Crackling and static in the right channel [resolved]

[Cowwe]

I appreciate the input, Doc.
The idea that it might be either dirty tube pins or a dirty socket occurred to me too, so I went and cleaned them both several times (the last time being yesterday). I don't have Caig Deoxit in Italy, so for the time being I used another product, but as of now cleaning contacts hasn't had any impact on the noise.
Most importantly I cannot seem to interact with the noise in any way anymore, neither wiggling the tube nor applying pressure to the chassis or messing with wires seems to be changing the noise. It might also be a bit hard to tell since the noise is very randomic: at times it's quiet for several seconds and sometimes it's unbearably persistent. It really puzzles me that a couple of weeks ago I was actually able to make the noise change by moving the tube now I can't anymore.

One aspect that came to my mind recently and that might be a useful detail, is that I remembered when I heard this noise for the first time: I was listening to some music and suddenly, only in the right driver, I heard a very loud noise that would be comparable to having an aluminum foil crumpled up into a ball close to your ear. At the time I got pretty scared and quickly turned off the amp, but for a period of time after that event the amp kept working normally.

Tonight I am going to try cleaning the contacts better and I will keep looking for the source of the noise as I have been doing every day these past weeks, but I am really at a loss right now.

[Cowwe]

As unfortunately expected, cleaning the pins and the socket did not make a change in the noise I keep hearing, and spending more time looking for bad solder joints and faulty cables with a chopstick still hasn't revealed anything.
I have tried changing power chord, wall outlet, turning off anything that might create interference and taken my kit elsewhere, and nothing changed.
My Crack is still unusable and I think I have run out of ideas.

[Doc B.]

The next step would be to try a different 6080 tube.

[Cowwe]

I have already tried all of my tubes, both 6080's and 12au7's that used to sound perfect. All of them showcase the same exact noise

[Doc B.]

I just went back and listened to the sound file again. This week I returned a Gates limiter to a friend who brought it in saying made a similar sound and was unusable for recording. I had replaced all the tubes and replaced the film coupling caps but the faint crackle persisted. Bear in mind this is a 60 or more year old piece of equipment. I went through and chopstick tested the connections and found that a string of terminals in the middle of the chassis were causing the problem. Perhaps the old solder flux had degraded the joints over time, which caused less than perfect conductivity. Reflowing those terminals and adding just a bit of fresh solder completely solved the problem. I know you have already gone through reflowing the joints, but it could be that one has just not quite reflowed well enough. Beyond that my suggestion would be very unlikely things like a slightly leaky capacitor somewhere. Since it is only in one channel it would have to be some component on that side of the amp. Unless some part has been physically damaged the odds of this being the issue are quite low.

[Cowwe]

In the last couple of weeks I haven't updated my thread, I have done some more testing and inspecting to no avail, which brought me to biting the bullet and bringing my kit to a local hifi repairman.
I have explained to them in detail every piece of information I had gathered on my issue and finally got my "fixed" amp back yesterday (the man was rather vague about what he did to solve the issue, and was also very vague at describing the noise itself).
Naturally, the combination of my newfound ineptitude at electronics and my bad luck meant that when I plugged my headphones into the Crack the noise was still there and I most likely got scammed.
As suggested, I have made one last attempt at reflowing every single joint in the amp, adding just a slight touch of new solder, paying very close attention that (from what I have learned) the joints all look good and have the right amount of solder to them. It didn't work.
As it is still not clear to me, could you please specify which terminals are responsible for the right channel?

[Deluk]

It's a pity you had your wallet squeezed to no effect with this repair. I don't know where you are but those funds would have been better used for sending your Crack back to BH HQ for repair. That is something to consider as an alternative to chasing your tail at home.

[Cowwe]

Thankfully the wasted money wasn't a lot. The real disappointment came from thinking I could finally listen to my amp again and having my expectations betrayed by a supposed professional.
Still, I have thought about the possibility of sending it back to BH, but that has to be my last resort. I live in Italy and the money and time that it would take would probably be comparable to getting a new amp altogether. Plus I don't know how the built amp would hold while traveling across the sea.

[Paul Birkeland]

This has been a bit of a long thread and I'm not sure that I see it in here, but you didn't use any additional flux right?  There have been some occasions where the wrong soldering products were used and conductive residues were left (which could usually be cleaned off).

[Cowwe]

I have made 100% sure to only ever use the suggested 60/40 solder, nothing else.

[Cowwe]

Since I'm still not sure about it, could I ask you to point out which sequence of terminals is responsible for the right channel in the crack?

[Paul Birkeland]

The red wire going from the red RCA to the pot, the red wire leaving the pot, the red wire leaving A6, the red wire leaving terminal 2 and going to B1, the red wire leaving B3 going to terminal 7, the red wire leaving terminal 6, and all the black ground wires.

[Cowwe]

Hello again. I hope everyone spent some nice holidays.
I would love to announce that in my month and a half of absence from this thread I found a solution to my noise issue, but it unfortunately isn't so.
I do have a rather bizarre update though:
I had, as usual, double, triple and quadruple checked every and each solder joint inside my amplifier at length and couldn't for the life of me find anything wrong that could be the source of my problem.
So I decided to bring my kit to a well respected hifi repairman that specializes in tube equipment (I had done this once before but the man couldn't find anything wrong in my amp). After hours of testing with my tubes and his, my power chord and his, and no source attached, my kit never made a noise. I have listened to it at his place with my own ears, and the amp is completely silent. So it turns out the previous repairman I had contacted most likely did not scam me.
I brought the amp back home and tried it anywhere I physically could, and in each of the 5 different houses I have tried it at the noise appears again and the Crack is unlistenable.
There should have been no difference between how we tested at this guy's place and mine, and yet my kit was perfect at his place.
He himself inspected the kit and found nothing wrong with the build. The only thing he recommended I replace is the tube sockets (in his experience those have caused him contact issues and noises), so I went ahead and replaced the octagonal socket but of course nothing changed.
At this point I am once again at a loss about how to proceed. While rewiring the octagonal socket I tried moving the right channel output to the left and viceversa, and the noise did indeed switch from right to left.
I have tested the grounding of my home outlets but they are fine, and my current measures 245V (hence the way I have wired my transformer according to the guide).
I don't know how useful this information could be.
If any idea comes to your mind about what I could test and what I could replace, please let me know.

[Deluk]

Off the wall but try to put a tin box over the whole Crack. Maybe a cooking foil dome would also work. It should show if it is suffering from EMF problems. Wrap your input leads in foil too.

[Cowwe]

Off the wall but try to put a tin box over the whole Crack. Maybe a cooking foil dome would also work. It should show if it is suffering from EMF problems. Wrap your input leads in foil too.

I had thought about possible disturbance causes (even though it would be weird, having the same exact noise at many different places except for some that have no issues at all), so I recently tried using the amp while it was completely inside of a microwave, which should be shielding, but the noise was unbothered.