Fascinating interview with Class D inventor Bruno Putzeys

Or maybe class D amps are coloring the sound?...

 

Maybe, but this should be easy to measure.

 

I prefer to move my amps around with one of these. I know they make electric ones; but, I'm old school.

 

Hmm. I'm getting a malware alert from that link, oddly enough.

 

Changed... cause, we don't want that.

Has Stereophile not reviewed (and measured) any Class D amps?? I don't subscribe; but, surely they have... right?

Do the measurements note any obvious frequency response "issues"?

 

Those wheels don't have tubes!

 

Most SS amps, regardless of topology and price, turn out flat response measurements, but they obviously don't all sound alike. What's colored or neutral is completely subjective, as are most topics on this forum. I was merely sharing my impressions. We certainly don't all have to agree.

 

Here you go! -- Bel Canto e.One Ref600M power amplifier Measurements

Same amps were also "Product of the Year" with Absolute Sound last year.

 

I think also that in many cases Class D amps perform and measure differently depending on the load presented by the speaker.

John K.

 

This is likely true for all amps. Perhaps it's more of an issue for Class D amps than others, although I would expect Class D amps to be less impacted, because in general they drive low-ohm loads well. Indeed, my Pioneer Elite receiver is one of the few receivers in its price class - perhaps the only one - rated to drive 4 ohm loads, thanks to Pioneer's D3 amps.

 

Indeed, as is the case of the Bel Canto amp in the link posted above. One will notice that a load of 8 ohms does produce a rise in output right at about 2KHz. It's only about 1.5db but that's plenty audible.

 

Most half-way decent amps, regardless of topology, can drive 4 ohm loads. Even the entry-level class AB Yamaha amps can handle 2 ohms.

 

I also have a Class D Pioneer A/V receiver, a SC LX-76 from 2012 also sold in the US under a different reference and the Elite Badge. I love it, great music sound from an A/V receiver, 'tough it wasn't cheap by Spanish's standards, 2000 €. It performs great either with CDs (not the best way to get the most out of it), Hi Res (it sounds better with either 176.4 or 196 Khz than with 88.2 or 96 Khz, it must be a D/A thing), SACDs and vinyl LP's played on an inexpensive Goldring GR-1 TT (a Rega Planar 1 rebranded), a Sumiko Pearl cart and an EAR 834 "clone" Phono preamp with Matsushita tubes at the moment. I've always been a Marantz guy after a friend of mine that works at a department store called me to force me to discover this great A/V Receiver. It really impressed me at to the point that I got back home with one. That same day my old Marantz SR-7000 went out and my new Pioneer SC LX-76 got in, and I'm not thinking about parting with it in the near future.

 

Well, most A/V receivers weren't coming with halfway decent amps, then. I have noticed recently that many of the high end Denon and Marantz receivers support 4 ohm speakers - not sure about the lower end of the market. Presumably Yamaha does as well, since they all seem to maintain parity with one another.

 

The SC-LX501 supports DSD as well - I need to reconfigure my Sony Blu-ray player to output DSD from SACDs.

The phono preamp in this thing is surprisingly good. I was surprised it came with a built-in preamp - I didn't realize that when I bought it.

 

I was referring more to integrateds, but it does seem that manufacturers have stepped up there game in the AVR arena. I suppose using class D amps does allow them to actually meet their published 5-channel power ratings, which were typically bogus in the past.

 

Are they using Class D amps, though? At the higher end of the market I think only Pioneer does, with their D3 amps. I think the Yamahas, Denons and Marantz are all A/B. I know some of the smaller Marantz receivers were Class D - I didn't think they sounded great, but they weren't awful for the price. Just what you'd expect.

Denon and Marantz are owned by the same holding company now. Their manuals look alike. It's kind of disturbing. The same outfit owns Boston Acoustics (they've seen better days), Definitive Technology (ditto in my opinion) and Polk Audio.

Onkyo bought Pioneer, sadly. I haven't been impressed by Onkyo's kit in decades - here's hoping they don't ruin Pioneer.

Yamaha seems to be doing OK. Sony has greatly improved over the past 5 years or so - it would be nice to see them return to their former glory.

 

Im not quite sure what you are looking at here - all the response traces are ruler flat in the audible band.

 

The "gray" trace in the graph.

As a result, there was very little variation of its response with our standard simulated loudspeaker (fig.1, gray trace)
Read more at Bel Canto e.One Ref600M power amplifier Measurements

 

It's true that impedence at the outputs is where perceived sound signatures primarily come into play. In effect, where an amp has a relatively high impedence at the outputs, it is being used as something of a tone control - you are manipulating the speaker designers likely intended FR response of those speakers. Two SS or indeed a tube amp with low impedence operating within its power parameters at matched volumes will sound alike, if not indistinguishable.

Of course, there's nothing inherently wrong with preferring one sound signature over another, or indeed having preference for additive harmonic distortion etc. In fact, when other variables are considered, notably the room, manipulating a speaker FR may prove preferable. I've had fun lately using mini dsp to replicate other amps signature in a/b testing - with time and some skill, I've been able to make my yamaha sound indistinguishable from valve amps.

 

Fixed it for ya. Although with the fix, your "plenty audible" assertion is plenty debatable the way I read the graph.

As for me, I have also owned quite a few class D amps. Started fairly early with the PS Audio Trio C-100 and Bel Canto S-300. I actually liked the PS Audio amp. As those were fairly low powered amps by class D standards, I tried a few other more powerful amps and always found them less than satisfying after a month or so.

My last attempt with a class D amp was the Wyred4Sound mAmp monoblocs. They use a fairly advanced ICE module. If pressed for a description, overly sterile is how I'd put it. I'll bet they measure very well so what is my problem. I actually wished I liked them better as their size and versatility was impressive.

 

In a recent interview with Nelson Pass he had this to say about class D
NP: Personally I think it’s a miracle that they work at all, but then I think that about my phone, too. I have great respect for people who can make Class D amplifiers sound pretty good, and for delivering low cost, high power, and efficiency. They have earned their place in the industry.

That said, I am not tempted to go in that direction.

 

My bad. You're correct. I didn't look that closely at the Y axis. That should be inaudible. As I initially noted when they started bringing up measurements, most modern SS amps produce a flat frequency response but they certainly don't sound alike. I only mentioned the "1KHz boost" because that's how they've always sounded to me, though "sterile" is a more fitting description.

 

If you look more closely, I think that you'll see any deviation from ruler flat response is only .1% - .15%, a tenth of what you are suggesting.
-Bill

 

I'm going on ~ 5 years with a Yamaha P7000S power amp in my 2-channel/HT 7.0. It was a vast improvement over the early ICE amps in a Pioneer SC-07, which became a preamp for front Polk RTia9s. Now have a Yamaha RX-A1050 "pre." No sonic differences between the "pres."

The P7000s was $599.99. For 700 WPC @ 8 ohms. The Polks are known as a bright-sounding speaker, & I believe they are with < 200WPC. Sterophile's measurements of the RTiA1 are used as documentation re; brightness, with Audio Research Reference 110 (WPC); Creek Audio Destiny 100 WPC & 5350SE 85 WPC.

The Polk Audio forumites found the a9s really came around with > 200 WPC; Parasound HCA-3500 Power Amplifier ~ 350 WPC for the sweet spot. AFAIK, only one other RTiA9 owner used > 350 WPC (EMOTIVA XPA-1 MONOBLOCK AMPLIFIERS, 1,000 WPC.

Yamaha was adamant that the P7000s power amp was NOT Class D; but a hybrid of Class AB and Class D using Yamaha's EEEngine (Energy Efficient Engine).

@LARGERTHAN, I've mentioned previously that the day will soon come where a Class D amp's remote will allow audiophiles to toggle back & forth between DSPs for McIntosh, Audio Note Japan Ongaku , Pivetta Opera One or Opera Only, Ether Audio Abbssolute Intuition, Rike Audio Edzard , Ultrasound Otello or Parsec, Wavac SH-833, Goldmund Telos 5000, or your own tweaked sonic colorations. Holograms of appropriate hue (blue) & logo will run twice the price for © sakes!




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