Random single Pop noises from new SEX

[yay]

So i've been using my SEX now for a few days, and a few times a day a single pop comes from the speakers (and headphones). Most of the time on the left side, but i have heard it from the right side before. There doesn't seem to be a pattern when it happens, it just happens randomly. Like once an hour or so, not sure.

The noise FAQ says something about failing capacitor?
My measurements are all on point, and i thoroughly shook the amp to make sure no debris is still stuck inside and no bad solder joints seem to be present.

Should i just resolder some specific joints first?

 

[Mordicai]

Are you using a C4S? I had the same problem and turned out to be a bad solder connection on the center lug of the transistors on the C4S. Mess around with a chop stick while powered on and you will probably find it.

 

[yay]

no, not using the c4s - i got the 3.0.
should i have speakers plugged in while chopstickin' around or just voltage measure/resistence measure?

 

[yay]

i chopped around while running, tapping everything a few times, waggling around and could not reproduce the pop or other sort of noise, everything seems well in that regard.

 

[yay]

anyone got other ideas what i should check?
should i post pictures of the interior? i guess i will do that in a bit, can't hurt i guess

 

[mcandmar]

Could be a bad connection, which it looks like you have covered above.

Could be a bad tube, i have come across a few 6DN7s that will work fine, but every now and again give a very loud pop, enough to make your ears ring when using headphones.

Could also be mains noise, something electrical switching on/off in the house.  Light switch, washing machine, AC units etc.  ...probably the most likely scenario.

 

[yay]

Could also be mains noise, something electrical switching on/off in the house.  Light switch, washing machine, AC units etc.  ...probably the most likely scenario.

wouldn't i have the same with my crack then? only have it with the SEX, and 80% of the time only in left channel

 

[yay]

i ran the amp without input, but speakers connected and the pops still came. does that narrow it down a bit?

 

[fullheadofnothing]

Have you reheated every solder joint yet?

 

[Paul Birkeland]

You almost certainly have loose connection.  You almost certainly do not have a failed capacitor (that requires either 20 years of use or putting the cap in backwards during your build).

As others have mentioned, you can power the SEX up and hook it up to an inexpensive speaker (I suggest getting something from the thrift store or pulling one out of an old TV).  You can poke around in the circuit with a wood chopstick and eventually you may find a joint that, when disturbed, will cause popping out of your test speaker.

-PB

 

[yay]

i have reheated everything, but my solder iron broke and already wasn't working very well during the reheat.
i was gone for a few days, and have a new iron now. in a few days i will update here once i resoldered everything again. after the resolder i introduced a buzz, probably because the iron didn't seem to be heating very well and some connection i resoldered actually got worse  :

 

[yay]

resoldered every joint thoroughly with a much better working solder iron, problem still persists. not sure what to do

 

[yay]

i have some extra information, which might be relevant or normal:
when i have my crack plugged in, and turned on and then turn on the SEX i can hear a THOCK through my headphones (plugged into crack) - without inputs connected to the SEX, only sharing same outlet.

 

[yay]

I took a bunch of pictures, not sure if it's too many to post

 

[yay]

again i tried to chopstick around very very thoroughly, and not softly.
i could not produce the pop or any noise of any kind. the solder joints seem very solid, i ripped at the cables, tapped all joints and other parts, waggled everything around while using cheap headphones (pop is with speakers and phones) and could not get the sound to reproduce.
i'm seriously at a loss right now, i would try any farfetched idea you guys have.

 

[Paul Birkeland]

Well, at this point I would bring in another potential source: outside interference.

Can you take your SEX amp in to work to see if the same issue happens there? 

What I'm thinking is that you may potentially share your power utilities with neighbors, or there may be some appliance in your home that is sending out some noise into the power lines periodically, and that may be what you're hearing. 

In a lot of solid state electronics, there are regulators that can swamp out this transient garbage, so you may not have noticed it before.

-PB

 

[yay]

Hey, i'm getting a UPS for my pc and monitor, (waiting for it to arrive) and will also hook up the SEX to it. As far as i understand it, that might be able to help if it's the fault of "dirty" power(spikes). will post about results here. i wouldn't be surprised if it's power related, lots of people live in this building and it's a very old building.

i could also try switching out the tubes, i switched the left for the right one but the popping still kept happening 90% of the time on the left side. (switched speakers and speaker cables too)

 

[yay]

Okay, long time no update.
I asked some other people, and they suggested switching some of the capacitors from left to right to see if that moves the pop.
it seems the 0.1uf 400v capacitor might be the problem.

i want to just buy a replacement here, and check it out.
they are not very expensive, and i want to get some mundorf since they are widely available in germany.

0.1uf 630v 3% with a size of 10x19mm should work fine?

 

[fullheadofnothing]

That's pretty close to the size of the Daytons, so it should work fine.

 

[JeffYoung]

Yes, the Mundorf MKP should work well there.


If you decide to upgrade to one of the premium Mundorfs, do the parafeed caps at the same time.  (They're the 1.5uF 630V ones.)



Cheers,
Jeff.