[Solved]Bottlehead Crack Left Channel Crackling/Popping and Humming

[Coma]

Hello Bottlehead people,

im new in the bottlehead crack gang. I found a prebuilt Crack on ebay where i live and bought it since i wanted the crack in the future. I got it and it works, sound comes out of it but i have a few problems with it.
The first thing is pretty bad crackling, popping in the left Channel. Its there basicially all the time  a few seconds after pushing the power button. I had it running for a few hours, with no change, it still crackles after hours. I have 7 6080/6asg7 tubes and 3 12AU7 tubes to test. Its always the same. The RCA6ASG7 Black Plates which i had in my Darkvoice( The darkvoice is dead silent with the RCA and a Sylvania 6SN7GTA) changes nothing.
Ive read a bit in here a mod with diodes on the ground pin of the power connector and applied it with two diodes that i had. Dont know if they fit for that, but they havent solved the problem.
Some solderjoints looked pretty bad and one of the caps hat broken joint. I resoldered some of them and reheated most other besides the tubes sockets. Im not a solder pro, but what i have done looks definetly better than before. Some are still a bit ugly i guess ( probably all).  Unfortunatly i burned the isolation of a cable on the power connector a bit, which is seen in the picture (black wire). This hasnt changed anything from my initial problem.
I noticed that the pins in the socket of the 6080 tube are somewhat loose ( maybe 3 or 4 of them), means i can push them slightly down in the socket, but they wont stick in there. Ive tried to tighten all the loose pins while running it, but nothing changed.
Tilting the tubes doesnt do anything.
I switched the resistors on the headphone jack from left to right but the crackling remained in the left channel only.
I have it, even if nothing is plugged in the RCA. I tried it on different wall plugs, different power cables and turned all my wifi/phone/pc stuff off for testing and it still crackled.
I tried the chopstick test and found what i described above, but nothing  that obviously produces the crackling.
It is still there if the volume is completely down. If i turn it up i get pretty audible humming that gets louder the more i turn it up.

I have recorded soundfiles of the crackling that might help, but im not allowed to post links here.



It seems that it is not a perfect stock build, but i hope someone can still help me sort it out.

The second thing that i have to ask is about its sound. I own a Darkvoice, like i said, that is running with a RCA black plates and an ~1950s 6sn7gta silvania. Its dead silent like this. I compared the too a bit and the most obvious thing is the bass performance loss when plugging my headphones in the crack. The Darkvoice has really a lot more lowend and it seems a bit lacking in the crack. The crack on the other hand sounds more open, cleaner/ more refined. Just first impression. But the bass performance confuses me. It doesnt fit to the things ive read about the crack and im wondering if that is just the sound of the crack or if it is a problem with my build.

Ah and should i replace the wire with the damaged isolation? Where can i find a spec for the cable ( im in germany, ordering from the USA takes forever and is complicated)..

I use Beyerdynamic T1.2, DT880 600 Ohm and Sennheiser 6XX.

unfortunately i cant find my Digital multimeter, but im working on a replacement.

Many thanks in advance
Coma

[Coma]

More pictures.

[Paul Birkeland]

So, there's a lot that's wrong with this build.  There's a ton of wire in there that shouldn't be there, caps that are there that shouldn't be there, the IEC power entry module is installed backwards, some of the caps aren't attached to the terminal strips, etc.

Can you send this back?

All those mods are bound to cause some problems.  I still see many solder joints that look like you could just pull the wires right out.

[Coma]

Thanks for the answer!
I think i can´t sent it back unfortunately. ..
So im trying to figure it out the best i can. Ive noticed aswell that the IEC is installed backwards, should i change it?
Something else, the blue wire looks totally different than the normal wire that should be there and is a flexible wire. I guess i should change that aswell?
Even though the wires are all soldered and i cant pull any of them out, i will try to resolder all the other suspect joints tomorrow. I hope i can sort the voltage and resistance checks out since there are no numbers anywhere.

[Paul Birkeland]

The power supply capacitors being mounted on extra pieces of wire is pretty terrible.  I would exert maximum effort on initiating the return process. 

[Coma]

Allright i will see what i can do..

[Coma]

Wanted to do a little feedback.
So i couldnt sent the crack back so i had to troubleshoot it myself.
So the crackling came from the 22.1K Ohm resitors. Replaced both and the crackling is gone.
The crazy lack of bass came from the 2 Silver Audyn Caps with 1,5uf that the previous owner mounted. I replaced it with caps that are similar grade to the originals and resoldered the whole thing.
Now it sounds like i expected it to sound, very awesome!
I still have to replace a few wires that shouldnt be there, but for now im enjoying my amp.

[Laudanum]

So the amp had 1.5uF output capacitors in place of 100uF capacitors?  ...  Yep, safe bet that would explain the missing bass.

[Paul Birkeland]

I didn't realize those weren't in parallel with the stock caps. 

The builder of this Crack certainly "knew better" than we did I guess...