I would bet my house that there is more going on than a test like this can reveal.

For my own part, I believe so much is down to phase coherence. I'm just not sure what happens when aliasing etc comes into play. For example, in the quad upsampling case, the left and right are not 90 degrees out of phase... but some of the components are - I suspect those that arise from aliasing (though perhaps these should be 180 degrees out of phase?).

The situation is too complex for me to understand fully, but I do find these sorts of tests to be useful.

Will try get some images using upsampling in Foobar for comparison.

Mani.

Actually, thinking about it, the quad upsampled image suggested a 90 degree phase shift between left and right channels... I think.

Any other ideas anyone?

Mani.

Leo, they're not just pretty pictures. These things are taken very seriously in broadcast studios and in the post-pro and mastering field.

A Vector Audio Spectrum shows the level and phase differences between the left and right channel (often referred to as a Goniometer).

From the second you see the double upsampled image, you know something is wrong - it should be symmetrical when fed, as it was, a mono signal.

The quad upsampled image shows the effects of aliasing...

Hope this helps.

Mani.

Actually, my P70 transport is also capable of double and quad upsampling. But it's part of my other system. If I have time, I'll connect it's dig output to the RME and see what happens.

Mani.

Yes, I realised the files names as I pressed post.

Here's another pretty picture...

Mani.

No, things haven't changed for the worse. I preferred no upsampling then and now.

Have a look at these two images on the RME Vector Audio Scope. Guess which one is quad upsampled...

Mani.

I'm with you Peter - I don't like it. (Actually, my strong preference is 'DAC is 16 bits 44.1 KHz' when I'm not listening to 24 bit files.)

Using my headphones, the stereo imaging has definitely contracted.

I agree Leo, it's softer... but lost the transient edge IMO.

Mani.

Has anyone else noticed the drastic contracting of the soundstage when upsampling either to double or quad, or is it just me?

Mani.

Hi y'all,

I've just been playing around with some FLAC files and checking them out using RME's DigiCheck. Here's what I've found:

1) set to 32/192, giving the full 24 bit res
2) set to 16/192, increasing the noise floor
3) this is the same 16/44.1 file extracted from CD with 'Double' and 'Upsample' on - why it is measuring at 17 bit res I have no idea

In any event, FLAC files on 0.9u-4 sound wonderful!

Mani.

0.9u-4 plays my Linn-downloaded FLAC 24/96 files just fine. No error messages. Thanks Peter.

They sound wonderful!

There is a huge difference switching between 'DAC is 32 bits 192.0 KHz' and 'DAC is 16 bits 192.0 KHz'.

I have the 16/44.1 files of the same tracks extracted from CD. However, these are all HDCD-encoded. I will try to compare these with the FLAC files this weekend (IMO HDCD files sound awful without an HDCD decoder and my wife is currently hogging the other system with HDCD decoder).

Mani.

Well, now that you're asking, could you knock up a quick 3-way phase-coherent x-over and DRC function... by the weekend would be good.

Cheers, I look forward to that.

Mani.

Peter, or anyone else,

At some point, I will be looking to buy a dedicated laptop for my main system - I'm currently using my business laptop and am getting fed up of connecting/disconnecting all the time.

For work, I use a PC. But for the home system, I could use Mac.

Is it as difficult to get decent sound out of a Mac as it is with a PC, or is the architecture used inherently superior for audio?

Arthur, did you manage to get XX going on your Mac?

Finally, it there an audio program designed for Macs that could compete with XX?

Mani.

Thanks for the link(s). Very funny. Looks like you all had a blast with this stuff.

I was also in contact with Bruno and Peter at Hypex before the 700HGs appeared on the market. My specific requirement was to buy 8 identical amps to run a quad-amped system... and class-D seemed the way to go.

I wanted (and still intend) to do a detailed comparison between different crossovers for Hi-fi World magazine here in the UK:
1) passive (from speakers)
2) analogue (Pass Labs XVR1)
3) digital (DEQX PDC3.0, when it's available - I wasn't impressed with the PDC2.6)
4) PC (probably Acourate)

I think many people underestimate the importance of the crossover. I my case, pulling out the passive crossovers and using my XVR1 analogue crossovers (set to 1st order) is the biggest improvement in SQ I have ever made...

Mani.

I'm having problems playing 24/96 FLAC files (downloaded from Linn).

1) The first error I get is "Length error in FLAC file". 'OK'ing this allows me to play the file. The error often appears again.

2) With Q1=0, the file only plays for a few seconds and then stops. Changing to Q=-2 solves this... for some files, but not all.

3) At some point I get the error "Engine #3 did not start within the expected time!". If I ignore this, the music continues to play. As soon as I press OK, the music stops.

4) The slider doesn't move throughout the song. If touched, I get the attached error.


Incidentally, I have buffer size set to 96 samples and 'DAC is 32 bits 192.0 Khz' selected (these FLAC files don't play on 'DAC is 16 bits 44.1 KHz').

Peter,

I use Hypex 700HG amps in my quad-amped setup. I searched around extensively for class-D amps that sounded at least acceptable in the high fequencies. These did the best job, though not as good as my trusty old single-ended class-A Pass Labs Aleph 4 

They're phenonmenal in the bass though... and my electricity bills remain manageable

Mani.