Herbert "Crackling" question. Tubes?

[slyvren]

Bad pretube sounds like you're tapping on a guitar pickup or something usually. Sometimes they crackle. Mainly for me it sounds like the tube becomes like a microphone or something. You hear the taps. Usually poppy crackly fizzy problems are preamp tubes. Replace v1 and use contact cleaner if you can lightly on an old tube and plug the tube in and out 10 times. I would try to eliminate all the other variables first.
Good luck!

Ok--I put the amp back on top of the VH4 and plugged back into the 1960A. After about 10 minutes of playing, the problem re-surfaces. I need to change the speaker cable and try a different cabinet in that room.

Question: when testing for microphonic preamp (or power amp, for that matter) tubes, what is the condition I'm looking for? When I tap the tube, what sound will it make if it's bad? Static? Crackling? Both? Something else?

Also, if it's a good tube, what should happen when you apply the "tap" test?

I'm seriously confused, but I guess I don't get to be that confused until I swap out the cabinet and the speaker cable in the music room. What baffles me is that the condition is not consistent--only occurs after about 10 minutes, and only on Channel 2. Heat-related? Environmental?

 

[racerevlon]

Well, I received an e-mail from Herr Diezel saying it's either a bad V1, or a worse problem, so start by changing V1. Well, I changed V1 and amp happy to report the amp is back on top of the VH4 in my music room and the problem has not resurfaced since the tube change.

So I wonder... (and I asked, too)... does Herr Diezel get tired of being right all the time?

Thanks to Herr Diezel and all who helped me through this issue!

 

[Ventura]

If it doesn't do it in the music room, I'd look at everything else that is different. If the amp is fine in one place and not fine in another...it's not the amp...it's the place.

J

From casually browsing this thread, ya, I doubt it's the amp or the tubes - now that you've done a complete re-tube and everything seems to be working perfectly fine on the bench. My guess is it's something to do with the cab in your session space, the connections, the cable, something along these lines, otherwise, why would it happen only in that room and not on the bench??

Secondly, testing for microphonics - one can only hope that the new tubes are good, solid and not veering towards the behaviour of microphonics - as the test for 'microphonics' isn't always that good for the tube. Case in point, to test - outside of the usual cranking the amp to the top and seeing how things rattle out - one's instructed to tap the tube with a pencil...well, unfortunately, this can actually cause damage to the tube. Usually this method is employed "BEFORE" all the tubes have been replaced, so that if the test itself screws something up, no biggy. But we're kinda going backwards here - brand new glass and now you're wanting to hit it with a pencil

Anyway man, let us know how this all pans out...

Mo

 

[Ventura]

Well, I received an e-mail from Herr Diezel saying it's either a bad V1, or a worse problem, so start by changing V1. Well, I changed V1 and amp happy to report the amp is back on top of the VH4 in my music room and the problem has not resurfaced since the tube change.

So I wonder... (and I asked, too)... does Herr Diezel get tired of being right all the time?

Thanks to Herr Diezel and all who helped me through this issue!

Well shit - there it is... I took too long to type my reply and this is the answer... Nice.

Herr Diezel to da rescue.

V.

 

[racerevlon]

Well--so far so good. Interesting thing: I got three brand new Ruby 12AX7AC5 HG+ valves for the Herbert. I put the highest-rated in V1, next in V2, next in V3. The amp sounded great and had GOBS of gain---right up to the point where it started crackling and popping. Now that I've got the "second-highest" rated tube in V1 and another NOS Ruby 12AX7AC5 that I had in V2, the amp isn't making any more weird noises, but the over-the-top gain is definitely gone. Still sounds great, just different. Guess you can't have everything. I'll order another Ruby HG+ and see how it goes.

Thanks again to all who helped. RT truly has a great bunch of people!

 

[Ventura]

Well--so far so good. Interesting thing: I got three brand new Ruby 12AX7AC5 HG+ valves for the Herbert. I put the highest-rated in V1, next in V2, next in V3. The amp sounded great and had GOBS of gain---right up to the point where it started crackling and popping. Now that I've got the "second-highest" rated tube in V1 and another NOS Ruby 12AX7AC5 that I had in V2, the amp isn't making any more weird noises, but the over-the-top gain is definitely gone. Still sounds great, just different. Guess you can't have everything. I'll order another Ruby HG+ and see how it goes.

Thanks again to all who helped. RT truly has a great bunch of people!

Just for shitz'n'gigglez, order a couple Chinese/Shuguang 12AX7B's or C's - they're cheap and they're fun to play with... They'll bring back your gain - with GOBS to spare

Not going against Poppa here, just sayin'....

My 2 cents,
V.

 

[racerevlon]

I have a box full of Ruby 12AX7CZ's AC4's, and 7025 selects. I could swap them around, but moving the Herbert around ain't the easiest thing in the world. Maybe have to save that for the weekends...

 

[slyvren]

I prefer Tung Sol in v1 usually. It's darker. I likes my amps dark. Ruby HG+'s cut like nobody's business though thats for sure.

 

[Ventura]

Correct me, somebody - anybody, if I am wrong, but aren't Ruby's for the most part rebranded Chinese/Sino/Shuguang pre's to start with??

I know TAD rebrands the Shuguang 12AX7A and B as a Premium Select TAD, but the 7025S is a definite solid tube and better in sonic quality than the rebrands...

Like I said, I'm up for correction on this topic, but I was almost positive this was the case

V.