I had an issue with my 1st PS-100, support sorted me out super quick and sent me a new set of power tubes. I installed the tubes and replaced the internal fuse. Since the unit was now providing output, I didn’t put any more thought to it. Now, I have a 2nd PS-100 and I am noticing that the original one is starting to get microphonic. I’ve swapped cables, inputs, and cabs yet the issue follows the PS-100. Question is, could I have installed the power tubes incorrectly to cause this, or do some tubes become microphonic once played for a few hours? I have no clue if this is a warranty issue or just operator error. The unit is rack mounted, so any help with minimal times of opening it up would be greatly appreciated.
Tubes are hit and miss, even new ones.
Thanks @Kelly, that gives me a little more confidence in having installed them correctly. Are you saying that even if I replace the tubes again, I am likely to end up in the same boat?
Like, @Kelly says, tubes are very variable these days, it seems manufactures have decided they don’t care about quality control. I guess this is because there is no really competition in the market. Anyone want to open a tube factory with me?
What do you observe and here when you say the PS-100 is becoming microphonic?
I do think you could have installed the tubes incorrectly, they only fit on way.
Regards,
Dan
Hi @dan, thanks for your reply. Agreed, it seems pretty fool-proof to installing the tubes when they are keyed. I didn’t want to point blame away from myself to start, tubes are pretty new for me.
By microphonic, I mean that when you switch the device to operate mode (I let it idle in bypass for at least 5 minutes from power on), you get an airy, almost hollow noisefloor from the cab with nothing being played. If you lightly tap on the front panel, you will hear an echo or reverberation of the tubes for a second as sound through the cab. Once playing starts, it seems to operate just fine and sounds great.
One other difference I notice compared to the 2nd PS-100; it runs slightly warmer. After playing for say 45 minutes, the front panels measure about 100°F on the 1st and 90°F on the 2nd unit using an infrared thermometer.
My concern is that this phenomena could eventually raise the noisefloor significantly, become audible while playing, or even damage the unit. Again, my tube ignorance has brought me to seek assistance.
If this is par for today’s available tubes, I will pray this doesn’t occur with my LXII, Two/Ninety/Two, or my 2nd PS-100.
If there are any safeguards I can employ to keep this from happening to the other amps, that would also be greatly appreciated.
Is it microphonic with no cables plugged in?
@Kelly no, it does not make any sound when no cables are plugged in. I would think this is a feature built into the unit to not run when no load is detected.