Thursday, 22 January 2015

'Last' Words on PONO - Mastering Analysis & General Comments

(A friend thought the new Broadway musical hilarious.)
At some point in a relationship, we reach the end of the honeymoon...

That's of course not describing my personal relationship with the Pono idea since I've been critical of the hype put forth by Neil Young and others (like John Hamm) since the start. I'm suggesting rather that the honeymoon between anticipation for Pono with 'the world' is about to end as the Kickstarter pledges have shipped and the public can start to purchase these PonoPlayers and browse the PonoMusic Store. What will they find? Would the public expectation for music that "sounds like God" be satisfied, or would there be many who at the end of the honeymoon recognize faults which up to now were perhaps graciously overlooked.

I've entitled this post "Last words..." because I don't think I'll devote any more time to Pono here or in the forums after these thoughts. Unless I get my hands on a PonoPlayer to measure of course. (I still have not seen any PonoPlayers around here in Vancouver yet.)

Vegas CES2015 has just passed and we see further revelations and morphing of the Pono business plan as expressed by Neil Young in this interview:
- Neil Young "couldn't listen to music for 15 to 20 years". Maybe because the mastering sucked in the last 15-20 years? Why not listen to LPs then?
- He used "The Revealer" to demonstrate sound quality between MP3 and various resolutions in his car - please release this "Revealer" software so we can have a look at what tricks were used on the artists.
- PonoPlayer and hardware probably will be discontinued not long from now (get 'em while ya can!). Mission accomplished on "showing people what can be done." What is this about not having "all the cash needed" to make all the players?
- "Certified Pono" or "Branded Pono" stamps of approval will be offered to other manufacturers/distributors for their hardware or music store. Happy to "share technology."  I'm not sure what special technology Young feels he has rights to. "Somebody's watching for the quality" supposedly. "Possible" subscription streaming service in the future.
- Streaming "sounds like shit". I doubt the man is aware of lossless streaming already in existence. I also wonder what the man thinks about compression like MQA :-).
- Supposedly "there's no hype." (LOL)
Apparently there's now news that "engineers" inside the Pono company aren't so sure about the sonic improvements either. Those darn engineers - always out to spoil a good party!

Also, reviews are coming out for the PonoPlayer. For now, it's safe to criticize the device for expected deficits like its limited functionality, basic UI, slow USB2 transfers, and potential issues with the Pono Store. In time, I suspect we will see comments of disappointment around God-like expectations from the sound quality itself - the core "feature" promised by Young and his entourage. I don't think I need to remind readers here that this is primarily a mirage with most albums marketed these days as high-resolution audio.

On the software side, we're now seeing some of the Pono releases on DRDatabase. What do we know so far if we look at the mastering? Let's look at a few from the store: (Thanks to the readers who sent me this info!)

Neil Young - Harvest (24/192) - good dynamic range. Almost exactly the same mastering as the DVD-A 24/192 release from 2002 (0.01dB difference). Kudos to Mr. Young for the excellent mastering of his older music. The thing is, this is nothing new, music lovers who have been listening to Young's high-resolution stuff have been listening to this for more than a decade.

Red Hot Chili Peppers - Stadium Arcadium (24/96) - ugggg DR5. About the same as the original released CDs. Clearly they did not use a digital version of the superior deluxe Steve Hoffman vinyl remaster from 2012. Can someone tell me what Pono's Californication sounds like?

Metallica - Death Magnetic (24/88) - DR5. Notorious overcompressed album. At least a little higher average dynamic range than the original CD measuring DR3. Not as dynamic as the Guitar Hero III rip which measures DR12 and continues as the best version for sound quality.

Metallica - The Black Album (24/96) - DR7 average for the album. This is the same loud remastering from the 2001 DVD-A. Curious choice since the HDTracks release from 2012 was more dynamic at DR10 (I'll hold judgment on this one as I've never heard this). My favourite version remains the original CD from 1991 (DR11) - just turn up the volume guys, it sounds great!


"But it's 96kHz!" some would say... Most of Enter Sandman's spectrum looks like the above by the way on playback - all that noise >20kHz is of no sonic value IMO. Looks like there has been lowpass filtering applied around 20kHz in this multitrack recording in any case.
Beck - Sea Change (24/96) - DR7. Looks like a high-bitrate version of the original CD mastering from 2002. MFSL did a lovely remaster in 2009 with DR12 and an extra track for those who like this album. The DVD-A released in 2003 was slightly more dynamic at DR8 (I've been told Pono version sounds about the same as this DVD-A).

Beck - Mutations (24/96) - DR7. Basically the same master as the original CD release but 24/96 and just slightly louder overall. It is a true 24/96 and not just upsampling, so this is good at least. I mentioned in a previous post the presence of a Canadian promo CD which managed to escape excess dynamic range compression (DR11).


No surprise, Pono prefers bit-depth and samplerate numbers over more important matters (IMO) like dynamic range. Realize folks that LOUD, compressed masterings like those DR7's from Pono do not deserve to be 24-bit files! Just because it's 24-bit doesn't make it sound any better - you've just wasted another 33% of your disk space. The dynamic nuances, life of the music has been squashed in ways worse than lossy encoding. Music mastered like this truly only deserves high bitrate MP3 at best. Mr. Young, can you comprehend this obvious fact!? You have not "rescued" any part of the art form but have just perpetuated the sale of suboptimal digital recordings wrapped in a high resolution PCM format. You keep bringing up Steve Jobs and your discussion(s) with him... I'm sure if Mr. Jobs were alive today, he'd surely fully understand this concern. He has been dead since 2011 and it's not good to be implying anything unless documented especially since Apple hasn't moved towards offering lossless, much less even the mention of high-resolution. Needless to say judging from the albums above, there is no evidence of any substantial remastering effort at this point from Pono. Since Mr. Young is often very blunt in his declarations, permit me to be just as blunt. Mr. Young, from the perspective of many who actually care about sound quality, you are selling shit masterings in massively oversized boxes, wrapped up in shiny paper with an elaborate bow on top, while effusing comforting hot air tinged with perfume.

For a moment, imagine if the Metallica Artist Signature PonoPlayers sent to Kickstarter supporters were preloaded with the original 16/44 release of Metallica's "Black Album" instead of the dynamic compressed 24/96. A note with image of the spectrum would accompany the player warning about how the original release sounds better than compressed "decapitated" dynamic peaks from the later 24/96 remaster available elsewhere (the old DVD-A). Finally, the note also explains how a 16/44 version was therefore chosen for this special edition since the 24/96 did not live up to standards of fidelity for those who appreciate the best sound quality version for the time being. An action such as this would have been "revolutionary". It would have raised eyebrows, created buzz and discussion on the audiophile forums and differentiated Pono as a company that took a stand and truly cared about the quality of the mastering. It would obviously also send a message that somebody is actually checking and doing something about it!

Alas, another one of many opportunities wasted. In my previous post, I asked about which mastering would be used when Pono sells Nirvana's Nevermind. So far, seeing the choices they have made, it's probably a safe bet to say they used the unfortunate 2011 24/96 compressed remaster or some close variant (maybe someone can double check and let us know?).

So Neil Young wants to make money by graciously allowing (for a small fee) others to use the "brand" Pono now? As far as I can tell, their actions betray the intent at this point. Pono is betting that somehow having their name on an item will add value and sales? Seeing a Pono logo on the outside of a device isn't exactly going to evoke the same degree of respect as THX certification, not does it imply some kind of desirable feature like the DTS or Dolby logo, does it? At this point, at best, we have a company that has produced a good sounding player device (there are a number of digital players out there capable of high-resolution as well; for a walkaround device, the iPhone 6 is already capable of good 24/48); and the music store just looks like typical stuff found elsewhere already.

I suspect people will mention that Pono promises to "upgrade" purchases with newer/better versions/masterings as they become available. Let me know when this happens (and likewise the promise of DSD - I wonder if it'll handle DST compression)! If Pono survives financially, and gets through the next year, I think its niche will be as a typical lossless music reseller as Neil Young's technically incompetent (though at times mildly entertaining) salesmanship cools off. I do believe it's already too late to make a good first impression for those who put value into sound quality and wished for an honest change. Or for Pono to be taken seriously as an authority on quality sound.

Alright... Enough said.

Goodnight, Pono. Let's see if the wedding works out.

PS: Could someone please fix "pono . com" - I can't seem to find my music there! Not exactly the kind of "media" the kiddies should be browsing either...

PS2: There's now a program called flactag that tags FLAC files so it lights up the Pono blue LED. Supposed to indicate an "authentic" music file from the Pono store I guess - whatever the value of that might be. See comments here.



Thursday, 15 January 2015

MUSINGS: Miscellanies on audio encoding (Dolby Atmos & Meridian MQA Concerns)

Hey everyone. It really gets dark in January in Vancouver; just the kind of weather to cozy up in bed with a nice book or maybe some spirits in front of the hi-fi system :-).

So, I thought I'd offer up a few miscellaneous thoughts this week as I looked over recent CES reports.

I figured it'd be good to spend a few moments on the new encoding techniques that came out or were announced in 2014. I think the biggest advancement in audio encoding (at least as it pertains to the home) this past year was Dolby's push for Atmos into the consumer space. Remember that Atmos has already been out for a couple years in the movie theaters since 2012's release of Pixar's Brave. This happened with announcements in June 2014 and the first Atmos-encoded Blu-Ray came out on September 30 with Transformers: Age Of Extinction. Not exactly a movie that will win Academy Awards (maybe in some technical categories), but appropriate to show off some sound effects I suppose.

With Atmos (and other techniques like Auro-3D and the upcoming DTS UHD/MDA), digital processing takes another step up... We all know about the role DSP's have played in home audio including bass management, then room correction (like Audyssey MultEQ), and now we have dynamic, object-oriented sonic rendering in 3D space adapted for one's speaker configuration on top of the typical multichannel (5.1/7.1) mixing. Cool.

I'm unclear whether this will have much relevance for audiophiles (unlikely I would think) given the relatively small numbers of "multichannel audiophiles", but it does represent a true technological step forward. The question is whether many folks will be able to have a home theater setup capable of experiencing a significant difference given the "need" to increase the number of speakers. Even having a dedicated sound room (the solution to the WAF issue of course!), I'm really not keen to cut holes in my ceiling for placing speakers up there and running even more wires to the audio rack for height channels. Dolby's push for ceiling-bounce speakers (like these Definitive Tech A60's [see review]) is an interesting though compromised solution when it comes to fidelity. From a physics perspective, there's only so much that can be done with what would be small up-firing speakers, room interactions, and the timing/phase issues that need to be accounted for. Even if there were compelling high-fidelity music to be enjoyed, I doubt many if any of these up-firing solutions would be acceptable for audiophiles used to very low distortions in their existing speaker systems. I see that Kalman Rubinson in January's Stereophile suggested the potential for 3D speaker arrays to be used for even more effective room correction. Hmmm, not sure if this would be worth it if those extra channels actually are of inferior sound quality... One could be creating more problems than it's worth.

Time will tell and certainly an interesting technical development to keep an eye out for if one has a multichannel setup now that the "800lb gorillas" (Dolby & DTS) seem to be seriously getting involved with their usual hardware partners (like Denon, Pioneer, Yamaha...).


The other "advancement" in encoding technique in 2014 comes from Meridian and their MQA. This certainly got lots of air time in the audiophile press late last year. Smart move throwing a fancy party (oooooohhhh... 69th floor! The audio must have been orgasmic!) and inviting your media friends of course - everyone loves a good party! Let us spend a bit more time on this one.

I don't know about you guys, but "Master Quality Authenticated" just sounds a bit pretentious to me and I'm feeling a bit confused about this declarative form of branding (how do others feel about this?). Perhaps I'm just too cynical, but when the web site is "www.musicischanging.com" and the word "revolutionary" keeps popping up, you really have to wonder how much is driven by advertising and how much is really technical achievement... Are we dealing with another "revolutionary" modulation technique (not just PCM, or 1-bit DSD?), new "revolutionary" algorithmic representation of music, something truly mindblowing?! Alas, no... Doesn't look like it as far as I can tell.

It looks like we have HDCD-on-steroids (HDCD 2.0? Fat HDCD?). Thinking back, I was quite impressed by the ideas that were incorporated into HDCD back in the late 1990's. Recognizing that generally music would not need the full 16 bits of dynamic range in a CD's 16/44 digital stream, the bright folks at Pacific Micronics decided to "borrow" the lowest 16th bit and encode instructions for their hardware decoder. Instructions for filter changes, peak extension, low-level gain control, etc. allowed the system to encode what would amount to ~20-bit dynamic range (in a "lossy" fashion of course since there's not enough bits there to be fully accurate if starting from a 20-bit source). Ingenious! Of course Microsoft bought the HDCD technology in 2000 and HDCD has long been superseded by true 24-bit PCM, DSD64+, and now high-resolution files. BTW, I spent some cash in my college days to buy a HDCD-enabled Harman Kardon CD player which sadly broke down after <2 years - the worst piece of hardware I've ever owned!

As far as I can tell from the audiophile press (I haven't seen articles from other mainstream sources yet), it looks like this concept is being reused for the next "generation" of streaming audio (or if there are storage limitations and you wanted to keep smaller files). Other than a few who have attended demos, articles here, here, and the comments here give us a glimpse at what Meridian is up to (a couple of patents linked in the comments as well - here and here). Although I admit I have not heard this CODEC in action yet (I'm sure it sounds great), I think it's worth thinking about what is likely being done, and to consider potential pitfalls.

Based on the best technical description from the Stereophile article by John Atkinson, it looks like instead of taking the LSB as the encoding carrier (as in HDCD), Meridian's technique will probably be harnessing the lowest 8 bits of the 24-bit audio data. I'm guessing about the 8-bits part because in the "Backward Compatibility" section of the article, it talks about non-MQA DACs playing the file as the equivalent of 16/48 (it's of course seen as a 24/48 file but the lower bits will essentially act as low-level noise), this is also suggested here by Dr. AIX. So the files will likely be 24/48 (2.3Mbps uncompressed bitrate), which can then be compressed down using your favourite lossless encoder like FLAC (maybe down to ~50% for a non-Loudness War classical track). Comments like "average bitrate of just 1Mbps" (Robert Harley - probably just parroting what he's fed) I believe is overly optimistic about the lossless compression ratio. Stereophile says "the data rate was not much more than the CD's 1.5Mbps" seems realistic.

Like HDCD, the MQA decoder will examine the bitstream, take the "encapsulated" data from those lower 8-bits and reconstitute an upsampled version of the music using the lossless 16/48 base and "filling in" the ultrasonic components to create what probably would be 24/192 data sent to the DAC, and maybe even up to 24/384 if the DAC can handle this level of upsampling (see picture in this article). While we can say that up to 16/48, this system is "lossless", I do not see how the overall algorithm can possibly be truly lossless for frequencies >24kHz. [See Addendum 2 below, the patents give us some hints different from what I'm considering here...] The "stuff" in the ultrasonic range >24kHz will have to be lossy encoded (or "accuracy-reduced") I would think in some fashion to fit into the limited bits available, using their "psychoacoustic" model although how one would psychoacoustically determine what is important/perceptible is questionable! I suspect they will use that orange triangle in Figure 3 of the Stereophile article, filtering out essentially everything by ~60kHz as the diagram suggests and keeping as much of what's in there as accurately as possible. Not unreasonable. As to how this is accomplished, I would guess one way would be similar to how lossy encoders like MP3 or AAC would do it; sub-band analysis and allocation of bits to those frequencies thought to be more "important" (in this case, more bits to the frequencies just above 24kHz and diminishing as we get to the ~60kHz apex of the triangle). We're looking at 768kbps encoding rate available in the lower 8-bits/48kHz stereo signal to create that ultrasonic facsimile. I would not be surprised if the encoding/decoding algorithm is simpler than MP3 since the psychoacoustic model could be less complex; after all, we're dealing with ultrasonic data of questionable audibility anyhow so the reconstituted waveforms above 24kHz do not need to be highly accurate. You would however need extra processor cycles because we're also upsampling. I also suspect the algorithm cannot be computationally intensive in order to accommodate low power and small portable devices. This kind of decoding scheme should be easy to implement as software to feed standard USB DAC's capable of high sampling rates with a computer of reasonable speed (I'd be curious how "open" Meridian would be in allowing third parties to write their own decoding software).

The final piece which I can see Meridian making a fuss about is of course their "Apodizing filter". Basically a minimal phase upsampling filter with perhaps some high frequency roll-off if there's a need to suppress the duration of the ringing. I had a look at this back in 2013. It's interesting that over the last few years, talk of pre-ringing and the use of minimum-phase filters seems to have died down. I would not be surprised therefore if Meridian will now resurrect this talk with MQA since the encoding method intrinsically employs upsampling and they can again show pretty pictures of impulse responses based on 192 or even 384kHz sampling rates (would the algorithm even bother to encode a single impulse when fed at 24/384 or would this be filtered out?). In fact, it looks like minimization of the impulse response is explicitly mentioned in this patent application which vaguely attributes long impulse response as "perceptually harmful" - the wording I suspect was purposely ambiguous. For those wondering about the significance of this, I would encourage everyone to play with minimal phase upsampling in SoX and see if you can tell the difference compared to standard playback or linear phase upsampling.

One somewhat interesting piece to the patents is around the potential for encryption (this patent). I wonder if this is in fact what could stimulate acceptance of MQA streaming. In effect, these files can employ a form of DRM (Digital Rights Management). Here's a possible scenario - without a MQA-capable decoding DAC/player, you'd be hearing essentially a 16/48 file but if you want "better" sounding high-resolution audio, you would need a device that can decode it but only with some kind of authentication if the content provider deems it. This would be like in the old days when DVD-A players would only output 48kHz digital off the S/PDIF rather than the full 96kHz data to prevent digital ripping (for full 24/96+ transport, you would need HDCP encryption through HDMI or another proprietary method). In an era of ubiquitous digital piracy, content providers would be pleased with this kind of control in place. Another example - you can advertise "high resolution streaming" exclusivity of MQA-encoded music before a high-resolution FLAC of the album can be purchased off HDTracks. Depending on how strongly the authentication mechanism is taken, an MQA-enabled device could conceivably not even play a file unless some kind of compatible key were provided and "Authenticated" (strong enforcement of DRM - essentially making the MQA data a form of inaudible watermarking). Also, I suspect some mechanism could be developed to tag the file - "This MQA data was streamed from Tidal on February 13, 2016 between 3:00-4:00PM PST" so piracy can perhaps be traced back to where "leaks" originated. I wouldn't even be surprised if the tagging could embed user information like IP address, or unique tokens which the server also keeps a copy of to prove origination (I've purchased PDFs from vendors already doing this for text documents). I'm speculating of course as I don't think anyone has discussed this, but it's worth keeping this potential motivation in mind. (If I were in business like Meridian, expecting significant financial benefits from licensing agreements, I'd be considering this to gather support from the content providers. And hyping this format big time to get as much market share as possible ASAP!)

I'm sure I'll be revisiting these encoding techniques, especially MQA in the days ahead. Reading over what I just wrote, I must say that I remain irked by the MQA acronym... They could have just called it HRS (High-Resolution Streaming vis-à-vis HRA for High-Resolution Audio) to signify that this is a format mainly for better streaming quality; that would actually mean something. Rather, this whole "Master Quality Authenticated" acronym just sounds grandiose to put it mildly (and here's a corresponding interview). Also, I hope I'm wrong about 16/48 being the actual base "lossless" component to the encoding technique. Although the blind testing last year did not show preference to 24-bit audio among audiophiles who participated, I think it would be nice to have true bit-depths down to at least 18-bits to feed our high-resolution DACs - at least this will ensure the "core" lossless data has potential for better-than-CD dynamic range (if I'm right about the DRM piece, I can also imagine content providers not wanting to openly go beyond CD-level quality). The lower 6-bits can then be used for whatever restoration of frequencies above 24kHz Meridian thinks is necessary; there's still >550kbps bitrate available...

Conceptually, it's interesting to note that this system stresses frequency range extension to that of 192+kHz sampling rate (there's also some vague discussion about dissociating the concepts of "frequency" and "timing" - we'll see about that!) as opposed to dynamic range extension with HDCD aiming for 20-bits resolution. I guess Meridian doesn't think we need >16-bits of dynamic range for high-fidelity playback! This seems like a step backwards...

Basically, other than some compression (the promise of 16?/~192kHz sound in a 24/48 container assuming you think that's better than a fully lossless 24/48) and Meridian employing their brand of upsampling DSP algorithm, there's probably not much else here for the consumer as far as I can put my finger on at this time. Certainly more "evolutionary" than "revolutionary" I think (that's if you even consider this a step forward at all)! There's likely no sonic improvement for those of us already listening to our favourite tunes in standard/flat/non-encapsulated 24/96+ FLAC. I can also see how this encoding technique can get in the way of audiophiles who are not streaming nor face storage space limitations. Imagine if your favourite album came out only as a MQA "high-resolution" download (assuming you have a MQA-capable DAC/player) and then later you have to consider re-buying when the record company finally issues a true lossless 24/96+ file up on HDTracks or equivalent. Other than convenience for online streaming, I'm also wondering why would I want to buy any hardware for MQA decoding knowing that MQA doesn't even seem to utilize >16-bit dynamic range if I (and probably most readers) already have a capable 24-bit DAC? It's maybe a feature to keep in mind if I consumed most of my music through on-line streaming, but I'm not sure if this is a "must have" otherwise.

I look forward to reports when this system gets out into the hands of actual reviewers beyond these early company demos - any decent recording played on >$30,000 Meridian DSP7200 speakers better sound good. I'd be curious how close my speculations are to the final product :-).

Remember, we need to be cautious what we hope for and consider the likelihood that what we have already is indeed better (ie. true 24/96+ FLAC "Studio Master"). When we're invoking the use of proprietary compression schemes with likely quality-reduced components to it (ie. accuracy of the >24kHz parts of the audio spectrum), we need to consider compromises with accuracy (whether audible or not) or freedom of use due to the proprietary nature. I hope things will clear up over the next few months.

Addendum:
Some more "explanations" about MQA here.

Notice again the insistence to use "revolutionary", "lossless", and the lack of meaningful specifics... There's also this piece about the DAC "lighting up" to mean that the file is "Authenticated". Oooo... Cool... Remember how HDCD also had an indicator light?


Addendum 2:
Thanks to the folks on the Squeezebox forum, I was directed to a more detailed patent description to look at. Indeed, the method described is one of lossless encapsulation but in a fashion done with some limitations which allows "97.6%" of 970 16/96 musical samples analyzed to fit in the 24/48 data space. That's pretty ingenious actually! So I guess we can call it "almost always lossless"? Presumably if there's a lot of detail and dynamic range in the original 16/96 file above 24kHz, then this technique will fail to be truly lossless.

However, I am concerned that this technique actually is only maintaining 13-bits of the original signal in a "lossless" fashion without an appropriate decoder (see the diagram)! So... Assuming this is the same technique being used in MQA, this means that without the decoder, it's more compromised than I had thought in terms of the "lossless core"; not even 16-bit lossless when playing these files through a standard DAC. Basically, for audiophiles, buying an MQA decoder is essential if you have a collection of these.

One more thing from the patent:
"We can conclude that a 16-bit 96kHz channel with appropriate noise shaping is entirely adequate as a distribution format, meeting audiophile requirements with some margin to spare."
Given the universal approval of MQA so far in the audiophile press I have seen, I guess we're all in agreement that 16/96 is all we need then? :-)

I still like my idea of 18/48 lossless core and use the lower 6 bits to encode a lossy ultrasonic facsimile with >550kbps data rate. Of course, with Meridian's insistence on the importance of temporal resolution, this would be anathema in their eyes (due to temporal smearing because of block lengths typically used in lossy encoding) even though I suspect it could sound better than their patented scheme; certainly would be more accurate with standard DACs and achieve >16-bit dynamic range. Hmmm, why would the audiophile world advocate going through this Rube Goldberg of a system?! And why should we consider this "revolutionary"? ("Biggest thing to happen to audio quality in decades!" - please think about what you're saying WhatHiFi?.)

-----------------------------

I want to encourage everyone to read the recent "As We See It" editorial Audiophilia Nervosa in the February 2015 issue of Stereophile by Robert Schryer! Good article and nice to see this perspective articulated well. See, I'm not always critical of the mainstream audiophile press. :-)

... Just watch out for Synergistic Research bull droppings by page 28 among other testimonies of "magic"!

Have a great week everyone!


Friday, 9 January 2015

MEASUREMENTS: Tascam UH-7000 USB Interface (Part II: As an ADC)

TEAC & Tascam combo with size differential. The E-MU 0404USB in the background to the left.
Alright, it's time to spend some time looking at using the Tascam UH-7000 as an analogue-to-digital converter. Remember in the first instalment, I showed that this device is already a very good DAC. This time around, I wanted to see whether this device did the job well as an ADC; my main desire being to use it for vinyl needle drops and to see if it can be used as a good measuring device in comparison to the Creative E-MU 0404USB I've been using for the last couple years (which I bought mainly as a DAC back in 2009).

In terms of the underlying hardware, the Tascam UH-7000 uses the Burr-Brown PCM4220 ADC compared to the E-MU's AKM AK5385A chip. On paper at least, the Burr-Brown should be significantly better with a rated SNR of 123dB compared to the AKM's 114dB. Of course, much of the final result depends on the circuitry built around the ADC such as quality of the pre-amplifiers feeding the input signal.

I. The Spectrum of Silence

To start, let's have a look at what "silence" looks like through the Tascam UH-7000, with preamps set to minimum:

Impressive. With the ADC running at 24/96, we're seeing very low noise floor essentially flat down to -160dB across the spectrum (Note: I found an issue with this later on - see below).

Compared to the E-MU (sorry about the difference in scale!):

Clearly the old Creative unit is noisier with sporadic noise spikes reaching up to -140dB and a slight tendency for the noise floor to rise from about 35kHz and up.

So far, so good... The Tascam is doing well!

Let's now run a few RightMark tests to see how some of my DACs measure using both the Tascam and E-MU. I'll be looking at the AudioEngine D3 USB DAC as an example of a very capable but "lower tier" DAC in terms of resolution and the TEAC UD-501 as an example of a higher-end desktop DAC which would likely challenge the resolution of these ADCs. This will provide an opportunity to correlate the results between different "instruments". If the Tascam results closely follow what I've been seeing with the E-MU over the years, then at least it's suggesting that I'm on the right track with these measurements :-).

Basic setup:
Windows 8.1 Surface Pro 3 --> 6' Shielded Belkin Gold USB --> DAC [AudioEngine D3 / TEAC UD-501] --> analogue cable (shielded RCA for D3 / XLR for TEAC) --> ADC device [Tascam / E-MU] --> shielded USB --> measurement Windows 7 laptop

Tascam latest Windows driver: 1.01
Tascam latest firmware: 1.07

ASIO (TEAC) or WASAPI (AudioEngine) drivers used for playback.
ASIO for all recording.

RightMark 6.3.0 used as measurement suite.

II. RightMark Comparisons


     16/44:

As usual, let us start with the most common audio resolution - good old CD-quality 16/44. Here is an overall score sheet:

A few graphs to consider:
16/44 Frequency response: Essentially flat.

16/44 Noise floor: About the same across the board.

16/44 THD: Notice a bit more "skirting" at the base of the primary signal for the D3 suggesting more jitter as compared to the TEAC. Both Tascam and E-MU consistent in picking this up.

16/44 Stereo crosstalk: Interestingly, the AudioEngine has lower crosstalk than the TEAC despite the TEAC using XLR cables. Both Tascam and E-MU consistent also in this finding.
As you can see, 16/44 is really no challenge at all for these DACs (D3, TEAC) and measure essentially identically using both ADCs (Tascam, E-MU). The results show essentially ideal measurements. Not surprising that in the 2010's, reproducing a CD-resolution signal is really a "piece of cake" for reasonable quality digital audio gear.

     24/96:

Time to delve into the world of high-resolution with 24/96 then. Here's the summary:

Okay, a little more variance this time around compared to 16/44. However we basically see that the TEAC is capable of better noise level and in turn dynamic range compared to the AudioEngine D3 DAC (about an extra 1/2 bit or 3dB better for the TEAC). Interestingly, the E-MU actually turns in slightly better numbers in both noise floor / dynamic range as well as composite distortion numbers than the Tascam. Let's have a look at the graphs then:
24/96 Frequency response: In terms of the DAC, the TEAC has a flatter more extended frequency response as demonstrated with the Tascam measurement. It's interesting that the E-MU tends to roll-off the ultrasonic spectrum >20kHz very slightly (<1dB difference at 40kHz).

24/96 Noise floor: Not much difference really... TEAC slightly lower and this is consistent for both the Tascam and E-MU measurements.

24/96 THD: More evident than with the 16/44 measurement above, there's more "skirting" with the AudioEngine suggesting perhaps more jitter. But what's that peak at 30-40kHz showing up on the Tascam measurement?

24/96 Stereo crosstalk: Again, interestingly less crosstalk measured with the AudioEngine D3 and this is again consistent with both Tascam and E-MU as measurement devices. Hmmm... There's that odd spike at 30kHz again with the Tascam measurement of the TEAC DAC.
Despite a bit more variance, we're basically seeing consistency in the measurements using the Tascam and E-MU devices. However, I noted that unusual spike in the Tascam measurement of the TEAC UD-501 at 30-40kHz. How odd... We'll look at this in greater detail in a bit.

III. Dunn Jitter Test Comparisons:

So far, RightMark results are reasonably consistent and there's agreement between the results from my E-MU and the new Tascam unit in terms of how the two DACs measure. How then do the J-Test results look?

AudioEngine D3:


TEAC UD-501:


Unfortunately I pushed the volume a little higher with the Tascam on these UD-501 screen captures. As a result you can see noise spikes like the 10kHz spike with the E-MU 24-bit J-Test show up in a more obvious fashion (refer to the image above of the frequency spectrum of silence with the E-MU).

In any case, I think it's quite evident that there's not much discrepancy between the Tascam and E-MU. Both the AudioEngine D3 and TEAC are demonstrating rather good J-Test spectra, consistent whether using the Tascam or E-MU as ADC "measurement" devices.

IV. Tascam, we have a problem...

Remember up above when I looked at RightMark results with the Tascam and saw that usual ultrasonic noise above 30kHz with the 24/96 measurements of the TEAC?

Here's what I found (these are all from the left channel). When I start the Tascam "cold", there doesn't seem to be a problem:
Tascam UH-7000 24/96 "silence" at startup. Beautiful!
Tascam UH-7000 24/96 "silence" 15-minutes turned on. Couple little oddities.
Tascam UH-7000 24/96 "silence" 30-minutes turned on - LEFT channel. Huh? What's that?
As you can see, as the machine "warms up", noise starts creeping into the ultrasonic range between 30-40kHz! Swapping USB various cables made no difference nor did changing computers (Acer laptop and Surface Pro 3 tried). Of course I also made sure the Tascam wasn't situated close to another device which could be causing this noise. I even tried it with my old MacBook Pro and saw the same problem with OS X drivers.

I also played with the various settings of the device mixer itself to make sure I didn't accidentally turn on some DSP effects but to no avail.

BTW, here's a look at what the mixer panel looks like with knobs and buttons for effects like the compressor, noise suppressor, EQ, limiter...:


Finally, I plugged it into my Belkin power conditioner which made no difference so I am left with the conclusion that the noise is originating from within the device itself.

The noise isn't as "loud" with the right channel but obviously still there:
Tascam UH-7000 24/96 "silence" 30-minutes turned on - RIGHT channel.
As best I can tell, this seems to be something that happens as it warms up. In cooler ambient temperature (like my basement), it takes longer but will eventually show this noise pattern. If you look at the 24/192 FFT, it looks like there's quite a bit of noise up at 60-80kHz as well (maybe the 30-40kHz noise is a subharmonic):

Tascam UH-7000 24/192 "silence" 30-minutes turned on - LEFT channel.

I wonder whether this is noise from the switched-mode power supply (SMPS) given the close proximity to the audio circuits and whether this could be suppressed with better line filtering or RF shielding of the power supply. Well, here is demonstration of one piece of audio equipment where the audiophile practice of "warming up" the gear actually deteriorates performance.

V. Conclusions:

Since I bought this unit from Amazon, I had the opportunity to return it hassle-free... And that's what I ended up doing after putting it through its paces over about 3 weeks. I made a 24/96 vinyl needle drop of the Paul Simon Graceland album (Side 1 - same as what I did for the LP Test a couple months back). No question, it sounded good; punchy dynamics, excellent details, sounds just like the original LP playback. The ability to fine-tune the level controls with those large knobs on the front panel and the beautiful LED indicators to monitor for clipping will certainly be missed!

Throughout the test period, I never ran into any crashes with the driver software (unlike the issues I have with the E-MU on occasion). I also like the aesthetics of the device - goes well sitting on top of my TEAC UD-501.

I don't know if this particular unit was defective but I've received feedback from a friend in Europe with the UH-7000 that he's seeing noise in his unit as well:
European Tascam UH-7000.
If this is a systemic issue, I certainly hope Tascam fixes this perhaps in future hardware revisions (hopefully it's just a firmware/driver issue)... I'm very happy with Amazon's return policy and I must say I'm quite impressed by the little E-MU 0404USB workhorse despite its age and buggy drivers that will on occasion hang with samplerate changes. The Tascam has demonstrated to me that the E-MU ADC tends to roll-off the ultrasonic frequencies slightly (only -0.75dB up around 40kHz) and the noise floor is obviously not as clean as it could be (perhaps related to the little wallwart power supply).

Ultimately, the noise I found with the Tascam ADC once it warms up is of low-level and would not be audible in regular use (certainly not audible with LP needle drops, but high-resolution multitracking studios and those using effects processors might care) due to it being ultrasonic and down at below -100dB (a subjective reviewer would not have been able to pick this up). However, it is an unexpected finding which does show up when I do high samplerate measurements. If it were not for this, the unit would have stayed as a fixture on my audio equipment rack in the sound room.

Can anyone recommend to me a good ADC that is highly accurate, reasonably priced (maybe $500-600USD), stable Windows drivers, has good level controls, and provides good visual feedback of volume levels to avoid clipping? I'm certainly happy to purchase a Tascam unit like this one again in a few months and see if this issue is gone if by then I haven't found a better ADC.

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I hope everyone had a wonderful Christmas and New Year time! Time to get back to a hectic work and family life... May your 2015 overflow with good music :-).

Friday, 2 January 2015

Happy New Year!

Hey folks, welcome to 2015 :-).

I was hoping to post on the ADC component to the Tascam UH-7000 today but the wife and I decided on a surprise trip to Disneyland instead with the kids.



Let's aim for next week...

Happy New Years to all!

Wednesday, 24 December 2014

MEASUREMENTS: Tascam UH-7000 USB Interface (Part I: As a DAC)

0. Preamble


Well, look what Santa brought me early this month:

So apparently I had been "nice" in his books so he decided to see about getting me an upgrade on an ADC device for vinyl recording and measurement accuracy :-).

This is the Tascam UH-7000, part of the "pro" line of audio interfaces made by Tascam/Teac. It's a simple 2-channel model. On the front we have 2 large knobs to control the preamp input level for each channel - rotation feels smooth - good enough for reasonably precise volume adjustments. There's the "Phones Level" knob for headphone volume and when the "Link Line" LED is lit, this also serves as a master volume control for the microphone/XLR inputs. Holding down one of the two buttons for a few seconds above the "Phones Level" knob allows you to turn on the +48V mic phantom power. There are the corresponding multicolored 20-segment LED indicators; very useful to check for clipping.

Here's the rear of the unit:

To the left are the analogue inputs. This unit is meant for professional audio use so there are no single-ended RCA connectors to be found. Instead to the upper left we have 1/4" TRS balanced inputs, and XLR balanced below for analogue input. Analogue output is via balanced XLR connectors, and to the right we have XLR digital (S/PDIF or AES/EBU) in and outs, a USB 2.0 port below, and of course IEC connector for power cable.

You should not have much difficulty finding decent TRS to unbalanced RCA adaptors for line level input (should only cost <$5 at the local electronics parts store for decent gold-plated models):


The unit feels well made. It's a metal enclosure with the characteristic TEAC look, similar to the TEAC UD-501 DAC but not as wide. XLR connectors are nice with a good snug fit and reassuring click when locked. Latching mechanism feels secure and robust.

Currently, this model is on sale (I see $100 off in the US around Christmas time), I got it locally off Amazon in Canada for ~$600CAD. The device is compatible with Windows (32-bit and 64-bit) and Mac OS X. Not Linux compatible as far as I can tell.

I. The Tascam as a DAC

First, I want to explore analogue output quality when functioning as a DAC. Inside this unit is the Burr-Brown PCM1795 DAC which is the same as the Teac UD-501. The difference here is that the UD-501 is a "dual mono" DAC using 2 PCM1795s for lower noise operation versus this unit with a single DAC chip.

Hooked up to the oscilloscope, here's what a 1kHz 0dBFS square wave looks like with all volume controls at maximum:

Nice and clean. No clipping as confirmed by a 21kHz sine wave at 0dBFS. Beautiful channel balance as well.


Peak output from the XLR at 8.72V or about 6.2Vrms. (+18dBu referenced to 0.775Vrms. I believe this level can be maxed out to +24dBu according to the specs sheet if I use the mixer/control panel.)

Impulse response of 16/44 signal:

Typical linear phase filter with the usual pre- and post-ringing characteristic of fast roll-off filters. Absolute phase maintained.

As usual, I'm going to measure the output with the trusty E-MU 0404USB I have been using for the last couple years for consistency and comparison. The signal path looks like this:

Windows 8.1 laptop (Surface 3 Pro) --> shielded USB cable (Belkin Gold) --> Tascam UH-7000 --> 3' XLR analogue cable --> E-MU 0404USB --> shielded USB cable --> Windows 7 laptop (Acer)

Measurement software: RightMark Audio Analyzer 6.3.0 (I found some issues with the newer 6.4.0 version on the Windows 7 laptop).

Playback software is the newest foobar2000 1.3.6 with ASIO plugin.
Latest Tascam driver (1.01 for Windows) and firmware (1.07).

1. 16-bit Results:

Starting with 16-bit audio, here's the "big table" with results from a number of other DACs I've measured over the years:

As you can see, I've included a number of different models - ranging from the USB stick DACs like the AudioEngine and Dragonfly, to the iPhone 6, and of course better "desktop" units like the Oppo BDP-105 (oops forgot the P in the table), Logitech Transporter, and Teac UD-501.

Apart from the Dragonfly which has a bit more distortion and higher stereo crosstalk, 16-bit audio really isn't much of a challenge for modern DACs capable of high-resolution 24-bit audio these days.

A couple graphs:
16/44 Frequency Response
Notice a little more bass roll-off with the Tascam compared to the others, about 0.5dB down at 20Hz; otherwise not much to see here...

16/44 Noise Level
Good all around low noise performance.

Bottom line is that 16-bit audio is just great with any decent modern DAC...

2. 24/96 Results:

I believe 24/96 is the "sweet spot" for DACs these days. It's ubiquitous for any DAC worthy of being called "high resolution" including the simple USB DAC/headphone amps like the AudioEngine D3 and Dragonfly. Most high resolution album releases seem to target this resolution and "vinyl drops" tend to be 24/96 as well so it's important to function well at this resolution. A good DAC in 2014/2015 should have no excuses for not measuring well at 24/96 IMO.

Again, let's start with the "big table". This time, iPhone 6 not on the list as it's incapable of 96kHz.

Not bad! The Tascam UH-7000 squeezes out slightly >110dB noise level and dynamic range. On this chart it looks really close to the Teac UD-501 but in fact those results I have for the Teac are with the RCA output - the XLR results would be better and likely beyond the capability of the E-MU 0404USB measurement device.

Distortion values for the Tascam is low and it maintains very respectable overall stereo crosstalk result. However, if we look at the stereo crosstalk graph, it looks interesting:

There's a notable rise in the crosstalk starting around 500Hz and gets worse with higher frequencies. I have not seen this before with the other DACs. At 20kHz with -66dB crosstalk, it's arguable if this is ever audible of course despite the unusual finding.

24/96 frequency response: slightly more roll off with the Tascam at frequency extremes.

24/96 noise floor: Dragonfly worst performer here.

3. 24/192 Results:

Honestly, I feel that 24/192 is excessive already for consumer playback and I prefer not to have such large audio files eating up hard drive space with questionable benefit! Others disagree of course. (BTW: Consider also whether many 24/192 recordings actually have content in the high frequencies; for example, take a look at the recent 2014 release of Neil Young Time Fades Away.)

In any case, here are some numbers for the Tascam DAC and a couple others that support this samplerate:

The Tascam isn't as good as the Teac and Oppo in terms of noise level. Remember, the Tascam is about 3/4 the price of the Teac and 1/2 the price of the Oppo, plus it's also an ADC device which I have not talked about yet!

A couple graphs to review:
24/192 frequency response: Again the Tascam seems to roll-off more at the frequency extremes (not necessarily a bad thing to attenuate the ultrasonic content to reduce intermodulation distortion).

24/192 noise floor: Not too shabby!

4. Jitter

Using the standard J-Test as in my other posted reviews...
16-bit J-Test: Primary signal at 11kHz, spectrum from 5kHz to 18kHz. Jitter modulation pattern easily seen (good demonstration of the low noise floor).
24-bit J-Test: Primary signal at 12kHz. No sidebands around the primary signal. Minimal "skirting" around the primary signal.
What can I say, it looks nice. As expected for a modern asynchronous USB 2.0 interface, jitter should not be an issue. Tascam boasts that this device uses a high precision TCXO (temperature controlled crystal oscillator) down to +/-1ppm accuracy.

5. Subjective Sound Quality

The reality is that although I've measured the DAC function here, it's unlikely I will be using this device as a DAC in my listening room... My primary interest with this is for ADC recording like vinyl needle drop archiving or as a measurement device like what I'm doing with the E-MU 0404USB over the last couple years. I connected the XLR analogue output to my main audio system in the soundroom for a couple of evenings to make sure the sound was good; indeed it sounded great - very similar to the Teac UD-501 from last year. Soundstage was nicely presented when played back through the Emotiva XSP-1 preamp and Paradigm Signature S8 speakers with SUB 1 subwoofer. I've also spent more time listening to the headphone output switching between the Sony MDR-V6, Sennheiser HD800 and AKG Q701 over a few evenings while doing other work.

I noted that the headphone out seemed more powerful than the Teac UD-501 especially for more demanding headphones like the AKG Q701. The sound is full and clear at maximum volume with no evidence of strain. Channel balance is very good throughout. Even though the frequency response measurements suggest relative bass roll-off, I can't tell a difference as music still sounds nice and full on the low end (not that one would expect to hear any anomaly unless one had truly golden ears since we're looking at <0.5dB down at 30Hz difference between the Teac and Tascam DACs!).

Whether through the headphones or speakers, sonic detail like Muddy Waters' guitar sounded precise and startlingly dynamic on "Country Boy" (off Folk Singer, Classic Records 24/96 HDAD rip). Vocal separation; that sense of "air" between singers on the new Pentatonix Christmas album (That's Christmas To Me) sounded excellent (check out the recent release "Mary Did You Know?"). Another holiday treat was Andrew Gant & Vox Turturis's Christmas Carols from Village Green to Church Choir also available as 24/96. A joy to experience these tracks through the Tascam with my Sennheiser HD800 for personal listening and also through the Signature S8 speakers with the family! Fantastic ambiance in the performance venue captured in high-resolution with excellent dynamic range throughout this "classical" recording (I always enjoy a nice performance of Veni, Veni, Emmanuel this time of the year).

As I have expressed over the years, decent DACs these days sound fantastic. The main impediment to good sound has more to do with whether the amp is adequate to drive the transducer and things like impedance matching for headphones to make sure the frequency response stays reasonably balanced (unfortunately the Tascam site doesn't list the headphone output impedance and thus far I have not tried low impedance IEM headphones).

6. Summary (as a DAC)

So far, so good. Plug-and-play DAC functionality with no issues around drivers so far. No crashes or any incompatibilities with foobar2000 or JRiver. I have not tried it with the Mac and assume it should be rather straight forward as well with the OS X drivers.

From a sound quality perspective, I have no qualms with the Tascam UH-7000 so far. The sound is subjectively excellent and objectively, distortion is low with good dynamic range and low noise floor. It has unusual stereo crosstalk results with increasing crosstalk as frequency rises but I expect this to be of academic interest only and inaudible. No evidence of jitter anomaly. So while not measuring in the "top tier" of results I have seen, the Tascam UH-7000 does perform admirably and would be commensurate with the relative cost of this device given the functionality.

Next week, we move on to exploring the ADC capabilities of this machine (what I'm most interested in)! Let's see how it stacks up in that department...

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Happy holidays to you and yours! Hopefully you're all enjoying the sights and sounds of the season - and hopefully you have been on Santa's "nice" list as well... :-)

Saturday, 20 December 2014

MUSINGS: Passion, Audiophilia, Faith and Money



Everyone is entitled to his own opinion, but not his own facts.   --- Daniel Patrick Moynihan


Human passion is an interesting phenomenon isn't it? With it, we as individuals can strive to achieve in ways we look back on and marvel. Passion drives creative pursuits like symphonic compositions or visual masterpieces. Prosocial acts of compassion and love flow from this most mysterious fountain to produce individuals of such distinction that we cannot help but show reverence. Scientific achievements likewise require the passion to fuel the drive for understanding whether in creative ways (consider Einstein's "thought experiments" resulting in the theory of relativity), or the power to endure and overcome the monotony of experimentation (how many prototype light bulbs did Edison make?).

As a community, a common passion provides the glue that bind us together. A sense of vision; of purpose. Consider the joys of a close-knit family, teamwork (hopefully!) at one's place of employment, or the excitement fuelling the rise of one's favourite sports team, or the pride of one's nation in the Olympic Games.

Passion also ties us together in less grandiose ways of course... For whatever reason, the fact that you're reading this post probably means you have an affinity to audio of some form. Perhaps you're an avid album collector revelling in the ownership and experience of music, or maybe passionate about the hardware side; the fascination with the equipment itself which can enhance the joy of music. Given that I have put together many articles on this blog on the hardware, I must count myself also in some way as part of the "hardware" subculture of audio.

As much as human passion (and emotion in general) can be positive, we must be careful of the converse effect. Consider notorious individual "crimes of passion", terrorist groups, racial acts of hatred, or destructive cults and religions throughout world history. Again, these are the extremes, but they highlight the dangers inherent in individuals or groups when emotions rule, but rational thought, and reality-testing become suppressed.

The folks on the Squeezebox Audiophile Forum bring up interesting articles on the web every once awhile. Recently, there's this discussion about this ethernet cables and jitter article. On the surface the author makes a case for timing being inherently important in audio. Sure, that's true. But of course, for anyone who understands the asynchronous nature of ethernet data communications and how jitter originates in the DAC and can manifest in the analogue output, it's quite clear that the simplistic explanations presented just makes no sense. Yet in the "hardware audiophile" subculture, it's somehow encouraged to accept magical thinking such as this about needing "better" ethernet cables and those who are bold enough to state the facts are often painted as "closed minded" or those unable to hear the reported subjective difference are branded as having "cloth ears" or accused of not using equipment of adequate resolution (or adequate price?). Of course, audiophiles of this variety discount objective analysis that "captures" and measures the sound and refuse to acknowledge methodology which would remove subjective biases as if they are immune to well described psychological phenomena (eg. banning discussion on ABX or blind testing in some forums).

When a group of people gather together with a common passion, share ideas initially based on some semblance of fact but in time builds and are fuelled by purely subjective testimony, and ultimately discounts divergent opinions (confirmation bias), what we end up with is a subculture based on faith. It's quite evident that this is what has become of discussion around high fidelity audio reproduction in many parts of the Internet and in the print magazines in general. Where there is faith, fought with vigour, breeds a form of religion.

Since time immemorial, money and religion have always been intertwined. The sale of items of faith has always been a high margin proposition (consider the sale of indulgences). As a business, audiophile equipment is of course about the profit motive. However for years now, claims have been made about various dubious hardware (particularly tweaks, cables, "room treatments") and in recent years software (like OS optimizers and playback software) based on articles of faith without any evidence whether directly (see p. 128 in the January 2015 issue of Stereophile for a contemporary example) or indirectly through published articles in the audio "press". The question of journalistic ethics is certainly questionable with a number of websites where financial supports remain undisclosed. Complicit in this is the audiophile mainstream media's apparent lack of courage and conviction to take a stand to question or test these claims in any reasonable manner as to whether these items make any discernible difference. I can only presume with the loss of subscription income, magazines probably are at a point where they are at the mercy of advertising dollars to survive (in this regard, we can't blame them I suppose since "biting the hand that feeds" them will lead to their own demise). But without a media willing to engage in critical thinking to sort out faith from science, how then can the typical audiophile be educated? I cannot help but believe that in the face of all of this, independent blogs and message forums become important for critical thinking in this day and age (and not just for audio).

Much of what I describe above isn't unique to the audiophile world. Consider homeopathy, alternative health care, or the nutraceutical industry where likely much (or all) of the "effect" is placebo, yet many subscribe to the beliefs wholeheartedly and spend significant dollars as well. At least there are some regulations in that industry and even Dr. Oz got his hands slapped before the Senate earlier this year. Many of these alternative theories can of course be discounted, but medical science still holds many mysteries to be discovered as it develops and secrets of the body are revealed. The thing about audio of course is that this is a mature applied science we're talking about (especially digital computer audio), not discovering some new frontier in genetics for example! We could argue about audibility of things like 16/44 vs. 24/96 knowing that maybe 16/44 is cutting too close or that there could be filtering issues with some DACs around the Nyquist frequency. But there are other things like ethernet cables where there really is nothing to argue about by virtue of what it is and what it was engineered to do! All of that stuff about timing and jitter (referring to the article above) are just not possible "issues" between otherwise error-free ethernet cables. A belief or "faith" that it is possible constitutes some kind of magical thinking which when systematized (as the Industry might want to do to instill fear and uncertainty) adds to the overall audiophile myth. Not some new frontier for science to explore, but certainly more ground for manufacturers to create revenue from the unsuspecting audiophile told to expect an upgrade in sound and cheer-led by the press.

I do not begrudge companies for making £1,600 ethernet cables. If money went into the materials used in construction of these cables, I'm sure they'll look and feel nice. But Patek Philippe makes nice expensive watches and they don't claim superior time accuracy. But Chord feels their ethernet cables sound better ("big differences") and evangelism from the "priests" in the audiophile press continues (here, here) with not a shred of evidence over these years. (Could it be? There just is no evidence other than mere testimony? And how much money are you willing to tithe to the Church of Audiophilia?)



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Merry Christmas everyone! No matter how busy the holidays may get, I hope you find peace, love, and time to enjoy the tunes. :-)