Left channel fading in and out

Marek, after checking the turntable as Zd suggested, what you should do is to interchange the left and right channel connections at various points in the signal path, perhaps starting somewhere in the middle (e.g., at the outputs of the preamp). If the problem continues to be in the left channel, you will have established that it is being caused by something downstream of the point where the interchange was made (e.g., the amplifier). If it moves to the other channel, you will have established that it is being caused by something upstream of that point. Continue that process until you identify the component or cable that is causing the problem.

As Ray indicated, of course, shut down the system before changing any connections.

Best regards,
-- Al

Hi Marek,

A passive speaker (one that does not have a built-in amplifier, and an AC plug that plugs into the wall outlet) cannot make any sound without a signal being sent into it. And if the volume control is all the way down, there should be no signal being sent into it (apart possibly from very low level hiss or hum generated by the amplifier, or by preamp circuitry that is downstream of the volume control, or as a result of ground loop effects between the preamp and amp).

So I continue to suggest performing the channel swaps, to determine the component that is responsible. And I think that Bruce (Bifwynne) could very conceivably be correct that the problem is a tube.

Best regards,
-- Al

If it's a tube, would it be one of the power tubes or the input/driver or line stage tubes?

Don't know; could be any of the above, or something else. The fact that crackling occurred with the volume control all the way down, though, most likely indicates that the problem is either in the amplifier, or in preamp circuitry that is downstream of the volume control (for example, the output stage of the preamp).

Best,
-- Al

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