Monday, July 11, 2016

Wyred4Sound Remedy - Snake Oil or a True Panacea?

I've just ordered a Wyred4Sound Remedy.  I had been drinking and needed a pick-me-up and based on Digital Audio Review's positive impressions I ordered it.

What I have just realized however is that the Remedy is not the product I thought it was in a couple of ways.

Mind you, it's clear that for some kinds of low-grade digital audio sources the Remedy is probably a very good solution. I'm thinking of Sonos, Apple TV and Chromecast specifically. However, it is a terribly over-hyped product which smells of snake oil.

What Kind of Product is the Remedy? 

Of course, marketing people, being devoid of souls at birth, are free to call a tomato a vacuum cleaner and there's rarely any legal consequences. In my world however the Remedy should properly be called a sample rate converter (SRC) or Asynchronous Sample Rate Converter, a feature built into many of the top DAC chips today.  SRCs always includes re-clocking, so calling it an SRC with reclocker is redundant.

Using an ASRC is a very good way (and a little lazy by itself) to ensure minimal jitter with possibly very jittery sources, such as Internet radio.  The reason I'm kind of on the fence about this is that an ASRC is no longer bit perfect, but time-perfect. To ensure that every x picoseconds a new sample is processed, regardless of how the input signal may vary in the short and long term an ASRC resorts to a mathematical brute-force method, the details of which are beyond the scope of this posting.  Suffice it to say you can kiss bit-perfection goodbye, and not just for the interpolated samples either.

One major annoyance, that relegates the Remedy to mid-fi sources is that the input signal is ALWAYS recreated. What's worse is that if you have music with a higher sample rate, such as  24/192kHz, the Remedy will actually DOWN-sample it to 24/96kHz. This, plus having no input switching makes his solution seem kind of dopey.

For about three times more a more robust option is the Mytek Stereo 192 SRC. It gives you much better control over what you want to do with the signal, up, down or no change with equivalent or better jitter reduction, as well as being able to convert up to 24/192kHz

Of course, this is all spec-manship. Listening is the true arbiter of what you should buy.

Is it really a femto-clock?

Having examined one, it seems W4S has used one of the best commonly available Crystek oscillators, the CCHD-957 series, which does in fact have very good phase noise characteristics, among those affordable to mere mortals.  I'm still confused though. Based on W4S's own measurements this does not appear to be a femto-clock grade solution but a pico clock. What's the difference? About 1,000 times worse performance. It is possible that the internal clock device inside the case is a femto-clock class part, but that the other circuitry used can't take full advantage of it, or that it can only do so much in one pass. It would be very interesting to see measured comparisons using a standard Mac Mini or Apple TV to see how it measures to Mytek, M2Tech or Auralic with and without.

Consider this. The Auralic Vega with a true femto clock (and 10x more expensive) has jitter around 80 femto seconds. The image on W4S's own Remedy page shows jitter around 87 pico seconds. That's about 1,000 times worse performance. Of course, many would argue that you can't hear 80 pico seconds of jitter, but the point is the marketing hype. I don't like being lied to or misled.

Another similar device with a price point kind of in between is the M2Tech HiFace Evo 2. It is intended as a USB to SPDIF interface, but it will also take a coaxial SPDIF as an iput and allow you to select sample rate conversion.  Price is around $700 USD.

Why does this matter? 

My point to all of this is that the Remedy is doing more than just jitter reduction, and I would really have liked to know this before I ordered. Hiding major behavior is not a sign of a trustworthy vendor. Remedy is playing with the bits and I should have known that first. For more on why this is different, see my post on Upsampling and Oversampling.

It's a little odd as many DAC's make upsampling a key feature. They charge more for it and often tout their proprietary algorithms as being better one way or another.

In the end though I'll have to listen to it to evaluate the Remedy as having any sort of meaningful benefit. More on that in the next several weeks. One of my sources however will be Toronto Jazz 91 which streams at 24/96kHz already, this will let me do direct comparison to see if the jitter reduction is worthwhile, in addition to a small selection of 24/96kHz FLAC recordings I have.

Many listeners are easily swayed by "different." Even John Coltrane suffered this, always thinking his next performance was better. If jitter or SRC at these levels is audible it's quite possible many will be swayed by a different sound, but not necessarily a better sound.  I can imagine many will get worse jitter than they started with, and then proclaim how audible and beneficent the differences are!

No comments:

Post a Comment