UA 175b/176/177 pcb...

I've been giving this output trafo some thought.  (I'm learning how gain reduction circuits work, so please be understanding):

1. Throwing a 175 output trafo in there with a variac-type pot to dial down the trafo wouldn't work because without a corresponding gain circuit, the overall output signal would drop, correct?

2. Could the multi-tap output trafo be replaced with (4) step down trafos with a selection switch (or would that cause 'popping' during the GR selection)?

3.  Looking at the schemo of the 175 and 1176 (pre-A), could the 175 output trafo be used with a 1176-like gain reduction circuit?  Or is the magic in the multi-tap output trafo?

Thank you in advance,

DY

I'm thinking of doing a P2P UA 175B at some stage, has anyone tried the mod in the schematic below?  I'll probably build it stock to begin with and then mod it, but just curious to see if anyone's done it.

damnyankee said:

This is the modded UA-175b with the 6386 mod I'd drool over if it were in my rack:

Click to expand...

Hi,



  this is NOT stock, but modded to take 6386 . . .


    AndyP

Sorry, what I meant was, I'd build it stock with the original tubes and then mod it to use the 6386.

;D ;D ;D


  I think you will get a fairly small degree of compression with 6386, since it needs so much greater a voltage. Could be great for mastering, but perhaps 6bc8 is the one to go for . . . .


  Learned brethren, am I correct in this . . .


      ANdyP

strangeandbouncy said:

;D ;D ;D


  I think you will get a fairly small degree of compression with 6386, since it needs so much greater a voltage. Could be great for mastering, but perhaps 6bc8 is the one to go for . . . .

Click to expand...

Yes, that's a good point.  I'm more interested in just building a 175B to be honest, not hugely fussed about the 6386.  Is there an un-modded version of the 175B circuit floating around?  I can only find the 175A at Waltzing Bear.

I've send the original Drip 175 building info to the group account.
I hope it's OK, since Drip doesn't sell the boards anymore and this pdf was always available on his website.

Wow, thanks very much!