If i parallel a 82k resistor with a 25k linear pot....

[Chuck H]

Sort of the same thing. I don't see any reason changing a gain pot could DO anything to totally change an amp. In fact it can't. And you've done enough solder work and circuit examination by now that you probably know if the circuit is constructed correctly. So that only leaves the voices in your head. That's not an accusation of compulsion or insanity. Many of us have it. Perhaps you only wanted to believe the amp was great before, but it really wasn't. Or perhaps you only want to believe that it sucks now, but it really doesn't. And maybe it's just an amp and shouldn't be held accountable for any of it.

Going back to the modeler may be a good call for you if it allows you to play instead of thinking about your sound. The modeler sort of forces you into that place since you CAN'T do anything to it Then again...

You wouldn't play with the circuits if you didn't get something out of it other than tonal changes (like the "I made this" factor or knowing you have something exclusive). Maybe you can keep it at that level and try not to stress. Also... Different amps sound good at different times depending on, among other things, the weather, what happened to you the day before, ear fatigue, which personality disorders are prominent at the moment, etc. If you try not to make any particular amp THE amp and just understand that it's AN amp you might get to enjoy diversity in a small collection.

It's your call of course. For me, WRT amp circuits and design, a good corker can be a frustrating and satisfying exercise. I don't always find a satisfying solution, but sometimes, if I pull out enough hair, I do. In the end I laughed, I cried and just otherwise just did something that seems worth doing for it's own sake for reasons people outside of the genre wouldn't understand. That also makes me a little estranged and lonely. And I enjoy that a little too. The whole experience get's me closer to inner peace and understanding myself and the functionality of my dysfunctions. But if I weren't getting something out of it besides "tone" there's no way I would fuss with circuits to the distraction of playing. Because, in reality, it's not hard to buy a good sounding amp.

JM2C

[daz]

Sort of the same thing. I don't see any reason changing a gain pot could DO anything to totally change an amp. In fact it can't. And you've done enough solder work and circuit examination by now that you probably know if the circuit is constructed correctly. So that only leaves the voices in your head. That's not an accusation of compulsion or insanity. Many of us have it. Perhaps you only wanted to believe the amp was great before, but it really wasn't. Or perhaps you only want to believe that it sucks now, but it really doesn't. And maybe it's just an amp and shouldn't be held accountable for any of it.

Going back to the modeler may be a good call for you if it allows you to play instead of thinking about your sound. The modeler sort of forces you into that place since you CAN'T do anything to it Then again...

You wouldn't play with the circuits if you didn't get something out of it other than tonal changes (like the "I made this" factor or knowing you have something exclusive). Maybe you can keep it at that level and try not to stress. Also... Different amps sound good at different times depending on, among other things, the weather, what happened to you the day before, ear fatigue, which personality disorders are prominent at the moment, etc. If you try not to make any particular amp THE amp and just understand that it's AN amp you might get to enjoy diversity in a small collection.

It's your call of course. For me, WRT amp circuits and design, a good corker can be a frustrating and satisfying exercise. I don't always find a satisfying solution, but sometimes, if I pull out enough hair, I do. In the end I laughed, I cried and just otherwise just did something that seems worth doing for it's own sake for reasons people outside of the genre wouldn't understand. That also makes me a little estranged and lonely. And I enjoy that a little too. The whole experience get's me closer to inner peace and understanding myself and the functionality of my dysfunctions. But if I weren't getting something out of it besides "tone" there's no way I would fuss with circuits to the distraction of playing. Because, in reality, it's not hard to buy a good sounding amp.

JM2C

No. It's not that i'm telling you. Plug into a amp that you like where it sounds good with the treble knob is on say 12 noon the turn the treble all the way up and add more presence too till the plain strings sound like a freakin banjo. Thats not a "in your head" thing trust me. I know ear fatigue and it's limits, if anyone does it's me. The amp is total slop as i told you. Something simply went south likely due to how sloppy it is but i can't find it. I didn't say it was the pot either, it's something that happened while installing it.

[R.G.]

Something simply went south likely due to how sloppy it is but i can't find it. I didn't say it was the pot either, it's something that happened while installing it.

Suspects are broken wire, shorted leads, or ultrasonic oscillation from lead dress. All could cause the banjo string issue.

[daz]

Suspects are broken wire, shorted leads, or ultrasonic oscillation from lead dress. All could cause the banjo string issue.

Thanks, but i found it. I re-tensioned and cleaned all the preamp sockets. Not sure which was the issue because i did them all at once. But in any case thankfully that issue is gone. It made the amp pretty much unusable. I'm not sure why it happened right when i changed the pot but i've been experimenting with tubes and that may have triggered it just b4 or after i changed the pot. By the way, those sovtek LPS tubes sound great. Till now i preferred tung sol reissues but I think the LPS may now be my fav new/recent production 12AX7. Just I wish i could use em in the CF slot but neither these or the TS can be used there. Seems all the good sounding new production tubes have that spiral filament which i guess is a trade-off of ability to work for the CF in trade for tone that is better then non spiral filament tubes.

[Chuck H]

I agree that the Sovtek 12ax7LPS is a good sounding tube. You can use them in the CF position if you elevate the filament supply. It's not hard to do. We can tutor you on it if you're interested. One place you probably, actually can't use the LPS is the first preamp position. And that's where it makes the most difference. It may be ok when the amp is not being played loud, but they tend to be more microphonic than many shorter plate tubes. From a batch of six that I bought, not one was stable in the first slot. Not in a head cabinet and certainly not in a combo. You may find the same once you turn up the amp.

[daz]

I agree that the Sovtek 12ax7LPS is a good sounding tube. You can use them in the CF position if you elevate the filament supply. It's not hard to do. We can tutor you on it if you're interested. One place you probably, actually can't use the LPS is the first preamp position. And that's where it makes the most difference. It may be ok when the amp is not being played loud, but they tend to be more microphonic than many shorter plate tubes. From a batch of six that I bought, not one was stable in the first slot. Not in a head cabinet and certainly not in a combo. You may find the same once you turn up the amp.

It's in V1 but i haven't yet used it at stage volume except a few seconds here and there at home. It was fine in a quick test here but if it's not next time i'm out somewhere (a few weeks from now) i'll just have to swap it. But could be the circuit that makes it more or less likely to go microphonic. Mine really isn't a lot of gain, just typical classic rock style master volume type gain levels. So no metal or any of that hyper gain stuff. A level of gain that gets totally clean when the guitar is on 5. But if not i'll just go back to the tung sol (even tho they hum) and if still not good my old reliable stash of 80's chinese. Those sound good and never a problem with em. I have about 20 or so and they are what i have mostly used since the 80's.

[Chuck H]

Yep. The old Shuguang 12ax7's were very good sounding also. In fact, so are the new ones. The ones I had from the 80's seemed to be a little shorter lived. Maybe a less than ideal cathode coating? No matter. They certainly lasted long enough.

The amps I had the LPS trouble with were pretty high gain. Bordering on metal levels. And yeah, it sucks how many of the Rusky short plate tubes hum like they don't know the words. When I order them for a project, I always order an extra one for every three because I know about that many will be too noisy. And those are bought from vendors, not a box of ungraded crap. Pretty pathetic. If I boffed one in four paint jobs so bad that the house needed to be repainted again I wouldn't have any customers. If one in four oranges from a certain grocery store were moldy inside I wouldn't shop there anymore. But the tube venders have us by the short hairs.

How about that elevated heater circuit?

[daz]

Yep. The old Shuguang 12ax7's were very good sounding also. In fact, so are the new ones. The ones I had from the 80's seemed to be a little shorter lived. Maybe a less than ideal cathode coating? No matter. They certainly lasted long enough.

The amps I had the LPS trouble with were pretty high gain. Bordering on metal levels. And yeah, it sucks how many of the Rusky short plate tubes hum like they don't know the words. When I order them for a project, I always order an extra one for every three because I know about that many will be too noisy. And those are bought from vendors, not a box of ungraded crap. Pretty pathetic. If I boffed one in four paint jobs so bad that the house needed to be repainted again I wouldn't have any customers. If one in four oranges from a certain grocery store were moldy inside I wouldn't shop there anymore. But the tube venders have us by the short hairs.

How about that elevated heater circuit?

Thanks, but i really don't want to touch it anymore aside from putting the new presence pot in when it arrives. I have the tone back and i don't need to pull any more hair out. I put the chinese back in and it;s fine. The LPS has a bit fatter sound but then that can even work against you in a mix so no matter. The chinese actually have a more balanced freq response. I'll probably put the LPS in the PI.

[g1]

Great! Nothing left but to draw and post the schematic!

[daz]

Great! Nothing left but to draw and post the schematic!

I'm in the process but i'm using one from my el34 amp and just revising it to reflect the differences but i'm not sure i'll do the output and PSU, just the pre. We'll see....depends if i have enough geezer energy to in me.

[g1]

So not one for this unit then.
Not a lot of point in that for those who are looking for the special ingredients.
You really seem determined to not post the exact schematic .
If it's a trade secret type thing, just say so, no one will mind.

[daz]

So not one for this unit then.
Not a lot of point in that for those who are looking for the special ingredients.
You really seem determined to not post the exact schematic .
If it's a trade secret type thing, just say so, no one will mind.

No, not at all ! I could care less who sees it, but just because i like it so much doesn't mean it'll be anything special to others. My only reason for doing the pre section is thats where the tone is and i want it documented in case the amp is lost or stolen or whatever. I design my amps so that i get what i want in the preamp and the output is more of just what it's supposed to bein a MV style amp....a circuit to amplify the tone i created in the preamp. So i'm not real concerned with the power section because once i get the tone i like in the pre i can pump it thru any decent amp's power section and get the basic tone i created in the pre. I don't really spend a long time on the PA because i have never needed to turn up so loud that the output is contributing as much to the tone i designed in the preamp. Now having done this smaller 6V6 amp maybe that will change, but the thing is i can't work on the PA side at home because i can't turn it up loud enough. So i was just documenting the preamp because thats the part of the amp i would need to replicate in order to make another regardless of what style PA i use.

That said, maybe i will do the whole amp, but if i don't it has nothing to do with secrets ! Thats almost comical to me. It's have to do with being old and lazy and really hating spending hours in a drawing app doing more than i need to for my purpose. I'm sure most here have designed as good or better amps than i have so not sure why anyone would want to build mine anyways. But we'll see.