Do you really want to upset the NOS crowd???

Mani.

My limited understanding of upsampling is that it has a single potential benefit: it allows the use of a less-steep anti-aliasing filter to be used. This is turn reduces ringing effects in the audible range.

I do not understand how upsampling can create more information than is recorded onto the CD. The only technique that I'm aware of that helps with increasing resolution is dithering...

I kind of remember Bob Katz and others doing some tests on this. They found that in an ideal world, an anti-aliasing filter would have a low pass band starting no lower than 50 KHz or so. In which case double, but especially quad upsampling might make sense.

But what's happening here is that we are getting a load of (I assume) nasty digital artifacts above 22.05KHz, interfering with our beloved music. This cannot be good. But I don't understand why it doesn't sound worse than it actually does...

... maybe my hearing isn't good enough to hear the mess that going on up there

Mani.

Thanks Russ. I was beginning to think I'd lost it for a minute...

I totally concur with everything you say.

The only thing that doesn't make sense to me is this: why does quad upsampling sound as good as it actually does. No, IMO, it doesn't sound as good as no upsampling... but it still sounds pretty damn good. If you read the literature on aliasing, it is supposed to sound awful, even in moderate amounts...

Mani.

It's my lunch break, so I can do this quickly... with pleasure.

Find below the two curves. Just be aware that I'm using my system 2) at the moment - i.e. no external dac and no spdif.

I have no idea what Foobar's SRC does with the bit depth, though in shared mode, Vista pads it to 24 bits, no? (I have it set to 24/192).

Mani.

I think it's time to brush the dust off those old undergrad books on our shelves... or at least on my shelf.

Mani.

Hi Peter,

I'm assuming c)

In any event, here are the results with Foobar/ASIO (running 24/192 shared mode). There is obviously an AA filter being applied.

Mani.

Thanks Peter.

Just to make sure I understand correctly:

1) DAC is 16 bits 44.1 KHz -> data is pre-processed
2) DAC is 32 bits 192.0 KHz (or any bit depth > 16) -> data is processes in real-time

And this is what is influencing the sound, right?

The next improvement will be to pre-process data for all bit depths, correct?

Mani.

The genios are perfect with 0.9u-6 - the correlation remains at +1.0 througout... as it should

Upsampling/aliasing has no effect. And of course, it shouldn't - aliasing won't introduce any phase differences between L and R channels... just within each channel and hence the interference above 5KHz or so.

You know, this discussion reminds me soooo much of a discussion I used to have with a 'hi-fi nutter' friend of mine. He has the full monty dCS digital rig. I used to have a Sony SCD-1 and Marantz SA-1 - I jumped on the SACD/DSD band-wagon as soon as I saw it.

But DSD never seemed to be right to me in the top end. So much like I'm hearing here with upsampling (especially quad). You probably all know that DSD has less resolution than CD above 8KHz. What do you think that does to transient edges... even of something like a bass guitar?

And here, quad upsampling (without AA) is down some 6-7 dB at 20 Khz...

Mani.

1) No. At the moment, I'm using either my passive vol. control with my Genelecs or the vol. control built into the Stax driver unit. XX vol slider remains at -0dB in both cases.
2) More difficult. It just seems more 'alive'. I tend to tap my feet more... if that helps. I'm happy to do some more serious listening... when I have more time (maybe over the weekend).

I've never used the XX vol control. Let me know if I should try playing with this...

Meanwhile, why does selecting 16/44.1 sound different to selecting 32/192 when the vol slider remains at -0dB?

Mani.

Yes, selecting 'DAC is 16 bits 44.1 KHz' is what I do and what I want to say.

To me, this gives the best SQ for 16/44.1 files. I haven't done extensive listening, but so far, this seems to make an obvious and consistent difference. I will admit though that I have only really compared it to 'DAC is 32 bits 192.0 KHz'. I have not listened to any other bit depths.

For hirez FLACs, I select to 'DAC is 32 bits 192.0 KHz'.

Would love to know what you believe might be causing what I'm hearing.

Mani.

For those of you not familiar with aliasing, any signal above 22.05KHz is not 'real'. There is no information above this frequency (known as the Nyquist frequency) on a 'red book' CD.

Any signal above 22.05KHz is simply a mirror reflection of the signal below 22.05KHz. The problem is that it tends to interfere with the signal below 22.05KHz, if an anti-aliasing (AA) filter is not used. This leads, in my opinion, to a 'laid-back' though very pleasant sound.

Don't get me wrong, there are some very good reasons why you would want to avoid using an AA, but ultimately, it's all a trade-off.

IMO, the only real solution is getting hold of some high-resolution files... though with XXHighEnd sounding so good set to 16/44.1, I'm not sure if I'm going to bother for a while

Mani.

Great, absolutely no L/R phase problems, with or without upsampling ...

... but my preference is still no upsampling. Sorry Peter

For some reason, the best SQ seems to me to come for selecting 'DAC is 16 bits 44.1 KHz'. I've just been comparing with Foobar/ASIO... and in this configuration, there is simly no comparison. XXHighEnd is simply more musical... almost more 'stable' and 'solid', if that makes sense. The way I described it to my wife was; XXHighEnd is 3-dimensional, Foobar/ASIO is 2-dimensional.

I could listen to it all day long... and still believe it is the best investment I have ever made in hi-fi!

OK, as far as this upsampling melarky is concerned, well it sounds very 'nice' and 'listenable to', doesn't it? But even though it is now properly implemented (well done Peter), I still believe it robs the music of dynamics, transients and presence. Yes, no upsampling is definitely more 'in your face', but I prefer that to 'laid-back'.

That's my subjective opinion, though I'm probably heavily biased, having never liked upsampling on my P70 transport either.

Now, objectlively, I have even more issues with it. As I've mentioned before, aliasing has a definite effect below 22.05KHz.

Sorry, but I couldn't help myself - have a look at the following graphs.

Would love to hear your subjective views on the sound though - please feel free to tear me down.

Mani.

My pleasure.

Yeah, the genios are fun, aren't they?

I suppose I can speak for all of us; can't wait to get hold of 0.9u-6 

Mani.

Alaising definitely influences the sound below 22.05KHz. It has a filtering effect on the signal as it approaches the 22.05KHz cutoff. That's why there is a lowering in the RMS level of the 15KHz signal in the quad upsampled image.

And perhaps that explains why I hear a softening in the sound and a lowering of transient attack when using quad upsampling? In any event, I think we can all hear some change in the sound, no?

Mani.

My pleasure.

Mani.