Some guys I know that run a sound system here went & splashed out on a few CVR amps a few months ago.

They have:-

1 x D-1502

1 x DSP 3004

1 x DSP 3304

They've had a few problems, so brought them here for me to take a look. I've done a bit of poking around & basic scoping of the outputs, etc.

My initial impression is that the outputs are horribly dirty, with a lot of residual oscillation coming through & the outputs not tracking the input that well.  

Is this normal with these amps, or have these guys been very unlucky? 

I've also noticed a slight "clicking" noise coming from the SMPS transformers on the DSP 3304. Is that common?

Ok. I thought so, but the owners are worried. They are thinking about asking for a replacement, but bought in China, so good luck on that one. I'm not sure how much of a guarantee they'll have there. And it is very slight. Hardly noticeable, especially if the fans are running.   

Ok. Like I said, a slight clicking, almost like a relay that isn't engaging properly. 

Before opening the amp, I actually thought that it may be a relay, but obviously not. It is very quiet, almost unnoticeable, especially when the fans kick in. The owners have contacted the seller to see what they say. I no longer have the amps as the guys needed them for the weekend. I'll let you know if there are any comments from China...

EDIT:-  Oh yeah - my advice to the guys was to sell the amps & try get something better. They would obviously love to buy some Powersoft, but beyond their budget. Funnily enough, there are a few heavyweight Crests (MA5850's & CA's) on sale on one internet site here. They would be a lot better for them, but obviously weigh a lot more...

jacethebase wrote: I have loads of VZ5002’s left! Send them my way.

I image that they would be interested - but import tax & courier would be a PITA -- unless you want to come down for a holiday!! 

Ok.

The outputs were bad. I can't remember which amp it was, but I was getting over 2.5v of oscillation at around 250kHz on one, but all had substantial residuals and some ugly wave forms when pushed.

"Pulsing" a sin wave though them showed a lag in the output, i.e. the rails were collapsing a lot when pushed. Also, the 2 DSP models did have some phase shift, but I really didn't have the amps here long enough to do much more. The main problem was that the guys were getting shocks off the racks! I traced that to a bad lead on their distro, no problem!  

Yes, I know - residual oscillation will always be there - it just looks bad!   

What was worse was the collapsing rails & distortion on pulsed sin waves. That would be a problem. In any case, the guys were obviously more worried about the shocks they were getting off the racks. I was worried that there was a leak from one of the amps that could do some real damage! In the end it was the distro, so no problem. 

They know that the CVR's are a cheapish option for what they would really like, but no budget for anything better. They did splash out on their drivers. Sub & kick are all very nice 18 Sound drivers, that supposedly need large watts to drive them. I do remain skeptical that the CVR's really are supplying the power they claim, so would have used some CA 18's, or Crest 8001's, etc.

In any case, it's their choice, so as long as they're happy...