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Break-in of a Class D amp?

I'll spare everyone the "brand tribe" debate, and keep my question/details generic.

I recently had to have my 2ch ClassD amp "serviced" by the manufacturer.  Yes, it's an ICEPower derived unit.  I'd been SUPER happy with it for well over 18 months, until one morning when I heard a buzzing coming from inside the amp itself.  I took a video, poked the manufacturer, and they voluntarily opted to fix it for me.

Fast forward a week, and the amp is back in my stack.  But something is amiss. 

I can tell they wholesale replaced the entire ICE module, as the "power up" delay from standby is "different" than before, and it seems to exhibit less overall "gain" than prior to repair.

But the most disturbing thing, and one that literally smacked me in the face... was the lack of high frequency authority.  While there is a soundstage, and lows are not an issue... it's missing all the "presence" and "life" in the top end.  I have tracks that I can play that elicit EMOTION when I queue them.  All the detail and fidelity is like, muted.

The previous board had hundreds of hours of time to burn in, and boy I exercised it.  Is this what I'm now encountering?  Or has anyone out there experienced this situation?  

I would normally just knuckle down and "grind out" hours of "work" for the amp... and not come here asking for advice... but the fidelity difference is so striking... that I can't get over it.

Thoughts?
rabbottmke
georgehifi's avatar
georgehifi
10,312 posts
 
So indeed it is the same board. ICEPower 1200AS2. Comparing pictures, the only REAL difference, is the AC transformer has more "vibration isolation goo" packed between the windings and the core/cage.
While the high's are still not as pronounced, the bass is significantly more pronounced.


Strange all should be the same with just a mains trany change, unless some small damage was done to both channels of the Class-D board which limits the HF and gives the impression the bass is up.

By any chance did you listen to one of your other amps while this was getting repaired?

Cheers George


 
rabbottmke OP
25 posts
 
@georgehihi The entire ICEPower board was replaced... not just the noisy cap.  Same chassis, new board.
georgehifi's avatar
georgehifi
10,312 posts
 
Ok, but you said this
So indeed it is the same board. ICEPower 1200AS2.

If it was replaced you either got a dud or a new version with more hf  filtering. 

Cheers George
rabbottmke OP
25 posts
 
So after trying to listen to the amp last night, and giving up after just three tracks, I took a note from @russ69 and sent the mfgr an e-mail.

They confirmed what I noticed regarding the "goo", and suggested I keep going with the break-in:

Hello Richard,

Our tech thinks 100-150 hours should do it for break-in.

 

The only thing that has changed on these ICE modules, is that the replacements have more epoxy on the power transformer to help lower mechanical noise. We are not aware of any other changes.




tmcclintock
35 posts
 
Was at least 100 hrs for mine and probably more like 200, although part of that may have been breaking in my ears to the quieter background and more clarity at the extremes.  Sort of made the upper midrange seem shallower at first.  Did you listen to a different amp while yours was being repaired?
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