Still no break-up. 2x 5F1's.

[g1]

I still should have been able to see the pages of the thread, which I couldn't, must be a forum glitch.

Are you set to linear mode? Above the first post at the top of the page on the right hand side is the "display" mode button. That is where to check if you are set to linear.

[guitician]

Yeah, I've got linear set by default.

I've got two amps right here in front of me that I threw together from old parts from discarded record players/radios and they both sound like Ted Nugent playing "Cat Scratch Fever". I don't see how Sea Chief could be having so much trouble with such a simple amp?

[Chuck H]

Yeah, I've got linear set by default.

I've got two amps right here in front of me that I threw together from old parts from discarded record players/radios and they both sound like Ted Nugent playing "Cat Scratch Fever". I don't see how Sea Chief could be having so much trouble with such a simple amp?

He may be having trouble because he's not as much of a nerd as most of us here Finding the issue would be easy for any of us with SC's setup at our work bench. It may be a long road for the uninitiated. Some simply can't hang. Doomed to forever play through gear that has never had it's input checked

[Sea Chief]

He may be having trouble because he's not as much of a nerd as most of us here Finding the issue would be easy for any of us with SC's setup at our work bench. It may be a long road for the uninitiated. Some simply can't hang. Doomed to forever play through gear that has never had it's input checked

Input schmimput.

[Jazz P Bass]

109 posts & absolutely no definitive outcome.

[Chuck H]

109 posts & absolutely no definitive outcome.

Probably due to a lack of definitive information and testing!!!

It's LIKELY the input isn't the gain problem. But as Enzo has so wisely said, it's counter productive to look for reasons to NOT test something.

Most tests take very little time. Even at an experienced level one finds answers by relying of test data. Often the answers are revealed by tests that weren't performed with the actual problem in mind.

[guitician]

Hi Chaps-

some may be aware of my quest of getting some amp distortion. 2nd 5F1 and still none.

Ok amp1 one is a 5F1 + a tone + SS rectifier/ I cant remember exactly what it is! but a simple SE 6v6 5w. I turn up.. barely a fart of distortion. PT is rated only 254v-0-254v so for the mo Im going to leave this build/ call it the PT's low rating is cause for no distortion (this may or may not be true but line drawn for now).

Thanks Sea Chief.

I have a 240-ct-240@.070A Sec. power transformer running mine and it has plenty of distortion. Measure the AC voltages at various points while playing this amp in question to see where your losing the AC to drive the circuit into distortion. The wiper of the volume control would be a good place to start.

[Sea Chief]

I have a 240-ct-240@.070A Sec. power transformer running mine and it has plenty of distortion. Measure the AC voltages at various points while playing this amp in question to see where your losing the AC to drive the circuit into distortion. The wiper of the volume control would be a good place to start.

Im actually not dealing with this amp1 for this thread with its 254-0-254v xfmr. Im dealing with just amp2 with its 325-0-325v xfmr (2 amps to deal with is too much at same time). If I can sort one then can maybe use same ideas on t'other.

Al I know so far is the B+ is nearly 100v above what it should be. Isn't this a place to start/ ask the Q why so high? (Isn't it bad to run it at it is with such a huge discrepency-?).

I cant remember either what Im doing exactly re tests: I have the 4Ohm load resistor ready to go. Been silly-busy last 3 days hence not had time to start tests/ wknd set for. Thanks, Sea Chief.

[guitician]

Have you posted a schematic of the Amp1? What exactly kind of tone control do you have in it? A stock 5F1 has nothing but a volume control between stages 1 and 2, turning that up to "12" provides the user with a signal that has no attenuation at all. I added a 'tone stack lift' to a Champion 600 to get the grind I wanted. If there's a BF style network added to your Amp1, then that would account for a lot of signal loss. Might explain that amp, anyway.

Have you bypassed that Tone circuit? One stage of a 12ax7, which is what you get with the tone circuit dropping so much voltage, will not drive the 6V6 like a stock 5F1.
More voltage on the 6V6 may require an adjustment of the cathode(470R) resistor to a 330R. But I think the tone stack is where your problem lies.

[Sea Chief]

Hi guitician-

I'm not dealing with the amp with the tone circuit on this thread as its too complicated to solve 2 amps at once (I only mentioned this 'amp1' in passing- as to the 1st 5F1 that had no break up, and now a 2nd 5F1 has no break up). This thread concerns only the 2nd amp, 'amp2'. This is a plain jane 5F1. It has very high voltage readings afaict, and no break up (or barely any at all even with a fairly new gibson SG).

So 2 issues I need to address:

1) The high voltage- why/ what this implies/ is it detrimental to the amp/ should I be even using it?
2) Why there is no break up, or barely any.

[Chuck H]

Sea Chief,

I'm not sure if your goal is to simply resolve these issues so you can just play your guitar or if you are enjoying the mental exercise the problems represent. Either scenario is valid, just ask anyone here So...

I know you're in a somewhat remote in location, but if your goal is just resolution it would make good sense at this point to find a tech that is familiar with amps, guitars and their nature, as we are here. Such a tech should have no trouble getting you into some good overdrive from the gear you have. You may need to ship your gear or plan to travel for the purpose, but it would be done and you could get back to playing with something closer to the satisfaction you want.

If your goal is the mental exercise you'll need to get some more bench gear (like a scope) for doing tests and some books for study. This and a generous investment of time will eventually get you to a resolution. At which point there will likely be new things to fuss about. Just ask anyone here

These are the obvious courses for getting out of this snafu. There's a chance that some test done with limited gear will reveal something, but there's a chance it won't. And any further speculating about what MIGHT be causing your problems is just tossing offal at the wall to see if it sticks.

[guitician]

The drive of the 12ax7 into the 6V6 is where the 5F1 lives! A plucked low E string and my amp is putting 30 VAC into the 6V6 grid from the 12ax7 using the AC mode on my meter. What is yours putting out? Starting out with a .5 volt ac signal into one stage may get 15 VAC, then the other should bring it over 30 easy.

[Sea Chief]

Hi Chuck-

Ok if its a case of an oscilloscope to find the reason, then Im stuffed. I cant afford such a device. I have no idea where a tech would be anywhere near me. I just want a normal 5F1 & I dont think 9/10 5F1 builders will have or need to consider buying an oscilloscope to get their simple amp working as it should. If I cant with help get this little thing going, then Im in the wrong game entirely especially if I build 1, then buy another seemingly perfectly well made and neither do what a simple 5F1 should. Its a complete waste of time, mine and yours. But its so frustrating when I read "if it was mine Id have it snarling in 5mins.. or mine breaks up as early as 4".. this implies its can only be a simple problem, and so continuing to ask/ ploughing on with the thread seems appropriate. I'm thoughrally confused now as I was #1 with no progress whatsoever.

[Sea Chief]

The drive of the 12ax7 into the 6V6 is where the 5F1 lives! A plucked low E string and my amp is putting 30 VAC into the 6V6 grid from the 12ax7 using the AC mode on my meter. What is yours putting out? Starting out with a .5 volt ac signal into one stage may get 15 VAC, then the other should bring it over 30 easy.

Ok so I need to find where to put the MM probe between the 12ax7 and the 6v6 in order to answer this. Could you help? (Im not sure what " starting out with a .5 vac signal.." means: how do I put in a .5vac signal into the amp?).

[Chuck H]

Hi Chuck-

Ok if its a case of an oscilloscope to find the reason, then Im stuffed. I cant afford such a device. I have no idea where a tech would be anywhere near me. I just want a normal 5F1 & I dont think 9/10 5F1 builders will have or need to consider buying an oscilloscope to get their simple amp working as it should. If I cant with help get this little thing going, then Im in the wrong game entirely especially if I build 1, then buy another seemingly perfectly well made and neither do what a simple 5F1 should. Its a complete waste of time, mine and yours. But its so frustrating when I read "if it was mine Id have it snarling in 5mins.. or mine breaks up as early as 4".. this implies its can only be a simple problem, and so continuing to ask/ ploughing on with the thread seems appropriate. I'm thoughrally confused now as I was #1 with no progress whatsoever.

Did you test series resistance and continuity to ground on the input jacks???

As I said, probably not the problem. But the only way to know is to test for it. "Probably not" still leaves questions.

No, you probably don't need a scope to fix your amp. But a tech would use one to get the job done in a jiffy. I used the scope to represent the overall level of experience and proficiency you will need to get the job done yourself when you decide not to follow our advice or instruction.

There is no point is any further speculation. We need numbers and measurements, recorded correctly and indicated accurately. (<that's a period)

I want to read that you're happy and the problem, if it is one, is discovered, but there's too many man hours in typing alone already. These amps could have been fixed or modded in a fraction of the time.