Debate: Class D amps need 48 hours of warmup

I’m running a NAD M23 Purifi Eigentakt Class D amp (200Wx2 into 8 ohms). NAD makes no mention of warm-up requirement or benefit FWIW..

I’ve read it performs best with a few minutes of warm-up although I can’t say that has been my experience. If I truly scrutinize the sound on familiar favorites, I’d say it might sound a bit thin for 5 minutes. But, that may also be what I’m expecting to hear based on conversations like this. Confirmation bias? Perhaps.

Quite honestly, I don’t see why a Class D amp would take long to warm up. It doesn’t have a giant toroid transformer. High quality capacitors and circuitry tend to hold their charge. Class A/B would be far more likely to need a warm-up in my opinion as they are designed to run HOT, compared to Class D which is by design, COOL.

As with all amps containing large capacitors, they can, over extended periods, lose their retained energy. In those cases, some extra time may be needed to recharge the caps. Otherwise, Class D should require less warm-up by virtue of it’s inherent cool-running architecture.

Quite honestly, I don’t see why a Class D amp would take long to warm up

Me neither, honestly.  It's just kind of a curiosity that myself and a few others have noticed it, specifically related to ICEpower amps.   Not going to try to convince others, just asking for actual vs. theoretical experiences. :) 

My response last night didn't post, so I'll try again:

I agree with Ralph et al that cool-running Class D amps don't require long warmup before playing perfectly. That said, my earlier career in lab equipment design and manufacture suggests that the key to optimal performance is apt to occur when isothermality is reached. With my old Pass Labs Class A amps that warmup effect indeed took 1-1.5hrs. This was a great annoyance, as keeping them running 24/7 at 600w idle heat was VERY annoying to both my pocketbook AND Mother Nature.

My ArgentPur GaN-FET Monos reach isothermality (100F) in less than 30minutes. More importanntly, at 11w idle it's convenient to power them 24/7.

Yet I want to address another factor that I believe is at play, especially with those who remarked that their systems don't sound great until a brief warmup of, let's say, 10-30min.  My contention that this is a human ear-brain acclimation period to a novel acoustic environment, perhaps remarkably different from the prior acoustics, let's say, of your kitchen, bedroom, outdoors, in your car, etc. We simply need time to acclimate to the listening room, especially if there's a dedicated listening chair and well-sorted soundstage.  I believe that this ONE of that program directors and conductors play a throw-away introductory piece before the main program in a serious concert. Of course other reasons, such as late-coming audience noise, musician warmup and large force temporal gelling are in play.  It may be that the first few minutes don't sound necessarily BAD, but it does SOUND different a few minutes later...and usually for the better. Thoughts?

@erik_squires 

no such thing, there is no magic component inside....There is a dwell time for thermal equilibrium in a chassis of a certain size with passive cooling (assuming you have your hvac steady). If you have a fan or something inside your device that kicks on sporadically, it may become a different story.

I would wager 99.99% on the following. You are attributing an improvement in sound quality from varying powering quality levels through the day/night to a 48 hr warm-up period. If it sounded so great at 48 hrs, see if it got worse at 50 hrs, 52 hrs, 58 hrs, and got better at 60 hrs or whatever. Class D appears to be more susceptible to it.

You may have a rough time testing yourself blind at different intervals though.

If you are knee-bent on class D..do as follows.

Drop the class D and go with a digital amp like the Technics like the SU-R1000. From the ground up, design and execution are top notch. Actually, there was an ever better one called the SE-R1, but, it is no longer offered unless you find one used. I won’t be selling mine, of course.

p.s. I own a precision electronics company. I’ve been in the nitty gritty of this crap a lot deeper than some of you might have.... phd whatever and the world of theorycrafting, you don’t observe and learn the nitty gritty until you are 6 feet under on the floor everyday for months on end.

Hey @deep_333 as an engineer, of course I get what you are saying.  Temperature wise the system should be thermally stable within less than half an hour, if not much shorter.

So try to avoid giving yourself a concussion, but truth is myself and others, specifically with ICEpower based amps hear a noticeable benefit in leaving the amps on for more than 24 hours. 

I don’t actually know why.  I call it "warm up" for lack of a better word, but it’s unlikely to actually be purely a temperature thing, unless there’s some odd component that is kind of thermally isolated which would explain it. 

All I can say is my engineering knowledge and my actual listening experience have not lined up.