Sunday, September 29, 2013

Review: Sony D-E555 (1999)

Sony D-E555
This review is part of a larger comparison containing seven eight vintage portable CD players and the penultimate of these reviews. You can find the final conclusion here.


The Sony D-E555 was released one year (or a few months; were not able to find out the correct date) after the D-E705 and it happens to be very similar in every way. The only major, immediately visible difference is the design. IMO the design of the follow-up model isn´t exactly an improvement... though I like the blue colour (it also came in silver). Since it´s so similar to the D-E705 I won´t need to write too much about it. On the other hand, that circumstance leaves enough space that is going to be used for photographs instead. Yay!

Sony D-E555: rear view
You can see on the picture above that manufacturing quality isn´t the best. It´s OK though and - I´ve mentioned it - does not differ from the D-E705. It even came with the same accessories (cabled remote control with included display, battery pack, headphone)... blegh, it´s no use, this Discman is so similar to the D-E705 that I´ll concentrate on the (botched) design with the help of the aforementionend photos.

Sony D-E555: side view
Regarding the innards of the D-E555, please have a look at the D-E705, they are the same... well, almost. Instead of the ROHM BA3574BFS that serves as the headphone amp on the older model, the D-E555 uses the TA2120FN from Toshiba. So all important parts are now Toshiba. Funny for a Sony, isn´t it? Another thing that differs is the placement of the ICs responsible for the ESP. On the D-E705 they are soldered onto a seperate mini-PCB, hovering above the main-PCB. On the D-E555 these ICs have been incorporated on the main-PCB instead. But that´s all, at least to my layman eyes. So... time for a photograph again!

Sony D-E555: detail
Listening test

Headphone out

I hate to repeat myself... but don´t use the headphone output. Look further below at the measurements: the new headphone amp isn´t able to save the day. It´s still missing bass, this player will sound as thin as its predecessor. But we still have the...

Line out

... which won´t sound any different to the D-E705. Believe me, I´ve tried. I compared the sound produced by the D-E555 to my references, and, because I was so desperate for wanting to hear differences, to the files including the sound signature of the D-E705. But to no avail; the D-E705 and the D-E555 sound alike. Sometimes I was under the impression that the D-E555 sounds even warmer than the former model but that impression vanished the next second with different material. Just like the D-E705, the D-E555 sounds slightly muffled, yet it keeps differentiation. Holographic impression of the stage is still impaired by reverb that seems to be de-attached from the rest, singers still appear to sing closer to you. Shall I go on? Wait, I suggest something revolutionary new: why don´t you read the review of the D-E705 again? Oh, you did? Crap, I´m starting to repeat myself... not surprising when reviewing this Discman here.

Sonic Balance:
Stage / Ambiance:

Sony D-E555: from above
Fancy graphs (measurements)


Sony D-E555, RMAAs own quality assessments
Shall I go on and bore you with the same measurement graphs you´ve already seen on the Sony D-E705? I think not. Ah, wait... maybe jitter, impulse responses?

Sony D-E555, jitter
Sony D-E555, impulse response
Hm, fascinating: jitter is indeed different, just a bit. The thin spread I talked about in the review of the D-E705 has disappeared, instead the spread at the base of the sine got louder. Is this audible? I have no idea... but I don´t think so. The impulse response is the same and still atypical for Sony devices.

Headphone out

Sony D-E555, frequency response with headphones, several impedances
Sony D-E555, total harmonic distortions + noise with headphones, several impedances
Sony D-E555, intermodulation distortions with headphones, several impedances
As you can see, compared to the former model, distortions have been reduced. On this model, it´s also valid to say that headphones with higher impedances will perform better. Deep bass is still missing however, so prepare yourself for a tinny sound signature through the headphone output. Not as bad as the D-E705, but still miles away from useable. Since there´s nothing else to report... you know what this means, yes? Correct, another photo!!

Sony D-E555: detail
Last update: 29.09.2013

Wednesday, September 18, 2013

Review: Sony D-E705 (1998)

Sony D-E705
This review is part of a larger comparison containing seven eight vintage portable CD players and the penultimate of these reviews. You can find the final conclusion here.


Back in 1998, when the D-E705 was released, Sony was on top of the game. It outperformed the competition by being smart, innovative and - most important - cool. Only four years later Sony would be a company heading with lightspeed for its own retirement home. Thanks to constant pressure from Sony Music they imposed paranoid restrictions upon their hardware, forbidding this and that. In short, they took the fun out of handling their products; instead of channeling the creative power Sony was known for, they turned into a frightened, too careful and greedy company. During the '80s and '90s there was an expression typically connected to them: 'innovation locomotive'. Instead of following the market, they were leading it. Now, in 2013, Sony is only a pale shadow of this former glory. Samsung rules the home electronics market (along with TVs, smartphones, etc.) while Apple rules in coolness - they are the locomotives now and Sony only follows without much success.

Sony D-E705: German Sony catalogue excerpt (copyright: Sony)
Well, all of this might be over soon. Apple has already started to show signs of ageing by releasing a really stupid smartphone (iPhone 5c). Sony now is small (and desperate) enough to be innovative again: they´ve just released a line of smart high-resolution capable devices, including a small portable player able to play 24/192 files. Especially the latter is an interesting fact; while the market for those portable HiRes devices is small, this might be a signal that innovation is back. After all, Sony is the first 'big' electronics manufacturer branching out into a market previously occupied by boutique manufacturers like FiiO and iRiver. But hey, it´s too soon to talk about the return of all the glory. So let´s concentrate on the past again, on the Sony D-E705 for example.

Sony D-E705: headphone out, volume control, line / optical out and wallcharger input
Released in 1998, it should in principle bear the moniker 'CD Walkman', yet it instead is still called 'Discman' (reason: my unit is european, the CD Walkman moniker was first introduced in Japan). Inside, it´s pretty similar to the Sony D-E700, D-E800 & the D-E805. All share for example the D/A-converter which is an energy conserving Toshiba TC9438FNEL, a 1-bit converter complete with oversampling and analogue filtering. Perfectly suited for portable devices. Headphones are amplified with the ROHM BA3574BFS, which also seems responsible for the line-out via several additional parts. The Electronic Shock Protection is controlled by the NPC SM5902; in order to save on RAM the D-E705 employs lossy compression for the shock protection, in this case ADPCM as revealed in the datasheet of this IC. It´s important to know this because it means that using the ESP one will encounter possible sound degradation.

Sony D-E705: front and lid
Manufacturing quality of the D-E705 is OK but nothing to write home about. Everything fits nicely and while the used plastic doesn´t feel too solid it also doesn´t feel too flimsy. At least the lid doesn´t creak when opened or closed. The whole unit is small and lightweight, making it ideally suited for portable use. The models higher in line (D-E805) featured a slightly different design and an aluminum lid... they were more expensive of course. When it comes to reliability the D-E705 reads every disc I throw at it... unlike the Sony D-465 which tends to have problems with certain CD-Rs. Curious when one considers that both share basically the same laser unit (DAX 11-C/D). The D-E705 was reviewed by German audio magazine AUDIO in 1998 (see image below); they rated build quality as excellent. IMO an exaggeration. When it comes to the sound quality they decorated it with 70 points (100 points are their maximum), a rating only bestowed onto one other portable CD-only player, the Technics SL-XP 700. Since features were rated as being equally high it received their 'Best Buy'. Let´s find out if that´s a distinction well earned, shall we?

Sony D-E705: 1998 review in German AUDIO magazine (copyright: AUDIO)
Yeah, let´s start with features: the display isn´t illuminated. For me, this is a big minus point since a) it doesn´t look as nice and b) it´s inconvenient in the dark. On the other hand, the D-E705 came with a display attached to the cabled remote... which on the other hand used the stupid mini-connector typical for Sony. If you wanted another set of cans AND still wanted to use the remote it was imperative to look for Sony headphones. Blegh! Yet it came with a set of rechargable NiMH batteries and an optical output for digital recordings. I´ve alread talked about build quality so I´ll go right ahead to its sound.

Listening test

Headphone out

Here I go again: don´t use the headphone output. Several people have called this player 'thin' and it´s the truth for the headphone out. Using it you´ll lose deep bass & gain distortions (look at the measurements below). Useless and a disappointment. Thankfully, we still have the

Line out

Only the line-out will reveal its true sound signature. The D-E705 is in fact the first one of the compared players showing a partly convincing character differing to the one from my reference files. Meaning: with this PCDP you won´t listen to the original but to something having the appearance of 'emotion'. Naturally, it´s a fake, this is after all a machine, behaving to pre-set rules and conditions. The amount of treble seems reduced, crispness is partly lost. This affects resolution, especially low-level details suffer. On the other hand, differentiation is close to the reference files, I´m still able to make out details or decaying notes of cymbal crashes. This slightly warm sonic balance has an effect on the virtual stage impression too: it´s calmer and seems more stable compared to the reference files. This usually causes the stage to sound flat; not with the D-E705 however. It does the opposite and pronounces everything mixed to the center, effectively improving articulation of singers and solo instruments. I would have rewarded it more points if only reverbaration wouldn´t sound so... I don´t know... 'deattached', instead of being a part of the stage it feels pasted on. Holographic impression isn´t on par with the reference but nonetheless close. Not so close are timing, dynamics and punch: this player renders everything it plays faster than it´s supposed to be. Usually, this produces a nervous sound signature but the aforementionend warmth and calmness help to avoid this. Hence my 'special point' for Character: combining opposites into something new and tasty simply deserves praise. Just like the Technics SL-XP 505 it sounds more forward without added aggressiveness; yet it adds differentiation, speed and euphonic beauty not found on that model. Recommended if you seek a vintage portable CD player with character.

Sonic Balance:
Stage / Ambiance:

ESP (sound with Electronic Shock Protection)

You actually could use the ESP for tweaking the sound. When it´s activated the D-E705 sounds crisper and more aggressive. On occasion though this benefitial crispness turns into a piercing and shrill mess, the forwardness of material in the center now becomes too aggressive. Not recommended.

Listen for yourself!

In this section you can compare my reference files to the recorded output of the Sony D-E705. I´ve uploaded several 30-seconds excerpts (fully legal) to Soundcloud for you to compare. This an example of transparency you won´t find anywhere else; what magazine offers audio examples of the device it reviews? These examples also serve to show how close to the source itself any device sounds when level differences are eliminated. I fully expect that some of my assessments might sound arbitrary to you, that is because differences with sources are tiny in reality. But please remember that EVERY other reviewer in the world faces the same problem. When you hit 'play' the files will be streamed to you in 128 kBit/s mp3, badly encoded. Therefore, I strongly advise you to download the files, they´re in 24/96 FLAC. With these files you not only have the highest quality possible, you´re also able to have a look at the aliasing performance of the Sony D-E705 if you want.

Update 30.03.15: Soundcloud used to host the audiofile containing the compression artifacts. But just this day, Soundcloud decided to delete everything I ever uploaded because their automated content protection system detected several breaches of copyright.
Well, of course it did! For my reviews I need to listen to music and in order to make sound differences available to you, dear Reader, I uploaded several samples, each of them - at max - 30 seconds long. Naturally, this isn´t a breach of copyright, because a) I don´t have a commercial agenda nor background for this blog and b) I don´t advertise filesharers nor do I encourage to download things illegally. I don´t even want to mention, that only 30 seconds (!) of a particular song or piece are far too short to be enjoyed properly by anyone who attempts to be an illegal asshole. Yet Soundcloud fears the lables and their paranoia of copyright breaches which in turn prompts them to be paranoid and incompetent ninnies themselves.
I hate paranoia, I don´t want to have anything to do with stupid people / companies and everything was deleted anyway... so I decided to delete my Soundcloud account. Sorry for that, dear Reader.

Sony D-E705: control panel and display
Fancy graphs (measurements)


Sony D-E705, RMAA's own quality assessments
Sony D-E705, frequency response
Sony D-E705, noise floor
Sony D-E705, total harmonic distortions + noise
Sony D-E705, intermodulation distortions
The Sony D-E705 measures well. RMAA misinterprets the noise floor as being caused by the test sines (refer to the RMAA chart and the THD+Noise graph respectively), the only apparent distortions are even order distortions at 2,000 Hz. Odd order distortions at 3,000 Hz are so weak that they are negligible. Intermodulation distortions are a bit high at lower frequencies... I think though that they aren´t important. But who knows, I´m no expert, they could be one possible reason for the D-E705s characteristic sound signature.

Sony D-E705, activated ESP: total harmonic distortions + noise
Sony D-E705, activated ESP: intermodulation distortions
Sony D-E705, activated ESP: intermodulation distortions, sweep
The three pictures above make it clear that you should avoid the ESP if possible. On the RMAA graphs it comes across as a higher noisefloor. It´s true, it´s noise - but quantization noise. It isn´t random, sounds like harsh static, and it´s much more audible to our ear/brain compared to random analogue noise. I´ve already mentionend that the IC responsible for the ESP employs ADPCM compression; while the compression doesn´t seem to be too strong it´s still audible.

Sony D-E705, CCIF intermodulation distortions
Aliasing rejection doesn´t work that well, exhibited by a 900 Hz distortion that´s not supposed to be there alongside strong imaging products above 20 kHz. You shouldn´t be too afraid of the latter. I´ve yet to experience exploding loudspeakers or burning amplifiers supposedly caused by them... if you read the skeptics (very good article!) one could gain the impression that they are deadly to perfect music playback. Anyway, the jitter graphs will reveal a bit more:

Sony D-E705, jitter
Sony D-E705, ultrasonic jitter artifacts
Apart from numerous aliases of the 11,025 Hz sine, especially visible in the ultrasonic frequency band, jitter rejection works well indeed. Low frequency jitter artifacts are obscured by the noisefloor, high frequency jitter is - for the most part - absent (the aliases in the passband could pose a problem though). BUT: the thin spread of the jitter sine reaches up to -65 dB which might indicate problems. The aliasing filter of the Sony D-E705 might a) feature a less steep slope or b) isn´t that good. It could also be a completely outragous digital filter, something I´ve never seen used by Sony:

Sony D-E705, impulse response
WTF?!? I´ve never ever seen an impulse response like the one pictured above produced by a player that was manufactured by Sony! Pictured is an impulse response modeled after the first CD players (not from Sony) released to the market in 1982, showing no pre-ringing but lots of post-ringing and a severe phase error. When upsampling music I avoid these 'analogue' filter designs because they colour the sound. Why Sony employed them on a portable CD player (!) is beyond me. Philips & Grundig, yes... but Sony? C'mon, weren´t they known for perfect adherence to given rules? Apparently not. While sonic effects of impulses are overrated they still might be one of the reasons for its sound signature.

Headphone out

Sony D-E705, frequency response with headphones, several impedances
Sony D-E705, total harmonic distortions + noise with headphones, several impedances
Sony D-E705, intermodulation distortions with headphones, several impedances
Yuck... well, measurements of the headphone out are superior to the ones produced by the Grundig CDP 70 but are still far from good. The distortions can be partially avoided by setting the volume to lower levels (avoid anything above '8'). Yes, available gain will suffer... but whatever you do it´ll be pointless anyway: using the headphone output the Sony D-E705 will sound thin and bloodless because of absent low frequencies. I recommend a portable headphone amplifier like the FiiO E6 or - better - the FiiO E07K, connected only to the line-out. In fact, I wouldn´t use this player without an additional headphone amp. I admit, this makes the unit more clunky than necessary and doesn´t help portability. But ask yourself: how often do you actually use ancient portable hardware when outside?

Last update: 18.09.2013

Wednesday, September 04, 2013

Spectacular sounding MiniDisc tweaking - FOR FREE!


The following Article concerns itself with a piece of software called an Equalizer. Removing certain frequencies with this EQ enables the ATRAC codec necessary for any MiniDisc recorder to encode any piece of music in a superior way. Substantial proof will be offered by means of measurements as well as musical examples.
A warning: if you are lazy or if PC-based audio is a complete mystery to you this article isn´t for you. You also won´t be happy if you think that an equalizer is one of the devil's minions (an opinion clearly not based upon facts). Furthermore, the significant sound improvements described here require you to spend some time with your music, it means work. If you can´t afford the necessary time, you probably aren´t interested in good audio quality coming from MiniDisc at all. Or are you? ;)

Basics of lossy encoding

Lossy (or perceptual) codecs were developed for only one thing: making audio smaller without you, dear constant reader, noticing it. Using a datarate of, say, 128 kBit/s you´ll receive a file the size of only 5 megabytes (before: 50 megabytes). Every lossy codec available on the market performs this 'shrinking', it doesn´t matter if it´s ATRACMP3AACOGG or WMA. How do these codecs achieve this? They 'erase' or 'alter' parts of any musical material, getting rid off things our ear cannot perceive anyway. Erasing certain parts of any object reduces its size which is most convenient for portable players not having terabytes of available space; they can store more music that way. In the article that follows I will compare ATRAC (necessary for MiniDisc) to MP3. Both codecs are equally old (20 years), yet MP3 is still in development. ATRAC however was declared dead in 2004 with the introduction of Hi-MD, since then it hasn´t been improved. ATRAC is effectively one of the worst codecs around, it doesn´t help that its datarate is comparably high (292 kBit/s). It could have been more effective if Sony would have decided to fuck their desire for power constraints (a superior ATRAC IC would have drained battery power faster). Well, we have to work with what we´ve got and how we are able to improve it. Anyway, the following chapters will show you the most important basic instrument any perceptual (lossy) codec employs to fool your ear... or more precisely, your brain (Fig. I):

Fig. I: Equal-loudness contour, logarithmic scale (copyright: Wikipedia)
On the left of Fig. I you can see the Sound Pressure Level, measured in dB. The line below presents several frequency points of the entire frequency range our ear can hear (20 Hz to 20,000 Hz), measured in Hz. Now take the highest frequency at 16,000 Hz; it would need a level of roughly 25 dB to be perceived as loud as the 4,000 Hz tone. The key thing you have to understand is the difference between actual levels and perceived levels. Our ear itself listens with almost perfect precision, but our brain decides what part of the received audio material is kept. Our brain has been 'tuned' over the course of several millenia to recognize the human voice with immaculate precision, the area from 2,000 to 4,000 Hz is the most important frequency band  with the highest sensitivity. So listening sensitivity of the ear/brain combination sucks at low and - especially - at high frequencies. Those frequencies weren´t necessary for survival, so they have been 'dropped' as a result. Which means that we have to make signals at those areas much louder. But it also means that we´re unable to hear grave errors at low and high frequencies - and that´s where perceptual (lossy) codecs come in:

Fig. II: Multitone signal, -6 dB, .WAV, 24/44.1 (linear scale, Hanning)
Above (Fig. II) you can see a multitone signal (.WAV) in 24 bit and 44.1 kHz which consists of more than 100 seperate sines. Frequency response ranges from 0 to 22.050 Hz. There aren´t any errors to witness (the thickened bases of the several sines are caused by imperfections of the Hanning windows function used to display the results). Compare that to the same signal, encoded with MP3:

Fig. III: Multitone signal, -6 dB, MP3 (Lame, 256 kBit/s), 24/44.1 (linear scale, Hanning)
It´s evident that something has been added by the MP3 compression (Fig. III). This something is simple quantization noise, inherent to every digital system. In this case it´s at roughly -90 dB (original .WAV file: -144 dB). This amount of noise also reveals how lossy codecs work. It is always said (even I did so above) that they 'remove' or 'erase' parts of the music with surgical precision. Well, it isn´t true, they don´t really 'remove' anything (ignore the cut-off at 19 kHz for a sec'). What any lossy codec does instead is decreasing bit-depth dynamically, taking into account complexity, gain and composition of the signal. Example: a clarinet, formerly having a resolution of 24 bits now has a resolution of perhaps only 6 bits. The remaining 18 bits resolution are non-existent anymore which - BINGO - creates quantization noise. Effectively, the quality of any lossy compression is partly determined by how well it is able to hide this noise. MP3 is very good at this, a wonder given the fact that this codec is over 20 years old. You can also see that the quantization noise floor is shaped according to the Equal-Loudness contour (Fig. I). It is fairly low at 4,000 Hz (I failed to point this out with my red line) and rises slightly towards higher frequencies.

Disadvantages of ATRAC compared to MP3

Fig. IV: Multitone signal, -6 dB, ATRAC 4.0, 24/44.1 (linear scale, Hanning)
ATRAC (in this case 4.0; DSP Type-R doesn´t differ) performs much worse. Quantization noise is stronger (70 dB, Fig. IV, MP3: -90 dB)... WideBitStream my ass! ATRAC has a datarate of 292 kBit/s to its disposal, the MP3 example has even less (256 kBit/s), yet it yields superior performance. But it should be clear by now that ATRAC also follows the Equal-Loudness contour (Fig. I), just like every other lossy codec. However, ATRAC & MP3 do a bit more: they completely remove high frequencies. MP3 did it in my example at 19 kHz, ATRAC at 17.5 kHz. They get rid of those frequencies because A) we don´t hear them well and B) because their encoding hurts the rest of the frequency spectrum. How can the presence of high frequencies distort frequencies below them? Because both codecs use a constant bit-rate, they cannot adapt this bit-rate (and therefore possible quality) to changing complexity patterns. MP3 is of course able to encode with variable bit-rate (VBR). But I used constant bit-rate only (CBR) to create fair comparison conditions. ATRAC is forced to encode everything with 292 kBit/s, no matter what. Should a certain signal require a higher bit-rate, pity, ATRAC simply can´t do it and has to take away more information at other areas, informations it might want to keep instead.

Advantages of ATRAC compared to MP3

Fig. V: 1 kHz sine, MP3 (Lame, 256 kBit/s), 24/44.1 (logarithmic scale, Hanning)
Fig. VI: 1 kHz sine, ATRAC 4.0, 24/44.1 (logarithmic scale, Hanning)
The situation reverses with less complex signals. Fig. V and Fig. VI exhibit that ATRAC performs superior to MP3 with simple signals. Quantization noise is more evenly distributed, resolution of 20 bits is retained. Which means: the less complex a signal is, the better can it be encoded by a lossy codec; apparently, this is even more valid for ATRAC. But it has another advantage: its time/frequency resolution, expressed in block length. Perceptual codecs need to decide between long mode and short mode. The latter enables any lossy codec to encode transients (very short & loud signals, for example the attack of a piano or handclapping). For short mode, MP3 uses a window size of 192 samples (or 4.3 ms). Now if a signal is shorter than that it is ignored, it ceases to exist because it's effectively 'invisible'. In comparison ATRAC has not one but two short modes. For lower frequencies it´s 130 samples (2.9 ms), for higher frequencies 65 samples (or 1.45 ms). In general, ATRAC is better suited to encode very loud and short transients, helping dynamics and precision.

Sonic differences between ATRAC & MP3

Ask 'normal' people (not audiophiles) how they perceive the sound of MP3 and you´ll most likely receive the answer that it sounds slightly warmer to them, that is, if they can hear any difference at all. Yet your basic audiophile will call its sound 'cold' and 'digital' when in reality nothing could be further from the truth (their reasoning: it must sound that way because it uses lossy compression). Listen, all you audiophiles out there: MP3 encoded music sounds a tiny bit warmer compared to the original. The reason is not that it removes any frequency content above 16 kHz (also stated by audiophiles), the one and only true reason is that it fails at encoding short transients responsible for dynamics, attack and precision. When ATRAC still was used regularly it too was described as sounding 'cold' (for example in German STEREOPLAY magazine 15 years ago). Again, this isn´t true. At least not for ATRAC 4.0 and ATRAC 4.5. Both sound significantly more pleasant and warmer than the original (ATRAC DSP Type-R changed the situation somewhat). Responsible for this mellow signature isn´t a too short window size. These shortcomings are caused by the ATRAC codec attempting to encode signals up to 20 kHz. All those years ago, magazines and audiophiles alike (the german STEREO magazine paramount among them) constantly pressed Sony to improve rendering of high frequencies. They believed that if you could retain frequencies from 16 to 22.05 kHz it would yield true audiophile sound. Bullshit! ATRAC would have profited extremely if they wouldn´t have listened to audiophiles, I will show you how.

Tweaking ATRAC

Fig. VII: ATRAC standard encoding (24/44.1, linear scale)
By trying to encode signals up to 22,050 Hz (see Fig. VII) ATRAC is losing precious available bits better reserved for lower, more readily audible frequency bands. This creates an overall pleasant sound signature by producing soft compression artifacts. Of course, this sound is far away from the truth. The final critical band ATRAC encodes is the frequency area from 15,500 to 22,050 Hz, if it wouldn´t be present anymore, ATRAC would have more bits to spare for lower frequency bands (0 to 15,500 Hz). Remember: the less complex the music is (a.k.a. less frequency bands), the better will it be encoded by ATRAC. For that reason we will erase frequencies beyond 15,500 Hz with an equalizer so that ATRAC 4.0 or higher doesn´t need to concern itself with these frequencies anymore! Will this sound muffled? No, it won´t since ATRAC encodes transient responses with utter precision (compared to MP3 which always sounds slightly blanketed depending on the material). Getting rid of frequencies beyond 15,500 Hz improves quantization noise as a result:

Fig. VIII: Multitone signal, -6 dB, ATRAC 4.0, STANDARD ENCODING, 24/44.1 (linear scale, Hanning)
Fig. IX: Multitone signal, -6 dB, ATRAC 4.0, 15.5 kHz CUTOFF, 24/44.1 (linear scale, Hanning)
Look at Fig. IX and compare it to Fig. VIII by clicking on one of them with the left mouse button and scrolling through both of them. Quantization noise floor has been lowered by roughly 5 dB - and only because frequencies beyond 15,500 Hz have been removed. Stunning result, isn´t it?

Fig. X: RMAA frequency response, ATRAC 4.0 STANDARD ENCODING, four passes
Fig. XI: RMAA frequency response, ATRAC 4.0, 15.5 kHz CUTOFF, four passes
Even RMAA recognizes the effect. Fig. X & XI depict that the hole around 4,000 Hz, typical for any ATRAC version, has almost disappeared along with the odd response at subsonic frequencies (20 Hz). Increasing levels from 10,000 to 15,000 Hz on Fig. XI are caused by my equalizer setting (see below at 'Equalizing ATRAC (costly option)').

Equalizing ATRAC (free option)

I told you that this tweak is free, I therefore searched, found and measured a suitable equalizer. This was difficult, not many free equalizers around are able to process with high quality. I will however also tell you about costly alternatives, namely SoundForge and iZotope Ozone. SoundForge is the VST-host while Ozone is the equalizer I work with in that case. I will talk about them because they are yield slightly superior quality. Never, I repeat, NEVER use built-in equalizers (SoundForge, WaveLab, Adobe Audition, foobar2000, Winamp). I´ve measured them and they create so many errors that it´s shocking. Anyway, to achieve the tweak without paying any money while still retaining high quality you´ll need these things:
- foobar2000 (get it here)
- a VST-wrapper (get it here)
- the equalizer EngineersFilter from RS-MET (get it here)
- Audacity (get it here)
- the equalizer EngineersFilter from RS-Met 

Fig. XII: RS-MET EngineersFilter setting for ATRAC Cutoff
Fig. XII reveals my configuration for the cutoff filter. The EngineersFilter offers several other filtering methods but I decided to keep it simple in order for less tech-savy people to use it as well. Regarding installation/setup of foobar2000, its VST-Wrapper and the EngineersFilter I cannot help you however, you need to figure that out for yourself, the same goes for Audacity. Other recommendations are: keep the signal at 32 bit floating-point, regardless if you´re working with foobar2000, SoundForge or any other digital audio editor. As you know, the MiniDisc is capable of working with high resolution material so if you´re recording from a PC just keep it at that high resolution. If you don´t want to use a PC I´d recommend a CD-RW (which can be erased and rewritten). In that case, decrease bit-depth to 16 bit without using noise-shaped dither (the shaped and dithered quantization noise would otherwise confuse ATRAC again) and burn the results to CD-RW.

Equalizing ATRAC (costly option)

Fig. XIII: iZotope Ozone 4.0 settings for ATRAC cutoff
Fig. XIV: iZotope Ozone 4.0 general setup (-> click 'Option')
First of all you´ll need a digital audio editor like SoundForge, WaveLabAdobe Audition or Audacity. With these you´ll be able to load iZotope Ozone (in my case, version 4.0) which you will configure to the specifications pictured in Figs. XIII & XIV. The 1.5 dB amplification of frequencies at 20,000 kHz is optional and used by me to fool my ear into not recognizing that certain frequencies are alltogether absent. Why would you even use the iZotope Ozone EQ? Because it´s in my experience the best equalizer on the market, it doesn´t create phase distortions nor other distortions or errors and generally performs perfectly. Have a look:

Fig. XV: iZotope Ozone, phase response
Fig. XVI: EngineersFilter, phase response
The phase response sadly is very underrepresented when it comes to sonic differences between DSPs or units playing audio material. In this case it´s evident that iZotope Ozone has superior phase performance (Fig. XV) compared to the EngineersFilter (Fig. XVI), yet it is debatable if this is audible at all. Let´s be fair: the EngineersFilter EQ performs admirably compared to all the other free EQs I´ve tested. Impulses play a role too:

Fig. XVII: iZotope Ozone, impulse response
Fig. XVIII: EngineersFilter, impulse response
Fig. XVII depicts a perfectly symmetrical impulse response for iZotope Ozone. A high steepness of the cutoff filter produces better frequency resolution at the expense of perfect impulse response. The same is true for the EngineersFilter, although here the impulse response (Fig. XVIII) is modeled after the first CD players with analogue anti-aliasing filtering. In the end you have to decide, I´ve written it years ago that the effects of impulses are overrated. BTW, the settings I´ve described yield the following measurable results:

Fig. XIX: frequency response, ATRAC 4.0, 15.5 kHz cutoff (logarithmic scale)
Fig. XX: frequency response detail, ATRAC 4.0, 15.5 kHz cutoff
As you can see on both examples above which were created by RMAA I´ve achieved the desired effect - without frequency deviations created by crappy equalizers and, almost (for the EngineersFilter) without phase distortions. The graph depicting the zoomed-in frequency response (Fig. XX) reveals a not too steep cutoff, yet it´s precise enough to get rid of frequencies beyond 15.5 kHz. The result of my procedure is evidenced by Fig. XXI: the picture shows a spectogram derived from an ATRAC encoded/decoded recording (compare to Fig. VII). The precise 15.5 kHz cutoff is clearly visible.

Fig. XXI: ATRAC encoding with 15.5 kHz cutoff (24/44.1, linear scale)

The sound

When I first heard the results I couldn´t believe my ears, the sound had improved by such a margin that I was wondering how I had been able to listen to it before. Precision, attack, stability and holographic impression of the stage were sounding so much better now... But listen for yourself. The following files were recorded digitally with the Sony MZ-R 55 featuring A) the standard full-frequency and B) the 15.5 kHz cutoff discovered by me. In both cases, the original files were at 24/44.1. After recording I played them back using the Kenwood DM-5090 (also digitally) and recorded its output with the optical input of my Creative Labs Soundblaster X-Fi HD USB. After that I merged three 30-seconds examples and uploaded them to soundcloud. INSTEAD OF LISTENING TO THEM ONLINE, DOWNLOAD THEM! Reason: both are ATRAC-encoded/decoded PCM-files, encoded again with MP3 by soundcloud (at 128 kBit/s). Should you just press 'play' you´d only hear a transcoded file, revealing compression artifacts clouding possible differences. Downloading them however you´ll be able to listen to the pure, ATRAC-encoded/decoded, Kenwood-derived, digital files in pristine 24 bit quality without further influence from soundcloud. You would even be able, should you desire, to perform a DBT listening test; these two examples were edited with sample precision.

Three ATRAC 4.0 encoded samples, standard encoding

Three ATRAC 4.0 encoded samples, encoded using my 15.5 kHz cutoff filter


And? What do you say? I feel that the result speaks for itself. I admit that this tweak requires some effort but I think that it´s worth it. I now can use ATRAC 4.0 again! Oh yes, I almost forgot... why didn´t I use a more recent ATRAC version? While the effects will be superior using ATRAC 4.5 or higher, the ATRAC 4.0 equipped recorders I own (MZ-R 30, MZ-R 50, MZ-R 35, MZ-R 37, MZ-R 55) have high quality drives, producing MiniDiscs running without flaw on any other MD recorder / player. Later units (MZ-R 900, MZ-R 909) featuring superior ATRAC ICs fail to do this. With the exception of the Sony MZ-N 510 they all record with unreliable results. I also admit that it isn´t very convenient to use MiniDisc these days. The reason to use them, for me at least, isn´t their sound. Every other lossy codec employed today around the world is superior. I´m sorry, but it´s a fact. Still, I love those little discs. The players/recorders are of high build quality, sound well enough (in some cases more than well) and you get the joy of bringing some amount of 'slowness' into your musical life by occupying yourself with media you can actually touch. Let´s face it, I´m an idiot. An idiot... just like people still listening to vinyl. Like them I believe in an ancient and deceased format. But have I mentionend yet, that it´s pure joy? Oh, I did? Never mind! Anyway, with my tweak you´re able to prolong the lifetime of MiniDisc before it´s completely replaced by superior codecs and playback devices. And while you´re at it, use it in combination with the FiiO E07K, it´ll sound even better this way. Use this chance well and enjoy the results!

Last update: 06.09.2013
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