Thermal Equalization

How many hours do your amps take to achieve it?

I always leave streaming gear engaged. That takes days. I found my amps need 45 to 60 minutes.

Until then scratch bass that rattles the walls or crystal clean vocals. It is like somebody flipped a switch once it hits.

Anyone have amps with thermal trak transistors? Do they work from the get go and do they run cooler?

I have a recurring daily alarm set for 5 PM reminding me to turn on my amps. With the C4 app on my phone, I can do it remotely. I usually get around to listening between 6 and 7 PM.

Like you my digital gear is on 24x7.


I use Meridian 857 ref. Power amp. It takes 20 - 30 minutes to sound right.

About an hour for both the BHK and PASS amps. I leave them in standby all the time. Digital gear is on all the time.

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The manual for my amps suggests 3 days to equalize. They aren’t bad until then, but they do get more involving over the first day or so.


Electrocompaniet AW400 takes 20minutes to sound good. However it takes almost 2hours to stabilize from power consumption perspective - see pic showing startup. I also think it still changes a bit for better after running over a day. Data take from my P10 ,it includes also tube preamp powerup:

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My amps are on 24/7. This makes the bus capacitors last longer as they don’t need to charge (“fill”) every time the power is applied. Standby power isn’t much 10’s of watts (not pure class A). My Pass Labs preamp is also on continuously using about 20W. DS DAC in standby (really on) 24/7. No warm up period for me.

EDIT: Just noticed you mentioned “ThermalTrak” transistors which are used in my Sanders Magtech amps. The heat sinks are only barely warm to the touch when idling (on always). No warm up time required to sound great.

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I have Nakamichi Stasis Receiver. It takes 20min to sound glorious.

Researching the ThermalTrak has been outst least 10 to 15 years few manufacturers tout using them. It would seem like a logical selling point but they are more expensive to buy.

I was wondering if any DYI amp builders have noted them to have any penalty in sound quality?

As the manual states and my ears agree, my Pass Labs amps are very different after about an hour.
For reasons unknown to me, my Pass line stage preamp needs most of a day. So I leave it on all the time.


I did some searching. So far ThermalTrak Amp companies using or having used them I could find.

Audio Research, McIntosh, Arcam, Mark Levinson , Ayre, Theta Digital, ATI, Benchmark, ESK, BGW, T+A Electroakustik,Outlaw, Alpine,

Anyone know of others using ThermalTrak Transistors ?

Interesting there is a patent for ThermalTrak for tubes

As stated earlier SSS (Sanders Sound Systems) Magtech amps:

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You guys make me feel like I’ve been such a cad to my system over these years. :face_exhaling:

Nope, definitely not left on 24-hours a day. Definitely an hour warm up, tops. Why? Output tubes running in Class A. With my AtmaSphere MA-2 amps (20 output tubes per channel, all running in Class A), the room would just overheat, plus the electricity bill would kill me. Now with my dinky little BHSE amp and just four EL34s, I suppose I could get away with it, but the cost of tube replacement would create some friction with my listening partner. :roll_eyes:

This all-analog system had 144 tubes in it, so definitely not friendly to tube replacement costs.


I find my BHK 250 thermally stabilizes in 30 minutes or less. But that doesn’t account for power supply stabilization. Power amplifiers typically utilize a lot of capacitance for filtering and energy storage. The RC time constant can be long and it’s exponential. I find after initial warm-up the amp continues to subtly settle in for another 1-2 hours. I wait at least 2 hours before any critical listening.

I have to leave my system on 24/7 it takes the krell amp several days to sound it’s best. I leave the tube preamp and separate power supply and tube dac on a long with it, tube life isn’t an issue with small signal tubes and 866a mercury rectifier tubes.

electricity is now stupidly expensive in the UK.
Class A (unless small) is not practical, and i now turn off my class B quad amps for my long sleep in the mornings.
they take around an hour to really settle and sing but sound pretty good from the off (current dumping design so no output stage bias at all to worry about :slight_smile:

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Yes power most everywhere is triple of the past. Iam not ready to go all class D

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I tend to leave everything on but on standby where the kit allows and with displays dimmed, as applicable.

I have settled on waking the amps up from standby about an hour before sitting down to listen.

I never turn the digital stuff off, either.



Lately, I have noticed that the system sounds a bit sweeter and more balanced at much lower volumes very late in the evening. Seems my house must be full of ambient and electrical system noise that has to be overcome with dBs earlier in the day.

This is a new observation and I wonder if it might also be linked to having the system “all warmed up”.