SYT-4 Microphone

http://www.shuaiy.com/product02.asp?plt=60&pone=5

What i can say?
First chinese made microphone body which i like (my have completely different finish).
Circuit maybe interesting, after modification.
Tube seems to be really good.
Capsule really fine, but not for this circuit obviously.
In general, typical yucky bright sound, but really good for tweaking.
Could someone remind me what was the point of connecting filtering caps (33nF) to the cathode potential not to ground?
There was pretty good explanation in some thread but i can't find it.
Of course it's about noise, but more advanced explanation would be more interesting

And here's modified schematic which i will probably use in the circuit,
Transformer probably 7:1, big bastard, i will have to cut PCB
Capsule of course will be changed for something different than  K67.

Where did you buy it and how much does it cost? I like it too...

Transformer probably 7:1, big bastard

Click to expand...

Gotta love 'em big. 

lampas said:

Where did you buy it and how much does it cost? I like it too...

Click to expand...

I bought it used, unfortunately with wrong PSU and "tweaked" schockmount, but still am happy
http://www.ebay.de/itm/Studiomikrofon-Kondensator-Mikrofon-Grosmembran-/131937099111?hash=item1eb8105d67:g:ryAAAOSwMgdX1t02
Looks better in reality

I couldn't find new one except weird rebranded from US  (if i remember correctly).
I forgot to write, PCB is really high quality and really well soldered.
I wanted to build circuit bsed EF12 or E13 or EF14 in it, but i think i will stay with modified original - it have potential.

micaddict said:

Gotta love 'em big. 

Click to expand...

SYT-4.

GT-2B body, no?

SY stands for ShuaiYin, of course.
And T for Tube?

Everyone here knows the SYT-5.

No, GT-2B is ShuaiYin SYT-5000:
http://www.shuaiy.com/product02.asp?plt=64&pone=5
T? Probably
SYT-4 is completely different quality body (outside parts).
It's longer, bigger diameter and doesn't looks so "chinese made".
Pipe is brass (rest i'm not sure), headbasket frame is one piece, not glued/soldered.
I truly like the shape of that head, its proportions.
With GT-2B am making always reshaping of upper dome, becuase i don't like it as hell
With SYT-4 probably i would prefer much more classic outside mesh, but usual chinese mesh sucks, so maybe it's better.
From sonic point of view it's totally great, transparent as hell, but need to get used to the look
It's not that i don't like the look but even if i had hundreds of microphones in my hands, this is something new for me
I need also highlight the fact that i didn't looked for any "U47 clone" look (as also making circuit copy) etc. just good looking microphone

That's rebranded version:

http://www.jarrellguitars.com/html/MIC_J_DivaIV.html#

There's no price.

Original transformer is 4:1 and replacement also will be similar ratio and still big bastard

What's the plate voltage they're running?

Tried one of these 6S31's a while back, and it's easily the quietest tube I've tested... Used same settings as Lomo 19A19, plate below 30V.

Banzai said:

What's the plate voltage they're running?

Tried one of these 6S31's a while back, and it's easily the quietest tube I've tested... Used same settings as Lomo 19A19, plate below 30V.

Click to expand...

Hey Mike,

don't know what plate voltage should be, i bought it with different PSU than original.
I wrote imediately to manufacturer, but still didn't get any answer.
I tested it with 120V, but i think to drop it to 100V.
Yes, quiet as hell

I read somewhere that AG use russian tube as replacement for VF14 with great result. Is it possible that this is the same tube (6S31B) ?

lampas said:

I read somewhere that AG use russian tube as replacement for VF14 with great result. Is it possible that this is the same tube (6S31B) ?

Click to expand...

He makes  an EF12 replacement now, too.

At least some of the latest Flea U47s have it.

lampas said:

I read somewhere that AG use russian tube as replacement for VF14 with great result. Is it possible that this is the same tube (6S31B) ?

Click to expand...

Truly don't know  :-\

I think there's a lot of tubes, especially russian, which still aren't re-discovered for microphone circuits.

I updated a little my mod schematic.

Am "reworking" one capsule for it, but i'm not sure if i be able to make it, if not probably try chinese k47 or gefell M7, we will see.

ln76d said:

Could someone remind me what was the point of connecting filtering caps (33nF) to the cathode potential not to ground?
There was pretty good explanation in some thread but i can't find it.
Of course it's about noise, but more advanced explanation would be more interesting

Click to expand...

There are a few possibilities.  First, the cathode potential only wiggles up and down a few hundred millivolts (depending on the cathode current).  It's pretty close to "ground", and may have simplified wiring up in the high impedance section.

The other possibility:  from the point of view of the grid, the cathode signal follows the grid minus a few dB.  Feeding this back through the polarization network places two 90 degree phase shifts (once through the 33nF caps, then once again through the 1nF gate coupling cap).  This will make the feedback -180 degrees, making for a bandpass response.

The cap sizes are probably chosen to limit the gain of the amp at frequencies higher than the audio range.

Thanks Matador!

I think i saw that solution before in one sided capsule microphone circuit, but don't remember where.
Also i if i remember correctly someone  here (wasn't you?) wrote something about better noise figure.
In case SYT-4 is a little bit confusing.
Both diaphragms filtering caps looks like make connection at cathode for multipattern operation.
Also it looks like a feedback as you wrote.
In my mod schematic i have only two filtering caps, i will try it as on schematic as also move connection to ground (probably via switch comparison) and see what happen
Before that circuit, i only connected output transformer to  cathode - with really good result.
I know that in opposite it's basic mod for UM57, but don't have opinion about that, because i didn't modified it that way.
With other mods and still transformer between plate and cathode UM57 worked wonderfull