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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
rabbottmke OP
23 posts
 
Thanks for the feedback, everyone (pun intended).

I guess I'll keep at my burn-in over the next week or so, and if it's not improved... it goes back in the box, and into storage or something.

I've always lusted after blue VU meters.  Maybe it's time to chase some down.
russ69's avatar
russ69
3,552 posts
 
Call the manufacturer and tell them what you are hearing, they might be able to explain it. 
rabbottmke OP
23 posts
 
Yeah, I thought about sending a note to the mfgr.  But having worked in the industry on the sales/consulting side in my earlier days... I can't rule out that something in the past week has not changed.  My streaming/dac just processed a firmware update, the weather has changed here in "Cheddar Land", and maybe my ears are clogged... 

There are too many variables to discount, before I start pointing fingers at a brand new (and supposedly certified) amp.  As a vendor/retailer, I'd be suspect of my situation, before I'd be suspect of the amp.

I'm grateful the mfgr did the repair... cause "letting the smoke out" would have been worse.  I don't want to be "that guy".  
oldhvymec
5,101 posts
 
The first thing I would do is contact the repair person and ask if they replaces the module with the same type? With a different startup delay and sound, I'd be asking a question or two.. You have nothing to loose and maybe a discount on a second module.  If they don't sound or work the same way, that's really not in the best interest of ANY stereo system.

It's not fixed... BUT it will work.. I've had to FIX a lot of those repairs in my life. We have a different term for it though.. It's called 1/2 A$$ed.
BUT you have a working system making sound. Certainly better off than you were AND maybe the guy didn't know there would be a difference.

I don't think there was anything malicious, just uninformed.. AND he sure can't fix what he doesn't know about, AY?

Those Blue meters can be spendy. I've owned the MC601s and 1.2s.

My back is hurting thinking about them.. I have vintage Mac gear.. Valve gear.. They are heavy too.. Not Class Ds, where you have to ADD weight.. LOL
rabbottmke OP
23 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.

I'm positive this was just a "board swap".  No harm, no foul.

And yeah... MC601's yada... Maybe an MC302 cause I don't need TONS of power/reserve for my particular speakers.  But indeed.  Heavy.  :)
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