I just got a NEW 402D, through my dealer,in cooperation with Mr. David Glass from CROWN. I just tried it out. Here's what it is doing. If I power down, with the gain up in the 9 o'clock position, I get the thump. If I turn the gain all the way OFF, or down, I am not getting any thump at all. My previous problematic unit was giving me the thump no matter where the gain was. Up,down, it was always thumping. This NEW unit seems to be ok so far. I haven't had a chance to really push some signal through it yet. I guess that will be the test.If you have concerns about your unit, don't hesitate to call Mr. Glass and talk with him. He is very helpful! You could also check on Crown's main website for a service center near you. That may be an option. If you do take it to a service center, be sure to print out this entire dialog and show it to them. The more information that they have about the problem, the easier it will be for them to diagnose the problem. It kind of appears that there may be some kind of issue with either the design of this amp, or the internal components. I'll post any more "findings" on this new unit as soon as I put it through a "real world" test this weekend.
Wow this really worries me as I have been talking to crown support and they have told me that this problem was limited to only the first couple of hundred amps that were shipped. When I turn down my gains there is no thump but with the gains turned up I do get a thump. I'm running 3 402D's with one 402B in my home theater. The 402B does not have this problem at all as I can shut it off with the gains turned up with no thump. Can someone at Crown please let me know if this problem can be fixed (Turning off the amp with the gains turned up and not getting a thud in the speakers) or is it just the way it is. I don't mine sending out the 402D's for repair/replacement if it indeed can be fixed.