Issues of phase coherence and timing...

[Steve Toy]

The key to enjoying your music collection at all hi-fi levels

Originally posted by Marco:

One thing though, I'm 100% convinced that streaming lossless files via a PC/laptop and high quality media player, connected to a top-notch DAC (such as my DAS-R1), or a similar quality computer audio set-up, produces results that *NO* CD player can replicate, regardless of cost - purely because of the lack of mechanical interfaces in the chain and the sonic signature they impose on the sound.

I still have some phase coherence/timing issues regarding computer audio. As long as they are addressed I'll be happy to proceed.

We had a chat on the phone yesterday during which you stated that you were less concerned with issues of timing than I am, suggesting that timing is something, if important at all, that can just drop into place when all other aspects of so-called realism have been addressed.

Me, I'm not so sure. I think it entirely possible that you can have a system that gets all the musical fundamentals spot on, including timing. You then upgrade it in various different ways, revel in and wax lyrical about the improvements to detail, timbre, tone, dynamics, scale, harshness removed etc. only for it to dawn upon you some weeks or even months later that the very essence of musical enjoyment has quietly slipped away in all those extra hi-fi improvements.

Timing really is the key. To me it does not fall into place by accident and without it the music is devoid of meaning or soul. It is also what gives us the sense of tunefulness. Human emotional responses live or die by it so lets not neglect it in our quest for hi-fi nirvana.

My new Pure sound A30 valve amp is truly excellent in the timing department in part because it is very (subjectively at least) tonally neutral allowing the entire frequency spectrum an equal say in allowing all the musical info on the disc, and hopefully the rest of the audio chain, to reach my ears. I'm looking to have this amp modified extensively in the coming weeks and I hope that whatever improvements in terms of refinement and insight that can be derived from any modifications will also enhance this particular quality above all else.

[Marco]

For me it's simple, Steve: good hi-fi equipment (and that's the only kind I buy ), set-up properly, gets the timing right along with everything else. It comes as part of the 'package'. And incidentally, “good” doesn’t necessarily mean expensive.

We're slightly different in the way we listen when judging equipment. I simply select equipment which my ears tell me is 'getting it right' as per my own listening criteria. The timing aspect you're referring to falls into place naturally - I don't 'look out for it' or analyse it in the way you do.

Have you ever known me to own a system which doesn't get the timing right? And yet I don't actively 'seek out' this aspect of the presentation, so that should answer your question. My Naim system done it with aplomb (despite having other aspects of its presentation which were lacking) and my current system has no difficulty either in this area, as you well know

Regarding computer audio, with respect, you haven't heard enough of it yet in the right circumstances to form any worthwhile conclusions. You need to come up and listen to Ian's Helios media player streaming lossless files through my DAS-R1 DAC and compare the same music played through my X-777ES CDP on CD (with the DAS-R1), which is a very, very good CDP & DAC combo, and hear the former annihilate the latter to appreciate what I'm saying. I stand by what you quoted because that's what I've heard. You will probably hear it too when you obtain the external DAC for your Bel Canto and explore the high-end computer audio route yourself.

Marco.

[Steve Toy]

Regarding computer audio, with respect, you haven't heard enough of it yet in the right circumstances to form any worthwhile conclusions. You need to come up and listen to Ian's Helios media player streaming lossless files through my DAS-R1 DAC and compare the same music played through my X-777ES CDP on CD (with the DAS-R1), which is a very, very good CDP & DAC combo, and hear the former annihilate the latter to appreciate what I'm saying. I stand by what you quoted because that's what I've heard. You will probably hear it too when you obtain the external DAC for your Bel Canto and explore the high-end computer audio route yourself.

I still intend to explore the computer audio route as and when I get a separate DAC.

As I said,

I still have some phase coherence/timing issues regarding computer audio. As long as they are addressed I'll be happy to proceed.

[Marco]

Don't worry your sweet little head about it, darling

Marco.

[Ashley James]

Virtually all the music you buy and the films you watch are made by computers so how can there possibly be any disadvantage to replaying your music the same way.

As someone who has to relate a listeners comments to a possible fault, I have to say I don't understand the meaning of "Timing" in this context. The Hard disc in a computer is the equivalent of a CD but the read mech is better, which means you'll always get the same read every time whereas you won't with a CD because of Forward Error Correction and Interpolation (guessing or muting). Once you have noughts and ones, it's the same for both systems.

[Ashley James]

The Term Phase Coherence is used to describe the music coming from the tweeter and bass driver where they overlap or crossover. Because both are audible together over quite a wide area, it's important that the signals arrive simultaneously and that one does not lag behind the other. If it does then the speaker is not Phase Coherent and will sound at best harsh or if it's really out, you get the same effect as having wired one of a pair of speakers back to front but over a slightly narrower band of frequencies.

For an area at least an Octave each side of the crossover, the signals to both drive units must arrive at exactly the same time. The difficulty is that in reducing their output, a designer will also have changed their time of arrive of arrival. However Mr Linkwitz and Mr Riley worked out filter (crossover) shapes that would give a known change of phase and amplitude, so that it was possible to get it right, although you wouldn't think so to listen to many loudspeakers.

[jcbrum]

Steve, (sweety-pie) just for me, please, please, - pretty please, go and buy and edirol ua25 and have a go with it for a few days.

I would be really interested to know what you think of it

[Ashley James]

http://www.dolphinmusic.co.uk/page/s...roduct_id/4001

JC Can you use it as a stand alone DAC as well with a power adaptor and an Optical Digital in or are you tied to USB use only?

Presumably it'll better the Benchmark as well as offering more facilities because it's nine year younger technology?

Ash