Class D is just Dandy!

Hello Erik, Ralph, all,

I have endorsed Class D myself, and had some input on this thread, although I very much like music with my Class D Audio amps, I had an ongoing problem, dealing with noise generated by my two CDA 254 amps. I even posted a thread on this issue. but got no response, so I thought I'd try again here.

I have a three channel amp that I use for surround and center, with one module run in stereo, and one module bridged to mono for the center. The power supply is used by both modules. This amp is subject to a fair amount of noise.

I also have, in a separate chassis, two CDA 254 amps bridged to mono, and while this amp sounds great musically, it has even more noise being produced than the three channel amp. Again, both modules share a common power supply. My first Class D Audio amp was a stereo CDA 254, having the power supply to itself. It was very quiet running in stereo mode. I didn't start having noise issues until there were two modules sharing the same chassis/power supply.

I have the half-baked notion that the noise is related to having more than one module sharing a common chassis/power supply.

I have tried to get an answer from Tom at CDA, but he won't reply. I'm hoping one of you kind gentleman,will offer your thoughts on my problem. I'm thinking on buying another chassis, transformer, and power supply, and see if using two mono-blocks (in bridged mode) will solve my problem. I'll be very interested to see what any of your replies might have to say.

Thanks much, regards,
Dan  

Hi Dan,

I don't know enough about your amps to help you I am afraid. The DIYAudio web site is a great resource for kits and components.

The site is down for upgrading, but should be back up by Monday, July 10, 2017.  I would ask there.

While some digital amps have noise issues when you put modules too close together, I would not think this was an issue. I would suggest try unplugging all but 1 module, and see if that does anything to the sound quality.  If so I wonder if your issue is proximity.

Best,

E

@islandmandan 

I'll be very interested to see what any of your replies might have to say.

What sort of noise are you encountering?

Hello Ralph,

The noise is a bit difficult to describe. It's similar to a 60 cycle hum, with a sort of "buzz" in addition to the hum. Strangely, when my home theater setup is on (Comcast DVR, Primare SP 31 HT processor, Sony HDL display), when making changes on the Comcast remote, the noise abates momentarily during the sequence of time the button is being pushed. I know this sounds far-fetched, but it happens. 

Erik, Ralph, I appreciate your responses, thank you.

Regards,
Dan

...when my home theater setup is on (Comcast DVR, Primare SP 31 HT processor, Sony HDL display), when making changes on the Comcast remote, the noise abates momentarily during the sequence of time the button is being pushed.

Hi Dan,

That’s certainly an interesting finding. Perhaps the DVR is the root cause of the noise, possibly even when it is turned off and most (but presumably not all) of its circuitry is unpowered. If you already haven’t, you might try disconnecting it and pulling the plug on it. Also, does the remote communicate with it optically, or via RF? If the latter, you might try removing its batteries.

Best regards,
-- Al