HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

This may be inappropriate for a subjectivist forum but I’ll ask anyway.
Class D amplifiers are appearing in all sorts of audio products, they offer high power, cool running and lower cost. They are also light and small but, with all the output filters and processing, are they really Hi-Fi?

I have no current intention of buying a class D amplifier but I have used class D fold back monitors and nobody has complained about the sound quality. Of course it is very unlikely they will ever be DIY projects because component spacing is, apparently, critical and only surface mount technology can meet the requirements. I could also have got this completely wrong by reading a biased review, “Sound on Sound” as it happens.

Thoughts?

I have a Topping Class D pushing Doc Mod JPWs on my PC (used for PC stuff including searching for Music) - I don't listen for long periods on this system but I don't want to turn it off because it's awful.

It's hifi Jim but not as we know it. But what is hifi ? Can it be different for different people?

I have very little experience with class d. I am sure it has a role to play especially as it is so efficient and small - carbon footprint ? I believe the designs have come a long way in the years it has been around but it's still like a switch mode power supply in reverse possibly powered by a switch mode psu.

I would not automatically discount the technology but I can't see me ever adopting it because as you say Geoff, it's not so diy friendly and my distrust of anything switch mode is always lurking. Plus the filters on the output - filter is a dirty word round here (or should be).

A lifestyle product for occasional non critical use - I can't see a problem with that. That is hifi to some people, just not me.

The amplifier built into my Creative Gigaworks T40 active PC speakers is Class D.

For a laugh I once hooked them up to the main system DAC and was pleasantly surprised at the excellent sound they produced with a high-quality source: full, dynamic and with solid bass.

Very limited experience. The only Class D set ups I've heard (at shows) were originally very impressive but became tiring. Something not quite right in the upper registers, to my ears.

terrybooth wrote: ↑Sun Apr 25, 2021 9:17 am I have a Topping Class D pushing Doc Mod JPWs on my PC (used for PC stuff including searching for Music) - I don't listen for long periods on this system but I don't want to turn it off because it's awful.

Similarly I have a cheapy Fosi amp driving an old pair of KEF's, it's ok, and quite frankly I couldn't justify a 'proper' amp in that location. That said it doesn't make me want to leave the room.

The class d amps in the Squeezebox Radio & Boom don't get tiring, but by and large they are for background listening.

In terms of HiFi, as we know all to well one mans meat is another mans willy waver. In some applications it comes close to HiFi, but would I swap a class D for my NVA, Denon or Rega amps? In one word - Nope. And as much as I love my squeezeboxen I would never call them HiFi.

I have a pair of Temple Audio 2017 monoblocks and to my ears they are great!
In combination with the rest of my system no fatigue and I tend to have music playing
most of the day - background and serious listening.
Retirement ears perhaps a little jaded after a career at the chalkface, but I like ‘em!

A few years ago I had one very good Class D amp here, from a company called H2O Audio. It used earlier generation B&O Ice modules for the power section, but had a massive linear power supply. Supposedly the H2O amp could drive Apogee Scintillia and those drop to a 1 ohm load. It sure was a beast weighing in at 65 pounds or so. The amp was very nice and reminded me more of a tube amps presentation in the mids, very creamy and rich sounding. The top end did not have the transparency a good SS amp does, but it isn't missing the harmonics either that most Class D amps I have heard suffer from. I sold the amp to try another one that would better match my JBL speakers, but that is one I could live with and in a way wish I had back.

Now most Class D amps I heard are less expensive, and there is something about them where the top end is too smooth and is missing the decay and texture that a good Class AB amp has. Now I do not know about this latest generation of Class D amps done by N-Core or Hypex. They are reported to be improved, and perhaps they are. I have always wondered about the filtering that is necessary for a switching output device, but don't we essentially do the same thing with a DAC chip? Of course there is an output stage, so perhaps its not the same thing. I also wonder if transformer filtering like an autoformer that Mac used to use would be worth exploring? I dunno, but for me its easier for me to stand pat with a good Class AB amplifier.

The ones I've heard have made piano music - especially solo pianos - sound all wrong.
For electronic music they've sounded OK.

It's a while since I seriously auditioned a Class D amp. Some say they've improved a lot over the last few years. Maybe one day I will hear a Class D that will sound OK on piano? I'm not holding my breath.

There are lots of good Class AB amplifiers that can be had for £0 to £200.

Lindsayt wrote: ↑Sun Apr 25, 2021 8:51 pm There are lots of good Class AB amplifiers that can be had for £0 to £200.

Indeed there are and, if you have the skills, plenty that are easily repaired because of their simplicity. I don’t think anyone would call class D simple, they are certainly not simple to repair.