Resurrected Peavey Triumph 60

[ceedj]

The more I investigate this amp the more I think the 10pf bypass cap I added on the 1M resistor (or whatever you sub in) is having the most effect on the tone I am hearing. I reinstalled the original 1M resistor and bypassed it with a 10pf and then added a second switchable 1M in parallel to drop it to 500K when I wish. Even with the second 1M switched out (yielding the original 1M with 10pf bypass) the tone is much improved over the stock nasal tone. Again, I don't have the tech chops to understand why such a small capacitor has this effect but Fender amps also have this 10pf bypass cap. Leo must have put it there for a reason. Maybe and even larger resistor would improve the reverb.

This amp is sounding better by the day. I am not finished with my mods yet. My PS choke should arrive in tomorrow's mail. Tomorrow I will mod the bias circuit for variable bias and suitable voltages and install 1 ohm sense resistors and bias it up properly. I just bet this thing is currently biased colder than a witch's thorax. When I finish up this work I'll come back and post a list of everything I added, removed or changed.

Hope this is still relevant, just got a 120 for a song (HAH), did the tone mod, and replaced the resistor with a 470 and what a difference in tone. But I think I borked my reverb, as the tank makes noise when I tap it, but gets no input signal. Anyone have any ideas?

BTW, this is my first amp mod, but I've done electronic stuff for years, and since this is all pretty easy to follow PCB's, this really was fun and easy to work on.

[Jazz P Bass]

Please, please, please start a new post.

[ceedj]

All the relevant info to what I did to my amp is in this thread. Why confuse things more by starting a new thread?

[Jazz P Bass]

Because it is proper etiquette.
You can certainly link back to this page.
There are now 152 posts on this one link.
That is hell trying to navigate through it.

[ceedj]

I appreciate you bringing my obvious ignorance of the rules of this board to my attention. I also appreciate how you've obviously mentioned this to the other recent posters to this thread, while continuing the discussion in a obviously positive manner. I hope you'll forgive my obvious transgression, because obviously you are better at this whole internet forum thing than I obviously am.

If it isn't obvious by now, I'll take my questions elsewhere, obviously.

[Jazz P Bass]

What is up with the huffy.
I was merely asking that you start another, new thread.
You do not have to.
As stated, it is tough navigating through 150 some posts to get to yours.

[Enzo]

ceedj, welcome to the forum

Jazz wasn't picking on you. You'll get better response to your questions with a new thread instead of tacking on the end of a Long old one.

[Jazz P Bass]

Thanks, Enzo.
I guess I could have been a wee bit more diplomatic about it.
Maybe he did not know how to create a new post.
I do see his point that everything was right there, as far as the OP was concerned.

[Enzo]

Yes, everything might be there, but someone joining the thread would have had to read 150 posts to get up to date on the discussion

[wavetuner]

Hi Bill. All, Thanks for all the great info. I bought a Triumph 120 in great shape. I would like to revisit the "noise gate diodes". To me, the signal is clipped in both directions and smoothed by the following .001 cap. has anyone tried removing the cap after jumping the Diodes? The plate load is labled 10K but looks to be a mistake, the layout shows a standard 100K. Sort of a reality check, I cut the blanket jumper, so now V1a is more like a recovery stage to the tone stack via Peavey front switching. So the real OD could be focused on tweaking V2B > V2A to get a smoother sound. Please offer any suggestions you may have. It sounds a bit too harsh for my liking and doesn't seem to have the harmonics it could! The Clean is pretty awesome - Twin like. I was also thinking about 60/100 switch (6L6 cathode lift) at 50w, am I right the speaker should go to the 4 ohm tap to match the turns ratio? I'm way old enough to consider a lighter speaker for small gigs! That HD Scorpion is a monster!
Thanks, Great forum!
Jim

[Enzo]

The diodes do not clip, in fact they do the opposite, sorta. They slice out a bit of the center of the waveform as it crosses zero. They do nothing to peaks. The cap is there to smooth the crossover transition, to hide the diode notch. You can remove it, it rolls off a little high end. This amp is not lacking in high end, so...


Which plate load is 10K? Use part numbers please. Or if you are using a drawing other than the factory one I am looking at dated 8/15/88.

You wanna mess with the OD channel? Try a 5751 in V2 instead of the 12AX7. Try reducing the value of C14 or C18. The difference between crunch and ultra is the value of the pre pot. WHich sound do you prefer? Is either closer to your goal? R98/C63 is a tone shaper, massage that. Fiddle with C21?

COmpare this to the very similar Ultra or Triumph PAG.

Try some local feedback like on V5a in the 5150, R88.

[J M Fahey]

Just checked out of sheer curiosity: cedj joined on January 15th ; left forever on the next day.
*Big* question_of_the_day: has he solved his technical problem by now?
No, not the amp, but the [obvious] key stuck in his keyboard.
Oh well.

[Xenrelic]

Hi Bill. All, Thanks for all the great info. I bought a Triumph 120 in great shape. I would like to revisit the "noise gate diodes". To me, the signal is clipped in both directions and smoothed by the following .001 cap. has anyone tried removing the cap after jumping the Diodes? The plate load is labled 10K but looks to be a mistake, the layout shows a standard 100K. Sort of a reality check, I cut the blanket jumper, so now V1a is more like a recovery stage to the tone stack via Peavey front switching. So the real OD could be focused on tweaking V2B > V2A to get a smoother sound. Please offer any suggestions you may have. It sounds a bit too harsh for my liking and doesn't seem to have the harmonics it could! The Clean is pretty awesome - Twin like. I was also thinking about 60/100 switch (6L6 cathode lift) at 50w, am I right the speaker should go to the 4 ohm tap to match the turns ratio? I'm way old enough to consider a lighter speaker for small gigs! That HD Scorpion is a monster!
Thanks, Great forum!
Jim

If you're just improving the OD section alone and are happy with the clean channel:

Try changing the rk/ck values of V1A, V2B & V2A: R32, R30 & R26 to 2.7k and C14, C15 & C18 to .68uF

Then change C13 to .0022uF

Put the diode jump on an spst switch and leave C17 intact.

Make sure to use SBE 6PS series orange drop polyester film and foil capacitors from Antique Electronic Supply LLC for C20, C13, C16, C17, C19 & C63.

I also like to change the clean channel rk/ck values for V1B & V3B : R4 to 3.3k, C3 to 5uF, R16 to 2.2k, C10 to 5uF.

If you want more dirt on the clean, leave R4 and R16 @ 1.5k.

I also change the values before the input grid a little: R1 & R2 to 68k (my fav) or 47k (smoother), change C1 to .001uF and if you're using the 47k value use 47pF for C1, remove and jumper C2, Remove R3 and install a 1Meg resistor from the high or low gain input jack tip to ground.

Then you can change the power filter cap values a little bit: C43 & C42 to 220uF 350v or higher and feel free to change C4, C12 & C57 to 33uF 450v.

Adjust the P.I. values a little C59 to .022uF, C52 to .1uF, C56 & C60 to .1uF, SBE 6PS series polyester film and foil orange drops preferred.

Then adjust the feedback resistor R72 to 47k on the 8ohm jack or 27k on the 16ohm tap. For a hotter sound, stick with the stock 68k on the 8ohm tap or 100k on the 4ohm tap.

[wavetuner]

The diodes do not clip, in fact they do the opposite, sorta. They slice out a bit of the center of the waveform as it crosses zero. They do nothing to peaks. The cap is there to smooth the crossover transition, to hide the diode notch. You can remove it, it rolls off a little high end. This amp is not lacking in high end, so...


Which plate load is 10K? Use part numbers please. Or if you are using a drawing other than the factory one I am looking at dated 8/15/88.

You wanna mess with the OD channel? Try a 5751 in V2 instead of the 12AX7. Try reducing the value of C14 or C18. The difference between crunch and ultra is the value of the pre pot. WHich sound do you prefer? Is either closer to your goal? R98/C63 is a tone shaper, massage that. Fiddle with C21?

COmpare this to the very similar Ultra or Triumph PAG.

Try some local feedback like on V5a in the 5150, R88.

Thanks Enzo, I don't know about zero crossing circuits as notch filters. I made the mistake that seems to be common in that it looks like the clipping diodes in a classic TubeScreamer although the smoothing cap is across the diodes come to think of it.. I have the same date on my drawing and it is very clean. Its reads Triumph 60/120 8-15-88. On mine, the plate load resistor on v2B pin 6 on the schematic is labeled R1 10K. Huh? Looking down to the layout it is clearly labeled R21 100K.

The ultra and the crunch pots have radically different values. I haven't played with it enough yet to get a sweet spot. Ultra is too much for me I think. I'll look at your other suggestions. You always seem spot on.

[wavetuner]

Yes the clean is very nice. No surprise with that iron and voltage! I have a small collection of the classic Spraug PS 600v series. I bought this amp as a sleeper and the price was awesome. I may be poor etiquette to bring up another builder that favored these caps! That's my on going project with lots of interruptions ;-^) If you like the sound of Roben Ford's rigs, you know what I am talking about! I think with some changes as you suggest, this amp could be tamed a fair amount in that direction. I dig Peavey. I have resurrected a Deuce and a Classic VTX with the help of this forum. They are heavy duty!

I'll have to print the schematic to see where your changes go but I think I get the general drift. Thanks much. Jim