Loud static in left channel

[jxu1234]

Hi, new builder here, I've just completed a Crack build and begun testing, and when the amp is turned on before plugging any inputs in, I hear loud, radio static-like noise in the left channel that doesn't change when I adjust the volume pot, while the right channel stays silent. When playing music, both channels work fine except for the left channel noise which still persists.

I've changed both the preamp and the power tube, and visually inspected plus tugged on all solder joints to make sure they're secure, and it didn't mitigate the problem at all. What could the problem be, and what can I do?

Thanks!

[Paul Birkeland]

How are your voltages?

This may also be part of the issue:
https://forum.bottlehead.com/index.php?topic=11676.0

[jxu1234]

Voltages look fine as tested using the instructions in the manual.

I've plugged it into two different places in my home and the issue does persist - could the noise from power lines only affect one channel?

Though, I've only been plugging it into surge protectors with other appliances on it. Will try wall plug but I doubt that's gonna fix it.

[Deke609]

Maybe posts some pics, including a clear pick of the headphone jack wiring and one of the rca input jacks wiring.

cheers, Derek

[greenneedle]

First thing I would do is test the headphones in another amp (I use my 70s solid state) and make sure it isn't the phones or lead.  turn the jack in the socket, wiggle the lead.  This eliminates the headphones.

After you confirm the headphones are fine (like I did) then you know it is something in the amp.  In my case it was a weak connection in the 12AU7 socket.  Maybe an Led one or another but I re- flowed them all and the problem disappeared disappeared.  You might be able to replicate the noise (if it isn't happening at the time by just wiggling gently the 12AU7 in its socket.

If it is constant then it is might be the headphone jack wiring.

One other thing I noticed was a deepish hum when I was using mine.  Like background hum that you can often get with speakers / phones when turned up ridiculously high.  I accidentally found out then when I turned my landline off the hum went.  My landline is one of those that sits in a charger which sits on the shelf above where my Crack was.