good voltages, good tubes, bad tone.

[Colas LeGrippa]

Hi , I have built this preamp up to the master volume and I get harsh distortion although voltages all are good. The two last 50-50 caps were replaced by a single 10uF , 450V. but I don't think it is the issue. Shielded wires everywhere where needed.....good speakers, ( good guitar hey hey hey.... ).
I did not wired the lo input jack, instead I have put a 68k/68k signal voltage divider

Any idea welcome

regards

[3choplex]

10uF, or 100uF?

[Heinz]

I assume 100µF.

But nevertheless that also eliminates the 10k resistor between the two 50µF caps which provides filtering between the stages. Even though it does not affect dc voltages very much, it de-couples the B+ rails of the first/second and the tone stack stages. Dropping it could cause high frequency oscillation which may be responsible for the harsh distortion sound.

[Colas LeGrippa]

my mistake, everything's fine now, thanks

Colas

[stratele52]

When I read your title ; "good voltages, good tubes, bad tone"  I said to myself; this is half the amps on the market today .

Good to know you find . 

[Colas LeGrippa]

you're dam right !

[phsyconoodler]

So,what was it?

[Ritchie200]

When I saw this I thought it was Tubenit talking about his Tele again!

Jim

[Colas LeGrippa]

ooops sorry, I have miswired a 50/50 cap on the power rail, the schems are good, just my mistake.
Tone is marvelous now !
Colas

[stratele52]

Good news.

On a (re) built project almost all the problem is a mistake in wiring.