Rebuilding my kit - shielded twisted pair options, and a film cap [resolved]

Okay. If that's the case I'm honestly sorry to be taking up your time with the most obvious problem. I really did try to double check everything.  Any hints on where I could look based on the symptoms, or how I might diagnose? Everything really does look intact to me on the surface (I will visually inspect again though). Should I be powering it on upside down and tapping things with a chopstick or similar?
 
I would start by reflowing all of the headphone jack and speaker binding post connections as well as the output transformer secondary connections.
 
So I reflowed the headphone jack (all), the OT secondaries (all), speaker terminals (all), H1 & H8, and both sides of both output caps. The headphone plug/unplug pops are now completely gone, and it feels like maybe the noise floor is a touch lower.

All those joints looked pretty shiny already (definitely nothing like the 'bad' examples in the manual) so I'm at a loss as to which it was that resolved it, but I'm also very happy to eat humble pie and nail that one down.

I'm unsure if this issue is the same as the once-hourly pop, so I'll continue to monitor for that and post back if I either hear it again, or feel it's gone completely. It would be wonderful (if embarrassing) if they were the same issue, and unrelated to the problem with the original build. Faulty reasoning on my part I suppose, trying to connect unrelated dots.

Thank you both for your help.
 
Nope. The random popping persists.  :-\ This time I turned the amp on and just sat here with the headphones on and no music playing while typing an email. Maybe 10 minutes in, with no movement or change of any kind, the left channel went 'pop'.

I just received a few extra sets of tubes today, so I'll see if I have any more luck with them.
 
You might want to poke around in the circuit with a wooden chopstick to see if you can actuate the popping by moving anything.

I'd also use very, very hot water to clean off the tube pins on the tubes that were originally used in the amp, as there may be some flux remaining there.
 
Is it possible that this popping comes from outside the amp itself? Easy to check - remove all inputs and turn the volume all the way down and see if it stops.
 
So the GE tubes I swapped in didn't give me any grief for the hour I was able to listen last night, although that's not enough time to be certain, and I'm also mindful that reseating tubes is a confounding variable every time I do it. I'll listen more today.

Paul Birkeland said:
You might want to poke around in the circuit with a wooden chopstick to see if you can actuate the popping by moving anything.

I'd also use very, very hot water to clean off the tube pins on the tubes that were originally used in the amp, as there may be some flux remaining there.
Click to expand...

Flux on the pins of the old Sylvania tubes is certainly possible. I remember that back during the first build there was definitely flux on them - jostling the tubes before I realised that elicited a thunderous sound like a box of heavy books being kicked down a flight of carpeted stairs. This time around I gave them a bit of a clean with iso but it may not have been sufficient. I'll try the water thing. Would standing them in 80C water for a bit and then taking to them with a (clean) toothbrush do the job? I'm hoping they haven't contaminated the new sockets - if I have to pull the thing apart to replace those I might need to go swear loudly for a while. I don't think it's likely, though. Jostling the new GE tubes did nothing at all on the B side, and only elicited the slightest of susurrus noises I would expect is normal on the A side. Definitely no pops.

Paul Joppa said:
Is it possible that this popping comes from outside the amp itself? Easy to check - remove all inputs and turn the volume all the way down and see if it stops.
Click to expand...

I did have that thought (earlier in this thread) about my DAC. It has an internal switching supply and I understand that sometimes those can do unexpected things re: ground. I wasn't sure if having nothing on the inputs was good for the amp but if it's fine I'll certainly give it a try.

I think my plan of attack will be:
[list type=decimal]
[*]Keep listening with the GE tubes. If there are still pops...
[*]Remove the input and keep listening. If there are still pops after that...
[*]Poke with a chopstick until pops happen.
[/list]

Thanks again everyone. We're gonna figure it out eventually!
 
It is completely possible that running with the conductive flux could do some weird stuff to the tubes themselves, though the kits I've fixed with these issues haven't shown tube damage (that I can remember at least).
 
Paul Birkeland said:
It is completely possible that running with the conductive flux could do some weird stuff to the tubes themselves, though the kits I've fixed with these issues haven't shown tube damage (that I can remember at least).
Click to expand...

For sure. I'm keeping the Sylvania aside until I'm satisfied the amp is issue-free with other tubes, at which point I'll clean them and see if they behave. They're in the '?' box at the moment. It would be nice if they can be salvaged, as unlike the GE and RCA I've received from the folks at Vacuum Tubes Inc., the glowy bits on the Sylvania face forward when installed in the SEX. Which is just nicer to look at.

That said, the GE seem to be really nicely constructed.

Just as an aside, if I'm not the only dummy to fall victim to this water-soluble flux issue, I wonder if it's worth adding a disclaimer about it under the one about plumber's solder (unless it's there somewhere and I missed it). This really has been an ordeal I'd like to help others avoid, however much of a edge case it might be. For reference, I got to the idea of using ChipQuik by hearing younger folks working exclusively with SMD PCBs talk about it. It never occurred to me that dropping a PCB into an ultrasonic cleaner is a part of their process, and a lot easier than cleaning a point to point kit. There's also a lot of fear-mongering about rosin solder and corrosion out there, and it took me a long time to realise that RMA solder manufacturers will put it right there in the datasheet that cleaning is unnecessary outside of specialist industry (which audio ain't).

I'm also wondering now whether the pin cleaning method linked above might also work for prepping the lower eyelets of those Keystone 8 terminal tagstrips I had the trouble with that drove me to use extra flux in the first place. I might have to test that with a spare tagstrip at some point.

Edit: That's in no way an attempt to blame you folks for my mistake by the way - that's 100% on me.
 
The disclaimer is on page 7 and specifies that rosin core solder is to be used and nothing else or it will ruin your kit. 

 
Doc B. said:
There is also a video dedicated to soldering techniques specific to our kits on our youtube channel. The newer manuals include a link to that video.

https://youtu.be/EN16Pi7pcfk?si=x1-9aWg8UfsTL3lG
Click to expand...

Rewatching I can see that you do mention flux as part of your disclaimer about plumbing solder "and we are not talking about any kinds of additional flux that you would apply, stay away from those". I missed that, and that's on me.

Paul Birkeland said:
The disclaimer is on page 7 and specifies that rosin core solder is to be used and nothing else or it will ruin your kit. 
Click to expand...

To be fair, I did use rosin core solder - it was the additional (non-rosin) flux that did me in. In retrospect it's obvious that 'flux is the stuff that is in the solder, and if I say only rosin core solder I mean only rosin flux'. I didn't know enough to make that connection at the time - if you flush all the knowledge and experience from your mind and read the warning on page 7 with the question "can I use this water soluble flux?" in your head, it doesn't rule it out. It also doesn't rule out eating your own shoes, so I am saying this understanding that there are reasonable limits to the warnings a customer should expect. I'm open to the possibility that I'm just especially dense. It probably doesn't help that there are quite a few people out there using 'flux' and 'rosin' interchangeably, making it harder for the novice the understand that there is a difference.

What I should have done, when I had trouble getting a good joint on H2U-H7U, was come here and talk it through. Lesson learned.

I don't know if it's helpful, but the warnings that stick out in my mind are the ones on page 20 because they spell out the consequences of using plumbing or lead free solder.
 
Paul Birkeland said:
Water soluble flux that's conductive is plumbing flux.
Click to expand...

Hang on a sec. I've clearly got this all confused, as it definitely wasn't plumbing stuff...

*checks old Mouser invoices*

This is the stuff I used: https://www.mouser.com/datasheet/2/73/SMD491_10M-2511050.pdf

Now I'm reading the datasheet and it says it's non-conductive, so I guess it got into the socket and was preventing pins from conducting, rather than shorting them?

I think I understand now what's happened. Clearly edge-case stuff outside the scope of what you'd need to warn about. My apologies. I feel pretty thick right now.
 
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