Friday, 19 September 2014

MUSINGS: Vinyl Paraphernalia & Good Old (Free) Vinyl :-)

As I mentioned before, I've been going through the bargain bins at the local LP stores and it has been great finding stuff I hadn't listened to for years! Tonight, as I'm typing this I'm getting reacquainted with Henry Lee Summer's I've Got Everything album for example [recent article on Summer]. It indeed has been decades since I've heard "Hey Baby"...

Yup, old memories of high school - Gen-X and proud of the 80's :-)

Okay, on to the main topic for this post.

I noticed over the last month how getting into vinyl resulted in an accumulation of "paraphernalia". I've got a little collection of "things" now on my music rack that wasn't there before. Plus I've got a compartment where I keep my albums for a few of these things. It's all part of the ritual of maintaining a clean LP collection. I suspect you can tell the "serious" vinyl audiophiles from the "casual" based on whether they have these items hanging around; many of which I would consider essential! I'm sure this is 'old hat' for you vinylphiles already, but for those curious, without further ado, let's have a peek at what I've accumulated:

I. Cleaning Supplies:



Without a doubt, this "class" of products is essential. There's just no way to experience decent LP sound unless it's clean.

For dry cleaning, I started with the Vinyl Styl anti-static carbon fiber brush. It's relatively cheap at $15 or so and good to brush off surface dust as the disk spins on the platter before dropping the needle. Often dust is just moved around and you end up with a "line" of dust unless you direct the dust off tangentially. I've also seen a demo where the brush is moved medially towards the spindle to touch the central metal part. Supposedly this discharges the brush allowing it to hang on to the dust particles. I personally have not found this consistently does the job.

There are of course many such brush products out there. I've heard of folks complain that carbon fiber brushes can leave "hairs" or micro-scratches on the LP. I have not had either of these problems. Just don't press down too hard when cleaning the vinyl surface.

To the left in the clear plastic box is the Nagaoka Rolling CL-1000. I got this off eBay for about $120 from Japan shipped. It's not cheap. Basically it's like a fancy sticky (elastomer) lint brush meant for dry LP cleaning. I have wondered if the cheap sticky roller from the local store would do the trick but too chicken to try :-). In any event, this thing works quite well. I don't know how deep in the groove it can get but the ability to lift dirt and dust off is better than the plain carbon fiber brush. I had noticed with the first usage that I saw a little bit of residue which was removed with a second round of cleaning and no problem thereafter - I think it may have come from the clear plastic protector wrapped around the elastomer that had to be peeled off. I usually will use this on new LPs just to remove the small amount of dust/particles rather than doing a wet clean. Static charge builds up when rolling so make sure the environment is clean - I often will do the rolling on top of an anti-static inner sleeve. (I've noticed some much cheaper ones like the Stop-a-Clicks; I presume this would be fine at a much lower price point.)

The yellow box is of course the Spin Clean. IMO wet cleaning is essential! There's no way I'm going to play the majority of my used purchases unless they've been through a wash cycle. The Spin Clean Mark II works great. I have had some albums cleaned at a local store with their VPI 16.5 machine and I thought the result was really quite similar so long as I took care with the Spin Clean. I have not had any issues with scratching or abrasions. A few observations / suggestions:

1. Use distilled water especially if your region has high mineral content 'hard' water (not really a problem here in Vancouver).

2. After the wash, hold the LP over the Spin Clean to let the residual water drip off the disk before drying for about 10 seconds. This reduces the amount of fluid to wipe off and noticeably less water spots after drying.

3. Buy some good, soft, absorbent microfiber cloths to use for drying. The Spin Clean kit comes with a couple of rather substandard drying wipes.

4. I never use much of the provided cleaning fluid. My formula: fill the Spin Clean up to 90% distilled water, 10% with isopropyl alcohol, and just 1 cap of the starter kit fluid (they recommend 3 cap fulls).

5. Don't let the reservoir fluid get too dirty... I usually wash less than 20 used albums before throwing the fluid out.

II. Needle / Stylus Cleaner:



Have to keep the stylus clean of course. On the right is the "free" stylus brush provided in the package with my Denon DL-110 cartridge. Does the job with very delicate fibers.

On the left is the Onzow ZeroDust. Removing the plastic cover reveals a piece of convex gelatinous substance you can gently "drop" the needle on, removing any dust or pieces of vinyl stuck on. I first saw one of these at AudioPhil's place and liked it - easy and quick.

III. Calibration Paraphernalia:


Then I got all this stuff:

Precision electronic VTF scale. Good down to +/-0.01g. The manual scale on the Technics SL-1200 standard tonearm counterbalance is quite accurate already down to about 0.1g from experience. It's nice to have this for confirmation though plus it's not expensive (~$20).


Without question, the most arduous task with turntable setup is getting the cartridge aligned. A reflective alignment tool such as the ruler-like device to the right is helpful. However, with my Technics, the freely-available-to-print Baerwald Arc Protractor off Vinyl Engine is all I really need. Just make sure you print it out 100% with no print scaling to keep the dimensions accurate and punch the center spindle hole accurately.


I got one of these inexpensive ~400gm record clamps off eBay from Asia. I don't buy noticeably warped records so I don't use this much but there is a convenient spirit/bubble level on top to make sure the turntable is flat. The 50Hz stroboscope is useless for me here in 60Hz AC land.

Some people will use things like USB microscopes to check the Stylus Rake Angle (SRA) for VTA calibration. I haven't gone to this level of fine tuning yet (and possibly never will plus I really doubt it's all that important since slight warping is common yet I don't generally hear any difference when the needle tracks over those areas!). One idea has been to use a macro lens on my dSLR to take close up pictures using a well aligned tripod... I'll maybe give that a try.

IV. Sleeves:



After cleaning used vinyl, there's no way I'd put them back in the original old record inner sleeves. So far, I have found the Mobile Fidelity "Original Master Sleeves" a must have. They're soft, thin, and I have not had any problems with powder residue some have complained about. At about $20-25 for a pack of 50, they're not cheap though. One gripe I've had with a number of new 180g remasters (like my new Guns N' Roses Appetite For Destruction) is the shiny paper used without any soft inner lining. Often with the tight fit of thicker vinyl, the paper sleeve almost guarantees abrasions when putting the LP in or taking it out. Disappointing and all too common to take out a new LP for the first time feeling the resistance of the inner sleeve when pulling out and finding abrasions already on the vinyl.

Then there's the transparent outer sleeves which will keep the outer artwork safe from scratches. I've been able to find good 4 mil locally for about 25 cents a piece.

Summary:


Well, that's not too long a list of paraphernalia I suppose... But it's certainly more than one ever needed for a CD collection (all I had was a soft microfiber cloth to wipe off smudges and a few extra jewel cases). Taken together, there's at least $300 of "stuff" purchased; not counting the extras for the sleeves and obviously I'm not buying anything extravagant here. Of course, not all of this is essential, but significant considering the price of my used Technics SL-1200 M3D (only around $500). Something to keep in mind for those getting into vinyl. However, the bargain used LPs (at least a lot of the 80's stuff I like) can be had for really cheap!

I'd love to hear what other items you've found useful with your LP rig... How much difference do you think a vacuum record cleaning machine makes compared to washing by hand or a relatively inexpensive system like the <$100 Spin Clean?

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

To end off this post, I remember awhile back reading one of Stephen Mejias articles in Stereophile where he observed that when others realize one has a record collection, friends and associated will start offering up LPs they don't listen to any more... Indeed, I was fortunate enough to have a friend offer the following:


Interesting early Beatles pressings from Asia purchased when first released - Abbey Road and Let It Be appear to be pressed in Hong Kong, With The Beatles from Malaysia, and Sgt. Pepper's from Singapore. I'm not sure about the Red and Blue compilations.

I have both an early Canada pressing of Abbey Road and later pressing of Let It Be from the mid-1970's for comparison. As best I can tell, the Asian Abbey Road sounded cleaner and Let It Be was about the same. I compared Abbey Road with the recent 180g LP remaster and not unexpectedly, these older pressings sound softer, and perhaps less detailed compared to the more compressed and digital remastered LPs. This is the same impression listening to an early Dutch pressing of Dark Side Of The Moon (thanks Ingemar!) compared to my new 180g remaster. It's subjective which mastering one prefers of course but there is something special to be said about holding and playing an album of historical importance physically created before I was even out of diapers. As I have noted before, these properties of a physical object add to the joys of vinyl collecting irrespective of sonic quality (obviously I'm not getting the same vibe with new digital remaster LPs).

Finally, I also received the following box:

The Beatles E.P. Collection of 45's in both original mono and stereo! Mint vinyl condition! Thanks Paul :-).

Have a great weekend and week ahead. Gotta run off to listen to some "classics" now...

Friday, 12 September 2014

MEASUREMENTS: Microsoft Surface Pro 3 Audio.

Over the last couple years I have been using my ASUS Taichi ultrabook as my daily work/business traveller laptop. I've certainly appreciated the ultrabook form factor and speed! Although these little devices aren't cheap, there's no way for me to go back to anything larger these days in terms of a full function portable work machine...

"Unfortunately", I felt the need to upgrade the daily use machine as I was starting to run into headroom issues with 4GB RAM and needed something with substantially more battery life for the longer trips. Enter the newest member of the Microsoft Surface family with the Intel Haswell core - Surface Pro 3. Sure, I could wait another 6 months and get the Broadwell maybe in early 2015 but like anything in technology, you can't wait it out forever when there are true advances being made.

I got the i5, 8GB RAM, 256GB SSD model. I suspect this will be the most popular model of the i3/i5/i7 versions as a reasonable compromise between features and price. I was actually looking at trying the i7 model but I couldn't find any locally! I believe the i5 was released about a month and a half ago and the i7 just came out so demand was higher. In any event, the i5 should be more than adequate and I hope there will be some benefits to a less speedy model in terms of heat production, noise, and maybe improved battery life.

With blue Type Cover 3.
I'm not going to bother with a full review. You can find plenty on-line like AnandTech, or IBT. Overall I do agree with the reviews. It's certainly not the perfect tablet - too heavy and large still for casual browsing and media consumption. And it's not the perfect laptop/ultrabook for the price. It is however made very well with a nice magnesium case which is solid with a sturdy kickstand. It's certainly very easy to travel with, and the newest Type Cover 3 functions decently as a keyboard/trackpad. I actually was interested in the first Surface Pro when it came out in early 2013 but there were too many issues at the time with heat, battery life, and keyboard/mouse issues that I went with the ASUS Taichi then. With the improvements since, I thought I'd give this iteration a try.

Just a few quick comments:
1. The 3x2 screen is different. First time I've bought a non-widescreen (~16:9) computer/monitor in the last decade. For a small device like this, it works well. It's a little smaller than standard letter paper size. I love the screen contrast and 2160x1440 resolution - almost as high as my 27" main monitor! Note that some old software might not scale appropriately leading to ridiculously small fonts which might make it tough to use the touch screen accurately.

2. The digitizer pen feels good and works well. I started using OneNote more and can appreciate the capabilities. Seems to work well so far taking notes in meetings. Pressure sensitivity was good and allows some casual sketching (not that I'm much of an artist!). I find myself sometimes accidentally pressing the buttons on the pen which I need to get used to.

3. Mixed feelings about the kickstand and "floppy" keyboard. I'm actually typing fine on the Type Cover 3 keyboard - speed about the same as my previous ASUS ultrabook. The fact that there's no spacing between the keys increases the chance of inadvertent typos. What's different is the center of gravity and feel of the base. Normally the keyboard is the base of the laptop rather than the lower edge of the slate + the kickstand being the supports with the center of gravity pushed distally. It's not a big deal on a table since the kickstand is very stable; but feels initially strange and one has to be careful when placed on the lap - it can be easy to tip over with leg movement. This "lapability" issue is known and at least the kickstand can be adjusted further to improve balance but this also extends the front-to-back length.

4. Please Microsoft, consider two USB ports in future versions; I'd hate to carry around a hub. Sometimes it's nice to plug in my Logitech Unify receiver for an external mouse/keyboard and still have another USB for something like the Dragonfly or AudioEngine D3.

5. I'm glad they're using the DisplayPort for external monitor output. Easier and cheaper for analogue VGA adapters. Support for 4K, etc...

6. One beneficial result of the kickstand form factor is that it's cooler on the lap since there is no contact with the area around the CPU and heatsink. The fan is still audible with moderate to heavy computing but at least the heat is dissipated away from where there's physical contact.

On to the headphone sound...

For such a small device, the built-in speakers are fine and I do believe sounds better than the older ASUS Taichi. The first thing I noticed when looking at the sound playback settings is that the hardware is identified as "Realtek High Definition Audio" and the maximum samplerate possible is 24/48! I tried the latest Realtek HD Audio drivers here (R2.75) as well and still 24/48. It looks like previous versions could do 24/96. Though my preference would be at least 24/96 these days, I don't believe this is a problem; surprising nonetheless since almost all devices should be able to handle 24/96 by now. Perhaps the hardware is capable but there's something with the OS settings I haven't adjusted yet (using the current stock Windows 8.1 installation that came with the machine).

A look at the oscilloscope graphs:
1kHz Sine 0dBFS at 16/44.


1kHz Square 0dBFS at 16/44.
Oscilloscope indicates that at 100% volume with 0dBFS signal, there's no clipping. Nice. Also, channel balance is excellent! Maximum output voltage is ~1.6V. Not capable of playing music as loud as the Dragonfly v1.2 or AudioEngine D3 so make sure to go for higher sensitivity, less power-hungry headphones.

The 16/44 impulse response looks like this:

As expected, standard symmetrical linear phase digital filter. Less than usual pre and post-ringing suggesting earlier roll-off in the frequency response.

Time for the RightMark 6 results. Here are the 16/44 results with a few other devices for comparison. I used the usual measurement chain:
Microsoft Surface 3 headphone out --> shielded phono-to-RCA --> E-MU 0404USB --> shielded USB --> Windows 7 laptop

16/44:

The Surface Pro 3 is in the first column, followed by both the Dragonfly and AudioEngine D3. I then threw in my two compact portable devices the Nexus 5 phone and Nexus 7 tablet. Followed by the Transporter and Oppo BDP-105 as higher end devices. Apart from the stereo crosstalk being a bit "weak", we're seeing that 16/44 is not a problem for any of the devices these days. The defining factor likely would be the quality of the headphone outputs (eg. power, impedance characteristics) rather than accuracy of the DAC. As usual, a few graphs (click images to enlarge):
Frequency Response - Surface 3 slightly earlier high-frequency rolling off than others.
Noise Level
THD
Stereo Crosstalk - unusually high for Surface Pro 3.
24/48:
Since 48kHz is the highest samplerate supported, it's worth measuring since this would be the natural downsampling level for all the 96 and 192 kHz music. I don't do many measurements at 24/48 but I'll throw in the results from the Squeezebox Touch and Receiver from awhile back for comparison as well as 24/96 results from some laptops I had measured last year to show their 24-bit performance:


Noise level and dynamic range suggests that the Surface Pro 3's headphone output has about 17.25-bit dynamic range. With 24-bit data, the best devices I have like the Transporter will give me a measured result around -113dB (almost 19-bits) which is also likely a limitation of the measurements using the E-MU 0404USB. Distortion characteristics of the Surface 3 are comparable to the Touch, but again, we're seeing quite high stereo crosstalk of -66dB which is poor for digital devices.

Despite the 48 kHz limitation, it's nice to see that the Surface 3 is capable of better dynamic range than my old Acer Aspire 5552 laptop and ASUS Taichi ultrabook. From those tests last year, I was quite impressed by the Apple MacBook Pros and I see that the Surface 3 measures about the same as the old MacBook Pro from 2009 except for the poorer stereo crosstalk.

Again, a few graphs for completeness (only the 24/48 results):
Frequency Response
Noise Level
THD
Stereo Crosstalk
Let's finish off the objective stuff with the jitter spectra - as usual, the Dunn J-Test; 16-bit and 24-bit versions:

While the 16-bit J-Test results aren't the cleanest nor does it look ideal, it'd be hard to make a case for jitter audibility. The 24-bit results looks very nice. Overall minimal "skirting" around the primary frequency.

I'm not going to spend much time on the subjective descriptions here... The fact is, when I'm traveling, I just don't see why I'd need the full high-fidelity experience. I'm only likely ever going to be listening with this machine for any length of time on plane flights where the background noise is high and I'm likely distracted anyhow doing work. Suffice it to say, in an atypical and wholly unrealistic situation for me sitting in the quiet of my home with my Sennheiser HD800 headphones plugged into the Surface Pro 3, the sound is excellent. It doesn't provide as much power as the recently measured Dragonfly v1.2 or AudioEngine D3 so don't expect it to play very loud. It does however convey the resolution I'm used to like Donald Fagen's immaculately produced "I.G.Y." from The Nightfly. I had a listen with the AKG Q701 as well which is one of my more inefficient headphones. Again, the detail was excellent but perhaps a bit bass shy and at maximum volume, it's just capable of slightly louder than my usual listening level. This volume level would be fine with my high sensitivity IEM headphones I usually bring on my travels though.

Although stereo crosstalk is high compared to other digital devices, subjectively I do not believe this is a problem. Remember that vinyl has stereo separation typically between 20-40dB only and it can still sound excellent. It's one of those things where technical specification strongly exceeds real-world necessity (I would still like to see "perfect" execution of course from an engineering perspective).

Summary:
I'm impressed by how much technology can be packed into a small package these days! As I write this last bit, I have been using the machine for close to a month now and it's performing very well. The small form factor is convenient and shaves a few ounces off my work briefcase compared to the previous ultrabook. As need for increasing CPU speed appears to be plateauing and monitor resolution really doesn't need to get any better for smaller devices, it is going to be the form factor, weight, and usability that matters. While not ideal at this point, the Surface Pro 3 is clearly taking a step closer.

As for the sonic measurements. Stereo crosstalk is high for a digital device and I'm surprised by the 48kHz sampling rate limit. It does handle 24-bit data with decent dynamic range rivaling the old Apple MacBook Pro I have. Compared to previous Windows laptops, despite the size, it does quite well keeping the noise level low.

To end off, a few thoughts over the last couple weeks:

1. Sometimes the darn 'Connected Standby' sleep feature on the Surface Pro 3 makes the machine not wake up! Look here for a thorough article on this issue. It happened to me twice in the 1st week of ownership. I turned off the Hyper-V feature and thereby disabling this "feature". I've since turned Hyper-V back on and have not noticed a problem in the last 10 days... Maybe there was some software update that fixed this.

2. Here's a serious question/suggestion for high-end DAC manufacturers. I know HDMI costs money to license yearly. How about using the DisplayPort as a standard for audio data transmission - a royalty-free VESA specification? I've always wanted a high-end multichannel DAC/streamer (attention paid to resolution, lower jitter, etc.) - something like the Transporter with robust server system that can handle *all* my music files - both stereo and multichannel (maybe even DSD stereo/multichannel but that's lower on my priority list). What I'm currently doing with sending multichannel via the computer's HDMI to the Onkyo NR-TX1009 receiver works and will get me multichannel sound. But the Onkyo DAC isn't the best, occasionally I will run into disconnections and I would love to see unification on the software side where something with the power of Logitech Media Server can be used to serve both stereo and multichannel! The DisplayPort has the capability for 24/192 multichannel no problem and presumably cheaper for manufacturers without worrying about the licensing costs.

3. There's a guy who claims to be able to ABX high-resolution audio files as well as ABX using the Bozza track from the 24-bit test. He claims to be successfully doing it with an HP Zbook 14 laptop and Etymotic ER-4P. Given what I have seen with measuring the laptop headphone outputs, I'd be very curious what that HP Zbook 14's output quality looks like to confirm that it is capable of >16-bit resolution. Furthermore, I have the Etymotic ER-4B (as discussed in the Dragonfly measurements) sporting higher 100-ohm impedance - it's good but I can't say I've ever considered it that good in conveying sonic detail. Not saying that the guy cannot tell the difference but I would be a bit cautious given the equipment used and posting a "successful" ABX log is easy; would have been better if he responded to the survey and got 3/3 in a blind test... Needless to say, in my 24-bit test, I specifically asked folks not to just use the computer motherboard/laptop headphone jack simply because it more than likely outputs compromised sound compared to something superior like even the inexpensive Dragonflies of this world (if not a fully external powered DAC) if one is serious about trying to listen to high resolution audio.

That's all for now.

Have a great weekend and week ahead everyone!

Thursday, 4 September 2014

MEASUREMENTS: Digital Audio and the PlatterSpeed "Wow & Flutter" App

Shortly after my last post on the wow & flutter measurements with the Technics SL-1200 using the 7" test disk, Frans suggested in the comments a test using a CD to demonstrate what the results would look like using digital devices.

Great idea!

So, I whipped out good old Adobe Audition and generated a -10dBFS (same level as the Test LP signal) 3150Hz (for 33.3rpm) sine wave. I burned it on a standard Maxell CD-R - first time in a long time I've burned an audio CD!

To purposely not do anything special to reduce the "potential" for jitter (NB: I don't actually believe this anyway), the disk was burned at 48x on an older LiteOn iHAS DVD burner which I got either in late 2011 or early 2012. I did verify the burn to make sure the data was readable.  I used my electrically "noisy" quad-core home assembled i7 workstation to do the burn as well. Despite the strong temptation, I did not use any green "Stereophile recommended" StopLight pen to color the rim of the CD to improve the sound :-).

For the graphs, remember to look at the scale on the left to get a sense of the magnitude of frequency variation. I've aimed at measuring over the course of ~60 seconds.

To start, let me just show what the results look like with my network devices streaming off my server computer before I throw the CD into a few spinners:

Logitech Transporter - balanced analogue output, wired ethernet connection to music server (main soundroom system with Paradigm Signature S8 speakers):




Logitech Squeezebox 3 (Classic) - RCA analogue output, wired ethernet connection to music server (living room Tannoy MX2 bookshelf speakers):





Logitech Boom - wireless connection to music server at 30% signal strength 2 floors apart (built-in speakers):




Home Theatre PC to TEAC UD-501 DAC via USB using JRiver Media Center 19 to stream the shared file off my server machine in another room in the house (essentially the typical PC-DAC setup):




Alright, enough with the streaming devices... Time for some CD spinners now playing the burned Maxell CD-R...

Panasonic Blu-Ray DMP-BDT220 player (2012 model) in soundroom connected via HDMI to Onkyo TX-NR1009 receiver with Paradigm Signature S8 speakers:




Windows 8.1 Intel i7 computer with CD played off LiteOn iHAS DVD burner to ASUS Xonar Essence One DAC (USB) with desktop AudioEngine A2 speakers. To make this even more "challenging", I have 8 computing threads running doing WAV --> FLAC compression just to create 100% CPU load with heavy hard drive activity:




"Lo-Fi" Sony CFD-S05: Finally, my lowest fidelity device that plays a CD; an all-in-one cassette / CD / radio. About $70 and worth every penny just to play the occasional cassette tape :-).





So, what can we say looking at the above graphs and numerical summary? Exactly what the jitter measurements over the last year or so suggests. Timing anomalies as can be detected in frequency shifts are minuscule in the digital world compared to what is seen with a turntable set-up. Dunn J-Test utilizes detailed FFT analysis to look for tiny sideband distortions which typically show up below -100dB with most decent DACs these days. There is a world of difference between what's found with the J-Test compared to the timing errors with typical turntable measurements as reported by tests like PlatterSpeed.

Looking at the mean frequency (remember, target exactly 3150Hz), every one of the devices achieved essentially perfect scores except for the inexpensive "lo-fi" Sony all-in-one (average 3153.7 Hz). Even with the Sony, my guess would be that this is due to the low fidelity speakers or "defective by design" (remember the poor frequency response) rather than an underlying digital timing inaccuracy.

If we look at the "raw" frequency graphs, we see that the major variation is at the end when I press the STOP button and the iPad is picking up the "click". Otherwise, other than the Logitech Boom and the i7 computer connected to the ASUS Essence One with very low levels of frequency undulation (I've seen this with the Essence One before with the USB interface but not with SPDIF inputs), the rest of the plots are flat lines. I am impressed by the iPad and PlatterSpeed app for being able to pick up tiny <1Hz variations.

As for the numerical analysis... Frequency fluctuation results are essentially perfect across the board and better than any turntable set-up; this includes the inexpensive Sony all-in-one CD player. The small deviations are for the most part just the bits of ambient noise or that "click" at the end being detected.

Is any of this surprising? Of course not. It doesn't negate the fact that a good turntable system can sound very good, but is a reminder of the technical limitation of a physically spinning turntable and of human hearing (ie. a non-specialized "instrument" like the iPad can pick up imperfections easily, more so than the threshold of hearing that would interfere with enjoyment of music). In fact, we might even hypothesize that a small amount of wow and flutter using a turntable adds to the "texture" of the sound, making it less "digital" sounding perhaps.

No matter how one views it, these results are a reminder for those who aspire for "high fidelity" as synonymous with "high accuracy" that digital is clearly superior (at least in the time domain as per this discussion). I was frankly surprised how well the little Sony "lo-fi" fared, actually!

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

Well, it was a blast zip-lining and white water rafting over the Labour Day long weekend! It's September so time to get back to work full swing... Hope everyone had great summer months in the northern hemisphere :-).

As the rainy and cool months approach here in Vancouver, I'm looking forward to some quality listening in the 'man cave'... Enjoy the tunes, everyone...

PS: Back to School question of the week - in 500 words or less, why would anyone want to buy the 24/96 version of Maroon 5's "V" on HDTracks for $22.98? Please provide plenty of subjective descriptions :-).

Thursday, 28 August 2014

MEASUREMENTS: Technics SL-1200 M3D Wow & Flutter - PlatterSpeed + Dr. Feickert's Test LP...

So, I got the Dr. Feickert's Adjust+ 7" Test LP in the mail the other day direct from Germany. It looks well pressed on good quality vinyl.

It's great to see the measurement screenshots from Michael Fremer for the various turntables reviewed so I thought it would be interesting to do my own measurements with the Technics SL-1200 (M3D) here at home. I believe that all the Technics SL-1200 quartz-controlled direct drive units (MK2 onwards) have the same servo mechanisms so they should measure similarly.



I'm using the current PlatterSpeed iPad app (v.2.2) to do the measurements in concert with the Test LP.

Recorded over 60 seconds, here's how the wow & flutter graph looks for my Technics with the stock rubber mat in place and stock tonearm at 33.3 rpm. The turntable sits on my sturdy basement hardwood floor as in the picture above. The M3D's "reset" button was activated to quartz-lock at the standard pitch. Cartridge is the Denon DL-110 with the Emotiva XSP-1 preamp:



I also did the measurement with the Funk Achromat 1200 and did not see any difference (not unexpected of course since the mat itself should not be causing any platter rotational change unless there is slippage of the LP or mat over the platter).

As you can see from the lowpass-filtered green line, the overall speed is very accurate, hovering right around the 3150Hz test tone. Notice too that this doesn't look like the more chaotic "raw" graph from something like the less expensive "clone" Audio Technica AT-LP120-USB recently reviewed. You can also compare this with the Music Hall MMF-11.1 graph, and the Zorin Audio TP-S3 - way more expensive tables. And here's a supposedly "modestly" priced AVID Ingenium review with rather significant speed stability issues. (When look at these graphs, remember to mind the scale differences on the left, not just the shape of the raw tracings.)

If you have a subscription to Stereophile, the Analog Corner article in the May 2014 issue (p. 33) also has some numbers and graphs for the VPI Classic Direct Drive Signature, Continuum Caliburn, and the very smooth looking graph from the Onedof One Degree of Freedom (the review is also posted on-line.)

Here are the numerical results for my SL-1200M3D. (I paid a few bucks to get the DIN IEC 386 / IEC 45507 plug-in measurements as well for those interested.)


Lowpass-filtered, we see a nice +/-0.02% deviation. Over the course of ~60 seconds, it's good to see that the maximum deviation remained <+/-10Hz for the 3150Hz signal - good stability (Fremer's measurements are usually for ~30 seconds).

I try not to be a zealot over hardware - it's just a "thing" after all and can be replaced, but I do value objective "truth" as best I can show evidence of and am curious if I actually do experience something unexpected subjectively... So please don't take my comments as being some kind of "religious" cult-lover of the Technics SL-1200; I got it at a great price used, it has excellent build quality, and so far it sounds fantastic to me. That being said, here's something that Michael Fremer wrote in the May 2011 Stereophile in his Brinkmann Audio Bardo turntable review:
Virtually all electric motors "cog," ie, their rotational speed regularly fluctuates above and below the average speed as each magnet pole goes past each coil. A high-torque motor needs a greater number of poles—in some designs, dozens—and the more poles, the more cogging. With nothing to counteract the motor cogging that inevitably occurs directly within the platter of a high-torque, low-mass, direct-drive turntable, large amounts of wow and flutter are also inevitable.
Regulating a direct-drive motor's speed with a phase-locked loop produces tight speed control and measurably low levels of wow and flutter, but the motor's constant, ultra-high-speed hunting and pecking as it over- and undercompensates in the attempt to produce a consistent speed can create a jitter effect in the mid-treble to which the human ear is particularly sensitive, adding a hard, brittle texture to music. That describes the sound of Technics' now-discontinued SL-1200 series of direct-drive turntables, and explains why, despite their high build quality and relatively low price, few are used in serious audio systems, though some listeners claim that these 'tables can be modified to improve their sonic performance. 
Well, that sounds a bit scary doesn't it? But unless substantiated with some objective evidence, it remains just another scary theory among many promulgated by the "high end" (eg. the dreaded jitter, WAV vs. lossless compressed FLAC sounding different, digital cables, power cables, strange "room treatments", funky playback software, just to name a few). Surely something so ominous can be measured, right? Others have also voiced doubts about these claims; for example KAB doesn't seem to think this happens with the SL-1200.

So, I'm looking at the graph above and am wondering whether I'm seeing evidence of "ultra high-speed hunting and pecking". The frequency variation looks quite regular and clean. I assume we should be looking for significant random chaotic ups and downs in the graph that could be (supposedly) perceived as the "jitter" artefact. Sure, the Technics is not as good as the symmetrical, smooth and constrained undulation of the Onedof turntable (ahem, $150,000 folks). For less than $600 or so that I paid including the LED cue light replacement and aftermarket Funk Achromat, this 1970's Japanese designed performance seems pretty decent I think!

On a side note, if anyone dares to complain about jitter as a significant variable in digital playback, just look at how much 'jitter' is present with timing errors from vinyl! We're talking orders of magnitude compared to the usual picoseconds from typical decent CD players.

Ultimately, rotational speed accuracy and stability are just a couple of the variables in the complex vinyl playback chain; but important ones. Remember that the test LP itself will add its own variation and affect the results (eg. if the spindle hole is slightly off center, mild warping, etc. - the lowpass-filtering is supposed to compensate for this). I wouldn't therefore read too much into these measurements other than a guide to know when something is really abnormal. I agree with Fremer when he wrote in the VPI Classic Direct Drive Signature review:
The Onedof and Caliburn measure similarly, but their frequency graphs look very different. Are the sonic differences the result of differences in bearing smoothness, motor control, or both? At this point, I don't know.
Personally, at least I feel secure that my >10 year 'young' SL-1200 is holding its rotational speed well. A measured result of 3149.8Hz (3150Hz ideal) is essentially as good as it gets.

As for the supposedly audible complaints of "hard, brittle texture" in the earlier quote above charged at the SL-1200, I have no idea what he's talking about... Just because something uses quartz doesn't mean it's "hard and brittle" :-); just like silver cables = "fast" and "bright", right?

There have been debates about direct drive vs. belt drive vs. rim drive turntables over the decades but as far as I am aware, good controlled listening tests/comparisons are lacking so I think it's more important to focus on the actual execution of the turntable rather than lumping drive mechanisms in a simplistic fashion. I'm sure there are some terrible direct drive models just as there are terrible belt drive models.

For completeness, here are the Feickert PlatterSpeed test results at 45 rpm on my SL-1200 M3D over about 45 seconds (test signal target is 4252.5Hz):



As expected given what was seen at 33.3rpm. A bit more frequency deviation/fluctuation with the 35% higher rotation speed. Note that the +16.3Hz raw max frequency deviation is an anomaly due to that little spike at the end when I took the stylus off the record... Should only be +11Hz at most. Very good result I think!

Overall, I suspect the results here would be superior to many very expensive "boutique" turntables out there. I'll show some other measurements in the days ahead when I come across the opportunity.

Off to try out some zip-lining and white water rafting at Whistler this Labour Day long weekend. Enjoy the tunes everyone...

-----------------------------------
Addendum: Here's another interesting thread and the original thread where the test was done on the idea of "cogging" with direct drive motors from a few years back. Clear as mud. Again, even if these results demonstrate imperfections in the drive mechanism, where's the evidence for perceptibility?

Friday, 22 August 2014

MUSINGS: "Pure, Perfect Sound - Forever"

Remember that much-maligned phrase "Perfect Sound Forever"? Of course you do! For the audiophiles out there who read the usual magazines, how can we not!? We only seem to be reminded of it every few months as it's trotted out like a nagging parent bringing out old transgressions - never forgiven, never forgotten.

The name of the person(s) who came up with that catch phrase has been lost in time; perhaps someone in the advertising back office at Philips... In full, it's actually "Pure, Perfect Sound - Forever" as prominently displayed in one of the earliest CDs from Philips (circa 1982):


This demo disk consisted of 14 tracks; combination of rock/pop (Elton John "Blue Eyes", Dire Straits "Once Upon A Time In The West"), with classical selections [see here]. Personally I have never seen a copy but can imagine that it would sound like the usual early pressings - a first pressing Billy Joel Piano Man perhaps (which incidentally needed de-emphasis processing to sound right [see list]).

As a marketing slogan, it has obviously worked. After decades, at least within the audio world, apparently people remember the "promise" of digital audio. I would of course agree that these early 1980s "first press" CDs were not the "ultimate" best sounding audio, but as I opined previously here (in reference to Pono and John Hamm's comments), just what is the best version of any album is a subjective judgement irrespective of whatever carrier medium... There have been many instances where I would easily prefer these old releases compared to modern dynamic compressed, distorted remasters (the inferior 2009 UMG Rolling Stones remaster of albums like Emotional Rescue from 1980 came to mind the other day as I was listening to it). The issue with the interpretation of this marketing phrase with many in the audiophile press and analogue evangelists when they malign "perfect sound forever" is that they're taking it to mean "best sounding version forever". Furthermore, some folks take this advertising slogan and heap upon it their own unfounded biases against digital as if the phrase somehow is evidence of an inherent "flaw" with digital audio! Remember, it has been 30 years since the introduction of the CD technology and we have yet to see credible evidence to demonstrate that well-digitized 16/44 isn't transparent beyond anecdotal opinions (just like there's no good evidence to demonstrate superiority of 24-bits or >44kHz sampling rates; assuming we're using a decent DAC playback system).

In the context of what I wrote previously with my adventures in analogue/vinyl, I believe that "pure, perfect sound - forever" as it relates to digital is more accurate than not. Let's look at the mains points.

Pure: I take it this refers to purity of the signal recorded free from extraneous distortion and noise. I don't think I need to say much about this since the digital format is indeed capable of encoding mathematically precise, "pure", even synthetic waves. Sine, square, triangle, sawtooth; whatever... It will be encoded on the CD within the resolution limits of digitization - precisely. Of course the analogue-to-digital converter plays a massive part in digitization quality but they're extremely capable these days. Noise and distortion technical limits of 16/44 are well understood of course. Vinyl in comparison as a physical object will have limitations in terms of noise and other distortion long before the mathematical precision of digital 16/44 data... This leads us to the second point...

Perfect: In reference to a digital sound storage system (ie. the CD and modern day digital files), one can say that perfect retention of the data and replication of the sound as encoded in the data is possible (or at least perfect enough for all practical purposes). It does get a bit boring measuring DACs these days because typical high quality DACs measure and sound very similar (atypical ones that employ vacuum tubes output stages or complex internal DSP operations for example, are a different matter!). I suspect it is this fact that leads various companies to shift attention to tiny differences like "jitter" to differentiate themselves or claim audible differences. In comparison, you can never say that any aspect of a vinyl system's music reproduction is "perfect". The mixing process for an LP requires compromises, the cutting itself could be imperfect, mass reproduction does not result in perfect copies (consider even the varying quality of the vinyl material used), packaging and shipping issues (abrasions, warped records anyone?), accidental scratches, dust and grime, imperfect turntable setup (VTA, VTF, azimuth, leveling, antiskating...), varying quality of cartridge/stylus/cantilever (tracking issues, inner groove distortion), phono pre-amp RIAA curves, etc.

Compared to the data integrity of a digital system, analogue just cannot match. The consistency of playback with digital would have had been revelatory back in the day; certainly a much more consistent quality of playback each time and sonic differences between good CD players are much smaller than that between different turntables and cartridges. As I wrote previously, I do believe analogue LP playback can sound fantastic and IMO there's no point rehashing the tired analogue vs. digital debate since there are so many factors influencing a good sounding recording and playback system. Yes, some LPs can sound better than some CDs and vice versa. Digital has fantastic sound quality if the original source isn't dynamically squashed to distraction, and vinyl has attached with it the pride of ownership unmatched by CD/SACD/DVD-A/Blu-Ray/files.

Forever: If anything, this is perhaps the least true comment about CDs. As an enduring object, the petroleum-based, non-biodegradable vinyl LP cannot be beat by digital as far as I am aware. It has been said that an LP can last 100's of years if stored properly. Easily spanning any of our lifetimes. On the other hand, there are instances of CD "rot" over time although personally I have many CDs hitting 20 years and they look good so far. Even 15-year old CD-Rs seem OK to me so far stored in a cool basement away from direct sunlight or inclement weather. Hard drives are more problematic and in the last 10 years of running my music server, I've probably had to replace each hard drive every 5 years on average with regular use. Solid state drives (SSD) are a bit of a mystery to me so far. I use them as boot drives rather than music storage due to cost and so far my oldest unit of about 5 years seems to be OK.

However, with digital, we do have the ability to make perfect copies each time so with some discipline around backing up (probably good to have 2 extra copies around stored at different physical locations), one should be fine for a lifetime. PCM is ubiquitous and the free FLAC file format I suspect will easily outlive any of us reading today... I wouldn't be nearly as confident about DSD file formats' longevity however (especially given how primitive they are).

"Perfect sound forever" as a description for the CD and digital audio in general has a 'ring' of truth to it. The key is to say it within a reasonable context and seeing it for what it was meant to be... A catchy ad slogan which did highlight the merits of digital audio. And it worked!

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

In keeping with my recent interest / "re-acquaintance" with the vinyl format, here's an interesting article on the "rise" of vinyl. We'll see how this pans out in the years ahead. As I've checked out the vinyl stores locally, I notice that there's a nice mix of young and older folks looking around. I see about as much interest in the used vinyl as the used CD bins 'round here. There's a local large chain store that sells new LPs and I don't think there's large volume going thorough. Vinyl growth or not, I think it's fair to say that sales of a physical music product peaked at least a decade ago and it's not ever coming back for many reasons - convenience, storage, maybe environmental consciousness, the economy...

As imperfect as vinyl is, I'm having a blast rummaging through the bargain bins sorting through the oldies from the 70's and 80's constituting memorabilia from my "soundtrack of life" through the formative years :-). I've found many very clean, essentially mint albums over the months. To be able to buy it for "pennies on the dollar" makes it even sweeter!

One last thing. Needless to say, economically, there is one very important reason for music labels to "push" for a resurgence of vinyl. Anti-piracy. "Perfect sound forever" also means "perfectly copied forever". I sure hope we don't get a systemic situation where digital becomes maligned, crappy CD/digital downloads are released, and sonically decent versions are reserved for the LP release only at high prices. Doing so would sadly bias sonic quality towards the technically less accurate format.

Enjoy the music and the rest of summer (N. Hemisphere)!

Friday, 15 August 2014

AudioPhil's Corner: Viewpoint and Follow-up on the Dragonfly 1.2...


I was offered the opportunity by Archimago to share a few thoughts regarding the Dragonfly v1.2 which I graciously received as a pre-wedding gift from my good friend the Mago himself. However, before I go into that, I'd like to provide a little background on how I feel the entire subjective high end audio hobby has changed over the past two decades or so. This leads up to why I believe that the majority of consumer electronic products have mostly reached a technological performance plateau over the last few years and why I don’t think there are really any truly “bad” audiophile products out there any more in general.

First of all, I've followed the general evolution of the high end-audio scene off and on for the greater part of two decades and have shared insights with friends from both the subjectivist and objectivist camps; with members of both camps invited for hi-fi auditions on a few occasions which led to some very interesting dialogue ☺. [Ed: War!] As for myself, I feel that I’m currently straddling both sides, being able to recognize the merits (and flaws) of each. However, over time, I feel that there will be some kind of eventual reunification as the once elusive “high end” audio performance can now be obtained at far more attainable prices.

The one area in which all audio enthusiasts can unanimously agree to is that digital audio has improved significantly over the last 20 years, with the overall performance bar taking a quantum leap in the 90s, and then having that state-of-the-art performance trickle down gradually into much less costly products since the turn of the millennium. I still vividly remember being in complete awe with mouth agape when I first saw the Mark Levinson No. 30 and No 31 DAC and transport combo at a local high end store in the early '90s. That combo was insanely expensive, costing more than a new luxury car, and looked like it could have come off the captain’s quarters from Star Trek: The Next Generation’s USS Enterprise. It didn’t just sound incredible, it was the pinnacle of acoustics, aesthetics and literally cost-no-object build quality that made it widely regarded as the Holy Grail of digital high end audio for several years to come. It would have been my “preciousss” had I been able to afford it.
Mark Levinson No 30 Reference Digital Processor (Photo courtesy of Stereophile, Feb. 1992).
Although it cost a whopping $30K back then, it was so far superior to the quality of cheap mass market consumer electronic products at the time that if one could afford it, it might possibly be justified, like buying a Ferrari. Even today, the No. 30 and 31 are still sought after as icons of audio history.

Fast forward a few years and I was similarly awestruck when I saw my first HDTV feed on a 42” plasma display which at the time cost a cool $25K. Today a 42” LCD TV that is superior in every way would sell for closer to a hundredth of that price. Similarly, audio electronics have also advanced significantly in price-to-performance. Archimago not long ago measured my Oppo BDP-105 which had a measured performance that is off the charts, with noise and distortion levels that are significantly below the thresholds of human hearing acuity.

In fact, I believe that the “perceptible” (as opposed to measurable) performance of most consumer electronics products, which includes everything from digital cameras to flat screen displays to audio products have reached a plateau several years ago so the continued marketability of these products have primarily come from improving aesthetics and at the same time drastically reducing prices.

All these technological advances and marketing efforts are slowly but surely killing the subjective high-end audio industry. Once upon a time, there were mighty Mark Levinson products which were lusted for by many but attainable by only the most affluent and dedicated audiophiles. But today, something close to the “absolute sound” can be quite painlessly acquired by the masses, and it is that mass-market availability that has in no small way led to the decline and possibly the inevitable demise of high-end audio as we once knew it. An audio dealer will likely require significantly more persuasion to convince an ever shrinking base of hardcore and well-heeled audiophiles that a dCS Vivaldi digital playback system is worth $100K when one can buy an Oppo BDP-105 for a tad over $1K which also gets you one of the best Blu-Ray players available. That’s a pretty steep diminishing marginal return curve to climb no matter what your available resources. After all these years, the current reigning “preciousss” has in my opinion lost much of the sizzle in the ”s”. My MacBook Air is technologically advanced and also beautifully sculpted from curved shiny aluminum yet doesn’t have to cost six figures...

Stepping back to the subjective camp for a moment, I will make mention that Archimago stated that he feels that the Dragonfly gives an overall “warmer”, more pleasant and less hard-etched sound than the AudioEngine D3 despite a bit inferior measured performance. I think that’s yet another example of the paradox that fuels the never-ending debate between the subjective and objective camps. If the original audiophile goal should be to seek the most accurate reproduced sound possible, why do subjectivists (or even normal human beings without the “golden ears”) seem to often prefer euphonic distortions in the form of tubes, vinyl, etc.? However if the ultimate goal is to simply enjoy the music, then should we even care?

Finally, I will say a few words on my overall impression of the Dragonfly, but really, there is nothing much more that need to be said that hasn’t already been covered by many others before. It is well made and feels like a very solid and weighted USB stick. I never had the chance to do an intensive A/B test with it but the Dragonfly does a fine job of radically improving the headphone output from my MacBook Air which is most obvious when listening to AKG K-702 headphones, even though it is still a very noticeable improvement even with cheap earbuds. The soundstage is much larger, with instruments having far better stereo imaging and voices had more body and depth. The Dragonfly was able to extract significantly more micro-details, especially on live recordings so it is able to more convincingly put you at the recording venue when compared to listening straight off a MacBook Air or iPhone. The bass is full but not bloated. Overall, the sound is detailed yet well balanced and smooth. There was minimal listening fatiguing even after a couple of hours of critical listening, and I was able to listen at louder than normal levels.

Overall, this nifty $150 DAC offers exceptional price-to-performance much like a $500 DLSR or LED TV, or the latest Android smartphone or many other techno gizmo these days. Heck, it may even sound as good as the revered ML No 30 DAC (in a DBT, of course) if plugged into my main system. Near state-of-the-art performance in consumer electronics products has never been better or more attainable.

Happy listening!

Thursday, 7 August 2014

MEASUREMENTS: AudioQuest Dragonfly v1.2 Reviewed

An audiophile buddy of mine (AudioPhil) got married a few months back and a few of us decided to chip in to give him one of these Dragonfly DACs for being a good sport :-).

I don't think the Dragonfly requires much introduction since it has been around in the 1.0 iteration since 2012 and Stereophile had it grace their cover page with a full review back in September 2012. It uses an unspecified ESS Sabre DAC (not sure if confirmed, likely the ES9023 with integrated 2Vrms driver - there's also the older ES9022 chip) and the USB communication part is the TI TAS1020 performing asynchronous data transfer. I haven't read anywhere if these parts have changed in the 1.2 version. Supposedly, the new version has improved sonics ("Even smoother and more open sound!" seems to be the official tagline).


It looks good and feels great in the hand with a slight rubberised texture to the surface of what seems to be a metal shell underneath. As you can see above, it is slightly smaller than my AudioEngine D3 previously tested. Despite the smaller size, the weight on the Dragonfly feels heavier; hence a noticeable ruggedness and density to the package. It comes with a small black pouch for safe keeping along with the USB cap. I don't think the Dragonfly comes with a 1/4"-to-3.5mm adapter cable like the D3.

You can see the Dragonfly indicator change color depending on sample rate. AKG Q701 connected.
In use, I found that it didn't get too warm and was clearly cooler to the touch after about an hour of listening compared to the D3. AudioEngine was quite open about revealing the use of the LME49726 op-amp for the headphone output and presumably the Dragonfly utilizes the integrated op-amp function of the ES9023 (or similar chip) as per the "direct-coupled circuitry" in their promo material. From a price perspective, both the AudioEngine D3 and Dragonfly are priced similarly, $150CAD for the Dragonfly and $170CAD for the AudioEngine D3.

Other specs like output impedance (12 ohms Dragonfly, 10 ohms D3) and power (150mW Dragonfly, 200mW D3), both being driverless USB Audio 1.1 devices with a maximum of 24/96 sample rate (it is capable of the important 88kHz for DSD conversions) further adds to the functional similarities between the D3 and Dragonfly. These driverless USB DACs make it really easy to just "plug 'n play" with Windows and Mac OS X - I did not try using Linux but that should not be a problem.

I. Objective Evaluation

A. The Basics
As you may recall, at 100% volume, the AudioEngine D3 would clip. This was noted to happen with the Dragonfly v1.0 as well; discussed in the Stereophile measurements, and used to show some atrocious distortion numbers by Light Harmonic when they did their "Geek Out vs. the Others, 3rd Installment" (5% THD+N!? Sorry, that's just plain nasty and paints the situation in a much poorer light than it should even though objectively correct...). Well, it looks like this issue has been resolved with v1.2; here's the oscilloscope measurement from the unit I have on hand:
Square wave at 0dBFS.
Sine wave at 0dBFS. No clipping at 100% volume.
Peak volume of 2.63V correlates with an RMS voltage of 1.86V. Hmmm... I suspect this must be what they did to avoid clipping if the ESS chip used is the ES9023 with 2Vrms capability; dropped the highest volume level settings (notice that the Geek Out test posted was with 100% volume at 2Vrms).

There is bit of channel imbalance in the graphs above... It represents approximately a 0.5dB difference (left channel louder) at full 100% volume.

Impulse response is the typical symmetrical appearance of a linear phase oversampling filter. The signal maintains absolute polarity. No surprise.

B. RightMark 6.4.0
Okay, with the above done, let's have a look at the resolution of this DAC using the RightMark test bench. Like with the AudioEngine D3 tests, this was performed with the latest free version using the ASIO device interface.

Setup:

Test machine + AudioQuest Dragonfly --> shielded phono-to-RCA cable --> E-MU 0404USB --> shielded USB --> Win 7 laptop running RightMark 6.4.0

Summary of the machines tested (the laptops were described here in more detail although OS has been updated):

1. ASUS Taichi 21 Ultrabook (early 2013): Intel "Ivy Bridge" i5-3317U (1.7GHz dual), 4GB, Windows 8.1 x64, 128GB mSATA SSD, USB3 port, foobar + WASAPI component 

2. Apple MacBook Pro, 15" (mid 2009): Intel Core 2 Duo (2.26GHz dual), 8GB, OS X 10.9.2 "Mavericks", USB2 port, WD 640GB SATA HD, Decibel player (AIFF files)

As you may recall when I tested the AudioEngine D3, I measured that device with 6 different machines! It was clear that this made no difference to the measured audio output (and I heard no difference either - indeed folks, bit-perfect does mean something)... For these tests, I just chose a PC platform and a Mac platform, both are laptops, but with major differences like OS, file types (FLAC vs. AIFF), different generation Intel CPU, different player software, USB2 (Mac) and USB3 (PC).

Let's start with the 16/44 standard resolution (CD-quality) signal:

The 2 columns on the left are the measurements from the Dragonfly 1.2 - leftmost using the ASUS Taichi laptop, second one using the MacBook Pro. The middle column is the result from the AudioEngine D3 connected to the ASUS Taichi (exact same cables and setup as the leftmost column measured the same day), and the last two on the right are with my higher end DACs - the Transporter using XLR connection, and the TEAC UD-501 with XLR output measured awhile back. Note that because the AudioEngine D3 clips at 100% volume, the measurements were done at 91% which approximated the same maximum output voltage as the Dragonfly.

As you can see, when it comes to noise level and dynamic range, all these DACs are capable of ideal 16-bit resolution. Very low noise floors all around. Where things do seem to separate out is in the area of distortion - the Dragonfly appears higher in this respect compared to the others (repeated this a number of times to double check). Also, the stereo crosstalk is objectively higher with the Dragonfly. Here are a few of the graphs off RightMark:
Frequency Response - Transporter seems to roll off a wee bit more.

Noise floor.

Dynamic Range test.

IMD+N

Stereo crosstalk - note the significant difference between the Dragonfly vs. the others.
Now, let us look at the 24/96 (high-resolution) results:

The columns are arranged the same as above. Leftmost two columns represent the Dragonfly results, then AudioEngine D3, then the Transporter (XLR), and finally TEAC UD-501 (XLR).

Again, no difference in results between using the ASUS Taichi and MacBook Pro laptops despite disparate hardware and OS. The Dragonfly is indeed capable of >16-bit dynamic range, and at approximately 106dB, that's about 17.5-bits (same as what Stereophile found with their v1.0 review). As with 16/44 above, however, when you look at the measurements of distortion, the AudioEngine D3 is capable of less distortion and dynamic range is about 0.5-bits higher. Needless to say, the stand-alone "higher end" DACs like the Transporter and TEAC UD-501 with XLR outputs handily beat these little USB DACs by about another 'bit' of dynamic range and lower noise floor (especially the old Transporter!) measurable within the limits of my ADC set-up of course.

Frequency Response (no significant difference <20kHz)
Noise level - notice Dragonfly slightly higher especially in the bass.
IMD+N
Stereo Crosstalk - Dragonfly again significantly higher crosstalk... Very impressed by the Transporter using XLR cables! 
C. Jitter
As usual, I'll use the Dunn J-Test paradigm. Easy enough to do...


As in previous tests, with these asynchronous USB DACs, the Dunn J-Test spectrum generally looks fine. This is the situation here, no evidence of jitter issue at all using this simple measurement... Only very slight noise floor differences between the two laptop machines.

II. Subjective Evaluation

So I asked my buddy AudioPhil (the guy who actually owns this Dragonfly) to provide his subjective review and it looks like he'll be providing a little write-up of his own in the next while... While that's in "gestation", I figure I'll jot down a few of my subjective impressions and comparisons on this little device.

I spent about 2 weeks listening to music with this DAC/amp (some before, and some after the objective testing) and comparing what I heard with the same tunes off the AudioEngine D3 and ASUS Xonar Essence One (which remains my primary DAC on the computer workstation). Each of the devices have quite different DAC architectures; Dragonfly with the ESS Sabre, D3 with an Asahi Kasei AK4396, and the larger Essence One using TI/Burr Brown PCM1795s (quite unfair comparison given that it's not a simple USB bus powered device!). It's impossible to "instantaneously" switch headphones / DACs and then level-match compare... I tried my best.

A potpourri of DACs and headphones: AudioEngine D3, AudioQuest Dragonfly 1.2, ASUS Xonar Essence One; Sennheiser HD800, AKG Q701, Etymotic ER-4B IEM.
The published output impedances for the Dragonfly and D3 are around 10-ohms - the Essence One apparently has similar output impedance as noted by 'Xnoreq' in the comments although there are estimate of it being in the single digits [I'll need to have a look at this later]. So, to give them all a fair chance, I'll speak about what I heard using the Sennheiser HD800 (300-ohm input impedance) headphones primarily. Thankfully the HD800s have high enough sensitivity (102dB at 1Vrms) so music could be played reasonably loudly with the Dragonfly and D3 even with the lower power ratings. Of course from a price point perspective, the HD800 isn't the kind of headphone one would expect to see mated to an inexpensive USB DAC like this!

I started with listening to some "vocal audiophile jazz" - Diana Krall's The Look Of Love (2003 24/96 DVD-A) being one of my favourites over the years and particularly "Let's Fall In Love" as a track I've been using to compare new gear with since around 2000. I like the instrumental portion in the middle of the track and particularly the detailed resolution of the bass and piano through that portion. With the Dragonfly, the piano sounded rich and full. The bass was detailed with each pluck easily discerned. In comparison to the D3, the Dragonfly sounds more laid back and "smoother". The D3 just seemed to have a bit more sparkle, slightly brighter; for example the high-hats on the song stood out a bit more from the rest of the instruments. Personally, with my "Anaxilus mod" Sennheiser HD800, I preferred the D3 rendition but I can imagine with even brighter headphones, the Dragonfly may be preferred.

While staying with the vocal genre, I listened to some Nat King Cole - Cole EspaƱol (HDTracks 24/96 release, and no, I don't actually believe this album has enough resolution to warrant the high-resolution format). On a track like "Quizas, Quizas, Quizas", the Dragonfly was a joy to listen to with the HD800! This old 1958 recording can be a bit "brittle" through many DACs and the Dragonfly just made the instruments sound less harsh and the voice "ultra-smooth". I found the same on some traditional Chinese erhu recordings where the pleasant demeanor of the Dragonfly helped impart an enjoyable, smoother experience.

Time for some heavier fare - how about AC/DC Back In Black (1988 DR12 CD)? Pump this baby up to rock! The intro to track 1 - "Hells Bells" - with those church (er... hell's?) bells sounded realistic in terms of the attack and smooth decay using the Dragonfly. While not exactly the paragon of audiophile recording technique, this analogue recording from 1980 is about as "hard" as I like my rock to be and the Dragonfly was able to render it nicely. However, I found the Dragonfly to be a bit more on the "polite" side of things as compared to the more aggressive sound of the D3 which I thought fits this type of music better.

I listened to a number of other genres to get a feel for things - Pet Shop Boys Actually (2001 remaster), Yello Touch Yello (2009), Eiji Oue & Minnesota Orchestra Stravinsky: Song Of The Nightingale, Firebird, Rite Of Spring (1996 Reference Recordings), Ed Sheeran x (2014). In general, I thought that the Dragonfly performed well but was more at home with an acoustic set than say the synthpop or electric guitar rock. Despite the dynamic range compression especially near the end of the song, a track such as Ed Sheeran's "I See Fire" with overlaid vocals and relatively simple instrumentation found on x sounded just fantastic through the HD800 with the Dragonfly; bass response on that track was simply cavernous in depth.

Not unexpectedly, the much larger (and unportable) ASUS Xonar Essence One sounded better than the USB stick DACs. This has more to do with the quality of the headphone amp than the actual DAC function I believe - providing a more full-bodied, powerful sound overall (even more cavernous bass at the end on "I See Fire"!).

Near the end of my subjective evaluation, I put on some mono music to see if I could easily detect the channel imbalance noted above. For this I used the mono Beatles remasters from 2009. I listened to most of the Revolver and Sgt. Pepper's Lonely Hearts Club Band albums one evening. On the whole the stereo imbalance at normal listening levels with the Etymotic ER-4B balanced armature IEM (100-ohm impedance, excellent noise isolation) was subtle when I compared it with the output from the D3. I was concerned about perceptual bias knowing the objective results earlier so I asked my wife and she identified correctly the slightly louder left channel after listening for a bit. So, we're looking at a small, but perceptible imbalance.

III. Summary / Conclusions

There you go, the objective and subjective evaluation of the AudioQuest Dragonfly v1.2. Overall, from an objective perspective, it doesn't measure as well as the AudioEngine D3. The Dragonfly's 24-bit dynamic range is lower by about 0.5-bits in comparison, plus harmonic and intermodulation distortions measure higher. Furthermore, there's a bit more stereo crosstalk with the Dragonfly. Realize of course we're looking at tiny differences in terms of real-world audibility. For example, what audible difference is there between 0.011% THD (Dragonfly) versus 0.0009% (D3)? Would our headphones/speakers be able to manage such low level of distortion or our ears capable of such resolution? Remember that a typical NOS DAC like the old TDA1543 measures 5-10 times higher in terms of THD and IMD yet they can still sound OK (and in fact some audiophiles swear by them). The other difference was increased stereo crosstalk with the Dragonfly measured around -72dB. Compared to the others around -90dB or less, this sounds like a lot. Again, remember that a typical LP cartridge has "only" about 25-40dB channel separation at 1kHz. Therefore, again it's unlikely you're going to notice an audible problem.

The one area of concern for me was the channel imbalance on objective testing at 0dBFS on the oscilloscope with this unit. Even so, it was difficult to detect a difference at normal listening levels through my Sennheiser HD800 and AKG Q701 playing stereo music but could be detected with mono recordings using the Etymotic ER-4B IEM. This could really be a problem if one's headphones also had a slightly louder left channel imbalance issue. Perhaps others can double check if this imbalance is present with their own Dragonfly units.

I cannot help but suspect that the advertised "direct-coupled circuitry" where the op-amp is integrated into the ESS Sabre chip might be the reason for the relatively poorer objective test results. Compact size is achieved with this kind of arrangement but physical factors like significantly higher heat production could I suspect limit absolute sound quality from the DAC chip itself. I don't know if AudioQuest could have also "tweaked" the settings for the DAC chip to bias towards a more pleasant sound.

Here's the bottom line... If you're looking at the AudioEngine D3 versus Dragonfly v1.2 and want the best objectively accurate sound quality, go for the AudioEngine D3. It measures and sounds like a much more expensive separate DAC on a stick! However, the main caveat is that it clips at 100%, so keep it around a maximum of 92% and you'll hear some really clean audio. Remember what I also said previously about allowing a portable device to clip - it may not be an unreasonable trade-off when you just need that extra bit of volume in a noisy environment where a little distortion is fine. The D3 is also a little bit more expensive around here currently (only talking about $20 difference).

On the other hand, the Dragonfly is built very well and I would rate the look and feel of the unit higher than the D3. The color-changing dragonfly indicator based on sample rate is also a nice touch. Furthermore, it is slightly smaller and significantly cooler to the touch than the D3 after an hour of music being pumped through. Output impedance isn't much different between the two (both around 10-12 ohms), so check if you have higher impedance headphones (80+ohms) for best performance. The D3 can play a bit louder but remember this is with the potential for clipping at 100% volume. My usual benchmark for a "good enough" headphone amp is one where I would not need to put the volume to 100% to enjoy my AKG Q701s... And the Dragonfly is clearly good enough in this respect for what I listen to.

The main criticism I have of the Dragonfly is that ~0.5dB channel imbalance I found which I hope is just variability among samples rather than a systemic finding (remember that even well regarded cartridges for vinyl playback can have stated channel variances up to 2dB). Subjectively I thought the Dragonfly imparted a "pleasantness" to the presentation rather than aim for absolute technical precision as demonstrated objectively. Compared to the typical headphone jack on a laptop, it'll provide your headphones with more power, lower noise floor, and more dynamic range especially for 24-bit audio. I'd be very curious to know what objective differences there are between a 1.0 and 1.2 version of the Dragonfly if AudioQuest claims that 1.2 sounds better (other than no clipping at 100% volume)...

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

Happy listening everyone... Considering the 24-bit performance from the AudioEngine D3 and Dragonfly, consumer audio technology is clearly getting better, smaller, and more affordable!

Weather has been very nice here in Vancouver lately. Off to an Alaska cruise next week so hopefully there will be blue skies and maybe see a few whales along the way. Catch you all later...