Oh, there's one thing I forgot to mention. My DAC (actually an AD/DA converter) has some very accurate peak level meters built in to the front panel display. On virtually every 16/44.1 file I play with QAP engaged, the max level warning lights come on. This does not happen with the same files played without QAP.

QAP really is adding something somewhere...

Mani.

A couple of days ago, I had the chance to listen to 0.9y-4 and compare Quad Arc Prediction upsampling with the standard playback of 16/44.1 files on my DAC (i.e. using its own oversampling, the precise details of which I know very little about - I think it's 4x for 44.1).

Let me just start by stating that my DAC is a very capable DAC for 16/44.1 playback. The sound is very fluid, with an incredible bottom end. The dynamics are phenomenal - to the extent that it makes ALL other DACs that I've listened to (quite a few!) sound flat, lifeless and boring. (These include top-end DACs from dCS and Esoteric.)

But my God, QAP still manages to improve things further. It shows up a hint of 'bloom' that my DAC produces with its own oversampling engaged. The sound really is smeared without QAP (but still in a very nice and listenable way).

With QAP, everything becomes more focused. Details and harmonics that were smeared out before can now be heard - it's quite incredible.

There is only one downside that I hear (or at least I think it's a downside) and that is that the bottom end doesn't sound so 'full' with QAP. This could well be that QAP is actually reducing smearing down there. But in any event, it somehow doesn't sound so satisfying without that  bottom-end bloom.

On a final note, and without meaning to upset Peter, there is one thing that I'd like to mention. As good as QAP upsampled 16/44.1 files are, they are absolutley no match for the RR 176.4 HRx files... on my DAC at least.

Mani.

Hi Peter,

Sorry, I've been busy running a workshop all day... But at least it was in beautiful Paris!

I'll be back in the UK later today and will have a listen to all my HRx files over the weekend to see if there are any more 'dynamic' tracks that I can identify.

Nice post on CA, BTW. In English, we have an expression, "Double Dutch", used when you really don't understand a word of what someone is saying. I can't help feeling that you are considered the Master of DD on CA! But thanks to you, I think I'm becoming more fluent in this language myself 

Mani.

Peter, I'm really interested in your thoughts regarding the a post I placed on another thread:

earflappin,

I like it. (Though I've never heard one, the Alpha is supposed to be pretty damn good too, no?)

But I always try to remain as objective as possible about gear - stuff that I once thought was good has turned out to be pretty mediocre... especially my old DAC compared to the Model Two.

In any event, I will buy a NOS1 DAC when it's released, and you know something, I will be genuinely pleased if it beats the Model Two. I won't sell the Model Two though - it's simply too 'special' to part with.

Mani.

Peter, have you tried the Reference Recordings 176.4 material? It is the best hi-rez material I have come across (SQ-wise, not music-wise!). This may be because I am using the same ADC/DAC that is used to record it. It may also be because of the following, from one of the designers of the ADC/DAC:
"If it's going to be 176.4 or 192kHz, then we will not decimate that signal; we use a proprietary filter [non-oversampled] optimized to that sample rate."

When I have my system set up again (hopefully in next few weeks), I will record from LP at 44.1 and 176.4KHz rates and then compare Arc Prediction upsampled to non-upsampling.

Mani.

Ah, a bit complicated... and probably too off-topic to discuss here.

What I will say is that my DAC (it's actually an AD/DA) seems to 'like' quad upsampling with AP. This is by far the best upsampling I have ever heard. I've pretty much been dead against upsampling until now, feeling that the onboard over-sampling does a better job. But if you can switch this over-sampling off (and also any upsampling that might be going on) then quad AP definitely seems to be the way to go.

But if you can't switch these things off, I can't see how quad AP can do it's magic... which I think is what you're experiencing.

Mani.

Sorry Fidelio, but I think you're missing the point here.

Others won't be able to replicate your experience, unless they have the same gear that you do. For example, your experience is totally the opposite of mine. But I'm not surprised, because we don't have the same gear (apart from my WB Chimeras).

But this is OK... and actually to be expected, I think, from what Peter has said.

Mani.

I'd be very interested in hearing people's thoughts on the following:

1. engage double or quad upsampling
2. select 'No upsampling' - take a listen
3. select 'Arc Prediction' - take a listen
4. what are the differences between 2 and 3?

It would be interesting to see if there is ever the case where (with certain DACs) 2 could sound better than 3.

Mani.

Hence why so many of us wait with baited breath for the commercial release of the NOS1 DAC... me included... even though I might already have a DAC that is 'in the league'.

These are very exciting times!

Mani.

Uh no, Arc Prediction is definitely working in attended mode, else I'm hearing things!

I'll get around to trying unattended one of these days...

Mani.

I've just been listening to Keith Jarrett's Koln Concert. Wow!

I've never heard the ambience of the concert hall like this before. And for me, this is the key difference between 'Arc Prediction' and 'no upsampling'. The latter gives the impression that everything has been recorded in an anechoic chamber. With the former however, you can hear the natural reverberation and decay of the hall. Stunning!

So, where exactly has this extra information come from???

Also Peter, when are you treating us to a 'real' CD ripper? When you do, I might seriously give up on hi-res material and stick to 16/44.1 for a while...

Mani.

Arc upsampling is in a word... "Amazing!"

In between loads of international work travel, a house refurbishment/move and... oh, a new baby(!), I haven't had much time to listen to music these last few weeks. But I just had to try 0.9y-4. And then I just had to write something here. But I only have time for one word right now. So, once again, "Amazing!"

Mani.

PS. I believe my DAC is non-oversampling at 4fs.

I'm pretty certain the RME and Weiss firewire implementations have always been 'asynchronous' (a term which I still find really confusing in the context in which it's being used - but maybe I'm just too stupid...).

Thanks for describing the sonic differences. I have to admit that I lost you a little though - too many different permutations going on.

I'm not sure if I have any other insights to share from my own experiences. All I can say is that 'master' mode has always sounded significantly better to my ears than any other word clock mode. To me, this makes perfect sense because the clock sits right next to the DAC chips... as it should.

The exact mechanism by which this clock then controls the stream from the PC, I have no idea about. Sorry.

Mani.

Peter,

A very short response for now - I'm working in Houston all next week and need to get a lot prepared before my flight first thing tomorrow morning. Sorry...

I remember when I first started using the Fireface (slave) with the Esoteric D70 (master), I wanted to experiment with getting better quality sound out of DVDs. Using Media Player to play the DVD, I found that I could indeed control the 'speed' of the video by adjusting the clock frequency on the D70. More recently, I recall playing a programme on the BBC iPlayer and again being able to adjust the speed of the video with the D70.

Ergo, the D70 in master mode was definitely affecting the way the stream from the PC was being sent...

Not sure if this answers your question. I'll post again from the States when I have a minute.

Mani.