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.

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. :-)

RESULT: Archimago's LP Needle Drop Blind Test

Okay, finally it's time to put up the test results for the "LP Needle Drop Blind Test"!

Of course the TMS system looks great compared to my "man cave" vintage Technics rig. :-)

A big thank-you to those who spent the time to listen to the 3 vinyl rips and then entered your results in the survey site I put up!

As I noted with the test page, this test is more for fun and obviously has less potential significance than the previous high bitrate MP3 listening test, or the more recent 24-bit audio blind test. Nonetheless, I think it does illustrate some points about vinyl sonic reproduction to those who had a listen and provides an opportunity to talk about the relative cost of audio hardware and what that actually buys in terms of sound quality...

Procedure:

As described previously, the purpose of this blind test was to ascertain the preference of respondents listening to a high-resolution rip of Paul Simon's "Diamonds On The Soles Of Her Shoes" from the same Graceland album (2012 25th Anniversary Edition - RTI 180gm remaster - Matrix / Runout (Side A): 88691914721-A RE1 20315.1(3) STERLING RKS). The samples were all ripped with the same ADC (my Creative E-MU 0404USB) and laptop (Acer Aspire 5552-7858) using Audacity 2.0.5 at 24/96 bitdepth/samplerate. The raw audio files were edited with Adobe Audition 3 for equivalent fade-ins and fade-outs, and average volume was normalized across the three samples (alas resulting in a few clipped samples which I do not affect the final "gestalt" of the sound). I felt that a 2 minute sample was adequate for evaluation of sound quality. Instantaneous A/B testing with something like the foobar ABX Comparator was encouraged.

A significantly more expensive turntable system consisting of the Roksan TMS, SME309 tonearm, Ortofon Cadenza Black moving coil cartridge and Whest PhonoStage.20 preamp was compared with my own modestly priced stock Technics SL-1200 M3D turntable with either a Denon DL-110 (high output moving coil) or Shure M97xE (moving magnet) cartridge fed to an Emotiva XSP-1 preamp with phono input. 

In total, I received 39 responses to this test. I know that my FTP site uploaded >150 copies of the audio test file so I suspect many more people must have listened than took the time to respond. There was also an alternate download site so I suspect much more than 150 people downloaded the samples.

Compared to previous tests with survey result of >100 responses, 39 results is relatively small but realize that this is still larger than most informal surveys I have seen done on audiophile forums. Also, compared to previous surveys, this one wasn't advertised to nearly as many places. Vinyl rips are a little odd, "straddling" both computer audio in that they're often ripped at high-resolution (24/96 in this case) so ideally the tester has high-res digital playback gear, but the actual sonic differences are mainly due to the analogue hardware and would likely only interest those who know about turntables and cartridges. Needless to say, despite the growth in LPs, the LP format remains a niche market (8.3 million LPs in all of 2014 for the U.S. isn't bad, but remember, weekly CD sales is on the order of 4-5 million units but dropping).

I announced the test only on the Audio Hardware forum on Steve Hoffman Music Forums, the Squeezebox Audiophile forum, the Vinyl forum on Audio Asylum, and the Vinyl Circle at AudioCircle.

As in previous tests, the responses came from various countries around the world:

Interestingly the majority of survey responses came from Europe - ~54%. Followed by North America with 33%.

Results:

In the survey, I asked respondents to rate which of the 3 files they liked the MOST, the SECOND, and finally LEAST.

As you can see Sample A marginally edged out Sample B as the "best" sounding file by only 1 vote. However, if we include results for what was "second best", clearly Sample A beat out B and C as preferred. Consistently, Sample C was considered least well liked.

A weighted score (3-points for best, 2-points for second best, and 1-point for least preferred divided by total of 39 entries) results in:

Sample A - 2.28
Sample B - 2.03
Sample C - 1.69

So, what analogue gear produced these samples:

Sample A - Technics SL-1200 M3D with Denon DL-110 cartridge
Sample B - Roksan TMS/SME309/Ortofon Cadenza Black cartridge
Sample C - Technics SL-1200 M3D with Shure M97xE cartridge

Overall, it looks like the Technics SL-1200 and Denon combo connected to the Emotiva XSP-1 preamp was the "winner" in this survey! Not by a huge margin of course.

To gauge whether respondents thought the difference was worth an upgrade between the "best" and "worst", these were the results:

In total, about 1/3 of respondents thought the difference was worth the upgrade versus a combined 51% thinking there's probably not enough of a difference to consider a $1000 upgrade (of course the price difference between the TMS system and the Technics is much larger!). Interesting to see that 15% basically found that the difference was significant but would not change their level of musical enjoyment if upgraded.

I was curious - of the 33% who thought an upgrade was warranted, which system they thought sounded the "best", "second best", and "worst" (to get an idea of which system they thought was most worth upgrading to):

Weighted score of the data above (of 13 respondents, maximum 3 "Best"):

Sample A - 2.23
Sample B - 2.0
Sample C - 1.77

Again, we're seeing a similar pattern to the results of the full sample; that overall Sample A (Technics SL-1200 M3D + Denon DL-110 cartridge) was preferred and the same turntable with the Shure M97xE was least preferred. There was no evidence of any special preference with the group that heard a greater difference.

Like with my other tests, I asked the respondents to identify the digital gear used to listen to these samples. Also like before, clearly most audiophiles who took this test used very good equipment to listen with. DACs used included the Schiit Modi, Naim DAC-V1, Meridian Explorer, ATOLL DAC 200, M-Audio Delta 410, iFi Micro iDSD, FiiO X3, Benchmark DAC2, Mackie Onyx Blackjack, Simaudio Moon 100D. Only about 4 respondents reported using the built-in computer motherboard DAC. About 50% of respondents identified themselves as using headphones for the evaluation. Headphones identified included many using Sennheiser models (HD800, HD650, HD600, HD280, HD580, HD428), Sony MDR-7520, HiFiMan HE-500, Audeze LCD-2 rev2, AKG K530, AKG K612 Pro, AKG K701, Denon AH-D2000, AudioTechnica ATH-M50x, Grado SR80. Speaker systems included Monitor Audio RX8, Linn Isobarik, B&W 805, Rega RS5, Klipsch Heresy, Dynaudio Contour S3.4, Devialet 200 + B&W 802D system, Meridian active speakers, Mission 702e. 18% reported using foobar ABX Comparator or equivalent.

Summary - So What?

Well, I did say this is for fun, right? But I think there are a few general facts to keep in mind when talking about vinyl drops in general and specifically analogue gear.

1. I believe a well recorded LP needle drop (especially at high resolution) does represent the actual sound produced by the turntable/cartridge/preamp - essentially 100%. I tested this by recording the track at 24/96 (with the old E-MU 0404USB) and volume matched with the turntable playing back the song in realtime, switching between inputs resulted in indistinguishable sound at least for me (and my wife was willing to lend her ears); as in all subjective experiences YMMV. Of course, it's important to make sure you play the digital files back with an accurate digital front end. As a result, I believe one can evaluate the sonic differences quite easily - audibly obvious compared to say high bitrate MP3 vs. lossless or the difference between 16/44 and high resolution digital. for example, a friend sent me his rip of this same track using the Audio-Technica AT150MLx and the high frequency boost from that cartridge was easily heard.

2. A number of people commented they did not like the sound of vinyl rips in general compared to the CD rip. I can totally understand, especially since so many respondents used headphones for evaluation. Vinyl rips, especially when completely untouched like the samples in this test do contain the imperfections of vinyl playback. Surface noise is heard during quiet segments and the occasional crackle and pop will be heard from dust, static, or vinyl defects. I have seen people post on forums that they've never experienced surface noise and never heard a pop - that's just nonsense. It's not uncommon to find new LPs with noisy background even after thorough cleaning and many of my records from the oil crisis days of the early to mid-1970s clearly were made with noisy, probably recycled vinyl. (Interestingly, most of my 1980's LPs sound great even though they may appear thin on inspection.) Over the years I have checked out some beautifully recorded vinyl rips rivalling the quality of professionally produced remasters; there's a real skill and art in restoring the sound especially for music that was dynamically squashed in the CD/digital release.

3. I think this is a nice demonstration of how important the choice of a good cartridge is! Notice that the "best" overall sample was the Technics turntable with Denon DL-110 cartridge. And the "worst" sample was the Technics turntable with Shure M97xE. The only difference being the different cartridges. Nice to know that the more expensive Denon in this case was felt to be superior on the whole (at about 3x the price). The main complaint about the Shure was that it accentuated the sibilance in Paul Simon's vocals (like in the word "she"). Even so, 20.5% of respondents thought the Shure sample sounded best so there's obviously significant subjective variation.

4. BUT a much more expensive system like the TMS turntable + SME tonearm + Whest phono preamp did not draw higher preference overall from the respondents. It goes without saying that there is always a point of diminishing return with mature technologies and it's no surprise that price itself is not necessarily a determinant for best sound quality. I have already previously posted on wow & flutter measurements for both the Roksan TMS and Technics SL-1200 M3D demonstrating that the Technics is actually more accurate in terms of absolute speed. A few respondents and chatter on the Steve Hoffman Forum noted that Sample B (TMS system) had an audible hum in the silent portion. This is true and can be heard at 57 seconds at the end of the Ladysmith Black Mambazo segment as it transitions to the Paul Simon vocals. This is much more obvious with closed headphones or a quiet sound room with low ambient noise. It's obvious that not everyone heard this anomaly though. I've gone back to my friend's place and confirmed that it's coming from the Whest phono stage (rather than the TMS turntable or phono cable). It serves as a good reminder of the importance of sensitivity to noise of an analogue setup. Remember that the Ortofon Cadenza Black is a low output voltage (0.33mV) moving coil cartridge (vs. 1.6mV Denon vs. 4mV Shure). This means there's greater amplification applied by the phono preamp and a concomitant increased risk of picking up hum in the system. The quality of the phono amplification stage therefore becomes extremely important. I cannot tell if this hum is unique to my friend's Whest unit (which is a number of years old at this point). For the record, vibration isolation isn't really an issue in this case because I was recording the needle drops without the speakers playing the music and the room was basically silent during LP playback.

Well folks... I hope you enjoyed listening to the Paul Simon LP samples. I'm still having fun with some used vinyl collecting. Lots of good stuff out there to collect and at exceptional prices as well. I know a few people have gotten into vinyl and have been disappointed with the sound. I think there's a lot of hype out there around this almost mythical "sound quality" of vinyl that some people will excitedly plunk a wad of cash down expecting audio nirvana to emanate from their speakers. Sure, if everything goes right, the sound can be excellent, but like everything in life, it's important to have realistic expectations. :-)

Hope you're all enjoying the music as we head into the Holiday Season... Thanks again for all the respondents; I obviously wouldn't be able to do any of these blind tests / surveys without your time and participation!

I have a new audio "toy" to play with over the holidays! Stay tuned...

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ADDENDUM:
Last night I went to watch the movie Interstellar at the local megaplex. Wow! Neat movie; reminds me of 2001: A Space Odyssey with all kinds of sci-fi ideas - AI (robots with humor!), evolution of humanity, almost "divine" guidance, centrifugal artificial gravity and cryosleep. Elements of modern science gets thrown in: black holes, wormholes, Grand Unified Theory, space-time relativity, and genetics. Of course we must throw in the human elements: love, family, relationship, fear, loneliness, perhaps even madness. Highly recommended flick and one I'll be looking forward to on Blu-Ray.

But as reported elsewhere (here, here and here for example), the movie soundtrack was remarkably "loud"! Although I didn't have any issues with deciphering the dialogue (seriously, Matthew McConaughey's southern accent and lack of enunciation at times doesn't help), there were parts that were obviously rife with clipping distortion. I have actually never heard these levels of distortion to the point of hearing "pops" and "crackles" at this specific theatre before (with excellent sound setup including Dolby Atmos decoding). As I noted previously, the Dark Knight Rises soundtrack (another Christopher Nolan film with Hans Zimmer score) from 2012 was remarkably compressed for an orchestral score. I really don't know what the point is of doing this other than annoying the moviegoer! Loud is one thing which the theatre can accomplish by turning the knob up, but to the point of pushing the levels to "11" on the mix itself? That's obscene. (In fact, ironically I wouldn't be surprised if this theater turned down the volume if many viewers complain thinking it's their sound system crackling rather than inherent in the soundtrack mix. I believe I've heard louder transients in the theater before on other movies.)

E-Mail: "Full Dynamic Range" - Now there's a marketing phrase to get behind!

 The other day, I got this E-mail from an audiophile friend:

Hi Arch, 

I think this is funny. A contradiction in every way imaginable which is why I wanted to share it with you. I know it’s not your type of music and although I still listen to it sometimes, it’s mostly youth sentiment for me. One of the loudest and fastest bands back in the days was Terrorizer. Their drummer (Pete Sandoval) is one of the fastest drummers I have heard, he's amazing. But unfortunately production for this kind of music wasn't always very good. It's often compressed to hell and equalized with typical "rock" settings; increased lows and highs and suppressed mids. It's often overdone in my opinion. I do think production of hard rock and metal albums have improved over the years but back then, some were just downright bad. This particular album wasn't that bad though, it was actually pretty decent from what I remember. 

Terrorizer was a so-called super band. Some of the best musicians from different bands came together to produce one album. The band split up that same year but after 2005 they came together a few more times to release other albums. This album was their debut from 1989, titled World Downfall. It is considered one of the most influential albums in the genre and now a classic that every fan of the genre should own. I ordered this album on vinyl recently, limited to 100 copies, in "Downfall Orange". What struck me was that it is marketed as a "Full Dynamic Range" version. I would never have ordered it if that wasn't mentioned! Could this be the new marketing phrase? The end of the loudness wars? How much dynamic range can be in music like this? And how good can it really sound? I was curious and I could not resist the urge so I bought it ... :). Fitting label too, Earache! Haha!
 

Here's a screenshot of the waveform. The entire album looks similar:

The average album DR is 12. I think that's amazing! 

The album sounds spatial, black background, there's air around the instruments and the drums sound natural. Basically, the album just sounds very good. Obviously the entire album is one massive wall of noise so I can't say it’s not tiring to listen to but at least now it’s a good sounding wall of noise haha! :D. 

I am surprised that the end of the loudness wars (if that ever happens) would see a start with albums like this. But if this is it, it definitely looks promising!

Funny story about the drummer, the band once played a prank on him by making him listen to a band that used a pre-programmed drum machine, and pretended it was a real drummer who could play faster than he could. He was gutted, and went on to practice until he managed to play faster than the machine.

PS. I don't advise you listen to the album. If you decide to do so you it's at your own risk. I'm not liable for any damage this might cause, physically or mentally! Haha! Just kidding! You’ll live J.

Well. That would be amazing wouldn't it?! To start advertising music as "Full Dynamic Range" (with a nice logo maybe?) to grab the interest of those who actually understand the importance of mastering quality. Slowly this could build into a "movement" of sorts that might even capture the interest of the mainstream music industry - imagine seeing CDs being advertised like this...

As I noted in this previous article, I actually think that the next round of remastering will actually swing the pendulum towards "full dynamic range" to differentiate the sound from current loud dynamically overcompressed releases. A movement of this sort would be a true advancement of sound quality that would make the push towards "High-Resolution Audio" and format wars like PCM vs. DSD (yawn...) audibly irrelevant in relative significance.

Remember, we should be cautious about reading too much into DR values of vinyl rips and comparing directly to a CD version, of course. However, also remember that vinyl is limited in how much compression can be applied in order to prevent tracking issues. I wonder in fact if this limitation may be an important reason why LPs have survived - they can sound better than the corresponding CD because the masters used to cut the vinyl have always needed to be of a decent dynamic range. Although the track is loud; visibly so zoomed out like this, I'm sure zooming into the waveform would reveal zero clipping / peak limiting which is what kills the DR value.

In other news: we just saw the release of Bruce Springsteen's Born In The U.S.A. available on HDTracks at 24/96 with a DR of 9. Original first CD release in the 80's - DR13. Born To Run is even worse with DR8 (I think even the 30th Anniversary CD release may be better). Hey Columbia Records, you do realize a little bit more audio realism can be squeezed out from 24-bits, right (which I hope is what audiophiles are looking for in these "better than CD" releases)? As usual, I highly recommend checking out the Dynamic Range Database to get a sense of the mastering quality before jumping into these so-called "high-resolution" albums.

BTW, I jEst liStenEd to dA TerRoRiZER AlbuM... i'M pReety ShuRe Im OhhKaAaY! EErAchE inDeeD. :-)

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Thanks to everyone for trying out the "LP Needle Drop Blind Test", especially those who took the time to submit survey results. The survey site is closed although the FTP remains open for now. I'll likely close that off this weekend.

Work has been crazy-busy this last 2 weeks so I'll try to get results up in the next week. Stay tuned...

Enjoy the music everyone! (I'm trying to find the time as we head towards a busy holiday season...)

LP Needle Drop Test: Final Week!

Just wanted to remind everyone that I'm closing off the LP Needle Drop Blind Test survey at the end of this week (November 30). Thanks for all the submissions so far... Thanks for the downloads so please submit your results!

No real audio discussion from me this week... Just been readjusting to the work and time zone now that I'm back in North America. One thing I will note however:

That's the Sony A6000 mirrorless camera. I'm very impressed by the travel images I got from this little device! Even with just the kit zoom lens (E PZ 16-50/3.5-5.6 OSS) [35mm equivalent 24-75mm zoom].

I carried this little guy through the 2 weeks in China and over the 2 cities I visited and worked at. Light weight but good build, reasonably fast, really excellent autofocus mechanism, and best of all, image quality even with challenging low light situations using ISO3200 resulted in usable images thanks to the 24Mpixel APS-C sensor!

Although I would love to bring my Nikon D800 along, I just don't have the space during work trips and this little guy performed admirably.

Sure, the EVF viewfinder isn't as good as a bright SLR and I would have loved greater depth of field with my f/2.8 lenses. But for 95% of the situations, this little Sony was more than adequate.

Time to get reacquainted with my audio system back home :-)...

Have a great week everyone!

MEASUREMENTS: Roksan TMS (1) Wow & Flutter - PlatterSpeed test.

Greetings from this place:

Port city of Xiamen, China - just across from Taiwan.

Wrote this up right before I left Canada to go to Asia...

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Hello folks, while you're working on the vinyl LP test and as I prepare to go overseas for a few weeks, I thought it might be interesting to post the objective PlatterSpeed results from the Roksan turntable as well as a couple more pictures of the setup...

It is a thing of beauty:

Although there have been updates to the TMS design (I think TMS 3 is the latest, here's a TSM 2 review from 2003), the appearance and general design principles seem to have stayed constant over the years. The build of this device is top notch and smoothness of operation appears excellent. Switching from 33.3rpm to 45rpm is easy with the push of a button up front.

Using the same Adjust+ Test LP to measure as I did previously with the SL-1200, here are the 33.3 rpm charts and calculations as per PlatterSpeed measured off the same iPad:

As you can see, it measures quite well. It's running a little fast with a mean frequency of 3156.5 Hz instead of 3150 over 60 seconds or so. Wow measurements with the DIN IEC 386 plugin is a little higher than the SL-1200, a similar pattern with the raw frequency maximum deviation. But when lowpassed, the maximum deviation was the same as the Technics at +/-0.02%.

Here it is measured at 45 rpm:

Again, it's a bit fast at 45rpm as well. Remember the target "mean frequency" at 45rpm should be 4252.5Hz. There's only a slight increase in the DIN IEC 386 wow measurement and slight increase in the lowpass-filtered result compared to 33rpm demonstrating good stability with the increased table speed.

It'll be fun to see the LP blind test results! Keep the entries coming - you have to end of November :-).

Enjoy the tunes.

MUSINGS: Articles of Disservice - Stereophile November 2014

Over the months, I have put up posts critical of magazine articles (like this one) but I must say that the November issue of Stereophile was an "impressive" read.

I just wanted to bring up a couple of notable articles that I found interesting but highly misguided. I found these articles disturbing because they perpetuate the status quo or express an opinion that lacks constructive merit and I think ultimately do a disservice to advancing the audio hobby.

First, I think it's worthy asking ourselves, what is the "mission" of the audiophile publications? I looked around but was not able to find a page describing a "mission statement" for Stereophile. I'm sure the purpose must include informing, and educating the readership around new products. Reviewing albums to consider. Cover trade shows to let us in on what's "around the corner". The objective measurements embedded in the reviews which I have commented on previously are useful. But at the the end of the day, is there a basic mission statement? You know something catchy like "the waging of war against the tyranny of inferior audio" (Audio Task Force) as quoted in the recent NY Audio Show report. Considering that audiophile magazines are "for profit" companies, I think it's all the more worthy of consideration; especially these days where ads and the relationship the magazines make with the industry has likely become the main source of revenue.

Steve Guttenberg's "As We See It" article titled Communication Breakdown touches on the supposed ills of dynamic range compression (see Loudness War). He starts off with a provocative statement: "Classical and jazz notwithstanding, an awful lot of new music is highly compressed, processed, and harsh, and it's about time we got used to it." He then talks about some "superstar producer" not liking his suggestion to have 2 mixes (crushed & non-crushed). Then he reminisces about childhood tinkerings with AM radio and how he likes the background noise slightly mistuned (hey I liked it slightly higher pitched when mistuned but can't say I liked the noise, just more as "tone control"). Then there's a little history lesson on distortion in rock & roll. Then a little something about analogue distortion vs. digital distortion. Then he basically says he has learned to enjoy the music "through the grit". So... I guess it's okay then to accept compressed and distorted music (including many jazz and soundtracks these days).

Well Steve - hell no. You've learned to tolerate the grit and enjoyed the music - I'm happy for you. You seriously don't think that most of us have clutched "to our chests our 180gm LP's of Dark Side Of The Moon and Aja and rejected all the new music" do you? I mean seriously, the Loudness War has been raging since the mid-1990's and I doubt many of us music lovers have not been able to explore "new" albums and bands for the last 20 years - a full generation! Talk about resurrecting and perpetuating a ridiculous straw man stereotype of the "old audiophile" (hilarious that the magazine front cover contains the artwork for Gaucho). Do you seriously think that many of us haven't moved on from Dark Side or Aja? The issue is not that we're not "used to it", the problem is many of us are sick of it because we know it can sound better.

Over the years, we have had tantalizing tastes of what good masterings could sound like with new music. Remember the "Unmastered" mix of Red Hot Chili Peppers' Californication (DR10 vs. DR4)? How about the Guitar Heroes III rip of Death Magnetic (DR12 vs. DR3)? Recently I was discussing with some folks about the Canadian Promo of Beck's Mutations (DR11 vs. DR7). How about the much improved Steve Hoffman vinyl remaster of Stadium Arcadium? Whatever people may think about using a simple algorithm like the DR Meter, there is no doubt when listening with a high-end system, nuances can be heard and listening fatigue is reduced tremendously with these alternate masterings. Audiophile reviewers often talk about "veils being lifted", well here is a clearly tangible one which the press could speak out about but instead we have articles like this nihilistic justification of the degradation of sound quality in Stereophile of all places!

Now before I get labeled as some kind of "distortion hater" for rock and pop, surely I am not. I accept an artist's decision to add distortion, noise, Protools plug-ins of all sorts; heck, Autotune is fine (better than raw talentless singing in some cases). Some albums are 'lo-fi' by design, I get it although it's not the kind of music I prefer. But certainly this does not mean we need to endure digital clipping distortions and flattening of dynamic depth across almost all genres, does it? When it clearly gets so bad that on a high-end sound system, the terrible distortions become so obvious, are we to just tolerate it and not complain? If all recordings sound poor, why even bother with expensive gear at all? New artists (and producers who make their music) need to understand that a poor sounding recording damages the credibility of the artist in the eyes of many. And there truly are limited opportunities to make a good first impression. Audiophiles may be a small part of the music listening public, but we can be quite vocal in "spreading the word" among family and friends, and I bet we buy more music than the vast majority of music listeners.

One example I can think of is perhaps the "lowest-fi" of all the albums I have - Iggy Pop did a "great" job with his 1997 remix/master of Raw Power (DR1!). Okay, so apparently he wanted it that way. But even there, I would argue that when Kevin Gray remastered the mix in 2012 for the vinyl release (DR10), the result was obviously superior - you could at least easily understand the lyrics. I don't recall Iggy launching any accusations that this less compressed mix somehow destroyed his artistic vision. Assuming the original master recording isn't too far gone, I hope to see a day when the dynamic peaks can be restored in the music of Arcade Fire, The War On Drugs, The Black Keys, or The Killers. (You can have a listen to the vinyl releases to have a preview of what these sound like with less compression!)

The article ends on this: "Over the long term, sure - maybe sonic realism will be the next big thing... In 2025." It's said in the financial trading world, "they don't ring a bell at the top" (or the bottom). Well, ding ding ding, Mr. Guttenberg. I sure hope this article marks the beginning of a shift towards musical realism. 2025 is only about 10 years from now - that's not really a terribly long time from now and a typical time frame for trend changes considering we've been enduring needless dynamic compression for 20 years. I suspect the next round of remasters will indeed be back to a more realistic sound because they just can't squeeze the dynamics any more! Furthermore, I would argue that for the high resolution digital audio movement to gain any traction, it will have to be married to a remastering renaissance with better dynamic range in mind in order to demonstrate a perceptible difference. (Generally, I consider buying a 24-bit album with DR<12 to be wasteful of money and storage space and will check out DR Database before considering any such purchase.)

Already, I'm encouraged to see the recent U2 album Songs Of Innocence (DR9) being better than previous efforts (No Line On The Horizon DR6, How To Dismantle An Atomic Bomb DR5). I was even more surprised by Train's recent work Bulletproof Picasso at DR11 (good job on the music and mastering boys; better than California 37 DR6, Save Me, San Francisco DR5)!

If I am correct, and we do see improved mastering and more sonic realism, it will certainly not be thanks to Mr. Guttenberg and Stereophile for their lack of advocating for true high fidelity in this issue. Gross "communication breakdown" indeed. Leadership gentlemen... Please find some courage to speak out with conviction.

Well, that's the software bit... How about the hardware side?

Consider Art Dudley's "Listening" column. He really should have subtitled this piece "Rage Against the Double Blind Test". In it he quotes from Malcolm Gladwell, takes liberties with comparing blind testing with the "Pepsi Challenge" (as if this is somehow highly relevant), seems to consider objectivism in general with disdain, and apparently has a phobia of guys in white lab coats, engineers and "Daddy-with-a-clipboard" (hmmm, father issues?). Anyhow, there really is too much in there to comment on completely so I invite the reader to have a gander.

"Daddy" (sans clipboard).

I hate to break it to you Mr. Dudley. Sit down so you don't hurt yourself... Those engineer guys (with clipboards) designed your sound system. Yes, they (at some point) figured out how to "cut" sound into that spinning vinyl disk. They used some fancy maths to figure out your tonearm to reduce distortion as it traced out the grooves. They studied electronics to design circuitry for that RIAA compensation curve. They figured out how to make speakers with low distortion and even put them together with appropriate crossovers. They considered the theorems involved in digital sound sampling and spent time researching fancy ways of encoding and error correcting that shiny disk. They figured out how to amplify a little signal with low overall distortion so it sounds decent at multiple watts. They figured out how to engineer computer programs to store, sort, decode, and transmit sonic data. They even were so thoughtful as to make something called the "remote control" so you could sit on your favourite listening chair and not waste energy getting up to change tracks if you desire! I almost forgot, since you love the Playstation 1 so much, I'm sure some engineer came up with that lovely plastic game controller too. Shocking, right!? How's it possible that anything that can convey artistic beauty come from measurements, graphs, charts, scientific principles, and yes, the occasional blind listening test (oh the horror!)?

Well, let's try to answer a few questions raised by Mr. Dudley in the article shall we?

"Are we disappointed when our favorite analog recordings are remastered from 44.1kHz files rather than from the original master tapes, because someone convinced the company that "that doesn't make any difference"?"

Yes. I would be disappointed I suppose if I were looking for a "pure" analog pressing as a matter of principle. That's not however to say that just because it's analog, it's good or has to be better than a 44kHz master. Many old 1980's LPs were derived from ~44kHz digital source recordings and sounded great (Dire Straits Brothers In Arms and Telegraph Road, Don Fagen The Nightfly come to mind). Many reissued LP's since have used well mastered 44kHz source and sound great. Let me ask you this... Would you honestly be able to tell where the source came from if the mastering engineer didn't reveal it to you? Over the years, other than with objective means, has any of the subjectivists been able to come up with a list of SACD's that look like they're sourced from 44/48kHz PCM by listening? If they haven't been able to do so with high resolution DSD audio, how plausible is it that vinyl listeners would be able to do so with the remixing and application of the RIAA EQ inherent in making LPs (not to mention distortions like surface noise)?

"Are we disappointed when an otherwise good electronics manufacturer lowers its manufacturing costs by switching from hand-wired circuits to PCB construction, because the company was persuaded that "that doesn't make a difference"?"

No. What makes hand-wired circuits "good" and PCB construction "bad"? Why would a company be "otherwise good" based on this construction criteria? Why do you engage in such black or white dichotomies? Over the years I've seen some really shoddy "hand crafted" construction so that's nothing special in my mind - made worse when it costs more. For complex circuits, I would consider good quality PCB construction superior in fact due to the likelihood of better precision if made by a reputable company. I also see nothing wrong with being able to repair a complex piece of electronics with replacing the PCB. Furthermore, if the manufacturer can lower costs and pass the savings down to the consumer, what's wrong with that? Please, give us a concrete example where switching from hand construction to PCB boards with essentially the same design resulted in a clearly diminished sound quality that was audible but not detectable by objective assessment (which is presumably what the engineer used to persuade).

"Are we disappointed when a manufacturer of classic loudspeakers begins making cabinets out of MDF instead of plywood, because an engineer convinced the company that "that doesn't make any difference"?"

Well, I can appreciate solid cabinetry and am happy to spend more on it if it's what I desire. But again, if the cost reduction is passed down to the customer, what's the problem? Are you again being black and white declaring that solid wood is definitely better? Are you mixing sturdiness, longevity, and aesthetics with "better sound quality"?

Of course, Mr. Dudley answers all these questions with this gem: "Yes, of course - and, in every case, we have the most single-minded, hardheaded objectivists to thank for lowering quality across the board." Pssst... Mr. Dudley, please do not muddle up material/physical/luxury "quality" from "sound quality". Has sound quality not generally improved over the years in both the low-end and high-end thanks to engineering efforts? I cannot help but feel that this man is angered by the very people and scientific know-how that has given him such pleasure over the years.

Then there's this beauty:

"The trouble is, many of the loudest people in the skeptic community, by their own admission, appear to be less interested in investigating seemingly anomalous events with fairness and an open mind than in shooting down everything that strikes them as "woo-woo"..."

Are you serious!? So, do you mean to say that an "open minded" subjective reviewer plugging in a pair of cables and declaring that the $500/ft pair sounds better than the $100/ft one after a bit of listening is "investigating". The term "investigate" requires some form of process of systematic inquiry by definition. Over the history of the subjective audiophile press, how many PWB rainbow foils, StopLight pens, expensive cables, and dubious "room treatments" have undergone systematic investigation? How about the recent Synergistic stuff like the Tranquility Base or the recently demo'ed Atmosphere? If anything, there is a resistance to scrutinize and investigate the most specious of claims by manufacturers - exactly the ones that need to be investigated. The whole point of blind testing is to remove potential confounding variables and an attempt here to discredit controlled test methods like blind listening tests is essentially to say one is really not interested in serious investigation into "anomalous events" or to try to separate verifiable fact from opinion.

To end off. Consider this quote:

"Perhaps it's our warm-and-fuzzy emotionalism that keeps those blinkered objectivists coming back again and again: We foolish, insecure record-lovers wish, in our hearts, for Daddy-with-a-clipboard to tell us what we ought to and ought not to buy - even though, in our brains, we know how thoroughly, obstructively mistaken they can be."

Well, there is one thing he is correct in. There's a sense of insecurity and fear in some audiophiles as embodied in articles like this. A desire to split what is good and what is bad yet oddly try to present the idea that it also doesn't matter to him (see the "Get off my lawn!" portion) but in an aggressive and divisive manner. I haven't seen a scientific looking bogeyman come out to push a product or tell anyone what to buy or not buy in ages! Rather, it's primarily the subjectivists who announce recommendations, sometimes conducting uncontrolled listening "tests" declaring the next best speaker / DAC / preamp / amplifier / cable / room treatment / etc. as worthy upgrades and in the process fueling insecurity. Articles such as this seem to be unable to dissociate between sound quality, aesthetics and material quality as if they are one and the same. If anything, the objective test results damper the hype in many product reviews and provides a point of reference on what is objective reality in terms of the quality of the sound itself. I can see how some manufacturers might not like this and find it inconvenient.

Just remember Mr. Dudley, many engineers over the decades made sound reproduction not only possible, but fantastic! That's a fact. Another fact is that objective analysis whether by blinded controlled listening tests or instrumentation can and is used to determine accuracy of the sonic reproduction, that's sonic fidelity. And I think many audiophiles would want high fidelity as a primary objective in this hobby.

[BTW: Alright, who has been using a robot avatar to cause grief to Mr. Dudley!?]

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I come back then to where I started. What ultimately is the "mission statement" or goal of an audiophile magazine like Stereophile? Is it anything like "the waging of war against the tyranny of inferior audio"? I actually hope it is... But do articles like these advance audio quality or foster reasonable discussion?

-----

PS: I'll be away for the next few weeks. Don't forget to participate in the LP Needle Drop Test :-). Enjoy the music...

TEST: Archimago's LP Needle Drop Blind Test.

Hello everyone. Welcome to another "blind" test! Unlike the previous High Bitrate MP3 Test last year and the more recent 24-Bit vs. 16-Bit Test, this one is much more subjective and essentially for fun :-). Not that previous tests weren't fun, but the results of this one is more for the experience of having tried (that's at least part of the fun of this hobby I hope!)...

This time, we're looking at vinyl "needle drops"; digitized output from turntable setups. You can download the test file here:

ftp://lptest.dyndns.org 

Login: LP 

Test: test

Download the file "Archimago's LP Test.zip" (~125MB).

Alternate download site (thanks again Ingemar):
www.privatebits.net/archimago/Archimago's LP Test.zip

Within the ZIP file, you will find 3 sample FLAC files - A, B, and C. Each is a high-resolution 24/96 audio recording of 2 minutes, 2 seconds duration. I trust this is a long enough sample to evaluate the sound quality.

Each file was created with the same LP; a 2012 180gm remaster of Paul Simon's "Graceland", specifically the last track on side 1 - "Diamonds On The Soles Of Her Shoes" (Matrix / Runout (Side A): 88691914721-A RE1 20315.1(3) STERLING RKS) so there's maximal inner groove distortion potentially. This LP is completely "virgin", purchased new about a month before I did these recordings and never been played before these samples. The LP looked clean and about as perfect (eg. no warps, dents, fill defects, scuffs, scratches...) as can be. I used an air blower to remove any obvious surface dust. It was NOT washed prior to playback since I did not want to inadvertently add anything (nor can I say I removed any potential deep embedded dust from the factory).

The recordings were done in the following order with the following systems:

1. Roksan TMS (first generation), SME309 magnesium tonearm, Ortofon Cadenza Black cartridge fed into a Whest PhonoStage.20 preamp. Audio output was through a pair of shielded 6' RCA cables plugged into the preamp (no balanced XLR on the Whest). Total cost for this setup should easily exceed $5000 on the used market.

Took a shot right after the vinyl needle drop was done...

2. My own stock Technics SL-1200 M3D turntable. Denon DL-110 cartridge fed into the Emotiva XSP-1 preamp (Gen1). This cartridge is a high-output moving coil (HOMC, 1.6mV) so the preamp was set at standard MM load and 47kohm load. Output recorded off 6' of MonoPrice balanced XLR cables. Total cost of this would be <$2000 considering the Technics was bought used. The Denon DL-110 costs about $150-$200 new shipped.

3. My own stock Technics SL-1200 M3D turntable. Shure M97xE cartridge fed into the same Emotive XSP-1 preamp (Gen1). This is a standard moving magnet cartridge with 4mV output. Again, 47kohm setting used on the preamp. Output recorded off 6' MonoPrice XLR cable. Slightly less expensive than (2) above with the Shure cartridge <$100. Again, total cost of this system would be <$2000.

Technics setup calibrated using Baerwald geometry and SME tonearm using the SME-supplied protractor (Stevenson?). Vertical Tracking Force optimized with digital scale (Ortofon = 2.3g, Denon = 1.8g, Shure = 1.25g dynamic stabilizer disengaged). Azimuth set to perpendicular by visualization using a mirror protractor. I tried to optimize the "stylus rake angle" to something like 92-degrees (I honestly believe it makes no sense to spend too much time or effort on this unless extremely misaligned; vinyl thickness differences and mild but common surface unevenness will easily affect this):

eg. Denon DL-110 stylus on vinyl. Photo taken with Nikon D800 using Tamron SP 90mm/2.8 macro lens at f8, manual focus on small tripod. Angles estimated & measured on screen with MB-Ruler.

Analogue-to-Digital conversion was done with the Creative E-MU 0404USB device at 24/96 using Audacity to record. I can confirm with A/B switching while playing the digital file off a Squeezebox Transporter and the Technics turntable playing at the same time that the sound is essentially identical when volume matched.

For consistency, the digital files were:
1. Trimmed to ~2'02" in length.
2. First second essentially silenced to provide the same "lead in".
3. Last 2 seconds faded out to silence.
4. All file volumes RMS normalized to -18.87dB. Note that there are a few clipped samples due to unanticipated dynamics of this recording but should not impede evaluation.
5. All samples compressed to FLAC lossless and tagged.
6. Randomized to Sample A / B / C.

Other than the above there was no other processing done to the files. Nothing like noise reduction or ClickRepair for example.

As you can see from the DR meter log file (foo_dr.txt from foobar2000 plug-in) in this ZIP file, the music has a good dynamic range of 14dB. (Excellent LP remaster!)

Your task:

1. Listen to the 3 tracks in native 24/96. Which sample did you think was the best? Which did you think was the worst? (It's OK to also feel there's no preference or even if you notice a difference, think that it would make no difference to musical enjoyment.)

2. How much difference did you hear? Although the cost differential is much more between the Roksan vs. Technics setups, suppose your system sounded like the "worst" sample, would you spend $1000 to upgrade it to sound like the "best" sample?

3. Go and fill out my simple survey. All 7 questions are mandatory and I will have to delete responses that have not been filled out correctly. Should take <5 minutes. Please also let me know which computer/DAC and what headphones/speakers used. Also whether you used something like the Foobar ABX tool for evaluation.
(http://freeonlinesurveys.com/s.asp?sid=9qk9tpzbxq8uwlk539831)

As usual, thanks to all who try this out! It's not often that one gets to hear turntable setups side-by-side and this was about as "controlled" as I could find a way to do this to get a taste of what disparate gear could sound like. As usual, although this test is more subjective than previous tests, make sure to listen and not just look at waveforms in an audio editor, also, I think it's better not to discuss one's results until after the test is complete so as not to influence others.

I'm going to run the survey until November 30th - I'll be overseas for a bit so in case there are issues, please leave a note in the comments section if you run into any difficulties. Have fun with this!

Best regards,
Archimago

-----------------------
Disclaimer: I believe this test conforms to the spirit of "fair use" for copyrighted material for the purpose of education and research. The author derives no financial benefit from conducting this survey.

See RESULTS here.

MEASUREMENTS: Apple iPhone 4 & iPhone 6 audio output.

In terms of general look-n-feel, or usability of the product, there's nothing I can say here that has not been said about Apple's most popular devices - the iPhones. Though I'm not an Apple fanboy, my wife loves the Apple "ecosystem" and has been using an iPhone and Mac combination since the release of the iPhone 3G in June 2008.

There is no question that Apple produces some amazing devices focused on usability and pitched as lifestyle products. With enough financial resources, they can of course fund research and compete in the specifications arena as well. In the last few years they did fall behind on screen real-estate but it's good to see that with the iPhone 6, they're making headway in this area as well... This should really give the Android makers like Samsung some good competition in the Asian arena where logosyllabic writing systems predominate and a larger screen size is almost a must.

Since my wife hadn't upgraded her iPhone 4 in quite a while, out came the credit card for this thin "little" guy:

As you can see, this is the "gold" colored version of the regular 4.7" 64GB model (versus the 5.5" 'plus' model with the much-publicized bending tendency). I think the gold color looks nice - at least a little different from the usual silver or white and I'm sure this will sell well in Asia also. Not that it really matters much because if you use a case, the back will be covered anyhow (although the gold trim around the home button looks nice). Notice the camera lens protrusion. Some have commented that this looks bad. Indeed, it will prevent the unit from lying flat and it will "tip" somewhat. Again, it doesn't really matter if you use a back cover. I'd consider this a small cosmetic price to pay for better focusing mechanism, larger aperture, and optical image stabilization (the DxO folks rated the camera function very well).

As you can see, my almost-1-year-old LG/Nexus 5 phone on the right is a little larger with a 5" screen. But check out how thin the iPhone 6 (middle) is compared to the iPhone 4 (left) and Nexus 5. The iPhone 6 feels great in the hand. The rounded corners make it comfortable to hold and it's light but still feels solid. No, I did not try bending this thing :-).

One other thing to notice is that the headphone jack is now at the bottom of the phone. I find this less intuitive than the previous top-left placement.

In use, well, it's an iPhone :-). Runs all the usual apps, nice bright "Retina" screen (all modern 'premium' phones have excellent resolution these days anyhow), very snappy with the A8 1.38 GHz dual-core processor, 1GB of DDR3 RAM (modern Android phones have 2-3GB already). I'm curious what this M8 "motion coprocessor" will bring to the table in terms of future apps (funky 3-axis gyro, accelerometer, proximity sensor).

Let's Talk Sound...

It's interesting after all these years, I have seen few measurements of the sound quality out of these ubiquitous devices which I suspect has taken over the role of the iPod for music playback for many if not most Apple consumers. So without further ado, let's have a look at the output of both the iPhone 4 and 6 to compare and contrast what has happened in the objective measurements of these devices two "generations" apart.

Fist, let's look at the headphone out through the digital oscilloscope. Here's a 1kHz square wave played at full volume (0dBFS):

iPhone 4 - 1kHz square wave 0dBFS.

iPhone 6 - 1kHz square wave 0dBFS.

As you can see, the "square" wave tracings are very similar. Neither phones show any clipping (I confirmed with sine wave as well - not shown). The iPhone 6 is marginally "louder", putting out 1.4V versus the 1.3V from the iPhone 4. Channel balance is excellent on both machines.

Notice the "ringing" in the waveform with both phones... The reason why is readily apparent when we look at the impulse response:

iPhone 4 - 16/44 impulse response

iPhone 6 - 16/44 impulse response

They both maintain absolute phase but as you can see, both phones use a minimum phase filter with no pre-ringing. Interesting! Didn't know Apple has been doing this all these years...

Okay, let's now get to the usual RightMark 6.4.0 measurements.

Setup (the usual):
iPhone 4/6 [100% volume] --> shielded 3' phono-to-RCA cable --> E-MU 0404USB --> shielded USB --> Windows 7 PC

iPhone 4 firmware - iOS 7.1.2
iPhone 6 firmware - iOS 8.0.2

Screen brightness ~50%. These measurements were made with the iPhone 4 connected to my home WiFi router (no SIM card inside) and the iPhone 6 has my wife's SIM card inside and with cell phone and HSDPA data activated. I made no concessions for "better sound" since I don't believe people listen to these devices in a crippled fashion without data connection.

I used the latest ONKYO HF Player (1.2.1, $10 for the hi-res features and FLAC playback) to play the test files. No EQ or any other DSP process like upsampling applied for the test signals of course. I promised folks that I would try measuring the effect of various loads from the headphone output... Alas, I haven't found the time to get this together. Therefore, I'll just give you the results off the E-MU and will update with another post when I get some 30/100/300-ohm load measurements done.

16/44:
The summary result comparing the iPhones with Nexus 5, AudioEngine D3, Dragonfly 1.2, and TEAC UD-501 for a desktop "reference" DAC:

As you can see, the little iPhones hold their own in terms of 16-bit accuracy. As with most devices, 16-bit, 44kHz audio is not an issue these days and all competent devices would have no problem decoding this most basic bit depth and samplerate.

Slightly more high frequency roll-off with the iPhone 6. -0.5dB at 20kHz.

Noise level: All pretty close, Nexus 5 slightly noisier.

THD Graph

Stereo crosstalk: other than the TEAC using stereo RCA connectors, the others all using the same shielded 3' phono-to-RCA cable. The Dragonfly v1.2 has notably higher crosstalk.

24/44:
Okay, let us now go one step up into high-resolution territory. Can the iPhones manage better than 16-bits?

The answer is YES, the iPhone 6 is clearly capable of better noise floor and dynamic range when fed with 24-bit data. The measured performance is between 17-18 bits of dynamic range... Not bad for such a compact device and about on par with the AudioQuest Dragonfly 1.2 previously measured. Since I don't normally measure 24/44 with my other gear, I don't have comparisons in the table to other devices.

I measured the audio output using either the Onkyo HF player (FLAC files) or the Apple iTunes built-in "Music" app (AIFF). As you can see, the iPhone 4 functions as a 16-bit device in terms of noise floor and dynamic range performance when fed 24-bits. It benefits very slightly with 24-bit audio - at best 3dB improvement. Notice that there isn't any real difference between the Onkyo app and standard 'Music' app. Just remember to turn off any EQ feature to make sure it's bit-perfect (I noticed the iPhones Music app had set the EQ to "Classic" or something like that by default; I don't know if this was a setting my wife had previously set).

Some graphs:

Frequency Response: minimal difference.

iPhone 6 benefiting from the 24-bit data compared to the iPhone 4.

THD

Stereo crosstalk. Inter-test variation evident. (The -104.9dB iPhone 6 reading was atypically low; usually around -90-100dB.)

24/48:
Let us now raise the sample rate to 48kHz and see:

Click on the table to enlarge. 

Again, we see that there is essentially no difference between different music player apps on the iPhone (Onkyo HF Player vs. standard "Music" app linked to iTunes). This time I've included 24/48 results from the recently measured Microsoft Surface 3 laptop, the Squeezebox Touch, and a couple of USB DACs - the AudioQuest Dragonfly 1.2, and AudioEngine D3. Note that the Dragonfly and AudioEngine D3 were measured at 24/96 and I mainly wanted to demonstrate the noise floor performance. In terms of harmonic and intermodulation distortion, the iPhones perform well; the only "atypical" performer in terms of distortion is the Dragonfly.

In short, I am impressed by the low noise level and high dynamic range achieved by the iPhone 6's internal DAC! It's getting really close to the AudioEngine D3 in terms of low noise which is superb.

A few more graphs:

Frequency response: Squeezebox Touch seems to have more of a bass roll-off.

Noise floor. iPhone 4 unable to benefit significantly from 24-bit audio.

THD

Stereo crosstalk: Microsoft Surface 3 worst of the bunch here.

24/96:
The chart looks OK (using Onkyo HF Player with FLAC files):

But in reality, it's a no-go:

Neither iPhones are capable of native 96kHz samplerate and the data has been re-sampled down to either 44kHz or 48kHz.

Jitter:
The J-Test audio track was played off the iPhones with Onkyo HF Player for this measurement.

A bit more jitter noted with 24-bit data for the iPhone 4 (sidebands and wider "skirting"). Also notice the iPhone 4 has higher noise level so the jitter modulation pattern in the 16-bit test is not as evident compared to the iPhone 6.

Like essentially all decent hardware measured over the last while, it's hard to make a case for jitter being an audible issue given how low the distortion is; typically way below -100dB off the primary signal. The jitter spectra look the same whether I used the "Music" app or Onkyo HF Player; again, a reminder that software does not affect jitter performance as far as I can tell whether with these portable devices or with computer audio. Remember that this is even with either WiFi or HSDPA wireless data turned on.

Subjective:
iPhones are everywhere, go listen for yourself :-). Heck, bring in your favourite headphones and have a listen at the local Apple Store. Be that the case, I did of course listen to both the iPhone 4 and 6 with my headphones here at home. I really could not put a finger on any significant sonic difference between the two phones so spent most of the time listening to the iPhone 6.

What is most obvious using less efficient headphones like the AKG Q701 is that the headphone amp just isn't strong enough - no surprise there. 100% volume is merely 'loudish' with both the AKG and Sennheiser HD800. One effect of this is that bass frequencies requiring a bit more "oomph" just does not sound impressive using either headphone.

The iPhone 6 comes with the newer EarPod headphones with volume control. These sound better than the old earbuds from previous generations before the iPhone 5. They do feel more comfortable as well in the ear. But there's no denying that these don't sound that good with mediocre treble definition and muddy bass obvious within a few seconds after listening with the Sennheiser HD800.

I listened to both lossy 320kbps MP3 encoded with LAME and AIFF lossless music. The music sounds great using my Sennheiser HD800. Typical audiophile female vocals like Jane Monheit's Come Dream With Me sounded wonderfully detailed with vocal nuances intact. With the iPhone 6 plugged into my AudioEngine A2 speakers for "near-field" listening, the soundstage was excellent and voice well focused. The classic Miles Davis Kind Of Blue sounded nice and warm as it should - nothing was missing, including the elevated background noise and ambient sounds (is that someone clearing his throat 9 seconds into "So What"?). Mark Knopfler's Privateering sounds excellent with multi-layered strings, percussion and vocals on the title track. Loud tracks like Joe Satriani's "Crowd Chant" from Super Colossal (a dynamically compressed DR8 track) sounded fine with the phones capable to rendering details through the "mass" of vocals and playful guitar-voice interchange. More efficient headphones like the closed back Sony MDR-V6 or Audio-Technica ATH-M50 provide plenty of volume and as typical for headphones of this nature, the bass also takes on a more visceral property despite giving up a bit of detail compared to something like the HD800.

Summary:
Apple is without question the "800lb gorilla" of the music industry whether we're talking about music downloads or potentially the future of streaming audio. As a family of audio devices, the iPhone is arguably the most important music player in the world at this point in time. iPhones continue to be a point of entry in portable audio given the popularity. As I publish this post, I see the iPhone 6 is up for pre-order in China today; no doubt Apple will sell massive numbers there despite the higher price point compared to competitors.

While I cannot speak of the iPhone 5's audio performance, there has obviously been an improvement between the iPhone 4 to 6 with the ability to play 24-bit audio. The iPhone 6's DAC measures very well up to the maximum 48kHz samplerate. Furthermore, I was surprised that Apple has been using a minimum phase digital filter at least since the iPhone 4. Not that I really feel it makes much of any difference, but the iPhone can claim "no-pre-ringing" just like the Pono/Ayre folks might claim. Of course, with a typical minimum phase filter like we see here, there is quite a bit of post-ringing. The Ayre folks dampened that with a -6dB at 22kHz slow roll-off filter which IMO isn't necessarily a good thing if you want flat frequency response all the way to 20kHz.

As I mentioned at the start, I unfortunately have not had the time to start measuring using various simulated headphone loads to demonstrate frequency response anomalies especially with low impedance headphones. Ken Rockwell's review of the iPhone 5 puts the output impedance at 4.5 ohms which is excellent! Hopefully the iPhone 6 will be similar in this respect.

Given the measurements I'm seeing, the iPhone's DAC is excellent and can produce very accurate output. Given the small form factor and the need to balance power usage with other phone functions, headphone amplifier power is limited out of necessity. For sonic quality, therefore, the most important factor would be how well the headphone matches the amplifier. Assuming the iPhone 6 has an output impedance similar to the iPhone 5 around 5 ohms, a good ~40+ ohm set of high quality, high sensitivity headphones should provide excellent neutral sound. Not that lower impedance headphones would sound bad of course (most IEM's have low impedance for example), just potentially not as flat frequency response.

I must say that I am impressed by how smooth the iPhone 6 is in use speedwise and the thinner profile with softer curves definitely feels very comfortable in the hand compared to the more chunky iPhone 4. It reminds me of the curved iPhone 3G but with a more "premium" feeling metal case. My wife loves it already. Finally... There is one significant feature I wish the iPhone 6 had - inductive charging. Both my Nexus 5 and 7 have this feature and has wide compatibility with Qi chargers. For the better part of a year now, I have not had to plug the Nexus phone/tablet into anything at all. Even if the iPhone 6 were a couple of millimeters thicker, I think this feature would be worth it!

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Epilogue:

Over the past year, there has been speculation about when Apple might go "high-res" with iTunes. Considering that iTunes does not even offer lossless downloads currently, I certainly would not hold my breath! Furthermore, with the iPhone 6 capable of 24-bit but not higher samplerates beyond 48kHz, the idea of 88kHz+ music doesn't even seem to be on the horizon.

Although I think lossless 16/44 iTunes would be a great idea, I believe Apple is smart not wasting their time in the high-resolution space for the masses. As I expressed previously, I believe "high resolution" audio will be a disappointment to most people after the novelty wears off; it just doesn't sound much better if at all given the same mastering. That's one issues. Another issue is that with devices like the iPod/iPhone/iPad, where there is limited storage space, you can already upload music in ALAC (I don't see why anyone should waste space with AIFF these days) if you really want. 24/96 is approximately 250% the size of the equivalent 16/44 lossless files, and 24/192 would be around 500% the size. Considering how little audible difference there is between high bitrate lossy (256-320kbps MP3 or AAC) and lossless already, it makes no sense to load up a portable device with all these  huge lossless high-resolution files when there are so many other things the storage space could be used for (eg. movies, documents, apps, photos, books/magazines, videos...). When you factor in that the typical listener is likely to be enjoying music in suboptimal conditions like the subway, bus, car, walking around the streets, or exercising - having audio files taking up so much space just doesn't make sense.

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To all the Canadians out there. Have a wonderful Thanksgiving weekend! Enjoy some turkey and of course make sure to take in some lovely tunes...

Addendum (January 29, 2016):
Using a 1kHz signal, measured open vs. 20-ohm load, the iPhone 6 has an estimated output impedance of 3.2-ohms.