Noisy Right Channel

So I had my stereo playing while I was getting ready for work today, and when I changed the disc, I noticed some noise coming from the right speaker, when there should have been, you know… silence. Noooooooo!

I wouldn’t describe it as a hiss, hum or static. More like an irregular crackle, similar to a radio that is between stations.

The sound didn’t increase or decrease with adjustments to the volume control. It was present regardless of whether my dac’s inputs were set to coaxial (cd transport) or usb (streamer). Was present with my dac powered off. Was present with preamplifier switched to other (unused) inputs.

My interconnects are all shielded, and, along with my speaker cables, are not routed in close proximity with my power cables.

turning off my preamp (whilst leaving amp on) did cause the sound to cease.

Is it possible that this is a symptom of a (6h30) tube approaching the end of its service life?

Any suggestions for troubleshooting?



FWIW I don't feel that usually having 'matched' pairs is all that additive. At least I never used them in my ARC pre. Unless your pre-amp has provision for biasing small tubes I'd just cheap out and buy the Sovteks from the Tube store. If they are not perfect performers just use them until you can get better ones, i,e, a matched pair of them, a pair of matched EH's or some NOS (and very expensive ones) and keep them for spares and use them in an emergency like now.  

I had the same problem after I modified a Marantz Model 7 preamp (following personal guidance from Saul Marantz himself!) and had soft hiss and crackling in the right channel. Turned out I installed a defective coupling Mylar capacitor (Mylar because it was 1976), or else I applied to much heat on the capacitor leads while soldering in place. Problem went away after replacing the capacitor.

Could be a bad capacitor, as well as a failing tube.

Matched pairs is more of a power output tube issue than a preamp concern, though I certainly acknowledge that some are paranoid about this issue at every level. 

I’ve bought tubes from Viva, they may not be the cheapest but they usually have what I need and ship the same day.

Here’s a link to Upscale’s tube FAQs.