New crack build, two different hums/whines [resolved]

[carlman14]

Not to be too unkind but I'd rate most of your joints as improperly flowed and rather dirty. They should be smooth and with a nice clean appearance. Your iron tip is likely dirty and needs retinning properly. Wind the heat up a bit if it's adjustable or leave the tip on the joint longer. Add additional solder only after the existing solder has steaded to liquify. You may find a flux pen useful. They are very cheap.

Please, bring on the criticism! This is my first time doing this kind of project, so there's no doubt places I can improve!

When I reflowed all the joints last night, the joints did get noticeably cleaner/smoother. The pictures were also taken in poor lighting, and it makes the joints look darker than they really are.

I will definitely go over them with more heat and a clean tip when I do as Paul suggested and touch up the 6 lug strip joints. Thank you for the advice.

[carlman14]

Alrighty... I added some more solder on the 6 lug strips and reflowed everything that looked dirty/not smooth with more heat and a clean tip. Hum is still there. I could be wrong, but it seems like this hum is connected to the 6080 tube. Is is possible that the 6080 is bad? Or is there anything else I can try?

[Paul Birkeland]

I suppose it's also worth asking what headphones you're using to evaluate this noise.

-PB

[carlman14]

Right... that would be important. Sennheiser HD 6XX from massdrop (300 Ohms)

[Paul Birkeland]

You are welcome to try another 6080.  There have been several occasions of folks changing out a tube and having a noise go away, only to have it come back later and be tracked down to a problematic solder joint. 

[carlman14]

Fair enough. I'll get a couple cheap 6080's off ebay just to satisfy my curiosity. Until then, I guess I'll keep tinkering around. If you can think of anything else, let me know!

[Deke609]

Two suggestions:

(1) Re-do the joints on the rca input center posts - In one photo, the left channel joint looks like a classic cold solder joint.  These joints are tricky b/c it's so difficult to get the wire to sit firmly in the solder cup before you apply solder. My approach is to have the open side of the solder cup face away from the direction the wire is coming from, so that the wire end can be bent to grab the inside of the cup and pull against it (subtle manipulations of the wire further upstream can give you that tension).

(2) Double check that the ground tab near the IEC is tight against the chassis.

Good luck!

[Neil]

Hey so like i mentioned in that thread i linked to you, i had hum for about 4 or 5 years. the speedball upgrade has made it DEAD silent. i mean absolutely completely silent. however, adding a DAC was also very helpful before i did the speedball upgrade since my pc was causing some hum.
the tubes are the originals since i built it.
the hum used to be really annoying.

[carlman14]

Hey so like i mentioned in that thread i linked to you, i had hum for about 4 or 5 years. the speedball upgrade has made it DEAD silent. i mean absolutely completely silent. however, adding a DAC was also very helpful before i did the speedball upgrade since my pc was causing some hum.
the tubes are the originals since i built it.
the hum used to be really annoying.

That's interesting that the hum went away after the speedball upgrade. I was hoping to find the cause of the hum before fully upgrading to the speedball. My computer is definitely super noisy... specifically a ground loop caused by my GPU. I fixed that with an ifi iDefender. But this hum I'm hearing is present even when the crack is disconnected from the rest of my setup.

[carlman14]

I have good news! It was indeed the 6080 tube! I got a couple cheap 6080 tubes off ebay. With both of these tubes, the crack is totally silent. And to confirm, I plugged the original tube back into the crack, and the hum returned.

Just for the record, here's another difference I noticed between the new tubes and the original: With the original, every time I bumped my desk (like with my chair), I could hear it through my headphones in the form of an echo-type sound (the crack is sitting on my desk). Even "little bumps", like just typing on my keyboard. On every key press, that was enough of a "bump" on my desk that I could hear that odd echo sound through my headphones. The new tubes don't do this, which further reinforces my claim that the tube was the problem.

Thank you everyone for your help. I really appreciate it!