Crack 1.1 noise in right channel

[A Jedi]

Went back through all resistance and voltage checks again for a sanity check. All ok. AC between 18 and 19 is 170V, between B7 and B8 it's 1.3V.

[Paul Birkeland]

My guess is that your meter don't have a low AC voltage scale? (Maybe it only goes down to 200V?)

[A Jedi]

My guess is that your meter don't have a low AC voltage scale? (Maybe it only goes down to 200V?)

Oops sorry - forgot to change range. B7, B8 are 6.17V.

[Paul Birkeland]

That's a good measurement, nothing to worry about there!

[A Jedi]

I went back and reflowed all connections. Again. No change. Again. I'm sending this thing to you guys. Hopefully you can fix it. I thoroughly enjoyed putting it together and it sounds great. But the endless noise problems have taken all enjoyment out of it.

[takkos]

I have the same issue, right channel, quiet high frequency electric noise (like when your ear is ringing but quieter). When I lift the 6080 tube it gets better and my assumption was also that the transformator noise has been picked up by the tube, as the noise of the transformer can be heard with my bare ears from close. All joints are OK, went through all joints with a chopstick, nothing is changing. Also it is independent from the volume level or anything. And the noise is beginning ~10 seconds after turning the Crack on.
Has your problem been resolved, and if so, what was the problem with your build?

EDIT: Actually it is a buzzing sound at first that becomes high frequency. It is noticeable in the left channel as well but way better then the right.

[Paul Birkeland]

Transformer noise is 60Hz, which will sound like a low hum. 

For anyone who has this type of noise, it's certainly recommended to let your tubes run for a few days to cook in, as we have experienced many noisy tubes go totally quiet after 100 hours of burn in.

[takkos]

Hi PB, thanks for your reply.
I matched the noise based on this site: https://www.szynalski.com/tone-generator/
The noise in the right channel is 1970 Hz, so way above the 60 Hz you mentioned.
Do I need to have ~100 hours runtime in the tubes in total, or i have to have it turned on for 100 hours continuously? (It would be a bit unsafety)

One more thing: Is it ok to have music in the right only when I just slightly turn the potentiometer up? And the resistance in the RCA pins is different in the left (89,7k) and right (97,7k), I installed two 3A diodes after the ground pin to avoid PC noises, before that i think these numbers were higher.

[Paul Birkeland]

Do I need to have ~100 hours runtime in the tubes in total, or i have to have it turned on for 100 hours continuously? (It would be a bit unsafety)

100 hours constantly.  I do not know why this would be unsafe. 

One more thing: Is it ok to have music in the right only when I just slightly turn the potentiometer up?

See Crack FAQ #3/#4

And the resistance in the RCA pins is different in the left (89,7k) and right (97,7k)

That doesn't have any audible impact on channel balance. 

 I installed two 3A diodes after the ground pin to avoid PC noises, before that i think these numbers were higher.

This is rather unlikely. 

[takkos]

58 hours of constant runtime, still noisy. Right channel is louder, noticeable in the left as well. If I slightly tap the 6080 (RCA) tube, sometimes it gets quiter but after a while the noise comes back. I think that i might got a faulty tube, and the reason why i think this is that the noise only appears after the tube heats up, 10-15-30 seconds after turning on the device. If any of the joints would be the source of the noise, it would appear right after turning the Crack on. I will keep it going until it reaches the 100 hours, but my hope is fading away.

[Deke609]

I think that i might got a faulty tube, and the reason why i think this is that the noise only appears after the tube heats up, 10-15-30 seconds after turning on the device.

I'm not sure about this.  After many (PB and probably others would say too many) mods to my BeePre I was getting hum. It wasn't from the tubes, but would only start about 5-10 seconds after powering on as the tubes warmed up and started amplifying signal (including quiescent signal and any noise injected into the signal wiring somewhere else in the amp).

cheers, Derek

[takkos]

Waited for the 100 hours to elapse, still noisy. In the meantime i ordered a pair of Lewis & Kaufman 6080 tubes, and with this, the system is dead silent. So unfortunately i got a faulty (microphonic) tube with my order.
All in all, this amp sounds superb and i am really happy with it. 

[Deluk]

I'm not sure if anyone else has mentioned this and I think it's unlikely that I'm the only one with this situation. I suffer from fizzes. buzz and crackle now and then. Except for one, just after I built it, I've never found any bad joints. I do swap tubes occasionally and this often helps. I'm putting at least part of the blame on the 6080 8 pin socket. Mine is original and I keep it and the tube pins clean. The tube pins are gripped like a pincer. Fine, but the metal these are made of is soft so after wriggling tubes in and out a few times they get wider and you get a reduced grip with the potential for a poor connection. I know the metal is soft because I can squeeze them together again with just a pair of fine nose tweezers. This usually quieten things down again, until next time. I think I will change my socket to a sleeved type. Teflon ones are very expensive but you can get cheap ones on Amazon 4 for £9.79 with free post. From China of course. If they are better than the pincer type, at that price they could be considered for use as an original fitting. However the Bottlehead stores might still have 528 left from the original order of 1000.
If you've fitted the Teflon ones to cure noise and it's worked please comment. If you've fitted these cheap sleeved ones with good results I'd also like to know.

[Paul Birkeland]

In my repairs experience, teflon sockets can cause a lot of reliability issues. 

If you wiggle the tubes when you tube roll, that will put a lot of extra wear on the sockets and you should replace them.  It's much better to just pull the tube straight out.

[Deluk]

Thanks Paul but I've never had much luck getting them out with a straight pull. Getting a good grip on the metal mount isn't easy. Serial tube rollers must have very strong grip or change the sockets often. If there is a recommendation for a good but reasonably price socket that is better than the cheap sleeve type please advise. I read a previous comment by you about unreliable Teflon ones but at about £40 each I wasn't going to buy/try one anyway. I'm in the UK.