Random pop sounds in my system are scaring me

Hi, I need some help and expertise on this potentially expensive situation! The last few times I've powered up my 18wpc SET amp it has been plagued by some startling "pop" sounds at random intervals. The amp switch is in the mute position, with no source selected and yet at random intervals I hear an alarming pop sound coming from the speakers. The volume of the popping isn't SUPER loud, but it does startle me and has me worried. The weird thing is, sometimes it happens, sometimes it does not. I'll have to do some more testing, but I haven't noticed this happenig when a source is actually playing through the speakers. When I bias the tubes immediately after hearing a pop, I don't see any weird numbers or behavior on the bias meter. The amp is only about 3 months old and it took so long to get, I'd hate to lose it! I know it could probably be a million different things, but does anyone have an idea of what might be happening here? Help!
Snap Crackle and Pop? Kellog and Rice invented the moving coil loudspeaker while at GE and then went on to invent what they are best known for - breakfast cereal.

More seriously - this might be a capacitor breaking down...but it is hard to say as so many tnigs create Snap, Crackle and Pop - even milk!
If it is indeed a capacitor breaking down, is this something that has the risk of destroying the whole system if I keep listening?
Try tapping the driver and output tubes with a pencil. Sometimes a bad internal connection will cause the noises you are describing. If that doesn't narrow it down for you and the noise only occures in one channel: Swap all the tubes and see if it follows. At three months old: Isn't the unit still under warranty?
Yes, the unit is definitely still under warranty, but I'd need to ship it back to Japan! I'd like to avoid that if at all possible for cost reasons, as well as wear and tear from shipping. Thanks, for the suggestion, I'll give it a shot.
Hopefully- It will simply be a defective tube. Let us know your results.
I had the same problem a couple of monthes ago. I swapped my tubes left to right, the sound followed. Replaced the bad tube (kt88), no more popping. I hope this is your problem; cheap and easy fix. good luck
I vote for a bad tube. As has already been suggested swap the tubes from left channel to right and see if the popping sound follows the tubes. I had this once with some 300B tubes that went bad after a very short time so that's the reason I lean toward suspecting the tubes.
You may try cleaning tube pins as well as the tube sockets. The tube internals may be perfectly fine.
I agree sounds like a bad tube.
As Beerad and Jaiello said try the tube swap and post the results.
First, thanks to everyone who has offered their help and expertise on this, I'm new to tubes and need all the help I can get. I played around a little bit last night and I could reproduce the pop when I plugged and unplugged my phono stage. The weird thing is, it didn't happen every time! I have no idea what it could be, does the problem lie with the amp itself or my wall outlets, or both? Again, this is a new problem, only within the last week. It's strange because I was hearing it on its own, withough plugging or unplugging components...only today it happened when I plugged/unplugged my phono stage.
Are you saying that you are plugging in and unplugging your interconnects with the equipment turned on, and selector turned to that input? That's never a good idea, and will always result in a "pop". Lots of potential for sending an unhealthy transient to your speakers. Have you tried any of the above suggestions regarding your tubes?
No, no, I'm not unplugging the ICs, just the power unit to my phono stage and I haven't done the plug/unplug thing with a source selected...the times I've heard the sound, the amp's source select switch has been in mute! I've tried tapping the tubes lightly, but nothing. Its a strange problem as it seems very random, other than today when I plugged in my phono stage.
Yet another vote for a power tube going south, just happened to me the other day (grumble, grumble).

Do you have a spare? If so, change out the tube or tubes in the channel where the pop is occurring.
No surprise that you would hear a pop when powering up a source while the rest of the system is active. You've still not mentioned if one or both channels are making noises. If one- Have you tried the tube swap?
I think it's both channels, but I'm not 100% sure yet, as the last two times I've heard it I've been next to the left speaker. I haven't tried to swap tubes as money is a little tight at the moment...I'll definitely have to bite the bullet soon though, as a bad tube seems to be the most likely culprit. Its tough to figure out because the instances are so random. Also I've noticed that the pops seem to happen more or less within the first 20 mins after power up, after that point I haven't heard much. So many variables! I'd love to just move the whole thing to another room/power outlet, but this is impossible in my apartment at the moment.

when people tell you to swap the tubes, they don't necessarily mean to buy a new set, they mean for you to take the tubes that run the right channel and place them in the sockets of the tubes that run the left channel, and vice versa. by switching the tubes positions in the amp, you can narrow down if it's a bad tube causing the pop as the pop will travel from one channel to the next.

now, if the popping is in both channels, it might not be a fault tube. as you stated, there are lots of variables at work. out of curiosity, what amplifier are you using?
The amp is an Almarro 318B, about 4 months old. I will try the tube swap, but I'm pretty sure its coming from both speakers. I could be wrong though as its tough to tell as I'm never ready for it when it happens!
Well, I finally tracked down the culprit responsible for the random popping in my speakers...a bad 6C33C power tube. Thanks for all the assistance and suggestions, I should have just checked these first by swapping them to see if the popping sound switched speakers (which it did)...got a new one and everything is now fine.
Good to hear you solved the problem!! Happy listening! =8^)