's pretty good topology!
Capsule? - NO
Transformer? eee... response is pretty linear from around 20hz, so maybe not.
High polrisation voltage? Part of true, but with higher voltage than it's set, it can sounds even better.
Infamous 100nF RF capacitors? - sorry all the online "modders" but removing it change not much... The legends says that if you remove it, you will get almost U47 Not true. Of course they can be removed or changed for lower value, but still microphone sounds nasty.
So maybe capacitors quality? It's a part of true, but only a small part. If someone believe in that, micandmod have really nicely overpiced kit for these microphones. Few capacitors, overpriced chinese "made in france" k47 or K67. "With this kit, transform your microphone into C12, U47 or U67". Whoaaaa, what a bulls.it!
12AX7/ECC83 - yes, this is really big problem here! Do we need 6072/12AY7 instead? No not really - finding good, not overpriced 6072 is really hard. Sorry but EH 6702 for me sound really weak - not worth completely. Good (not from current production) 12AT7/ECC81 will be enough. Am using currently Siemens ecc81 made in Munich. Really good tube.
Ok, so what's the real problem with this microphone?
Overall gain is set to high! That's why these microphones sounds thin and overbrighted.
Going down with the gain i was able to use 6:1 transformer and it sound really good, especialy if we take into account the price of this microphone and not really many changes (ok i changed all the electronic parts inside the mike, but it is not necessary).
Final version will be made after "resurrection of the easter bunny" holidays, so maybe i will put here some voice samples.
If someone is looking for cheap tube mike, it's worth the effort and money.
It wouldn't be "hi-end" mic anyway, but all these clones with chinese capsules (even these overpriced) aren't "hi-end" also

Thanks. ^

T.bone SCT700, from what I "know", is the cardioid only version of the Nady TCM-1050.
http://www.nady.com/products/microphones-studio-wired/tcm-1050/
And the Nady TCM-1050 is in fact the Alctron GT-2B.

Several have reported the transformer is not bad. No Jensen or Lundahl, but pretty decent nonetheless.

Oh, and here's a guy who is fairly well known for modding these things. He's a modder; not a builder by any means, mind. Some like his mods; others don't.
http://www.oktavamodshop.com/product_info.php?products_id=147

But there's a good chance you know all this already.

Yes it's cardioid version of Nady and of course is rebranded Alctron without multipattern.
It's also cheapest from these three.
I'm not a fan of Lundahl in microphones, it's  too "transparent" for me
Also Lundahls are pretty big, too big for some projects.
I will not speak for Jensen, because i had only few and non of it was usable for microphone circuit so i didn't test it.
Am using here RFT/Funkwerk Leipzig (reversed) transformer and it sounds really great for microphones circuits.
In both way connection it's pretty linear from around 10Hz.
I will not be commenting MJ, only can say i'm not the fan
Did you ever had in your hands any microphone modded by him or you only listened his samples?
Am using all the time the same chinese k47 in several circuits but i discovered that 32mm alctron capsules are pretty usable so for this mike it would be enough
Main idea was to use lowest ratio transformer as possible, to get lowest loss.
Overall it's possible to use really low ratio transformer but it doesn't sound good that way.
6:1 is really good option here.
Also am not trying here to copy any other microphone sound signature.
Main idea is to make "fat" sounding microphone pleasant to the ears

I too prefer other modders and/or builders. 
Some of 'em are right here among us.

MJ does or did have his place, I guess.

That's why am sitting here not on gearslutz

I tried few 12AX7 and GE 6072 in my circuit. Of course the comparison isn't accurate because circuit is optimized for 12AT7 so it fit the best.  Both other tubes doesn't sound bad anyway. 12AX7 need to be good, i tried few -  sovtek, EH and chinese tubes aren't  good for this. Valvo which i have fits the best but with 12ax7 still sounds overbrighted, so the gain need to be lowered.
With 6072 top end sounds good but there's weak low end response.
Maybe another time i will make version for 6072

I have two T.bone SCT700 microphones. I seems the quality control is not very good, because the first microphone I got was very noisy and did not sound good. (I have replaced the capsule and added my own solid state amplifier circuit to this microphone.)
However: the second microphone is extremely quiet and does not sound bad at all!
I also checked the transformer and I think there is no reason to replace it: it measured almost 'flat' from 20 Hz to 40 KHz!
(And LF distortion is not a real problem here, because the levels at a microphone output are relatively low.)

RuudNL said:

I have two T.bone SCT700 microphones. I seems the quality control is not very good, because the first microphone I got was very noisy and did not sound good. (I have replaced the capsule and added my own solid state amplifier circuit to this microphone.)
However: the second microphone is extremely quiet and does not sound bad at all!
I also checked the transformer and I think there is no reason to replace it: it measured almost 'flat' from 20 Hz to 40 KHz!
(And LF distortion is not a real problem here, because the levels at a microphone output are relatively low.)

Click to expand...

Yes they can sound different, few  years ago i was selling them so i tested few
Main problem, i think, is the weak tube. It is not  even good for cheap guitar amp.
Yes it's usual quiet mike.
I also measure transformer, it's pretty flat in step down. In step up configuration it have bumped hi freq and loose in low end.
With lower transformer ratio, different tube and overall work on the circuit it sounds much better. Definetely not warm tube mike but much more usefull
When i finish it i will put schematic and some photos.

Finished, only need to modify the cable.
Sounds good.

So here's schematic of the mod.

Thanks a lot for this info, Im trying to digest it slowly.