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Sharp Minidisc Review

by Ira Wilner

I had been looking for a replacement for my personal Sony WMD6 Walkman style stereo cassette recorder that I've used to produce simultaneous safety or instant performer courtesy copies of location recordings mastered onto DAT. The Sony, after many years of service, developed excessive flutter. Cleaning and adjusting the indirect capstan drive mechanism made only a partial improvement. So it was time for a replacement.

Mini disc would eliminate flutter, tape hiss, head azimuth errors and provide longer record time. Also, being a non contact format, it might prove to be more reliable. The main drawbacks were cost and audio quality.

MD has had over five years to mature. The prices have fallen below that of quality analog cassette and the sound quality is now comparable to CD. After surfing the Internet and checking into the "Mini disc Community Page" from time to time I discovered a new machine that met my expectations at least on paper. It turned out not be from the creator of MD technology.

The Sony portables rely upon an AGC limiter circuit to ride gain during recording and do not allow manual level control once a recording is started! A less well known company whose products have always been a pleasant surprise is Sharp Electronics. I have one of their cordless telephones and it is the best sounding unit in my household.

Review of the Sharp MD-MS722

This is the latest palm size MD recorder from Sharp Electronics using their latest ATRAC 6 compression algorithm which is claimed to be a 24 bit process. Though not yet available in the US, at least one gray market importer in NYC has them in stock. The downside is no US warranty and the need to use a step-down transformer for its charger/wall supply to prevent damage. Japanese domestic models are designed for 100 VAC although they use the exact same wall outlet prongs as in the US.

Although this is the Japanese version the instruction booklet has an English section, the engraved labels on the pushbuttons are all in English and the LCD display supports English as well as Katakan characters.

Physically the unit is only slightly larger than a stack of three mini discs in their storage cases. Controls are on the top with the loading slot on one side. An additional pendant size remote control with its own EL backlit LCD display and headphone/line output jack is provided so that the machine itself can be safely nestled in a garment pocket while being operated.

I/O is achieved through 1/8 inch unbalanced stereo phone jacks, with the line output jack also cleverly doubling as an optical digital output port. The mic input port provides 1-2 vdc for consumer grade powered electret condenser microphones. Thus any direct professional mic connection will require some sort of DC blocking capacitor or transformer to reduce noise from this voltage source. I assume that one would opt instead to use a decent outboard mixer, such as a Mackie 1402VLZ and drive the MD recorder's line input.

Sharp claims that the unit will record for up to 8 hours or play for 10 hours on its fully charged internal battery. Compared to all of the other portables, the MD-MS722 holds the runtime record using only its internal rechargable battery. It accomplishes it, in part, by using a .25 micron LSI chip that replaces several power hungry IC's.

Wow Factor

Not until you hold one of these beauties in your hand and put it through its paces will you really understand where that technology is today!

Wow factor is impressive! No, not wow and flutter which is unmeasureable. This tiny machine has all of the control features you would expect on a full size desktop box. Cueing is excellent, very tight, maybe to a fault! The display timer can be set to count up or down. You can cue from cut to cut or second to second within a cut using a jog ring. Or you can do an audible search using >> or << buttons. And you can edit, combine, delete or label any cuts anywhere on the disc.

Mini disc is a magneto optical medium with 1/5th the data capacity of a CD. Thus the requirement for a perceptual coding compression scheme. Compared to ISDN or the NPR Comstream satellite system, 128k or 256k bits per second respectively, MD uses approximately 290kbps for stereo. In theory it should sound slightly better than NPR satellite audio.

The chewing gum pack sized rechargeable battery, which takes only three hours to fill up from empty, powers a platter spindle motor, head servo positioner, writing and reading laser, magnetic writing head, DSP processor, RF processor, servo controller, user interface micro controller, 1.5 megabyte audio buffer memory, backlit LCD display, headphone amplifier and more, all fitting in the palm of your hand.

So What About Audio Quality? The Golden Ears Are Awaiting

I own a couple of heavily modified Magnavox/Phillips CD players which I use for source material from CD. My critical listening device is a Stax Lambda Pro V headset driven by a Stax class-A high voltage audio amplifier. The output voltage swing is over 400 volts, not recommended for casual listening in the bath!

I transfered music from CD in the analog domain, from Telarc and other labels, consisting of piano, tympany, vocals, strings and flute to mini disc. This was done to judge the overall quality of the 20 bit A/D and D/A converters of the Sharp MD recorder.

In general, the frequency response, noise and overall distortion was indistinguishable from the original. I synchronized both recordings and switched back and forth mid stream to make any differences more apparent. There were some hard to discern subtle differences. After processing and transmission over an FM broadcast station those differences would most likely be even less discernible.

The MD sometimes had slightly less musical detail, hard to tell without the A/B process.

The MD had a slightly reduced sound stage. The low level ambiance information was somewhat truncated.

The MD had slightly reduced transient response. Sonic impact was slightly reduced on attacks. The non trained ear might perceive it as being slightly less bright.

More obviously, complex sounds with lots of white noise type of texture seemed to lose some detail and acquire some distortion artifacts. For example, violins would have a more rosin sound to the bowing. Flutes would sound a bit more breathy, the air sound would be a bit more accentuated and grainy. I assume that it is probably an artifact of the ATRAC data reduction scheme which dynamically allocates bits in a manner that attempts to be transparent to the ear. But it could also be a limitation of the converters or analog circuitry running with so little electrical energy.

Remember that we are comparing a machine running on a 3 volt battery and using micro power to a heavily modified AC powered CD player that actually runs hot to the touch! With that in mind, the quality of the palm size MD is amazingly good, not perfect, but still a remarkable achievement.

Apples And Apples Rather Than Apples And Oranges

I had the opportunity to compare the Sharp to a rack mounted Sony MDS-JE510. The conditions were not ideal. The monitor speakers were EV Sentry 100's in questionable condition. The mixer was an older Audio Arts console. I took the MD's I had recorded on the Sharp and played them on the Sony. Then I played the Sharp machine back through the Sony machine, EE mode, Sony in record pause. This insured that we were using the exact same audio path but listening to the Sharp's decoder. All listeners agreed that the Sharp provided slightly more musical detail.

Summary

Compared to a good original CD recording or a top notch DAT recorder the Sharp MD recorder is slightly inferior.

Compared to most sound card converters in personal computers, the Sharp is most likely superior.

Compared to an inexpensive reel to reel tape recorder at 7 1/2 IPS, the Sharp is better, especially from a noise, distortion and flutter perspective.

Compared to an analog audio cassette recorder, the Sharp is superior in every respect.

For critical studio mastering of music the MD format may be a bit thin. But I would not hesitate to use an MD recorder as either a safety backup to a DAT in the field or as a means of bringing home a high fidelity recording where larger, bulkier equipment would be impractical.

Remember that professional studios find even 16 bit DAT recorders lacking compared to the best of analog. This is why 24 bits at 96k sample rate is now a defacto minimum standard for digital mastering.

For one shot recordings for air the MD is more than adequate. If editing and post production is required with further dubbing to a lossy format such as MPEG for hard disk storage, MD is not the best mastering choice, though it won't be the end of the world if you used it.

When all is said and done, MD provides a recording that is free from wow, flutter and hiss. Those defects are easily discernible on an FM broadcast. The more subtle issues of sound stage, and occasional artifacting will be blurred by the distortion and noise introduced by the broadcasting and reception processes.

Meantime, the palm size miniature battery portable Sharp MD-MS722-S seems, at first look, to be at least as good as the current crop of low cost desktop AC powered MD recorders.

We received some questions in response to Ira Wilner's article. Here are the questions and Ira's responses:

Hi. I'm the audio technician at my church and we are starting to go to radio. My options are to record the services on DAT (by way of 2 Digital 8-tracks if needed) or to buy a Mini Disc recorder. Once I've recorded the service, music and sermon, I have to edit it by shrinking or expanding it to exactly 60 min and throwing in a few "hotspot clips" I believe they are called (voice intro things). It's going to be put on AM radio so I don't think the highest quality is necessarily needed, and I know that mini discs are easy to edit and rearrange so I was thinking that that would be my best choice. In that case, is there any advantage to having a large one vs. a portible one?

Thanks

Kelsen Depp

Hi Kelsen,

Let me start by answering your question about large or small minidisc recorders. I suggest the desktop model for several reasons. 1) They tend to be less expensive than portables. 2) They are more rugged than portables. The line level inputs are RCA rather than 1/8 inch miniplugs. 3) They have built-in AC power supplies. No wall warts to lose nor fragile power cables to fail.

Since recording a church service usually requires several microphones, pulpit, choir, etc., you should be using a mixer ahead of the MD recorder. Thus a MD recorder with mic inputs is not required.

As for editing, there are limits to the preciseness of MD edits. If you can live with that level of imprecision, then by all means use MD as an editable format. Remember, if a program runs long, you only have about 74 minutes worth of recording time in stereo. However, many MD recorders permit 148 minutes in monaural mode.

MD is the least expensive recording medium that gives you built-in non-linear editing capability. If you are producing for only one radio station and they are equipped with a MD player, you can provide them with your original disc. Quite a saving in time.

My other choice would, perhaps, be direct recording to a computer's hard drive using a sound card and an application such as Cool Edit. The benefit is the ability to make very precise edits. The drawback is that you still have to dub it onto another medium such as cassette tape, minidisc etc.

Ira A. Wilner

Rich Esposito writes:

I'm currently in the market for a minidisc recorder. I work in the TV industry for an ABC affiliate here in New Haven, CT. I was thinking about getting the Sharp mdms722. I've read so much about them, and in comparison to other MD recorders. I was thinking about at some point getting a DAT recorder, mic's, and everything for concert recording, but want to do without the bulk. I want to use the MD recorder for the local bar/clubs when my friends rock bands play. Then come home and burn a CD from it with my PC. The only things I'm worried about are sound quality (if it's noticeably a cheesy MD recording or something), using the headphone jack as a line out to my sound cards line in, and the durability of it. I can get one right now for $179 and don't see how I can pass that up!!!!! I'd appreciate any advice you can give me!! Thanks

Rich Esposito

Hi Rich,

To the average ear, MD sounds great. Indeed, the 20-30 age group seems to have tin ears these days if the popularity of boom boxes, very scaled down stereos and MP3 players are any indication. On complex music you may begin to hear some artifacts. Some MD's may be a bit thin on bass. Others may exhibit some tizziness on highs. The transient response may not be quite there.

For casual recording and playback of music, the MD is fine. But for recording artists who expect the most sonic impact, clarity and musicality even DAT may sound imperfect! Serious digital recording is now being done with 24 bits and 96 thousand samples per second. You can buy moderate priced sound cards for computers that will record at these higher quality rates. And you can buy similarly endowed digital multitrack recorders in the $3-4,000 range, too.

Therefore I recommend that you consider no less than DAT recording at 44.1 and using some type or bit resolution extension technology such as noise dithering or shaping, like Sony's SBM (Super Bit Mapping). For burning CD's at home you should equip your PC with a digital sound card to enable you to transfer your DAT recording digitally to your hard drive for final editing and assembly into a CD.

You want to avoid sending your sound through multiple conversions as each process reduces quality somewhat. The line input of a typical analog sound card and the headphone out of the typical MD player are noisy. You should stay in the digital domain!

Finally, a casual club recording can be done with a pair of mics in your lap and a MD recorder in your pocket. If you really wish to capture your rock bands with quality recordings that begin to sound professional, you will need far more bulky equipment! Each vocalist will require a mic. Instruments may require several mics and direct feeds from amplifiers and effects boxes. You will also require ambience mics to hear the hall and the audience when appropriate. You will have to actively mix unless you have the luxory to dump it live to multitrack tape. Since the band will already have its own P.A. system, you may need a mic splitter so you can share the mics. Your mic mixer should have no fewer than 16 inputs, maybe 32!

If you are not prepared to do serious miking, then anything beyond an MD recorder is a waste of money. Just don't expect those CD's to sound anything like a professional recording.

Ira Wilner

Graham Nelson writes:

I read Ira's review of the Sharp MD machine with great interest and noted he felt it was superior to cassette recorders.

I would be interested to know if he felt the MD was superior even to the best cassette recorders, e.g. Revox B215 or a Nakamichi Dragon or CR7?

Hi Graham.

Along with your selection of high end cassette decks you should include the JVC DD-9 which is my all time favorite. The DD-9, long out of production, featured three servo motors in its transport, very wide band heads, automatic, bias, EQ and sensitivity setup and Dolby C circuitry tweaked to provide extremely flat frequency response!

Metal tape and Dolby C on a DD-9 will provide somewhat superior fidelity than MD. But it is a close call. The DD-9 will have extended highs and exhibit none of the subtle artifacts of digital compression and quantizing to only 16 bits. But flutter, especially scrape flutter and ultimate noise floor are far worse on any cassette compared to a good MD.

You cannot get one hour plus of continuous stereo recording on cassette unless you go to C-120's whose tape stock thickness is dangerously thin! I do not recommend it and there are bias and setup problems along with mechanical issues when using such thin tape.

Minidisc is the preferred portable recorder over cassette. And it is more robust than the helical scanning heads of DAT recorders.

It really isn't appropriate to compare a Sharp portable MD to a heavy tabletop cassette deck. Apples and oranges at best. But compare the Sharp to any palm size battery portable tape recorder and MD wins hands down.

When considering other attributes such as built-in non linear editing capability, media life or run time on a set of batteries the MD leaves cassette technology in the dust.

Ira A. Wilner

Ira Wilner runs Wilner Associates, Broadcast Engineering, in Vermont.