Trem channel sensitivity

[Aaron]

can anyone give a kind of theoretical basis for why the tremelo channel on this amp is so sensitive to component brands/values? I STILL havent got mine to work and i have the feeling im just gonna have to rip it all out and start again...but that's beside the point. Im just wondering why its so picky. anyon?

-Aaron, previously "fuzz_a@yahoo"

[Jason]

Aaron,

Have you subbed a new 12AX7? This trem requires a good amount of gain for it to work. After you re-check your wiring, maybe you have a bum tube?

Jason

[Aaron]

i've subbed a new 12ax7, no deal. i've still got to put in that final 47pf at pin 7 though. so i'll see how that goes.

[Graydon]

The 47pF might help a little but it is not going to fix a malfunctioning trem IMHO. In all the amps I have built the only time I have had trouble with the trem is when I screwed up a wire position or forgot a component such as the 220K on Vv3. y position, I mean, I soldered a wire to the wrong eyelet. I do not mean that I had the correct schematic but with a poor physical layout of the wires. I have always used EI 12AX7s for customer amps and kits but I have also tried a number of NOS and used tubes which all worked just fine too. So, I don't really know what the problem is, but if you follow the schematic exactly, and copy the layout of Colin's amp exactly, you shouldn't have any trouble.

This photo shows a pretty good layout of the trem section... http://18watt.com/modules.php?set_album ... _photo.php

HTH

[Aaron]

graydon,

thats a good pic, thanks for pointing it out. one of the tubes i tried for the trem was an EI 12ax7. i'll take another look...

-Aaron