Tracing noise problem, TwinRev.

[Sea Chief]

Ok when you have all tubes in. start at V1 pull it noise still there? yes pull v2 noise still there? yes Solder area between v1 and v2. Replace tubes noise still there yes pull v1 noise still there? no solder area near v1. Simple as that. If none of that works, you possible have plate resistors to contend with. Nobody ever said this was easy or that anybody can do it as you are finding out.. There are amps I've run across that are above my limited skills you just have to know your limits.
nosaj

Hi nosaj. Great that's appreciated/ this is the sort of help I was after.

Actually it's not neccessarily hard at all I'd have thought, to go down your avenue. Im wondering if this progression-resoldering idea, isn't more long-winded than trying the plate resistors, which seems to be a 20 min job. But I guess the idea behind resoldering beforehand, is bc there's no components to replace per se, so easiest in this respect.

Is the fact that the pops ( especially loud, frighteningly so ) are so loud, signify any particular area more likely to be the cause? I mean if, as I roughly understand, the input gtr signal gets progressively increaced across the board.. does its huge volume signify perhaps that it is more likely being maximum amplified, thus if it has more stages to be amplified.. then the furthest point towards the 'start' of the circuit might be more likely the place it originates-?

All I can do you see, is add basic logic. But my idea here also might well be of no validity whatsoever.

Thanks SC

[nosaj]

From your description what I picture in my head are the sounds of a dirty pot when you rotate it and it makes loud noises.
being early in the signal chain means it gets amplified by every stage after it.

Here is an example of bad plate resistors.
nosaj

[nosaj]

Geofex article on popping noises
http://www.geofex.com/ampdbug/popping.htm

Symptoms of Bad Pre and Power Tubes

• Unusual sounds coming from the amp..(‘popping’ ‘hissing’ ‘crackling’ ‘humming’)

nosaj

[Sea Chief]

From your description what I picture in my head are the sounds of a dirty pot when you rotate it and it makes loud noises.
being early in the signal chain means it gets amplified by every stage after it.

Here is an example of bad plate resistors.
nosaj

Hi nosaj. Thanks for this clip!

Mine is very different though. i do not get this quiet uniform crackling. Totally different: with the vol at zero ( IE at minimum vol pot rotation/ at the very end, at the gap before the 1 ) I cannot turn it on without ear defenders on. When I do flip the standby up/ on, to turn the amp on, I am cowering waiting for a POP!! so loud it frightens me even with defenders on. That loud. If you're playing (over some intermittent liveble- with- crackling occurs concurrently but not steady & uniform like yours), & this sudden POP happens over the top too... it is terrifying. Absolutely sickening.

So even daring to turn the fkn thing on presently, is a wretched business. Having to do so time after time, test after test, is almost beyond possible.

Fwiw, I have played the amp from built, only say 25 times. So these JJ tubes, all 4 matched & new when I rebuilt it, only have 20 hours use. So if I add logic, I would say it is unlikely a bad power tube.

My hunch, & this means nothing as you know, but nevertheless my intuition... says it's a ( original component I put back in the board ) a bad carbon comp resistor, or a bad disc cap. This is not just a stab in the dark, it is a -bit- more logical. It takes into account the board seemingly no sign of conductivenes or moisture ingress & the fan heater test done without any change suggesting some validity to ruling this out; the tubes are only 20 hrs use; the vol pot changed, no difference whatsoever; I swapped in & changed around in all manner of different variables, all of the preamp small tubes, no change whatsoever; Ive pulled v2, 3,4,5, no difference whatsoever; I have never had one bad solder joint before ( this doesn't mean I can rule this out, it means it is logical to look elsewhere -before- resoldering section after section of the board ); My plate resistors.. i think/ Im fairly sure but need to check what/ where these are.. were not original CC's, but new ones: if they were original CC's I'd be going here next up, & just swapping in new ones being only a 20 min job & £2 cost ( ie applying logic ).

Is there any way I can diminish this wretched noise from the speakers, by doing each test via some other sort of speaker, or something else entirely, to lessen the stress to me?

Thanks, SC

[nosaj]

Can you make an audio clip?

Just because a tube only has x amount of hours on it does't mean it can fail. It is why we have warrantties on things. That kind of thinking can be a major hindrance to getting things done.

I'm thinking you have several tube amps. Please try another set of tubes just to humor us. just mark them so you know where ot what they came out of.
nosaj

Come to think of it your description makes me thing rectifier tube, but there is no rectifier tube.

Just thinking out loud to anybody. Could a flaky standby switch (carbon deposits from arcing) cause this?

[gui_tarzan]

I'm late to the discussion but I have to add my experience with the fiber boards and replacements. I have a SF Bassman 100 that had severely warped and extremely conductive boards. After much reading I decided to replace them with the black FR4/G10 glass epoxy board from Hoffman Amps. No regrets. I will be ordering more either from him or whoever has it if he scales back because "company X uses fiber board" is not good enough for me living in a state that gets very humid in the summer and fall months.

I'm also interested in the "pop" issue because I have an older Peavey 2-12 combo that does the same thing.

[nosaj]

Same goes for my traynor bassmaster removed the board , but paying jobs seem to get in the way of me populating the g10 board i got for it.
nosaj

[Sea Chief]

Can you make an audio clip?

Just because a tube only has x amount of hours on it does't mean it can fail. It is why we have warrantties on things. That kind of thinking can be a major hindrance to getting things done.

I'm thinking you have several tube amps. Please try another set of tubes just to humor us. just mark them so you know where ot what they came out of.
nosaj

Come to think of it your description makes me thing rectifier tube, but there is no rectifier tube.

Just thinking out loud to anybody. Could a flaky standby switch (carbon deposits from arcing) cause this?

Hi nosaj, thanks for the popping noise info/ a whole host of possible areas, which is way past my ability. Saying that, I can physically check for carbon deposits on power tube sockets ( in its previous dog's dinner life, I think Rift diagnosed one tube was blown by something he found ). I can replace a standby switch too.

So useful, logical avenues to explore here- thanks.

Im not stating my power tubes are good, Im suggesting the unlikelihood of one being bad considering how new they are ( & Rift oversaw innitial checks of my build ). I reiterate: I simply need to progress down a logical path, step by step, with my ability & equipment in mind, to attempt to locate the fault.

As I do not have spare 6l6 tubes, do not have money to buy a new set to swap in, do not have a tube tester... I cannot explore this avenue, or rather I could if I spent £200 on new tubes & a tester, but it is not in the realms of logic to do so.

Thanks SC

[Sea Chief]

I'm late to the discussion but I have to add my experience with the fiber boards and replacements. I have a SF Bassman 100 that had severely warped and extremely conductive boards. After much reading I decided to replace them with the black FR4/G10 glass epoxy board from Hoffman Amps. No regrets. I will be ordering more either from him or whoever has it if he scales back because "company X uses fiber board" is not good enough for me living in a state that gets very humid in the summer and fall months.

I'm also interested in the "pop" issue because I have an older Peavey 2-12 combo that does the same thing.

Hi there. As I have done a heat dry test of the board, can see no physical moisture ingress symptoms, board only 2 years old & looking as new & firm as it ever was, & considering repoulating the board is a massive 4 week job, & consideting all the usual testing avenues have barely even started, & consideting Rift amps/a professional amp maker & repairer did a host of tests of components & bits before coming to this finality diagnosis of this amp in its previous life ( totally unrelated in essence to it now )... it is logical to put the conductive board hypothesis aside, until way later. Until very very last.

And I don't care how many people band together to chip away at me that in their opinion it is a conductive board. They simply cannot come to this conclusion so soon. So why they would do so.. well, I've told you why I think they do it.

It is interesting though about the peavey 2-12, assuming its a 6l6 4 x power tube amp, & without preamp tubes ( i think?), & I know or rather Im 95% sure has no fibreboard but a pcb instead which I can I think safely assume rarely if ever have conductive board issues.

Can you explain further what sort of popping? As its also a beast I think at least 60w, there may be some useful similarities.

Thanks, SC

[Sea Chief]

Geofex article on popping noises
http://www.geofex.com/ampdbug/popping.htm

Symptoms of Bad Pre and Power Tubes

• Unusual sounds coming from the amp..(‘popping’ ‘hissing’ ‘crackling’ ‘humming’)

nosaj

I have to wonder why on this seemingly huge all encompassing list of Popping possibles..... a conductive board..... isn't even on the list!!

As far as the consensus of replies, the " gang of premature agreement ", the conductive board hypothesis should be FIRST to be mentioned on this list.

----

Please. Can we put aside this theory, as this is all it is, until absolutely last, when all other normal avenues have been exhausted. Thanks.

SC

[Sea Chief]

It says on this list & the very first sentence: " popping sounds are almost always an Arcing problem ". Ive not heard oft this term before though.

So it seems logical to explore this avenue, if & as far as I can with what limited equipment I have.

Ok I think I can pull two power tubes with this amp? IIRC it's alterate pairs. If so I can maybe "test" each power tube, IE if the noise stops by numbering them & switching them around. Is this a good plan?

I did see a slight bit of a carbon smudge ( like graphite from a pencil ) between ( but not quite linking ) two adjacent power tube socket holes, underside. I wonder if this signifies an internal arcing within a tube.. hmm.

Has anyone seen such a carbon smudge before?

Thanks, SC

[Chuck H]

Has anyone seen such a carbon smudge before?

I think I can speak for the forum in general and say 'many of us have'.

It looks like your power tube sockets are ceramic. So you should be able to clean off the smudge with alcohol, a little brush and possibly Q-tips. Don't be sparing with the solvent. Check the tube plug end also. And...

The smudge didn't happen for no reason. Check any component attached to or associated with the two pins. Clean and re-tension tube pin contacts. I would also suggest resoldering those connections with fresh flux.

This may well be the source of your problem. If something is intermittently arching there it could cause horrendous noises and possibly further damage. The problem could still be that tubes innards.

EDIT: As an initial test to see if this may be the source of your troubles you could just pull the tube associated with that socket. Fire up the amp. Noise gone?

[Sea Chief]

I think I can speak for the forum in general and say 'many of us have'.

It looks like your power tube sockets are ceramic. So you should be able to clean off the smudge with alcohol, a little brush and possibly Q-tips. Don't be sparing with the solvent. Check the tube plug end also. And...

The smudge didn't happen for no reason. Check any component attached to or associated with the two pins. Clean and re-tension tube pin contacts. I would also suggest resoldering those connections with fresh flux.

This may well be the source of your problem. If something is intermittently arching there it could cause horrendous noises and possibly further damage. The problem could still be that tubes innards.

EDIT: As an initial test to see if this may be the source of your troubles you could just pull the tube associated with that socket. Fire up the amp. Noise gone?

Ok hi Chuck, this is a promising avenue. Great tips there. Unfortunately I don't tend to number the 6l6's v7,8,9,10 just put them in. So I can't tell which tube was in that socket. But if Ive been doing this alot, logic says if it was the tube creating this smudge.. then I should see similar smudges on more than one socket. But I do take your idea on board: in fact I was just about to research if I can pull two tubes - i think you can - but a certain pair IIRC.

One other thing I notice, just now is this. I was putting the 6l6's back in, with the amp upended. I usually do so with amp flat upside down. So like the titanic sticking up in the air. I see a crack in one ceramic socket of v8. Right across it sideways/ only visible at this acute sideways angle. Lucky to spot it.

Now it might be that even like so, it still works fine. But my idea of using a pair of 6l6's - ok to- should be able to answer if it is the culprit. But it dies look to hsve bern there for a long time though, ie when it worked fine after i rebuilt it. Hmm.

Could you remind me which pair to pull?

Thanks, SC

[Dave H]

Could you remind me which pair to pull?

You want to pull one from each side of the OT, so that's either (V7+V9) or (V8+V10) or (V7+V10) or (V8+V9)

[Sea Chief]

You want to pull one from each side of the OT, so that's either (V7+V9) or (V8+V10) or (V7+V10) or (V8+V9)

Hi Dave. I've read that it's to pull either the outer ones call it 1st and 4th, or the inner ones 2nd & 3rd.

But I hadn't heard of other pairings. Which leaves me a bit bemused I must say. I don't want to anger the beastly thing.