noise in left channel

[soundsgood]

hello all, my son gave me crack for christmas, GOOD BOY! i had a lot of fun with the build. it sounds wonderful. i replaced the supplied rca 5963 with a french military radiotechnique 12au7wa that i had on hand. it brightened up the mids and highs just the right amount while still retaining that great bass bloom. as with all my audiophile gear i clean the tube pins with a sand eraser from an art supply store, then clean with q-tip and isopropyl alcohol and then a light coat of deoxit gold taking care not to bridge the tube pins. yesterday noise developed in the left channel. it is very faint and sounds like the static when the needle first hits the groove and is intermittent. i swapped the input tubes but no joy. i feel confident that my solder joints are solid. i am not a beginner with a soldering iron and rebuild old tube radios as a hobby. i suspect the power tube has become noisy. so here is my question: can you tell me what power tube was shipping last christmas? i would like to maintain this sonic balance. the tube only says 6080wb usa. it has 3 micas top one is round, double halo, white insulator at pins and silver coating is so thin you can almost see through it. thank you for such a terrific product and hope to see Bottlehead at T.H.E. show newport beach. 

[Paul Birkeland]

Hello Bob,

I'm glad to hear that you're enjoying your amp!

Does the noise develop immediately after turning the amp on, or after a while?

Do you have the Speedball?

As far as the 6080's go, we are not specific with the variants of old stock 6080's that we get, as we buy them in bulk.  There are a myriad of tube dealers online, and if you send them a photo of the 6080 that you have, they should be able to sell you match for ~$20. 

It sure wouldn't hurt to touch up your solder joints around the 8 pin socket, just to be sure.

[Doc B.]

Man, PB just keeps posting faster than me all night long. I ashamedly admit that I am not enough of a gonzo Crackhead to know the subtleties of the 6080 varietals. And we get whatever 6080s the various suppliers we buy from happen to have harvested lately so there is no sure answer based upon when the kit shipped either. But if you don't get an answer here from the more knowledgable tuboissuers (I'm pretty sure that's a word) there may be people on the Head Fi forum who post in the Crack thread who know exactly what that is.

[soundsgood]

it starts 6 minutes after turn on. noise cycles every minute or so.

[Doc B.]

If it's that exactly repeatable it's external interference. If it's just generally that time frame with variations it could be the tube or a damaged cap. If it's random intervals it could be a bad joint.

[soundsgood]

 i have already ruled out interference. would that be a coupling cap? btw no speedball yet

[soundsgood]

it was the power tube. thanks fellas