Pass Labs Amps - Does the heat bother you?

@8th-note 

My Krell was moribund when I got it, it had signs of heat-related distress, the power supply PCB was fried to the point it was a miracle it worked at all, and it sounded terrible.

Reason I’m bringing this up is that, as you pointed out, it’s a Class A pre so it runs on a very substantial bias current (higher than most Class AB amplifiers, actually) and the bias adjustment trimming potentiometers (aka trimpots) had slowly drifted out of spec, boosting bias current, raising operating temperature, which accelerated the trimpots’ failure, further increasing bias, etc. causing extensive damage over the years. I had my work cut out.

Your shop should have replaced the trimpots when they did the recap. If they did, you’re good for another 30 years! But if your pre still rocks original factory trimpots. I would recommend checking its temperature with an IR thermometer every month or two. Since you keep it on all the time the temperature should be very stable. If it starts getting sustainably hotter for no apparent reason, it’s time to have it looked at.

I totally agree that it is one of the best designed and built preamps - in addition to sounding glorious :)

My XA 30.8 doesn’t produce the heat my 300B mono blocks do and in either case the heat produced in minimal. The joy of hearing what the 30.8 brings to my listening sessions far outweighs any concerns or perceptions about it producing heat. If you are inclined to try Pass Labs I encourage you to!

Disclaimer: as you read the following, know that we’re Pass Labs dealers.

I have similar experiences with our Pass XA-25.  It puts out  quite a bit less heat than our NiWatt 300B amps do.

Having said that, more output devices (more power) = more heat.  The question becomes how much is too much, and what your alternatives are.

If you were to go with a large tube amplifier with a bank of KT-88s, then you’ll also be putting out a lot of heat.

If you go for a class A/B design, there are sonic compromises.  Of course, if your amp runs mostly in class-A (like Pass’ "X" series) before switching over, then you can sidestep these issues for the most part.

I have no experience with class-D amplifiers.

When you get to the point of considering a ~300 watt amplfier, it’s time to ask yourself some questions.  Is it time to consider a speaker swap?

We do our best here at Galibier to expose audiophiles to the joys of high efficiency speakers - smaller amplfiers, with less dyanmic compression, and the thing no one seems to mention about high efficiency speakers:  late night listening at lower volume levels becomes more satisfying.  It's not just about loudness per watt.

Thom @ Galibier

I have an enclosed studio that has no central air, just a mini split for cooling and circulation.  I use a pass Labs xa30.8.  It stays warm in there or even hot over night.  I leave the amp on because it takes days for it to sound best, partially because I have some sort of electrical issue that I haven't been able to hunt down that my friend and I believe is related to having a transformer box in our back yard.  It emits a buzzing sound here and there that is intermittent.  When I leave the pass on all the time, it is silent.

This is all to say, I feel like Pass Labs amps sound the best being left on.  If you don't have good ventilation or your AC is loud, maybe avoid pass Labs?

Curious if anyone has any experience with the Coda s5.5 and if that thing is hot as well?  Would love to audition one to try vs my XA30.8

coda amp are much colder, they don't heat up

I live in Phoenix and leave my BAT monoblocks on for days.  Each has 12 tubes and I can feel the heat just walking in past my 15 x 25 listening space.  The space  gets warmer when the DAC (6 tubes)  and preamp (18 tubes) and phono stage (10 tubes, I think) are switched out of standby mode.  It's gets a little toasty, but it's worth it. I have a quiet ceiling fan that stays on high speed to help cool things down and my A/C is set to a chilly 77 degrees (That's chilly for those of us who live in the desert).  Personally, if you love the sound, I wouldn't be concerned if an amp runs a little warm.