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.

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.)

Yes, this is one of the things I used to like about using a laptop - the SQ went up audibly on unplugging the SMPS and running on battery.

I still think a laptop can be a 'good' solution... but I no longer think it can be the 'best' solution.

Mani.

I agree that I think a lot has to do with the rest of your system.

In my case, there is just a certain 'magic' at buffer=32 that gets lost for larger buffers. I think I can attribute this to 3 main reasons:

1. My RME card really seems to be happier at 32 samples than anywhere else. I'm not sure if anyone has tried KS Normal mode (why would you?), but my RME almost refuses to play without clicks and pops unless it's set to 32 samples.
2. I'm currenly using my old Pass Labs Aleph 4 amp - 100wpc, class-A and single-ended (not push/pull like 99.9% of amps). This is a seriously (too?) laid back amp.
3. I'm currently using Quad electrostatic speakers, which are nowhere near as dynamic as more conventional speakers.

For these reasons, Adaptive, Q1=1, buffer=32 seems to work well. Yes, not as full or rich as higher buffer settings, but then again, I just don't need more fullness or richness. A little more of the gorgeous, taut and rounded bottom end that I'm currently getting would be very welcome though

As for my DAC, well it just seems to provide an open window to whatever is fed to it.

Mani.

Peter, any idea of release date yet? I mean, are we talking Q3, Q4 or into 2011?

Cheers,
Mani.

You mean hirez HDCD? I'm not sure what it's doing exactly, but the HDCD flag is there.

Mani.

Oh, but I can... as long as it's a hirez HDCD. HDCD indicator on DAC is coming on with buffer=32 and Q1=1, so I guess no noise here...

Mani

I've just extracted the XX.zip folder over the top of these files and cancelled trying to overwrite them. XX works fine under both demo and undemo modes.

However, running regsvr32/u isanaloglibrary.ocx and regsvr32/u isdigitallibrary.ocx no longer works (these did work when I originally tried them).

BUT... as I said, XX is working fine!

I think this still may be relevant to look into in case other people try to uninstall for a clean install.

BTW, the only reason why I wanted to clean install was because AntiImage wouldn't work and I wanted to try it with my MF DAC. When I originally installed XX on this machine, I had to cancel some things that wouldn't run. (Strangely, FLAC did work even though I thought I'd cancelled its install...)

Mani.

I think it's the distortion.

I've just tried a RR 24/176.4 and there is a -105dB peak in noise at 25KHz, which gradually dies down. The highest peak I'm measuring at 81KHz during playback is around -90dB.

If I reduce the buffer and introduce noise, then indeed, there is a lot of HF energy going all the way up to 81KHz.

Mani.

I'm not sure if this is relevant, but I can get clicks and pops when I have DigiCheck on, i.e. not when recording, just when it's on and XX is playing.

However, this has everything to do with the buffer size. The following buffer sizes give the following results:
32 - Digicheck crashes
64 - clicks and pops on playing through XX
256 - works fine

As I mentioned, this is NOT when I'm recording, but just using something like the Totalyser.

DigiCheck's a really neat piece of software though...

Mani.

Peter,

I wanted to uninstall XX on my office machine to try to clean install. BUT... I tried deleting the files before I read:

Kind of important : While so far we could manage without really installing anything (Registry stuff), now it takes two OCX files to be registered. Two subsequent messages at the first startup of 0.9z will tell you so. Notice they can be unregistered manually only. When you want to do that (hence get rid of XXHighEnd in the first place) do this, and to it *before* you throw out your XX folder :

- Open a command window (cmd.exe from the Startbutton - Run). Then go to your XX folder (CD \yourXXFolder) and in there, type these two lines :
regsvr32/u isanaloglibrary.ocx
regsvr32/u isdigitallibrary.ocx

Both commands should be followed by a message that the Unregistring has succeeded.

OK, so I have 14 files that I just cannot delete, even after running through the instructions that you give (although, I now understand that I should have done this FIRST).

What should I do?

Mani.

PS. sorry to be a pain!

I know this is in totally the wrong place (I mean, what has this got to do with the optimal PC setup?) but nevermind...

I asked Dave Peck of Avid (formerly Euphonix) a few questions regarding the Model Two (otherwise known as the PMI). His response, and that of Keith Johnson (one of the original designers of the PMI, head of Reference Recordings and chief design engineer at Spectral Audio) are shown below:

1. What is the max. RMS output voltage of the Model Two?
(from KJ)
The PMI converters produce a specified maximum output of +24 dBu from 0 dB FS modulation, which translates to 12.28 volts RMS. or 34.7 Volts peak to peak as seen on a scope. I believe the output impedance is less than 20 ohms so the machines produce roughly 11.5 Volts into a 600 ohm load. The driving amplifier is capable of at least twice this output so it can accommodate DAC outputs with ringing and other filter artifacts that might be introduced or chosen for sonic reasons. It can energize loudspeakers to reasonable volume.

2. In the DAC THD test graph, can we assume -10dBFS applies to the output (as opposed to just the input)?
(from DP)
Yes, -10dBFS is the output.

3. Do you have any DAC THD figures with band limiting switched off? (I realise that this may well be impossible.)
(from DP)
Sorry, there is no standard test for this. It could be done but it would require modifying the unit and setting up a special test fixture. The graphs and figures we sent were from our suite of standard production tests.

4. Having used the Model Two for a year or so now, I am convinced that it is non-oversampling at 176.4/192KHz rates. Could you confirm this either way?
(from KJ)
Up conversion is not used at 176.4 kHz and 192 kHz sample rates. Instead, A passive analog filter with group delay correction removes alias products so that all 24 bits of information are captured from each sample by the ADC process. Conversion is made with ladder-pipeline architectures and analog added - DSP subtracted dithering, a first of its kind that is still used for instrumentation. Unlike sigma-delta methods, jitter sensitivity is low and accuracy does not degrade at high program levels.

Mani.

Ivo,

With 0.9z, I'm getting good 'performance' from XX on my Atom PC with hiFace. With the buffer set to 256 (or higher), I can use the following settings:
Special Mode - Q1=-1, (8 samples!)
Adaptive Mode - Q1=1

But loading is still painfully slow... especially hirez FLAC files. As might be expected, graphics are also very slow.

BUT... it works!

Mani.

I don't know what Romy would say if he were here. But I don't think he'd take issue with what I've written. Here are a couple of quotes from his website:

"What greatly surprises me is that fact that all playback software sound very different."

"So, I wonder what makes a WAV player to sound good. I would write up my own WAV player if I have any idea what makes a player to sound good…"

Mani.

I really like the upper-left pane, with all the digital readouts (I drive an old S2000 and still love the dashboard... even seven years on!) But it'd be great if the bit depth and sample rate readouts didn't keep defaulting back to '0' once XX resumes from Unattended - it's really nice knowing exactly what's going in and what's coming out.

Mani.