Does this mean I have a bad tube?

Chris_B · « **on:** 20 Jan 2006, 02:19 am »

I have a varying very high pitched whine that I think is coming from my tube preamp. Would a bad/microphonic tube be the cause? It is only in one channel and goes away when the mute is one.

thanks,.

Chris

Carlman · « **Reply #1 on:** 20 Jan 2006, 02:22 am »

Sounds like it definitely could be. Do you have any spares to swap in and see if that's the case?

-C

jon_010101 · « **Reply #2 on:** 20 Jan 2006, 02:29 am »

I'd first give the tubes a little tap-and-wiggle before swapping -- make sure the unit is off though to avoid loud popping noises and such

. Sometimes they just need a little poke to get their innards in proper position. But if it continues, it is likely time for a tube swap.

Chris_B · « **Reply #3 on:** 20 Jan 2006, 02:29 am »

Yes. I have a spare pair. I plan to swap them this weekend. Apparently 5687s tend to be microphonic.

Thanks Jon. I'll try the wiggle first to see if that affects the whine.

jon_010101 · « **Reply #4 on:** 20 Jan 2006, 02:35 am »

Quote from: Chris_B

Thanks Jon. I'll try the wiggle first to see if that affects the whine.

And, as I said in the edit ... Be sure it is off when wiggling! Scary noises may occur otherwise!