Left channel fading in and out

As I was listening to records last night I noticed the left channel started to fade in and out, not completely, but audibly. No distortion, just slight fade-out for about a second at a random pattern. At first I thought it was the new used record I bought and was listening to for the first time, but it continued when I switched to another record I was familiar with and didn't remember having this issue. What could cause this?

I have a solid state phono preamp, tube line stage, and tube monoblocks. Could it be the speaker? A failing tube? Problem with one of the interconnects? Any input would be greatly appreciated.
You don't say, but I assume the system was working before and this is a new problem. I would first check your TT setup to make sure that your cart didn't get knocked out of alignment, or something similar. If the problem is still there, I would start with swapping components, one at a time, until you find the problem. Do the easiest ones first, like cables.
Great advice from Zd542! I had a similar problem.Turned out to be the power switch on my tube preamp.Good luck,Be careful not to short anything out when troubleshooting.To be on the safe side ,turn everything off when changing cables,tubes ,and let us know how it goes.
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
What Almarg said.
With reference to Zd's idea, I cannot imagine how "knocking" the cartridge out of alignment could produce the phenomenon that you described, but you're going to find out whether the cartridge is the cause by swapping channels all the way up the chain.

Unfortunately, IME, when one has an intermittent problem such as this it typically fails to reveal itself when one is hunting for it. I have been trying to find out for 8 months what is wrong with my Sony CDP. It malfunctions in my house but not on Bill Thalmann's workbench, except for a brief moment which allowed us to confirm that I am not imagining things.

"I cannot imagine how "knocking" the cartridge out of alignment could produce the phenomenon that you described."

It can easily do that. The groove in a record is shaped like a V. The info for the right and left channels are on each side of the wall. If the cart is not aligned properly, it may not be fully able to touch both walls the amount it needs to produce full resolution, causing an intermittent problem. I also said "or something similar". Things like not having enough tracking force, anti skating and SRA, can also contribute as well. If the problem is alignment related, it can very well be a combination of the above. Or, like you say, it may be something else entirely.

As far as your CD player goes, that seems like an interesting problem, as well. I think you need to find out what is different about Bill Thalmann's workbench than your equipment rack. (I know that sounds like a smart ass remark, but its not.) There really may be some difference you are not aware of that is causing the problem. It could even be temperature related. Just by taking it out of your system for a while may let it cool long enough for to work.
Actusreus, everything Al said -- try. Got a funny feeling though you've got a weak or failing tube. Nevertheless, follow Al advice. Please let us know how your detective work fares.

Good luck.
Thank you all for good advice.

Can anything be eliminated as a potential culprit? I was going to ask whether tubes could be crossed off the list, but just saw Bifwynne's post...I was also going to suggest the speaker since I'd think any damage would be fairly obvious, not as subtle.

I will recheck the cartridge alignment. I actually checked the VTF that very same night before I started hearing the problem, and it was as intended. I probably have about 1000 hrs on my Delos.
Actsreus, I still think whatever Al says is good advice. But try this short cut. Switch speaker cables left/right. See if the fading problems moves. If not, in some goofy way I do not understand, it could be the speakers. If yes, moving downstream, check the bias of the power tubes on your amp. Btw, how many hours on the tubes? If your pushing to the outer edge of the envelope on tube life span, I'd be looking to retube regardless. After these quick checks, back to what the folks above said.

Any problems I've had with my gear -- which have been few -- were tube related.
The speaker cables are the Anti-Cables (solid core copper with a thin layer of coating) with bare ends so switching L and R would most likely not show anything.

I checked the tubes and the bias was spot on. They are relatively knew as I replaced them in late July. I'm of course talking about the power tubes in the monoblocks. I don't know how to check the input tubes in the power amps and the tubes in the line stage. Those are over year and a half old.

I might contact Rogue Audio to get Mark's input on the tubes. In the meantime, I'll follow Al's advice, which is always a good idea :) Thanks again for the suggestions; I'm pretty bummed about this.
It appears it is the speaker, after all. When I turned the system on, with the volume knob all the way down, I heard some crackling sound coming from the left tweeter. When I turned it up, with no music on, the crackling disappeared, but the fade-in and -out continued with the music playing.

The night the problem started, I apparently put a record's sleeve on the volume remote by accident and left the room to get a drink from the kitchen. With a delay, the volume began to go up. I ran back to the room, and a friend of mine who was in the room, grabbed the remote and turned the volume down, but the knob must've have gone up almost all the way up for a second or two. It is possible that it caused some damage to the tweeter. I'm surprised since we listened to several records with no issues after the remote incident before the problem revealed itself. But at this point, it's seems to be pointing to the speaker. The SR-17.5 from Silverline Audio are incredibly well-made and I know they can handle a lot (apparently max output is 126 dB), but I guess all it takes is a moment of inattention and bad luck sometimes.
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
Yes, the low level hiss is what I would usually hear with my ear close to the tweeter. But when I powered up the system today, that hiss had some crackling as well.

I checked the cartridge alignment and it was correct. I will start the check as you suggested. If it's a tube, would it be one of the power tubes or the input/driver or line stage tubes?
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).

-- Al
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.

-- Al

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.

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.


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.