Testing a few amps

[manisandher]

I had a couple of friends over yesterday (what my wife refers to as my 'hifi geeks') and we went to work comparing a few amps driving my electrostatic speakers. Without going into details, we compared an OTL 300B SET (5W), a SS single-ended class-A (100W), a SS class-AB (200W) and a class-D (400W)*.

These guys have seriously high-end systems. And they were blown away by the... class-D amp!!!

BUT... I've heard many class-D amps, and can tell you that they are not all made equal. There is one make that stands head and shoulders above all the others I've heard. And that is Hypex, designed by Bruno Putzeys and made in Holland (does anyone get the feeling, like me, that the Dutch are taking over?).

The amp we heard was one that I put together using two Hypex UcD700HG modules with their recommended voltage regulators and massively over-specified linear PSs.

I just wanted to share this, as I believe you can now buy a serious power amplifier for very reasonable money.

Mani.

(* All power ratings into 8 Ohms.)

[PeterSt]

Somehow I have the feeling that you're leaving out something of the story. I mean, since the Hypexes are yours and they were catching dust in your garage, what is the real message ? hehe

Peter

[manisandher]

Haha,

The real message is that the Hypexes are no longer for sale... but the others may well be!!!

No, that really wasn't the point. I'm notoriously bad at selling gear - all that packaging up and shipping is just more hassle than it's worth. And as a result, I've got a whole basement full of stuff gathering dust. Hey Peter, we do have something in common after all

No, the point was that I really think these amps are good, and wanted to share this with others. Nothing more, nothing less.

Mani.

[Marcin_gps]

Very interesting. I considered Icepower amplifier from Polish manufacturer Audiomatus. A fellow at hi-fi forum says that Audiomatus humiliated his Bel Canto eVo 4 mk II monoblocks. Here's the review of those audiomatus - http://www.highfidelity.pl/artykuly/0603/audiomatus.html (the editor's reviews are now available on 6moons.)

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

[earflappin]

Mani, what is the nominal impedance and impedance curve of your electrostatics? 

[Telstar]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

No tripath chip is able to power his electrostatics.

[Telstar]

BUT... I've heard many class-D amps, and can tell you that they are not all made equal. There is one make that stands head and shoulders above all the others I've heard. And that is Hypex, designed by Bruno Putzeys and made in Holland (does anyone get the feeling, like me, that the Dutch are taking over?).

The amp we heard was one that I put together using two Hypex UcD700HG modules with their recommended voltage regulators and massively over-specified linear PSs.

Good to know. I'll use hypex modules for my subs

[manisandher]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

Hi Marcin,

No, I've never heard a Tripath, and as Telstar's pointed out, there'd probably be no point with the Quads. But I've owned ICE-powered amps before and actually still have a PS Audio somewhere - it's OK, but the Hypex UcDs are in another league altogether.

Mani.

[manisandher]

Mani, what is the nominal impedance and impedance curve of your electrostatics?

Hi earflappin,

You know, I shouldn't be talking to a 'sinner'. Now if you could find a way to get your MH working with XX, then all will be forgiven...

I can't find any impedance curves for the 2805s. One of the guys who was over at my place (very knowledgeable) doesn't believe they have the same sub-1ohm of earlier ESLs at high frequencies. Powerful as they are, I don't think the Hypex UcD700HG amps are very happy at sub-4ohm impedances.

Mani.

[manisandher]

Good to know. I'll use hypex modules for my subs

Before I got the Quads, I was multi-amping a pair of Wilson-Benesch Chimera speakers (yes, also gathering dust in my basement!) with a total of eight UcD700HG amps. Of course, you'd think that 700W into 4ohms for tweeter is total overkill. Yes, but boy did they sing with this sort of power on tap. In any event, the Hypex amps are mighty fine up top as well as down below.

Mani.

[Marcin_gps]

Mani, did you have a chance to listen to some good quality Tripaths (t-amps)?

No tripath chip is able to power his electrostatics.

Hmm, even Virtue Sensation? (65W per channel) I guess you know better, I haven't got any contact with electrostatics so far.
I wonder though, how come you prefer the old Pass integrated amp considering what you wrote about Hypex Just curious..

[manisandher]

The Pass amp was the '100W SS single-ended class-A amp' that I mentioned in the first post of this thread. It's not an integrated though - it's a 50Kg stereo power amp.

It's a laid back amp, and sounds very nice when matched with the right speakers. I've managed to get very good sound using it to drive a pair of Celestion SL600 speakers. But with the electrostatics, the Hypex is better. The reason why I'd never mentioned the Hypex before was simply because up until that point I'd never tried it with the Quads.

Incidentally, one of the guys who was over at my place has dropped me an email. He says about the Quad 2805 speakers, "Hi-Fi World's measurements show a 6ohm average with a low of 3.2 ohms and a high of 12 ohms."

Mani.

[Telstar]

Before I got the Quads, I was multi-amping a pair of Wilson-Benesch Chimera speakers (yes, also gathering dust in my basement!) with a total of eight UcD700HG amps. Of course, you'd think that 700W into 4ohms for tweeter is total overkill. Yes, but boy did they sing with this sort of power on tap. In any event, the Hypex amps are mighty fine up top as well as down below.

Mani.

Personally, I would never use a class-d or any amp with global feedback for the tweeters.
But I think the ucd2k are just what my subs will need

[Telstar]

Incidentally, one of the guys who was over at my place has dropped me an email. He says about the Quad 2805 speakers, "Hi-Fi World's measurements show a 6ohm average with a low of 3.2 ohms and a high of 12 ohms."

Mani.

I think that the hypex modules provide lots of current that the ESL likes. Some other current monster SS may likely provide an overall better sound but at a cost several times higher (also a faster amp than Pass designs is needed to keep up with the Quads). Something along the lines of Viola and Mark Levinson.

[pedal]

The first generation ICE power amplifiers from B&O are seriously flawed. They mute the micro dynamics and rob the sparkle and life out of the music. You get a lot of watt, but no soul. Kind of a “stupid blond”. They are not to consider as high end.

If you want to do something serious with Class D, then the first thing is to get rid of the integrated cheap switching power supply. They really suck.  Building a huge oversized linear PSU “by the book” is mandatory. (Because Class D is so efficient, the PSU still can be smaller/cheaper than with an A/AB/Tube amplifier). I have also heard that the Hypex modules are better sounding than ICE.

I believe in Manisandher observations. Class D has potential if done right. But remember that all Class D is like an open loop circuit. Noise can enter from anywhere and will be included in the music signal. The chassis, the interconnect cables, the mains cable, the loudspeaker cables, –all these works like an antenna for unwanted noise. So Class D will always be troublesome. And that’s why there must be a coil on the output loudspeaker terminal. The coil acts like a low pass filter preventing noise being picked up by the speaker cables and entered into the circuit. But a coil is a coil. It decreases bandwidth and it reduces the amplifiers performance with high frequency square tones. Especially with high-rez music, like SACD/Blu-Ray/DVD-A @ 24/192, I think you will hear the shortcomings of the limited bandwidth. In this regard, you might say that Class D is reducing what XX HighEnd software and (future) filter less DAC is trying to improve…

Also, there is so much global feedback in Class D. With traditional amplifier design, we have learn that the less feedback, the better sound. But with Class D it's "all feedback" as far as I have understood. I would guess this also puts its signature on the sound. But, I have not heard the Hypex modules, so it's only a speculation by me. But I have heard the B&O ICE modules in my system, and they are cr*p sounding in a highend perspective. (But OK for mid-fi/consumer sound systems).