Wednesday, June 27, 2012

Sound quality differences with optical outputs - why?

For years I haven´t been bothered with digital S/PDIF connections. I basically stopped using them in 2001 when I got rid of my MD deck. This deck had been connected using its RCA digital input, only because everyone was saying that these gave superior sounding results. I never actually checked out if this was true with the result that I ignored optical Toslink in-/outputs back then. But my recent encounters with the Sony MZ-R 30 and the Sony MZ-R 900 forced me to use them again - they are the only way with which I can achieve digital copies with these MD recorders. Thankfully many of my vintage portable CD players are equipped with an optical TOSLINK interface, sometimes I also bought them for this reason. With an optical cable I can connect my PCDPs to an MD recorder to create a digital copy even including trackmarks automatically set by the MiniDisc recorder.

Optical mini-Toslink on the Sony D-335

During the last few weeks I recorded roughly twelve MiniDiscs. Some were recorded with the respective CDs played back by my Sony D-465 or the Sony D-335, some were recorded with the Creative Soundblaster X-Fi HD USB as their the digital source. To my surprise the CDs copied with those two CD players sounded different to what I´m used to, it was apparent that the sound signature had been changed somehow. The ones made with my Creative sounded pristine instead. To use an analogy: recordings from my CD players sounded like a decent analogue copy while the ones from the Creative sounded like the originals. But how can this be true? In both cases I used an optical cable that transferred its data digitally, effectively creating a second original (ignoring the lossy ATRAC compression). All the digital outputs I´ve used so far are bit-perfect meaning they won´t change the digital signal in any way. I´ve confirmed this with one of my CDs from TELARC, a rare example of a DTS-recording they released some 15 years ago. Our Sony STR-DB 830 QS is able to recognize the digital signal as DTS-encoded, it doesn´t matter which device is doing the playback. So why do I hear differences between digital signals? It just doesn´t make sense.

My optical fiber cable (copyright: Philips)

The cable you can see above is the one I´ve used for all my tests involving MD recorders and my Creative. Build quality is good... the gold plated "connectors" don´t make sense of course; the signal is pure light and cannot be influenced by the conductivity of certain metals. People seem to expect it though... what the heck, it looks nice doesn´t it? Back to the question of why I´m hearing differences. The S/PDIF protocol necessary for digital Toslink transfer has several disadvantages. The most significant is that the receiver of the signal doesn´t control it, the sender does. Because of that it must synchronize its internal clock (necessary for D/A converting) to the one contained inside the signal itself which is generated by the device transmitting it. Now in case of jitter (you knew that I would mention this, didn´t you?) introduced by an unstable or polluted clock the receiver (D/A converter or MiniDisc) won´t have a stable clock reference, in effect making jitter audible upon conversion to analogue signals. Research into this subject has been going on for years, for example from members of the AES. This influence can be reduced of course by reclocking the incoming signal. Both my MiniDisc recorders do exactly that: they reclock the signal with their built-in samplerate converter, effectively creating their own clock reference. Another impermeable wall for jitter is the MiniDisc writing process itself because it is another reclocking step. All of this should in theory eliminate jitter completely. Would it be able to survive it would result in distortions not unlike those found in intermodulation distortion and in a compromised stability and clarity of the stereo image. How are my MD recorders doing this reclocking? They probably use a phase-locked loop circuit (PLL) which you can imagine as a huge flywheel averaging out speed variations. Depending on the quality and implementation of the PLL jitter reduction is more or less successful, according to an article from Soundonsound it cannot ever be eliminated completely though. Attention: even with jitter the transferred signal will always be the same, it still contains the same 0 and 1, albeit at different places (sort of).

Jitter test signal on MZ-R 900, played back by Creative Soundblaster X-Fi HD USB

Jitter test signal on MZ-R 900, played back by Sony D-465

Look at the two pictures above by clicking on one of them, then scroll through them with your mousewheel. They were created employing the Sony MZ-R 900, its analogue output recorded with my E-MU 0202 USB. I set the MD recorder into record-pause mode in order for it to serve as a D/A converter only without the result being distorted by the ATRAC encoding. In both cases I used exactly the same signal, it´s the jitter test I usually use for my vintage portable CD players. In case of the Creative it was played back by foobar2000, utilizing the WASAPI interface of the soundcard - without resampling of course. Exactly the same file (this time burned on a CD-R) was then played back by the D-465. Level matching was unnecessary since both results have the same gain. On the pictures you can see that the spread of the signal is wider with the Creative. With the signal played back by the D-465 however there are additional sidebands absent with the Creative. The example below also exhibits a noisefloor higher for roughly 1-2 dB. While I assume these tiny differences to be insignificant, they (or something else) do have an audible effect on music. Recorded from the D-465 music has an unsharp and compact image, sounding a bit bloated and less crisp. Piano for instance sounds a bit distorted while strings loose their gloss. All of this was restored to normal when the Creative was used as a digital source for recording. I even did a DBT, not only for you but also for myself to make perfectly sure that I wasn´t hallucinating these differences:

foo_abx 1.3.4 report
foobar2000 v1.1.13
2012/06/25 20:54:42
File A: D:\Coast Guard Rescue Creative.wav
File B: D:\Coast Guard Rescue D-465.wav
20:54:42 : Test started.
20:56:15 : 01/01 50.0%
20:57:00 : 02/02 25.0%
20:57:29 : 03/03 12.5%
20:57:48 : 04/04 6.3%
20:58:08 : 05/05 3.1%
20:58:26 : 06/06 1.6%
20:59:45 : 06/07 6.3%
21:00:00 : 07/08 3.5%
21:00:06 : 08/09 2.0%
21:00:41 : 09/10 1.1%
21:01:01 : 10/11 0.6%
21:01:08 : Test finished.
Total: 10/11 (0.6%)

For this DBT I recorded the same track ("Coast Guard Rescue", The Perfect Storm) twice, again with the D-465 and the Creative. Level matching was unnecessary as both had the same level, they needed precise alignment of course in order for the DBT to be successful. By this example you can see that different digital sources might have an impact on sound, even when they are bit-perfect. I´ve subsequently tested several other players and their digital outputs: all my portables appear to be susceptibe to something that distorts the digital sound while still being able to transfer a bit-perfect digital signal. There was only one portable player coming closer to the clarity of the Creative transferred signal, the DE-J 725. It didn´t sound bloated but flat and uninvolving (strangeley mirroring its analogue signature). The player almost sounding like an exact clone of the Creative was my Pioneer DV-610 AV which is nothing more than a simple DVD player. Are the reasons for this jitter? Or is it something else? I´d like to know if you, dear reader, have made similar experiences. Maybe my portables do have an unstable clock source or their signal gets distorted by other factors unknown to me yet. In either case the Creative once again proves itself to be a very reliable device of high quality. Additionally a clean digital signal from the source seems to be vital for perfect sound. To all the doubters out there: a bit-perfect realtime signal doesn´t mean that it´s free from some kind of distortion! You might now think that everything is a bliss - you are mistaken there. Recording to MD with the Creative is quite tiresome, trackmarks are not transmitted and therefore I have to set them myself after recording which essentially means that I have to divide a single, 60-minutes track into several pieces. But I´m obviously not a person that loves convenience that much (Exhibit: using MD recorders) so my desire for quality usually gets the upper hand and in the end I´m rewarded with perfect sound quality from MiniDisc. Before I forget: my reviews for the MZ-R 30 and the MZ-R 900 have been done with recordings from the Creative.

Last update: 10.01.2013

Sunday, June 24, 2012

The Devil is an MD Recorder: Sony MZ-R 900 Review

You might ask: "Has she gone mad now?" No, she hasn´t. But an MD Recorder can be devilish good, that´s for sure. While the recorder I wanna talk about does not come from Spain like me in the movie "The Devil is a Woman" (pictured above) it still is able to embody the typical passion spanish Latin Lovers are known for. Well, I´m not a woman known for clichés and as much as my movie partner Cesar Romero actually was born in the U.S.A I never have been in Spain... nevermind. I´d really like to write about the Sony MZ-R 900 instead which is another MD recorder. In my last article I reviewed the Sony MZ-R 30 while also explaining the several ATRAC revisions Sony did over the 19 years the MD lasted. I also tested the Wide Bit Stream capability of my Sony MZ-R 30 and much to my surprise it was able to process digital data with a bitdepth of 24 Bit through its optical line-in. There was one obstacle though: its combined A/D/D/A converter works only at a bitdepth of 16 Bit; the 24 Bit ATRAC-processing was therefore useless. But a few days ago I was lucky and bought the Sony MZ-R 900 for very little money and that particular unit behaves a bit differently. When released in 2000 it cost 350,- Euros which makes it more expensive than my MZ-R 30 (300,- €) from three years prior. During these three years a lot happened with portable MD recorders... they became incredible tiny and loaded with features.

Sony MZ-R 900 compared to a cigarette

It´s exactly as big as an MD case (except height) which poses more problems than you might think: due to its small size and light weight it will move by itself when for example the recorder is lying on a table and one pulls on the headphone cable / FiiO E6 only slightly. It feels fragile even though its build quality is astonishing nonetheless. The precision Sony assembled it with is wonderful to look at, touching the housing feels lovely. The drive however... from my MZ-R 30 I cannot hear a thing when it records or plays a MiniDisc but the MZ-R 900 is loud as hell in comparison. According to the Manual this is normal behaviour but it still betrays its manufacturing quality in my opinion. This tiny recorder contains so many new features compared to the MZ-R 30... to write them all down here would be too much. I suggest you read about them on MZ-R 900' MD Community page should you be interested in them. Features are lovely, problems are not: our Kenwood exhibits some difficulty playing MDs recorded by the MZ-R 900. It will skip in the middle of one track to the next, it will even skip entire tracks. A few seconds prior one can hear its drive working hard to maintain the reading process. I guess the DM-5090 is starting to break down because the MZ-R 30 doesn´t have any problems whatsoever with these discs. Another thing: the headphone shares its output with the line out so you have to configure which one to use in the menu of the recorder. This wouldn´t be so unnerving if the recorder would actually remember this setting - the moment you change a disc or remove power it has "forgotten" everything. From what I´ve read the successor to the MZ-R 900 (MZ-R 901) rectifies this - a wise decision, Sony!

Sony MZ-R 900 in/ outputs

The MZ-R 900 is equipped with an ATRAC 4.5 IC, an improved version of the ATRAC encoder compared to the one built into my MZ-R 30. Through higher computational accuracy Sony managed to improve distortions by roughly 3 dB while also including a feature called "Adaptive High Band Control". The latter would ideally be responsible for an extended frequency response into higher frequencies. Just like the MZ-R 30 it also has a combined A/D/D/A converter, again from Asahi Kasei. This time it´s an AK4562, according to its manufacturer capable of recording and playback of 20 Bit signals. You shouldn´t hold up your hopes too much though: the tiny MD recorder and its converter IC are manufactured with portable use in mind and Asahi Kasei rates the D/A-part of the converter having an S/R of only -93 dB. This is not even barely good enough for pure 16 Bit performance with the result that I won´t expect too much from this unit when it comes to measurments.

Sony MZ-R 900 measurments (used as a D/A converter only through its analogue output)

ATRAC 4.5 measurments with the Kenwood DM-5090 (only through its optical output)

The measurments through its analogue output reveal nothing interesting for it behaves similar to many of my vintage portable CD players. But the chart above also reveals - just as I expected - that the D/A-converter isn´t really 20 Bit, it performs at 16 Bit at best (if I ignore the missing 3.8 dB). I have to add a little explanation: its true resolution probably reaches 20 Bits - useless though when it´s swallowed by noise resulting in a far less impressive usable resolution. For the ATRAC chart I used a testsignal recording digitally made with the MZ-R 900 that was subsequently played back by the Kenwood (it´s the only MD recorder I own that sports a digital output. Its digital signal was recorded using my Creatives' optical input. THD + Noise indeed have improved for 2 dB, IMD + Noise are better as well while the Noise level is 1 dB higher. Well done Sony... (small) step by (small) step you managed to improve the codec all those years ago (irony intended). Now I just need an ATRAC 4.5 Typ-R (according to tests it´s much better) capable MD recorder and everything will be perfect. As I mentionend during my last review I had a hard time hearing differences between the original and the ATRAC encoded version - but since then I encountered some forum posts stating that there are indeed signals able to "trip" the ATRAC ICs. I might perform some tests with these signals myself in case I should be able to purchase a unit equipped with 4.5 Typ-R.

Sony MZ-R 900 detail

The MZ-R 900 sounds very well indeed. True to the title of this review it shows explosive dynamics which on occasion tend to get too harsh and forwarding, sometimes they feel contrived and aggressive. In general it prefers high frequencies instead of presenting a completely balanced soundscape while base and mids are slightly underrepresented. This leads to a sound that can be described as euphonically charming, not the truth but tasty nonetheless. Because of its well articulated treble it presents details with analytical precision; even then the highest frequencies are diminished leading to a sound that´s drier and edgier than my references. I believe all of this to be caused by its mediocre jitter peformance; high frequency jitter brightens up the sound, low frequency jitter muddies lower frequencies. To me both results are evident here. The staging is another thing: it´s not as wide and layered as it should be, dimensions are reduced a bit. Performers mixed to the center for example tend to be too distant, on the other hand everything else surrounding these performers is encapsulated in its own 'stage bubble', including reverberation. The virtual room doesn´t sound like the original, members of an orchestra seem to change their places, reverb tails don´t seem to be as long as they are on the reference. In short: it replaces the original Ambiance with its own, highly characteristic one. Timing is another thing... while high frequency agility is excellent, mids and bass are slightly slower and miss punch and snap. All of this combined creates a dynamically powerful, slightly edgy yet charming sounding machine. It certainly is superior than other MD recorders, even superior than many of my portable CD players.
One word about its headphone output: usually I don´t talk about these, in this case I´ll make an exception because it sounds so well. The sound coming out of the MZ-R 900 when the FiiO amplifies my Sennheiser HD-448 does not change from the sound of its own amplifier. I´d use it all the time... if it wouldn´t be so weak. It simply isn´t strong enough to yield enough gain with my 32 Ohms HD-448 - a shame really.

Sonic Balance:
Stage / Ambiance:

Sony MZ-R 900 side
Sony MZ-R 900 with one of those famed white ES MiniDiscs

Concluding my review I´d like to say that I have mixed feelings about this little recorder. The finishing quality is wonderful but it´s too small for the purpose of residing on my desktop. Yeah, I´m stupid here, I know. I´m well aware that it is a portable MD recorder and that its size makes it very convenient to carry it around. But for that purpose its headphone output isn´t strong enough to power low impedance headphones convincingly. And while the sound oozes charme and explosive dynamics it can be too edgy and aggressive at times. I think that I will indeed search for a third machine to buy, maybe one that also is NetMD equipped, I don´t know. Stay tuned!

Sony MZ-R 900
Last update: 24.07.2012

Thursday, June 21, 2012

Blast from the Past: MiniDisc, Wide Bit Stream and 20 Bit

I cannot really tell you, dear reader, why I´m so interested in ancient digital technology. I suspect several reasons but none of them seems clear enough for me. But I know that it seems to be interesting enough for others too - otherwise I couldn´t explain the 3000 monthly pageviews I still find surprising given those geeky topics I usually write about. Today I will not only write about a nerdy subject but also about an example of now ancient technology that quickly became technically obsolete: the MiniDisc. Some months ago I reviewed several portable CD players I had acquired; in that same article I mentionend in passing my first MiniDisc recorder bought in 1996, the Sony MZ-R 30. I also published several measurments I made with this unit and talked about some of the technical features enabling the MiniDisc to function. Ever since that article I had the nagging feeling that I needed to elaborate a bit more on the technical aspects of that system as well as writing about its sound in detail. Well, here it goes.

MiniDisc logotype (copyright: Sony)

The MiniDisc was introduced to the market in 1992, at a time when sales CDs reached an alltime high and the Cassette Tape approached its final evolution with the introduction of Dolby S. By then it already was apparent that the Tape was going to be replaced by CD technology, just the same as Vinyl was. Additionally, Sony and Philips had already developed and standardized the CD-R format in 1989. Back then however the technology needed for CD-R (lasers and media) was alarmingly expensive & still in its infancy so both companies developed something else supposed to be equally capable of digital recording but much less costly. Philips decided on the ill-fated DCC format while Sony decided to use something more cutting edge: MO-discs. They also determined the new format to be much smaller than anything else released before; in order to achieve that they had to use a lossy compression scheme. The result was an MO-disc shrinked to one fifth of its former size combined with a newly developed lossy compression called ATRAC, all of it encapsulated inside a nifty package looking like a tiny floppy disc. This new format appropriately named MiniDisc was - just like DCC - released in 1992 in form of the portable recorder MZ-1. From the minute they presented it I was fascinated by it because it offered some traits completely new to the audio world. Beside being able to record something digitally the MiniDisc was highly portable (remember: we are talking about a time when flash memory was still in its infancy and had yet to be released). But it was the possibility to edit its content to your liking that catapulted the system into the limelight: a user was able to move around or to erase a particular track or several tracks, one could also divide or combine these tracks. In short the perfect personal "Best-of" was now possible - all in flawless digital quality with then unknown portability. Or so Sony thought.

Sony MZ-R 30: have a look at the "Erase" and "Track Mark" buttons - a first back then

Since Philips was going to unleash its DCC system in 1992 Sony had to follow suit in order not to loose marketshare. The engineers of the first MD recorder however knew that they would need at least another year to perfect the compression scheme ATRAC. Have you ever heard the first mp3-encoder from the Fraunhofer Institute? I´m old enough to remember that I did; it sounded just awful. I encoded some track from an Enya album with 128 kBit/s and after decoding it back to .wav I noticed a strange pumping effect and distortions like flanging and pre-echos. Clearly, mp3 wasn´t ready to be used - and the same happened three years prior when the MZ-1 was released. Early tests noticed some strange artifacts sounding like crackling fire on top of sounds in combination with a generally metallic and dull sound; the first version of ATRAC just wasn´t ready for public release. The biggest leap in quality was supposedly achieved with ATRAC 2 one year later: much less metallic, frequency cutoff extended to 18 kHz (before: 15 kHz) and less audible crackling noise. ATRAC 3 from 1995 came close to DAT in a DBT, the crackling noise had almost disappeared. But only ATRAC 3.5, released first in August 1995 with the home component MDS-JA 3 ES would be virtually indistinguishable from CD without metallic sound, noise or anything else. This story serves to illuminate the course of technical improvement being quite visible to the general public. Especially people in Europe were very critical of the new system: the MZ-1 was very expensive, MiniDiscs were equally expensive and all of it sounded just awful. Additionally Sony made an incredibly stupid marketing error: Instead of concentrating on the systems' recording ability they advertised it with pre-recorded MiniDiscs, leading many people to believe that the MD was the CDs successor. Back then people hadn´t yet accepted lossy quality and so they stayed with Tapes a bit longer. In Japan however the MiniDisc was successful from Day One.

Sony MZ-R 30, using the Wide Bit Stream capable ATRAC 4

But all of that changed with the MDS-JA 3 ES. The major reason for improved quality was the decision to switch to quasi-floating point operation within the ATRAC encoder/decoder circuit. Sadly it is an almost publicly unknown fact that virtually every lossy compression scheme (mp3, AAC, OGG) internally works with floating point arithmetic. Integer processing isn´t suited that well for audio since it only can support a limited range of values whereas floating point can represent an almost unlimited amout. The first three ATRAC IC designs processed by using integer values only, limiting their range. When Sony got rid of this restriction ATRAC was ready to work with improved quality, subsequently becoming able of capturing high resolution material. Using their patented "Block Floating Operation" the MiniDisc now was ready to process and store information with higher resolution than CDs 16 Bit. And instead of reducing the bit depth to 16 Bit again during en/decoding Sony just used 20 bit capable A/D-D/A converters in order to make sure that the improved processing depth would be preserved. Meaning: the MDS-JA 3 ES was the first truly 20 bit capable consumer recording device. In 1995 this was a small revolution - not one recorder had been capable of delivering a resolution that high up until that point. Sony therefore took the wise step by advertising it as such while making sure that every internal processing step matched this 20 bit capability, calling the entire process "Wide Bit Stream". On home consumer devices a resolution this high makes perfect sense, it´s an entirely different situation with portable recorders however. Even if a recorder like my MZ-R 30 would work within this bit depth it would be pointless; its combined A/D-D/A converter Asahi Kasei 4515 is a true 16 Bit converter, rendering the internal processing power useless as a result. Likewise, digital 20 Bit sources weren´t existing back then so this impressive processing precision effectively only made sure that CDs were encoded without flaw.

But since the day I first read about it I have been interested in finding out if Sony spoke the truth. Could a lossy device like the MD be capable of delivering higher-than-CD resolution? All those years ago I couldn´t do revealing tests myself only because I lacked the equipment for it. But hey, we now have 2012 and I own the Creative Sound Blaster X-Fi HD USB! As you know it features optical in/outputs delivering true, bit matched 24 Bit signals. My boyfriend also owns a Kenwood DM-5090 (1997) which I suspected to be Wide Bit Stream capable. BTW, despite being advertised featuring an ATRAC 4.5 IC the Kenwood only uses the same ATRAC 4.0 IC from my MZ-R 30. For measuring pure ATRAC performance I devised a  test routine that would protect the digital signal integrity at every step during my procedure without any analogue intersteps. I created an RMAA generated test signal with 24/44.1 and did the following:

SB X-Fi HD ---> Sony MZ-R 30 (recording) ---> Kenwood DM-5090 (playback) ---> SB X-Fi HD

Recording was done digitally using the MZ-R 30

Playback was done digitally with the ATRAC 4.0 equipped Kenwood DM-5090

The results were surprising to say the least. My old MZ-R 30 turned out to be a true Wide Bit Stream capable recorder - only when using digital connections of course. Just imagine you now would find out that a recorder you´ve known for 16 years has been capable of capturing high resolution all the time. For Christ's sake, this thing is from 1996, a time when not even recording studios were using 20 Bit regularly! The Kenwood DM-5090 was equally surprising since its digital output delivers a true 20 Bit signal. A) for a consumer device it would make much more sense to transmit with 16 Bits only and B) my resulting files were actually 20 Bits inside a 24 Bit .wav file (as indicated by the Bit-meter in WaveLab). Look at the results:

Entirely digitally transmitted 16 Bit test signal yields 16 Bit performance using ATRAC

A 24 Bit test signal yields 20 Bit performance thanks to WideBitStream

For comparison: mp3 320 kBit/s CBR (Lame 3.98.4) with 20 Bit output

Sony told the truth indeed: even a small portable MD recorder is capable of recording true 20 Bit quality (Dynamic Range would need to be roughly 10 dB better though). The 16 Bit signal results in 16 Bit quality while the 24 Bit signal yields 20 Bit quality. It would be interesting to measure the output of an ATRAC 4.5 equipped device since that particular ATRAC version was the first to use full 24 Bit processing. Furthermore you now can see how mp3 behaves when it´s properly decoded, allowing it to deliver the full resolution of its internal 32 Bit floating point data (for fairness decreased to 20 Bit in the example above). The mp3 measurment also serves as an example how much lossy codecs have improved during the last 16 years. Granted, results are a bit unfair since ATRAC uses 292 kBit/s whereas the mp3 test signal above was encoded with 320 kBit/s. The most important measurment for all three examples is Total Harmonic Distortion plus Noise (THD + Noise), ATRAC measures 8 dB worse than mp3 which might lead to more audible compression artifacts. But considering its age, its limited processing power and implementation ATRAC fares impressively well. Of course, with every lossy compression scheme only the output with real music counts so measurments might not reveal any sonic shortcomings. For that I not only recorded test signals; I also copied several music examples the same way as described above to find out if ATRAC sounds different to the originals. To determine if there was an audible change was indeed quite difficult, proof to how well Sony designed the whole process. It could very well be a placebo effect but I was under the impression that ATRAC widens & deepens the stage impression very slightly leaving tiny "holes" and a not so stable stage. It also seemed to sound either too harsh or too mellow depending on the material - but keep in mind that the perceived effects were so slight that I´m not sure I´ve even heard them. Impressive, don´t you think?

Sony MZ-R 30

But how does the MZ-R 30 sound? I´ve already talked about this before - but I didn´t rate its sonic quality with my new rating system. The sound of the MZ-R 30 is fairly balanced, blowing up upper bass while missing high frequency detail. Despite this it displays slight loudness-switch characteristics, emphasizing bass and treble frequencies around 10 kHz, efffectively draining sonic colour. Dynamics seem to be held back with the result that the MZ-R 30 always sounds "nice"; bass is soft and misses punch, transients in general are too soft. Staging is fragmented yet flatter and convoluted, guessing size and position of instruments is becoming difficult for the listener. It´s like hearing a fuzzy bubble without much depth and width. What suffers most however is resolution; details are rendered far to casual, more often than not high frequency detail turns into simple noise. High frequency intelligibility really isn´t very well rendered on this device, yielding a voluptuous and too warm sound. Don´t get me wrong, it sounds moderately well, definitely better than 40% of my portable players. Without colouring the sound too much it presents music very pleasant, you can therefore listen with it for extended periods without suffering from listening fatigue. Its headphone output on the other hand - although powerful enough - sucks big time. Using it one looses much crispness, it sounds surprisingly dull.

Sonic Balance:
Stage / Ambiance:

A personal Note

Of course it´s pointless to use such an ancient device in present times. Recent portable players can be filled with music in a matter of seconds, offer theoretically improved sound quality (using lossless FLAC and improved technology) and are much smaller in size while offering reasonable running times. With musical gadgets convenience always is key while quality plays a secondary role. Therefore technological obsolescence plays a major role in the death of the MiniDisc. 
But there are other reasons as well... up above I´ve talked about CD-R - since they were so expensive Sony estimated it would take a long time for them to become affordable. They were wrong: recordable CDs became cheaper than MDs in 2000/2001, rendering the MiniDisc an inconvenient and slow recording device with a compromising quality approach. The mighty giant Sony reacted with altering the MD format by introducing an advanced version of ATRAC called ATRAC3 (not to be confused with ATRAC 3) which allowed longer recording times by lowering the datarate (64 kBit/s & 132 kBit/s). Needless to say that such recordings were incompatible with older MD devices. 
Around the same time a second problem arose: portable mp3 players. Sony tried to counter these developments with another new feature released in 2002 called NetMD where you could - using your PC - upload your music to a recorder equipped as such via a built-in USB link. Of course, you had to use the proprietary ATRAC compression scheme, meaning that you had to re-encode your collection of mp3-files, lowering the quality even further (lossy re-encoded to lossy). For all consumers it was as clear as day that this was highly inconvenient and extremely impractical - but Sony found nothing by it. Subsequently many consumers parted with Sony and the MiniDisc. 

Kenwood DM-5090 - an MD recorder from the systems' heydays - and not even from Sony

The last nail into the coffin of MiniDisc however was the release of the iPod in 2001 and its subsequent success. Again Sony completely misinterpreted unfolding developments and tried to revive the almost deceased MiniDisc corpse by improving the recording quality. They introduced the Hi-MD in 2004 - for the first time in its life the MiniDisc was able to record and playback music in true lossless 16/44.1 quality, all of that combined with NetMD "comfort". Yes, they dropped the Wide Bit Stream feature entirely. It´s ironic: to infuse the system with new life they not only sacrificed something that made the MiniDisc unique (admittedly: many people didn´t care) but also compromised backwards compatibility. Sony subsequently lost its "coolness", the MiniDisc was just one of many decisions made in the first years of the new millenium that stank of stupidity. The once shining company that produced legendary components now is just a mere shadow of its former self, making more profit with finances (!). Remember: Sony is at heart a manufacturer of electronics and not a bank. Today Apple is hip while Samsung is market leader, both traits were personified by one company just ten years ago: Sony.

Sony may die a slow death - but thankfully their components are still around and obviously built to last for quite some time. I for one have decided to go back to the MiniDisc system for now, even though production has ceased in 2011 and I myself abandoned it in 2001. Why am I so stupid and unreasonable? I don´t really know... but the first time I touched the Sony MZ-R 30 I knew that I was in love. This never happened when I received my Sansa Clip+, it was just another device playing music. Furthermore I never trusted mp3 - without a logical reason really. By now lossy codecs have reached a mindboggling quality, with higher data rates they in fact are transparent. Still, to me mp3 always sounded a bit dull and compact. I know, I know... completely stupid and very likely a placebo. But I can´t help myself, I always perceived the MiniDisc to sound better. It also looks and feels very nice, it has a haptic mp3 cannot reach since it´s immaterial. Some weeks ago I read an essay in the German news magazine Der Spiegel called "You cannot love files". This article described how soulless downloaded music appears to many customers´and it argued that today you can buy music in a second and have it on your portable player the next. But you cannot hold it in your hand (like a CD , MD or even Vinyl), leading to a feeling of being disconnected from it. You don´t have to occupy yourself with it anymore, it´s just data confined within impersonal files. I´ve always wondered why I "remaster" every CD I buy (which are many), maybe it´s because I want to "connect" with it before it ends up in pristine quality on my HDD where it´ll only be a collection of files. My recent interest in vintage portable players or the MiniDisc forces me to do the same, I have to bother myself with the music, I have to spend time with it. In any case I have not understood the reasons for this yet, I´m just starting. Maybe it´s much simpler and I´m starting to get old. Equally possible but you know what? I don´t care because I want to enjoy music in very good sound - and the MiniDisc allows me to do that despite (or because?) its shortcomings.

Saturday, June 02, 2012

Review: FiiO E6

EDIT 16.01.2013: I´ve received a FiiO E07K a few days ago and the experience I made with it prompted me to alter this article. I´ve therefore updated / changed it considerably.

I bought the FiiO E6 in November 2011 and since then this tiny, little headphone amp has made me extremely happy. I´ve always loved its pleasant sound. Some weeks ago I started to think about this and asked myself: "Why do I like its pleasant sound so much? Should it really be this pleasant? Is it really neutral?" Should you be a faithful follower of my blog you already know that I´ve been using it for almost every review I´ve written for this blog, I´ve used it for my portable CD players, I´ve used it for my Sansa Clip+, I´ve used it at home, I´ve used it when I was outside, I´ve occasionally even used it with my ASUS Xonar Essence ST. The FiiO was the only thing during those months that was able to make me truly happy without showing any flaws whatsoever. And that´s where I have been wrong because it sadly colours the sound, neutrality really isn´t an advantage it has. My original conclusion to this article was:
"By now it should be clear to you, dear reader, that you won´t necessarily need an ultra-expensive headphone amp in order to experience sonic bliss, the FiiO E6 will do just nicely with headphones ranging from 32 to 150 Ohms. You shouldn´t trust someone who describes the FiiO being inferior to other amps because of its low price. I cannot imply you to buy it, you have to make that decision yourself. Will you like the additional little box attached via another cable to your portable player? I myself don´t mind but what about you? I´m afraid you have to find that out on your own. You might be in for a sonic surprise, a surprise you maybe won´t like: bass you were expecting from your iPod may now be absent just because the problem of mismatching output impedances has disappeared. In my opinion however you should try it out anyway, $ 25 won´t really hurt and you might be eternally rewarded with something you´ve never experienced before with portable players: almost perfect neutrality, nice design and more gain than ever before."
To reach this conclusion I´ve beforehand spent precious time on explaining what a headphone amp is, gave examples why you won´t need a costly headphone amp, why the FiiO E6 would also work for a headphone as expensive as for example the Beyerdynamic T50P... blablabla. But everything changed with the arrival of the FiiO E07K: To review that headphone amp / USB DAC I wanted to find out how it would behave against a reference, something that appeared to be impossible for me before. When I wrote the original review for the E6 I couldn´t think of a method to reliably compare it to an ideal reference and I´ve always hated that I seemed unable to find out how it really sounds, if it colours the sound, if it introduces errors... when all of it could have been so easy.

FiiO E6

This feeling of being unsure about my rating for the E6 and the aforementionend original conclusion has been nagging me since publishing this article in June 2012. But now I´ve found a way to come close to an objective-as-possible review. My E-MU 0202 USB broke down during the last days of December 2012 which has robbed me of my basic ingredient for my testing methodology. It not only forced me to devise a new method for comparing units like portable CD players to my reference files, it also prompted me to alter my testing chain for such an occasion so that I could finally perform listening tests with headphone amps. The solution for latter cases was the Creative Soundblaster X-Fi HD USB: by recording its lovely output with my ASUS Xonar Essence ST I would create a new reference against which the FiiOs would have to be compared. Therefore my usual reference files for the FiiOs wouldn't be the sources for the testing material themselves, instead I´d use the playback from the X-Fi HD recorded with the Essence ST. After that I would insert one of the FiiOs into the signal chain between the Creative and the ASUS to record the same material again. Have a look:


Creative Soundblaster X-Fi HD USB -> ASUS Xonar Essence ST = Reference files

Compared to:

Creative Soundblaster X-Fi HD USB -> FiiO E6/E07K -> ASUS Xonar Essence ST = FiiO results

Having done both steps I now would be able to compare the results from the FiiOs to my reference files. The sonic characteristic of the X-Fi HD USB embedded in the reference files would ideally be completely retained by the FiiOs and in case they´d colour the signal it would be incorporated as well. There are some obstacles which again might colour the results: the line-in of my Essence ST is electrically not comparable to a headphone which is what the FiiOs were designed for in the first place. From what I´ve read a line-in is a much easier load for a headphone amp than a headphone with an impedance of for example just 15 Ohms. Which means that when one of the FiiOs is driving the line-in of the Essence ST it could theoretically be 'easier' to 'hide' possible colourizations. But I nevertheless think that this method enables me to reliably spot differences compared to unplugging/plugging headphones from one amp to the next. To do it this way also made it feasible to create crude measurments; I wanted to see how these would compare to the professional measurments NwAvGuy did for his wonderful article about the FiiO E6.

FiiO E6 from below
To shorten this article I´ve partly removed the long & boring explanations about headphone impedances, gain and possible advantages of having an extremely low output impedance. Some of those sections can now be found in the article about the FiiO E07K; albeit shortened much. Reason: there are much better articles to be found anywhere else, much better than I could ever write them. Just a few words about the features the FiiO E6 offers: its high input impedance gets rid of every impedance mismatch error a headphone amp can possibly produce. It sports an output impedance of just 0.25 Ohms (according to NwAvGuy´s measurment) which should be perfect for any headphone and certainly doesn´t pose any problem for my Sennheiser HD-448 or my Superlux HD-668, even though these aren´t very susceptible to high output impdances anyway. I bought the E6 to rid myself of any possible impedance problem I could ever encounter with portable players. For example: most of the headphone amps inside my portable CD players or MiniDisc recorders have a fairly high output impedance and other obstacles not advantageous for good sound. Then there is the amp inside my X-Fi HD USB which supposedly has an output impdance of 36 Ohms and the one built onto the Xonar Essence mainboard (11 Ohms) - both are not suited for difficult IEMs. Connected to their headphone outputs the FiiO E6 simply renders this problem moot. But this tiny headphone amp can also be used with line-outs from stationary sources, for this purpose it is equipped with a special low-gain setting (2 Volt mode). However, you might run into problems should you be using it with one of those louder-than-usual sources I described in this article: instead of the quasi standard 2.0 V (which the FiiO adheres to) they sometimes output with 2.2 or 2.5 V, supposedly leading to severe input distortions when used with the FiiO. But now off to my own measurments and audio rating, yes?

FiiO E6, 1 Volt Mode (High Gain)
FiiO E6, 2 Volt Mode (Low Gain)

FiiO E6, Total Harmonic Distortions, 1 Volt Mode (High Gain)
FiiO E6, Total Harmonic Distortions, 2 Volt Mode (Low Gain)
FiiO E6, Intermodulation Distortion, 1 Volt Mode (High Gain)
FiiO E6, Intermodulation Distortion, 2 Volt Mode (Low Gain)
Click on one of those pictures and scroll trough them using your mousewheel, you´ll find that differences between them are not that big. In low gain mode the FiiO does have less high frequency distortions but I really don´t know if they´re audible or not. But low frequency distortions seem pretty strong to my layman eye, these could be responsible for its pleasant sound by adding something that doesn´t belong there. Everything else looks fine though, especially when you consider how small this amplifier is and that it is selfpowered - there must fit a battery somewhere into the small case. What I couldn´t find however was the overload problem NwAvGuy described in his article about the E6... strange. Well, I have to consider the possibility that my X-Fi HD USB simply isn´t loud enough on its line-out (I have to change the volume by +2.5 dB after recording anything that has been played back by it if I want to have 0 dBfs) to distort the input of the FiiO. It´s also possible that his unit behaved a bit different, who knows.

FiiO E6 power/EQ/voltage mode button
At this section you formerly could find sentences like "...seems to warm up the sound ever so slightly (...) sometimes it sounds a tad boring...". Being now able to compare the FiiO to my reference files good and proper I have to say that those sentences have been the understatement of the century because the biggest problem of the FiiO E6 are dynamics. It removes much of the impact transients have, bass punches disappear into nowhere and high frequency attacks loose their bite. This is very evident when the FiiO-derived results are compared to my reference tracks from The Girl with the Dragon Tattoo or Episode II soundtracks; both show an extreme amount of very high frequency attack diminished quite a bit by the E6. Deep bass impact is decreased as well, all of this reduces the impression of dynamics, snap and punch. Madonna's track "Skin" sounds mellower than usual, its timing is noticeably slower when amplified by the FiiO. Well, at least speed is reduced consistently throughout the whole frequency band. People call this lack of dynamics a 'laid back' sound, I call it wrong. Resolution and definition are other areas where this amp fails: cymbal hits by an orchestra are close to being reduced to simple noise, the characteristic noise of a bow striking the strings of a violin quite audible on the reference tracks sounds unintelligable through the FiiO. Rendering the depth of a virtual stage correctly is equally problematic because it flattens the stage considerably, the impression of a holographic recording disappears. On the other hand, sonic balance and character of a recording are retained decently. While deep bass and highest frequencies are diminished, this isn´t very noticeable because it is compensated by adding a small amount of upper bass even though this also thickens up frequency areas that shouldn´t be thickened up. This is very audible on the organ recording I always use (Vierne, Michael Murray)... in fact, the organ almost sounds as if having distortions (there are none of course on my reference files). I´m very sorry but here are my reconsidered ratings for the FiiO E6:

Sonic Balance:
Stage / Ambiance:

FiiO E6: black beauty
As it turned out in the end people deriding the FiiO for sounding boring were right - but I wouldn´t see it. Maybe because I didn´t want to or because I lacked a convincing method for comparing it. I´m not ashamed to rectify this error but have you noticed how many of my articles have been rewritten recently? First the one about the X-Fi HD USB, then the Sansa Clip+ and now this one. And then the articles about USB cables which in hindsight feel like a hoax... I really have to be more careful in the future when reviewing some audio gadgets. I have to measure what I can measure and I have to get rid of any error that could possibly happen. And I have to find and maintain valid methods for objective comparing before I´m writing a review. Anyway, sonic signature of the FiiO E6 is not as disadvantageous as it sounds because it can be used to create exemplary synergy effects with audio players or headphones. Take my Sansa Clip+ for example: combine it with this FiiO to achieve much more gain and you´d have a balanced sound you wouldn´t expect when listening to the Clip+ alone. The explosive dynamics of the Clip+ are a perfect fit for the mellow sound of the E6, its sonic disadvantages will compensate the ones from the FiiO. During the last days I´ve tried this combination and it indeeds sounds very well. Besides: both of them are tiny and don´t cost much. On the other hand, a combination of the FiiO E6 and the Sony NW-A 1000 has to be avoided; you´d drown in mellowness and boredom. This little amp would also be a good choice for overly dynamic or 'sounded' headphones (from Beyerdynamic for example). The FiiO doesn´t fit the signature of my Sennheiser HD-448 - but the opposite happens with my Superlux HD-668B. In the end it all comes down to your preferences: if you like a dynamic, very crisp and bassy sound signature you´ll have to shun it. But if you know what you are doing and if you plan to compensate for an aggressive sound signature the FiiO E6 will be perfect for you.

Last update: 16.01.2013
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