Left channel popping and noise/hiss [SOLVED]

[Grainger49]

There are a few questions outstanding.  It will help others help you.

Have you swapped the 6080?

Did you try diddling the volume control, I was serious?

Did you check the input RCA jacks?

Is the noise still a static sound?

Dan suggests to reflow every solder joint, not just the signal path.  Good advice!

BTW, the noise floor is regular, so you have something else causing the noise.

[Laudanum]

Yeah, what Grainger said ... did you swap out the 6080?

[Nick Tam]

Yes, UPDATE 4: Rolled in Tung Sol 5998 which is the output tube. Problem persists.

RCA jacks are fine, I've resoldered them too. Didn't help either.

Volume pot seems fine, the noise is constant regardless of the pot. The noise is as loud as always even when turned all the way down...

[Doc B.]

If the noise is constant volume the source is after the volume control.

[Nick Tam]

Basically everything else... oh my.

[Doc B.]

At least you have started the process of elimination. You know it's after the volume control. You know it's only in one channel so it's not the power transformer. So there are at least 50% fewer places where the problem could be than when we started. You have already swapped both tubes and it doesn't seem to be related to them. So you are getting down to the stuff in the left channel of the amp itself, that might be a problem. My gut feeling is that it is either a bad joint or it might be a semiconductor in that channel. Did you build the circuit in its most basic form before adding the Speedball? Or did you build it with the Speedball incorporated? If it was running OK before the Speedball was installed then the problem is probably related to the installation of the Speedball components. If it all went together in the initial build it will be a little more challenging to isolate the problem.

[Nick Tam]

So i should try running it without the speedball again?

i built straight to the speedball and it was fine, then one or two LEDs died so i reverted to stock form during the initial build. that was long ago though, so i should try taking off the speedball and see how it goes? but could i be assured that if the noise is still there the speedball circuit is definitely not the problem?

[Laudanum]

If you remove Speedball and revert back to stock form and the noise persists,  it isnt speedball.  If you pull speedball and the noise is gone, then it's on the speedball board or in the wiring to and/or from speedball.   I would try the chopstick test first while listening with an inexpensive headset ... poke around with a non conductive probe touching solder joints, terminals, passive components, wires, etc.  and listen for increase or decrease in the noise.   A wooden chopstick is actually a good probe.  Or, small dowel rod, etc.  You get the idea.   If that doesnt get you anywhere, pull speedball and see if that's it.   I should mention that Im no expert like a lot of the gang here but the chopstick test is a common troubleshooting method when the noise source isnt easy the figure out.

[Nick Tam]

Update 6: Was nudging some of the speedball board wires and some broke off... resoldered those. Was going to resolder joints anyways so I decided to replace some parts as well... replaced 270kOhm Resistor with a Kiwame and stock Octal Ceramic Tube Socket with a teflon one and resoldered completely, looks like the pops are gone for now. Now just waiting for it to pop or not at all. So far so good. Say give it 24 hours more run time? If problem still persists, then I'm probably going to replace all the wires as well...

Next up:
Replace volume pot with a DACT step attenuator, probs?

[Laudanum]

You werent specific where your wires broke, solder point or above but it's not uncommon for them to break where the insulation was stripped off.  You have to be careful not to nick the wire and it's more difficult with that teflon insulated wire.  Plus it's smaller gauge so easier to break if nicked.  Lesson learned, right?      If it stays silent, and I bet it will, I'd just leave it alone.  If you suspect more wires are on the edge ... you can find weak wires that may have been nicked pretty easily.  A little manipulation of the wire and if it's weak it will snap where it's been nicked.   

As far as the DACT stepped atten.,  never used one.   Personally, I havent had any interest in a stepped attenuator for Crack.   Being a headphone amp,  I want the finer control of the poteniometer.  But many use a stepped atten.  Consider whether you think you will miss the fine control if going to a stepped attenuator.  If you think you want to go that route, plenty here with experience with all types of attenuators.  Ask in a new thread here or in general forum.   There are also some nice sounding pots that track very well if you want to retain the fine control.  The PEC carbon is supposed to be very good sounding at about $35.  The Alps Blue sounds good and tracks very well at about $15.  Then there is the TKD for about 100 which is a conductive plastic like the ALPS but is supposed to be a sonic upgrade, very smooth and apparently tracks very well.  Im happy enough with the Alps.  Tracks well at low volume and is smooth and sounds good to me.  I would like to try the PEC carbon though.   Lots of stepped atten. options as well like DACT that you are thinking about.   Goldpoints seem popular as well but the SMD resistor models dont seem very well received here (with FPIII atleast).

Glad to here it's working well now.  Hope you have no more problems.  I think you got it figured out.

[Nick Tam]

The wire that broke off specifically was a ground wire from 9L to the board and the red wire going to the I slot the PCB board of the problematic channel, seems like it fixed it. Although I'm pretty sure the resoldering did the job as well.

Probably thinking of replacing the wires with OCC or silver, although that would be left to another discussion forum.

Later and thanks guys!

[Doc B.]

Yes, sounds like it was a wire nicked right at the insulation that gave from working around. We've had amps across the bench with that problem before. It would be worth taking a scrap piece of that wire, stripping the end and sliding the insulation back with different settings until you see a clean strip with no nicks, to make sure the problem doesn't continue to 'pop' up (sorry for the pun).

I'll put a post up in the tech tools section.