Is My Tube Amp Unfixable? Help Needed


Hi All: It's been a while since I have posted, but I am posting now because I need advice from those who may have experienced something similar. I really am in a tough spot with a tube amp that it pains me to say I am tempted to literally throw away or give away. This is a long story, so grab a beer or cup of coffee:

In October 2020, I bought brand new Quicksilver Mono 120s...FANTASTIC sounding amps, btw, and the third pair of Quicksilver monos I've owned (I also own their line stage preamp). Immediately, the left channel amp began emitting static pops and crackly, intermittent noise...low level but loud enough to hear from my listening position 8 ft. away. After painstakingly exhausting every possible source of noise (power tubes, driver tubes, speaker, preamp, interconnects, iPhone, CD player, electrical socket, power cords, etc), I called Quicksilver and was told to send the amp back...could be a bad resistor but now sure. Quicksilver looked it over and determined that it was working perfectly...no noise. I got it back 3 weeks later and...same exact noise. Several months later, I called QS and explained the situation in detail. They said to send it back a second time with the tubes I was using. Again, I shipped it back, and Mike Sanders did a very, very thorough check of the amp. He called me to discuss, and the verdict was the amp was exhibiting no noise and working perfectly. I got it back and yep...the same noise with the same exact tubes Mike had. In addition, UPS had dropped the box so hard in transit that when I received it from QS, 2 of the 3 binding posts has completely sheared off and were rattling in the box.

So now I had a noisy amp the manufacturer could not diagnose and that was unusable. I was not going to send it back to QS a third time ($100 in shipping a pop), but I needed the binding posts repaired. So I drove it an hour to a local tube repair shop that specialized mainly in guitar amps but who told me he could work on it. And yes, you guessed it..."Your amp is working fine. We checked it out top to bottom, and no noise." $160 later for repaired binding posts, this amp is STILL noisy and actually worse than ever. Btw, I have since moved to another state and set the amp up in a completely new place...same noise. 

So, I have a $2,000 amp that I cannot use and apparently no one can repair, and I am at my wits end. Btw, the amp is still under warranty, but QS no longer makes the Mono 120s, so they cannot swap it out for a new one. Do I simply just keep shipping this amp to random repair shops only to hear "it's working fine," or do I literally throw it away? Audiogon, I need your advice.

bojack

Get another brand and model and put into your system for 1 to 2 months. If you don’t hear the issue, your problem and aggravation is gone. Get rid of the amp. Don’t let the problem and loss of money bother you. I had this same problem with a manufacturer and sold both preamp and amp back to him at a big loss. My situation was very similar to yours. I moved on from the brand entirely. The reason? There are many, many manufacturers of audio and thousands upon thousands of available equipment.... many of which is capable of bringing you joy. It's not worth the aggravation of trying to get one pair of amps working properly. IMHO.

Bad Jokes Aside:

I had a similar unresolved situation.

Fisher 80AZ Mono Blocks, made in 1958, dead silent performance for 60 years. A few resistors replaced over the years.

Then, a low volume intermittently crackling. Silent for about 30 minutes, the crackling began and lasted about 30 minutes, then gone, played silent until the cows come home.

Switch left/right/cables/speakers/ go nuts, nothing changed the 30min/30min cycle.

Took to well known tech, he played them in his shop for a week, checked tubes, changed side to side: never misbehaved. Home, problem the same. After a while tried my friend’s beloved tech, same, no noise there, but guessed and changed a few small things. Home, same 30/30 min cycle.

Had a friend/buyer audition them, no problem, loved them, sold them, never a problem at his place for 4 years so far.

Current Cayin AT88T, same cables, same speakers, nothing changed but the amp: dead silent. Hope I get 60 years out of the Cayin.

 

 

 

Fishers Amps came in my Fisher Console I inherited from my Uncle, so there were memories, hard to part with them, but I got remote volume out of the problem

I actually had a similar situation years back with a AudioResearch unit. And it drove me NUTS trying to get it worked out. In my case it was what the tech called a "leakey cap" meaning the behaivoir would be interrmittent - which is the hardest to diagnose. Replacing the caps fixed the issue, but I will forever wonder why the manufacturer and electronics shops I went to either missed it, or flat did not want to deal with a cap replacement. I hope this helps in some small way. Nothing to match the anxiety of the few seconds before you turn your amps on..... - Steve

Assuming this amp uses a removable (IEC) power cord:

You mentioned power cord -- are you (still) trying different power cords? I ask because I actually had a very bad IEC power cord -- bending the cord made the problem (noise/static) even worse.

In the months before discovery, my experience was pretty much what you describe. When sent/taken to techs, my bad power cord stayed at home, and the amp was perfectly noiseless on test benches.

Is the issue apparent almost immediately after power up, or does it take a while for it to start acting up?

 

I had a somewhat similar issue with my little tube amp recently and it turned out to be a solder point on one of the resistors, inside. I went through and added a bit of solder to all the locations that looked like they had virtually no solder and the issue is gone.  Before that, the static would take about 20-30 minutes before it started and the amp was fully heated up. I guess the heat caused some slight movement through expansion inside and was revealing a bad solder joint.