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MartinT
23-05-2009, 23:55
The talk of MP filters, where all the ringing is moved to after the transient in the reconstructed signal, is all the rage. It's appearing in new inexpensive DACs like the Cambridge DacMagic, as well as grown up players such as the new Ayre MP players. I have contacted the distributor for my Ayre C-5xe universal player and ascertained the the upgrade kits will be in the country in a month's time and will cost about £185 to install - peanuts compared with the cost of the machine.

My question is: what does Minimum Phase sound like, compared with linear phase? Has anyone got the equipment to make a comparison? I'm even thinking of picking up a DacMagic for £225 in order to find out (and replace my ageing Assemblage 3.0 for Sky HD/Blu-ray duty).

MartinT
01-06-2009, 22:05
No one?

Dave Cawley
01-06-2009, 23:00
OK I'll bite; are we talking Butterworth against ??? More information please.

Regards

:bag:

Dave

MartinT
02-06-2009, 03:36
I can't reconcile the reconstruction filters used with classic curves such as Butterworth, sorry. All I can say is that Linear Phase reconstruction provides ringing both before and after the transient signal; minimum phase reconstruction moves all the ringing to after the transient. It is said to sound more natural since we never hear ringing before a transient in real life.

This source explains it better than me:
http://www.ayre.com/pdf/Ayre_MP_White_Paper.pdf

Dave Cawley
02-06-2009, 07:05
OK, got it! This looks like a computer/marketing generated issue. The plots are not real. However, I dare say it might be better. But digital filters are not me!

Regards

:bag:

Dave

DSJR
02-06-2009, 10:27
OK, got it! But digital filters are not me!

Regards

:bag:

Dave

Depends if you've bought any music released since 1985 or so, as LP's are often cut from digital masters now ;)

MartinT
18-06-2009, 07:01
For anyone who's interested, the MP upgrade for Ayre SACD and CD players is now available from the UK distributor Symmetry Systems. The cost is £159 plus shipping. I'm going to send mine in, converting it from a C-5xe to a C-5xe MP model, equivalent to the model now being sold.

MartinT
05-10-2009, 23:21
My Ayre C-5xe is going in this week for the MP upgrade - I got slightly distracted with holidays over summer. I will report my findings when I get it back at the end of the week.

The UK agency for these upgrades is Highend Workshop:
http://www.highendworkshop.co.uk/

MartinT
12-10-2009, 06:49
I've had the Ayre C-5xe back for a few days now. It needed a good 24 hours' warm-up and burn-in before settling to its new performance level. The new filters change the reconstruction waveform to push ringing away from before the transient edge (pre-ringing) to after the edge (post-ringing). This is said to be a more natural approach to sounds we hear when listening to live music. To my knowledge, Ayre and Meridian are leading the field in apodising filter research. The Ayre update brought my machine from 'B' to 'E' spec and cost £165 - very reasonable in the context of a £5k player. The re-branding came complete with new badge for the front and new serial number. It is now a C-5xe MP. The update should benefit CD and DVD-A replay, but not SACD.

The differences are subtle but audible. The Ayre was already a very good CD player and so there are no dramatic 'night and day' differences, but they do become apparent the more you play music. In choral music, the different voices and layering of the choir becomes more discernible with a small level of harshness removed, making the sound sweeter and further approach that of SACD. Well recorded rock benefits even more from the impact of drum kit and cymbals, together with a further appreciation of the original 'sound stage' whether that be contrived or a live recording. Perhaps the most surprising boost is to poorly recorded 1970s rock, where previously harsh recordings stand out with more apparent dynamic swing and a slight increase in warmth.

I still have lots of recordings to put through the player, but as it stands I can only admire Ayre for pushing what seems to be a mature format ever further towards acceptability and truly outstanding performance capability.

Primalsea
13-10-2009, 18:27
Basically this is nothing new, the idea of using different filters has been around and around and around and ar.................. Thats not to say that the conventional wisdom is more right than the alternatives though.

MartinT
13-10-2009, 20:09
Basically this is nothing new

It may not be new in the world of digital theory, but to my knowledge only Meridian, Ayre and perhaps one or two others have actually implemented it. The results are real and audible.

StanleyB
13-10-2009, 20:27
Jeez, and there is me thinking that I was one of the first to use this technology starting with the TC-7520SE:(. The MLC5/6 mod changes the waveform to push ringing away from before the transient edge to after the edge. A pity I did not see the potentials to make quick buck by offering to do the mod, instead of publishing the details on how to do it. I reckon it would have been worth at least £50 in each case:doh:.

MartinT
13-10-2009, 20:32
Presumably the Caiman includes this mod? Interesting.

StanleyB
13-10-2009, 20:48
The whole thing can easily be simulated in PSPICE, and then fine tuned by listening tests. I am aware that many manufacturers slap a massive price on even modest technical implementations that produce a modification of the audio signal.
There are four main methods of filtering that have been used by equipment manufacturers since the early 80's in the audio circuit of CD players. However, sometime in the late 80's the magazine Elektor published a major breakthrough in CD filter design that pushed all of the ringing from below 21KHz to outside that frequency. What was so striking about their design is that it did not cause any phase shift.

MartinT
21-10-2009, 17:57
There's more. Now that the player has been running for over a week, two things have emerged: 1) voice is brought forward, vivid and startling against an inky dark background with detail realistically placed in a three-dimensional soundstage; 2) the bass is both further extended and impactful with almost frightening ability to start and stop. I do have speakers to make the most of this (and a detached house), but the feeling of structural solidity to the music underpins it to an incredible degree.

I've learned to reel back over-the-top pronouncements when discussing hi-fi over the years, but I do want to say here and now that I've never heard better playback of standard CDs at any price.

Just wanted to share :)

leo
21-10-2009, 19:35
One thing I learned with diy and fiddling with stuff, never be quick to judge a tweak until its had chance to run in a bit:) quite surprising how much difference just a little run in time can have

MartinT
22-10-2009, 06:58
I totally agree. When I bought my first SACD player (the battleship Sony SCD-1), I was warned that it needed a full 200 hours of operation to give its best performance. They were right, it need that and more - it just kept getting better as new parts burned in.