Class D is just Dandy!


I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.

That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.

For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.

Please share your experiences with class D amps!
erik_squires

Showing 6 responses by islandmandan

I use Class D Audio amps I built from kits. My old Adcom 5 channel bit the dust, and I needed a low cost replacement. I made a three channel amp using two modules, sharing a common power supply. One module is in stereo mode for the surround speakers. The other is bridged to mono, for 500 Watts to the center.

I like this arrangement so much, I built another amp, using two modules bridged to mono, for 500 Wpc for my main speakers. Sounds ridiculously good, especially for the cost. I use this amp for 90% of my listening, an SET 300B for the remainder. They both sound good in my situation, though the modules that are bridged tend to be a bit noisy. They sound so good, I really don't mind.

Regards,
Dan
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  
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
Hello Al,

To shed a bit more light on the subject, and I don't know in what way it may effect your idea of the issue, but when the Class amp is out of service, and my SET 300 B amp is in use, there is no issue with noise. Even when my HT system is in use with the SET amp (I use a separate tube preamp that the front two channels are connected to, including having the processor stereo cables run to the two channel preamplifier).

So, my thinking is the noise emanates from the Class D amp, not from the cable box or processor.

Thanks again regards,
Dan 
Thank you Al, Ralph, for your always valuable input. I will re-insert the Class D amp into the system (I was taking time off from the noise, and very much enjoying the SET 300B in the system), and try what you have suggested. I'm wondering why, though, a single module, in stereo mode, is quiet, but a dual module/single power supply with both modules set to bridged mode is so darned noisy?

Thanks,
Dan
Hello Al, Ralph, all,

I disconnected the inputs on my stereo dual module Class D amp last night, and the right channel was silent. Inexplicably, the left channel was still noisy. Today, I rounded up some spare I/C's that were long enough to reach between the preamp/processor and the amp, disconnected the leads from the pre-pro to the separate tube preamp, and connected the amp directly to the pre-pro. The two channel and three channel Class D Audio amps are now quiet as a tomb.

From here on out, all my HT and multi-channel listening will be through the Class D amps, and two channel listening will be through the SET 300B and Transcedent Sound Grounded Grid preamp.

So your idea of the problem being input-related was spot-on. I also found I had my surround speakers connected to the rear surrounds on the pre-pro, which may have been causing some of the problems as well.

So, everything is working much better now, though I will be limited in my use of the Class D amp. I will have to re-think my connections to see how I can better utilize the Class D stereo amp, but at least for now, mission accomplished in attaining blessedly silent noise-free listening.

For that, I can't thank you men enough. Having your input on this forum is a true blessing!

Regards,
Dan