Review: Sony MZ-R 55

You´re about to read the second out of nine reviews. You don´t need to read them all, just pick the unit that seems to be the most interesting to you. In the weeks to follow I´ll review the following units: Kenwood DP-5090, Pioneer DV-610, Sony CDP-470, Pioneer BDP-140, iRiver IMP-550, Sony MZ-R 55, Sony MZ-R 37, Sony NW-A 1000 and the Sansa Clip+. Stay tuned and enjoy the second review, the Sony MZ-R 55! I also implore you to read the article describing my rigorous testing methodology before you actually start reading this one.

Sony MZ-R 55

The Sony MZ-R 55 was released to the market in 1998, it was the direct successor to the very famous and reliable Sony MZ-R 50. Both players have many things in common, they each share roughly half of the same parts. Sony reorganized the mainboard design for the MZ-R 55 in order for it to be much smaller, they also altered the power supply so that it would work fine with 3 Volts only. But both players still carry many of the genes from the Sony MZ-R 30. In fact, the MZ-R 50 carried over much of the same parts from the MZ-R 30, only the laser, the drive mechanism (smaller) and the amount of RAM were different. The MZ-R 55 continued that scheme and shrinked the MZ-R 50 drive mechanism further (retaining the high quality laser with its die-cast frame). Sony also changed the headphone amp, the A/D/D/A converter (AK-4517) and drive related ICs. The amount of parts however remained the same with the result that the MZ-R 55 has a tightly packed PCB filled to the brink with parts using all available space inside the small shell. When new it cost around 350,- Euros which is a lot considering it can only record and play MiniDiscs.

Sony MZ-R 55 closeup

While the MZ-R 30 and the MZ-R 50 are famous for their reliability the MZ-R 55 is not 'cause it has a reputation for being extremely vulnerable to anything out of the ordinary. For example David Popovits wrote at Minidisc.org: "A small machine. It looks nice but nothing more. Press stop and in many cases it will start recording. Leave a recorded, unprotected, disc inside the MD during charging and you may find the disc was erased. Drop the machine from a few inches and it will stop recording completely. Use a non-exact power source and it will die partially or completely. Press a bit too hard on the keys and the whole cover will bend. How can we take such a creature seriously?" I don´t want to disagree with David, he seems to be a very experienced fella. Nevertheless I do have a different opinion (until mine will break of course). Its outer metal shell looks exquisite and while it doesn´t seem to be as thick as the one from my MZ-R 30 it nevertheless feels heavy and luxurious. The finish of its entrails looks marvellous too, its drive seems as if built to last forever. The mechanics are also one of the most quiet I´ve heard from an MD recorder... lovely. I would have loved to own the silver/gold version but I´m very happy with its lilac colour scheme too (remember: in Japan this colour is associated with wealth and power; go figure). It looks and feels like a very expensive and heavy cigarette case, albeit one with a conservative purple design. I really enjoy holding it in my hands, to touch it, to press its buttons, to open its lid... ah yes, opening the lid feels great. It doesn´t really pop open with a loud crash like on the MZ-R 30, it just clicks open and you then have to apply slight force so that it finally opens with a soft slide. Boy, I could open and close the lid the whole day!

Sony MZ-R 55 closeup

Running time with the chewing gum battery is ridiculous, it´ll play for two hours before it has to be charged again. Because of that I tend to use it with the attachable battery case (which sadly makes it much bigger) equipped with two batteries. Since I use the wonderful Sanyo Eneloop it can play for hours and hours. BTW, I wonder why Sony supplied a battery case that can hold two batteries - one 1.5 V battery is enough for the MZ-R 55 to function perfectly. Most of the time however the player resides on my Desktop connected to its power supply because I fear that it´ll break in case I use it outside... its bad reputation might be true. But off to measurments:

Sony MZ-R 55 measurments

Sony MZ-R 55 jitter

Apparently it doesn´t have high frequency jitter, only the spread around the base sine indicates some slight low frequency jitter; this might be audible since some peaks are just below -100 dB. The RMAA chart reveals that it is relatively noisy and also has slight problems with distortions (except IMD, those are non-existent). Its sound is... well, very good. The only real problem of the MZ-R 55 is the timidness of the bass, punches at lower frequencies loose their might and impact. Apart from that it´s very balanced, retains much of the character from the reference files and shows a similar level of resolution and definition. Details are never smeared or lost, they show an articulation close to the source. Its dynamic problems do not extend to mids and treble, at these bands it almost sounds like the reference. The stage is way too compact but presents an incredibly holographic depth with lots of focus and an excellent sense of space: far from being a close match but an elegant deviation. Fairly well done, Sony!

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Sony MZ-R 55 in-/outputs

Sony MZ-R 55 closeup

Review: Kenwood DP-5090

This is my first review out of nine. You don´t need to read them all, just pick the unit that seems to be the most interesting to you. In the weeks to follow I´ll review the following units: Kenwood DP-5090, Pioneer DV-610, Sony CDP-470, Pioneer BDP-140, iRiver IMP-550, Sony MZ-R 55, Sony MZ-R 37, Sony NW-A 1000 and the Sansa Clip+. Stay tuned and enjoy the first review, the Kenwood DP-5090! I also implore you to read the article describing my rigorous testing methodology before you actually start reading this one.

Kenwood DP-5090

The Kenwood DP-5090 was released in 1997 and it is one of those players released around that time that managed to reproduce 16 Bit CDs with 24 Bit accuracy... or so. Back then many players claimed to be capable of playing CDs with a resolution exceeding their technical abilities. The proprietary Kenwood D.R.I.V.E (Dynamic Resolution Intensive Vector Enhancement) filter did - according to some reviews - well enough for this player to sound sensational. I´ve read several reviews praising its wonderful sound, many magazines ended up rating it higher than many other units. But we don´t want to concentrate on reviews from the past, we want to rate the real thing.
Build quality is nice as well, the front is manufactured out of thick aluminum, the rest of the case is fairly heavy and equally well built, even the drive mechanism is protected with a thick metal plate. Actually... there seems to be a lot of conflicting information around as to which parts the DP-5090 is actually using. The chaos starts with the service manual: the DP-5090 apparently uses nothing less than three seperate D/A converters. The first is the MN35502 from Panasonic, the second is the CXD2507AQ from Sony and the third is Kenwood's own KAN05. According to the manual only the latter is in use... but the streamlined signal flow depicted in the manuals' diagrams looks so chaotic that I might be wrong. Internally the DP-5090 is pretty similar to the cheaper DP-4090 - the main difference is that the more expensive model uses a combination of several ICs for the DSP stage. I don´t exactly understood if it uses two or three seperate digital filters: the SM5843 from NPC or another filter embedded into the KAN05 itself (or maybe the Sony IC?). In any case, the Service Manual confuses me and the layout seems needlessly complicated. Sure, I´m a layman in that regard... still, todays' much more advanced converters contain all the necessary parts in only one IC. Anyway, the D/A converter (or the whole converting stage) is surrounded by an army of transistors, SMDs, ICs and condensers, the output stage required for amplifying signals once they have been converted to analogue seems equally sophisticated. The player is able to read CD-Text information, it also is equipped with two digital outputs; one can therefore connect it easily to more modern D/A converters. When new it cost 350,- which is not exactly what audiophiles consider High End but it still was one of the more expensive mainstream players. According to my boyfriend (who bought it all those years ago) the DP-5090 never was very reliable, it always had problems reading certain CD-Rs or scratched CDs. That wasn´t an issue for me since the CD-Rs I usually create are of high and flawless quality. On the other hand it is not exactly causing me to invest much trust into it.

Kenwood DP-5090 measurments

Kenwood DP-5090 jitter

As you can see above this player measures exceptionally well, noise and distortions are simply absent. Jitter won´t be audible, it´s extremely low. It´s for sure one of the best devices I´ve ever measured. The sound however wasn´t able to hold up the promise of high quality; the DP-5090 is very far away from being a neutral player. Treble is exaggerated, this creates a lot of air and resolution but it also prompts Madonna to sound hoarse, sibiliant and shrill ("Ray of Light" is actually a warm sounding album). Secondly this player presents a very tight, extremely articulated and dynamic bass response with real punch. This would be wonderful if upper bass wouldn´t be diminished; vocalists lack chest, violins sound thin and brass piercing. True, a signature like this could have its advantages because of extreme levels of dynamics, impact and speed. On the other hand staging is flat and doesn´t show any depth, it´s very audible with organ recordings which crumble apart... well, at least it presents an extremely stable, consistent flat stage. But holographic stage impression? Forget it. This is a very aggressive, dynamic and cool sounding player, it has nothing in common with the sound of the reference files. It will turn music into a fast, coloured and icy warzone, presenting it with much more details and punch than it really has. It will also replace the musics' character with its own, not convincing character. I´m probably kidding myself because I have to assume that many people would actually prefer this sound. Not everyone has perfect neutrality in mind; Pop, Rock or Funk might even sound more appealing with the DP-5090 for some people. Jazz or classical music however sounds just horrible with it so I won´t ever recommend it, except maybe as a transport using its digital outputs. Disappointing.

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