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Are Class D Amps scaring the hell out of the BIG Boys ?

This is a little off topic but related. A couple of years ago I decided to get back to playing electric bass. There are a lot of new bass amps out there. Most of them are class D. I tried a lot of them and there was something not right about all of them. I found a used GenzBenz with a big fat transformer and the rightness came right back. There was a weight and punch that the Class D amps did not possess, regardless of watts.

The GenzBenz was not cheap and it weighs a ton, but I have a pretty dynamic style. I could not live with the anemic tone in the class D amps.
 
Frank Sol said:
Of course this one... I own it

http://classdaudio.com/complete-amp...s/sds-250c-class-d-audio-power-amplifier.html

Seriously :smoke: I've had many friends complement it... IMO , it sounds better with harder to drive speakers
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Have you had cause to experiment with the 'Gain' controls on each channel ?

class-d-audio-sds-440c-amplifier-back.jpg


A very interesting amp based on the sole review I found - will keep an eye out for this in future.
 
I got this from the review, but the manufacturer has a comment at the end of that review indicating that the design wasnt 'locked in' at the time of the review.

◦Two Channel Amplifier with adjustable gain
◦220W RMS Per Channel into 8 ohms
◦440W RMS Per Channel into 4 ohms
◦Size: 12″ X 12″ X 3.5″
◦Shipping Weight: 20 Pounds
◦MSRP: $665.00

http://www.highfidelityreview.com/class-d-audio-sds-440c-amplifier.html

Edit: no SnR/THD figures, but I dont get too hung up on those - I'd like to hear the amp for myself.
 
I repair guitar amps and I'd sure rather fix a broken analog amp, SS or tubes, than SMT class D. I do 'em, but I don't have to like it.
 
davidro said:
What are the examples of 'good' Class D amps?
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Rather than focusing on brands, look at the innards. There are at this moment only 2 companies I know of that have licked the technical issues of correct phase and frequency rolloff - Bang & Olufsen and Phillips/Hypex. Their modules are still under patent so other companies are waiting to bring out their products until they expire, since class AB and G/H is filling current market demand nicely. Phillips licensed their inventor, Bruno Putzey, to market their patented design as the Hypex brand.

Current production amps getting good reviews mostly repackage these 2 modules in various guises and sell for 1000 to 5000 (!) for the same thing with different boxes. http://www.audioholics.com/education/amplifier-technology/clone-amplifiers - Wyred4Sound has the most reasonably priced clone. I've heard it and it sounds really, really good (this coming from a tube fan).

Class D has been known since the 1950's. Took until the last 10-15 years for the high frequency techniques to work out. This type of amp is highly dependent on the power supply and until switching power supplies became cheap they were often not economical to make. If you search Bruno's writing you will see how important proper PS implementation is. http://www.piak.nl/pdf/REF24.pdf and http://sound.westhost.com/articles/pwm.htm
 
Great background, goldleaf - I cant wait to hear the W4S amps and their DACs are getting very good reviews too.
 
estreeter said:
I got this from the review, but the manufacturer has a comment at the end of that review indicating that the design wasnt 'locked in' at the time of the review.

◦Two Channel Amplifier with adjustable gain
◦220W RMS Per Channel into 8 ohms
◦440W RMS Per Channel into 4 ohms
◦Size: 12″ X 12″ X 3.5″
◦Shipping Weight: 20 Pounds
◦MSRP: $665.00

http://www.highfidelityreview.com/class-d-audio-sds-440c-amplifier.html

Edit: no SnR/THD figures, but I dont get too hung up on those - I'd like to hear the amp for myself.
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I was on the class d audio website and I couldn't find any specs on them at all.
 
estreeter said:
And you are absolutely correct - 'D' was merely the next available designation and the 'digital' tag came along later. My mistake and I will edit the earleir post - apologies to all concerned.

Edit : someone on Head-Fi claimed that Class D may have big pluses for speaker use, but was not a good design for a headphone amp : I dont have the tech chops to argue that, but W4S/Bel Canto and Peachtree all make a point of marketing the headphone amps in their integtrated speakers amps. No biggie to take a pair of phones to an audition.
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I don't think that anyone has proposed that D is better than A, but that D has in some cases gotten to the point of being very good and a viable option for those of us who either will not or can not justify the cash outlay in cost, space, and yes even additional air conditioning :), for a big heavy class A amp.

If you already have a class a Preamp stage capable of driving a set of cans, why not use it and promote the fact?

I just got my Decco65 and after the first weekend, I am very impressed, so far it's done everything I've asked of it and it's remained cool and collected. I am actually shocked that the warmest place on the entire case is right over the tube. No real heat at all where the amp stage is.
 
benclark said:
If Class D is better for subs and Class is A is better for high frequencies then why is there no amp that features both a Class D and a Class A amp inside one case?
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There are. Some active speakers manufacturers use class D for LF channel and AB for mids and highs. All in pro music business though. This setup only makes sense with active bi- or tri-amping.
 
estreeter said:
Have you had cause to experiment with the 'Gain' controls on each channel ?
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A little. When I use my Audio-gd NFB-6 as the main preamp I will sometimes cut-back on the Class D amp's gain. It is a little confusing because the NFB-6 has a high & a low gain output setting. When the NFB-6 is set on low gain the Class D amp can run at full gain

I've used 2 different analog preamps with this Class D amp and each time the full gain setting was OK
 
My only experience was with a Pioneer SC-27 using a variation of the B&O ICEpower. It was either very good or mediocre depending on what speakers I was using. But it was really quite promising. I would be surprised if more and more companies went this route. Sonically I preferred the actual "digital" amps made by NAD and TacT that I've heard. They were as good as anything I've heard regardless of price.
 
My Class D Onkyo A-9555 isn't going anywhere. I'm not real excited about how it sounds with vinyl (could be the Shure M97xE cart) but to my ear, it does something special with CDs.
 
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