Left channel fading in and out

I decided to switch the speakers to see whether the problem would remain in the left speaker or move to the right one. I figured this would allow me to at least eliminate the speaker as the source of the problem.

The fading in and out appears to have moved to the right channel, so I'm now pretty sure it is the speaker, not any of the tubes. Puzzling, the effect seemed less frequent after the switch, but it was undoubtedly the right channel that was fading in and out.

Marek, nonetheless I still find it hard to conceive of how a fault in the speaker could result in crackling from the tweeter when the volume control is turned all the way down. The likely cause of that kind of symptom would be a problem in either the amplifier, or in preamplifier circuitry that is "after" the volume control. Perhaps:

(a)The crackling and the fading are being caused by two different things. Or,

(b)The problem is being caused by the amplifier or preamplifier, but there is an intermittency involved which causes it to appear in different channels at different times. Or,

(c)Slight differences between the impedances of the two speakers result in an amplifier problem being triggered by only one of the speakers.

Best,
-- Al

Actusreus,

You said you "switched the speakers". Did you literally move the L and R speakers across the room or did you swap L and R speaker cables at the amp outputs? Makes a big difference in the interpretation of your results.

Al,

I did hear crackling for a few seconds, which I immediately attributed to the problem, but it has disappeared since and I did not hear it at all yesterday when I switched the speakers. I always hear low level hiss from the tweeters with the volume know turned all the way down; perhaps the crackling was the result of some irregularity in the current that manifested itself through the speaker. I'm not sure how else to explain it. However, it is puzzling that after the switch the frequency of the fade-out seemed to have decreased, even though it was still with the same speaker.

Doug,

Yes, I physically swapped the speakers so that the right monoblock was now feeding the speaker that used to be the left one (the one revealing the problem), and vice versa. I didn't touch the cables at the amp terminals. The fade-out appeared to have moved to the right channel with the speaker. I'm in the process of contacting the dealer I bought the speakers from to see what my options are. I think they definitely need to be at least checked out.

Since the problem seems to follow the speaker, you may want to try this. Check your speakers out really well. Sometimes the drivers loosen up over time. I would check to make sure everything is tight. I don't know for sure that's the problem, but its worth a try.