johnedward - 2009-06-08 19:57
NOTE : manual says DO NOT DEMAGNETIZE head or severe damage to head can occur . So if you play a lot of analog cassettes which produces magnetization of head which effects sound how does this unit handle that apparent fact of physics ? ? ? ?
YOU KNOW ITS NEW IF THIS CARDBOARD INSERT THERE
Notice the Square OPTICAL OUT PORT on right
NOTE : the smudge marks my fingerprints forgot to wipe clean
Beautiful ALL METAL casing dark titanium metallic
Here you have the 4.8 VOLT 1300 mAh NiCad battery with the standard gumstick battery for size comparison.
Here you have a really beautiful rare Panasonic late SX series cassette player for size comparison. They SX series player mfg. 2000. It is a magnificent glossy blue metallic with chrome play,ff and rwd buttons in a brushed alloy line very sharp clean design. Stay tuned in next month will post MY PANASONIC COLLECTION of 26 models from 80 to 2002 !
The wonderful LARGE window showing most of cassette has original sticker on it.. gosh wish I could remove it alas..... a no no it seems for the collect... GOD I want to use this player in the WORST WAY....
Great many function showing display window with wonderful green metallic background.
Here is a review done in 93 of this player.
DCC TO GO
A look at Panasonic's Digital Compact Cassette portable
by Mark Fleischmann
Philips' Digital Compact Cassette (DCC) and Sony's Mini-Disc (MD) have been jousting on an uneven playing field. The first DCC units were tabletop decks, while the maiden MD was a portable -- thwarting direct comparisons. More recently, Panasonic and Philips have released DCC portables and MD has come home as a Sony console. When Panasonic's RQ-DP7 DCC portable ($549) arrived in my listening room, I compared it with my initial impressions of DCC and MD.
My test tape was recorded digitally from a CD player to Technics' tabletop DCC recorder. Heard through the Panasonic portable and a better-than-average home system, the folk, blues, and jazz selections sounded slightly brittle and less substantial coming from the DCC portable than from either tabletop DCC or CD. But the more complex walls of sound in the rock and piano-concerto tracks felt just right, with the latter's string section still gratifying lush. (Strings were one of DCC's few definitive strengths over MD in my original tests.)
In sum, portable DCC works better with busy textures than with sparse instrumentation against a backdrop of silence. Tabletop DCC verges on perfect CD reproduction, but portables in general suffer from low-powered circuits and the bandwidth bottleneck of the eighth-inch mini-jack. This presumably applies as much to Philips' DCC portable, the DCC 130 ($549), as to the Panasonic.
Such sonic nitpicking fades to nothing in portable applications, where lightweight headphones and ambient noise overwhelm all fine distinctions. The Panasonic portable had no trouble playing an analog tape. With vigorous shaking, my DCC tape mistracked only once; the analog tape fluttered slightly in pitch but didn't poop out. Rechargeable battery time is 2.5 hours. At slightly more than a pound, the unit fits in a sportjacket's side pocket, though it doesn't match the shirt-pocket compactness of the better analog portables.
The biggest hurdle for DCC remains the fact that it's a rarefied high-end product aimed at a low-end listener who's used to paying far less for analog equipment and tapes.
This article originally appeared in Popular Science, December 1993.
Here is a good explaination of DCC with link posted below that goes into GREAT DETAIL MORE THAN I posted here of OTHER RECORDING FORMATS.
NOTE; comment about sound close to or BETTER than DAT with LARGER dynamic range than DAT or MINIDISC.
AUDIOTOOLS.COM FANTASTIC COMPLETE LIST OF DCC EQUIPMENT
DCC player home/portable LIST Digital Compact Cassette
A format introduced by Philips in the early 90's and poised to be the successor to the Compact Cassette, it's media was mechanically mostly identical to the cassette except that it is one sided and has a sliding metal dust protector not dissimilar to the one on a 3.5" floppy. Electronically it is very different however, it's a digital recorder that archives recording and playback via a stationary 20 track lithographed thin film head (i.e.. it's S-DAT), the sound format was initially a 1:4 compressed 16bit format @ 44.1KHz and later a 18bit format at the same sampling rate although all DCC recorders allowed for recording and playback of 48kHz and 32kHz most recorders did not have A/D or sampling rate converters capable of using those so recording of 48 and 32 kHz was usually only possible via the digital inputs if the original material demanded it. The compression format used is PASC. Despite having the ability to play back analogue cassettes with remarkable sonic qualities thanks to it's litho head and having sound quality close to or slightly better than DAT (depending on your objectives and equipment), much better than the Mini Disc and having a larger dynamic range than both, it did not do well in the market outside of mainland Europe and in 1997 Philips abandoned the format in favour of another one of their other inventions : CD Recorders.
ALSO GREAT LINK TO INFORMATION DCC Format
DCC @ WIKIPEDIASPECIFICATIONS OF THE RQ-DP7 with 18 CHANNEL HEAD
IMPRESSIVE Frequency response 20-22kHz Dynamic Range 90 DB and S/N 90 dB or moreCurious how Frequency Response for ANALOG tape for NORMAL, CrO2 and Metal ALL 3 show 20-18 kHz
HOW IS THIS POSSIBLE?
REVIEW OF THE SONY MZ-R501
Good Points
Easy to use; great on batteries (A rechargeable NiMh lasts the full 35 hours playback)! Great sound. Easy connectivity to almost any audio/PC device with audio ins/outs... Manual line-level record input stage level can be manually set to whatever the user wants; none of this auto-setup rubbish!
Bad Points
Heavy on battery if recording; remember your mains adapter if recording a gig or live DJ set!
Ships with Optical lead only, bad for non-technical folks! (Who may prefer the old Line-in approach).
General Comments
I was never much of a fan of Mini-disc, the first generation attempts sounded splashy and muddled, with obvious artifaction of the audio stream, even at modest listening levels.
This 4th generation Sony MZ-R501 Mini-disc player appears to have ironed out the wrinkle's as copies sound crisp and clear; especially when using the supplied Optical lead, that connects to CD players or PC's with suitable sockets, it will even automatically index the tracks in more or less the correct places (occasionally, mix CD's cause the odd error; understandable really). Even when using the analogue input. However this little box is amazingly capable, and can outperform the majority of "separate" MD decks that cost 4-5 times as much; and of course aren't portable, which is the whole point of MD technology; to be an ergonomic and cost effective, re-recordable (with no degradation due to re-use), easy to use, portable recording solution.
The single most important feature (which to my knowledge is a first considering the year this machine hit the streets) is the ability to override the automatic record level and set it to much higher, meaning much more personalised recordings, and the ability to keep it sounding RAW instead of lacklustre (typical auto level is 2.5-3 notches. Mine is more like 4.5-5 notches), and it saves so much time trying to normalise the volume levels in post production.
It can also double up as a very versatile studio sampler, as long as you have a means to input the signal (Mic, desk, P.C or Mac); plus an infinite resource as working tracks are developed and reviewed, being constantly updated and monitored; I would say the sound quality is easily good enough to get a good Post-production sound and an impression of the final result...(It is also quite nice to add some really hefty bass to some home-made beats courtesy of the 2-step Bass boost, come on admit it!)
The only thing keeping this product from getting straight 10's, is that surely nothing is ever quite THAT good! I would recommend this to anyone as a multi use piece of audio hardware. Mine has served me well
I like the fact that you can record 3 possibly 4 cds, onto just 1 minidisc, this reduces the amount of storage required, as a minidisc is about half the size of a cigarette packet, very handy if your out and about.
That is a very nice dcc walkman!
The philips version is the dcc130, I want to get me a dcc
walkman also but then the dcc175 that can record!
Hey there Nicole, Thank you. The Phillips 175 is the ultimate DCC BUT BEWARE if you find one often it is missing the cable to hook to PC. Totally not available and unique to this machine ONLY.
Here is info on that machine.
CC175 Portable Digital Compact Cassette recorder (UK)
DCC175, portable recorder, can be connected to a PC's parallel port with the DCC-link cable. Only sold in The Netherlands. It looks very similar to the DCC-170 but internally it is very different.
Pure, portable digital sound with Bitstream 18-bit resolution. Also makes superb digital recordings on DCC cassettes. Fitted with multimedia plug for connection to PC as storage/backup medium.
•Studio Recording Quality from digital or analogue sources
•Unified input jack for coaxial/optical digital, microphone and line sources
•Multimedia plug connects to parallel port of PC
•Plays analog cassettes with Dolby B
•DCC text display with scroll
•Track selection by title
•Remote control in headphone cord
•Dynamic Bass Boost
•Optical digital output for connection to HiFi system
•Rechargeable NiCd battery pack
•Also supplied with AC/DC adapter, coaxial digital cable, HiFi cable and carrying case
Very interesting reading regarding the Sony MD John E. When they were new I went to a Sony MD demo done by some company reps at a local stereo shop. I also checked out a Phillips Digital tape player/recorder (shelf size). I didn't buy either but was interested, non the less, in the technology. For some reason I was not thrilled with making the switch to CD.
Recently, in a unexpected ebay buy, my wife bought me a Sony MD Walkman MZ-n420D. Factory referbished with new head phones for only $37. It is very simple, but I like it. Havn't really used it much except to get it set up. I need some more MD media.
The Recordable Sony MD you have shown, do you record with a mike? Mine can be plugged into the computer to transfer files(yes--mp3's--yuck)or Cd quality stuff. Could you explain what the designation "recordable" means for the MD? And the optical wire??
Thanks,
Chris C
john,,do you have any feeling as to the life span of the rechargable battery. i have been very surprised at how long some of the used gumsticks from sony are lasting. the ni-mh14's that i think are origonal to the sony 915's and 925's cd players i have bought are getting 25+ hours of use playing with my headphones at a loud volume. all 4 of these batteries i would guess are at least 6 years old. i have not tried the AA tube yet but from what i read the time should be similar.
Nice Minudisc recorder, JohnEdward.
I have a MZ-R700 and a NetMD capable MZ-N510 myself.
It's interesting to see a DCC Walkman-wonder how it sounds.
Great photos of both, by the way.
I've got a home Sony MiniDisc recorder. Before CD recording became affordable this was the way to go! Almost picked up a car Minidisc player to go with it. Really wanted a portable, but they were pricey back then.
By the time I could afford one the Pioneer and Phillips standalone CD recorders came along. The MD ended up in the closet. I should dig it out one of these days...
As for the DCC, all you need now is some prerecorded tapes to go with it!
Found a very interesting site for information on many makes of stereo equipment not just DCC. Here is some great additional information on the DCC format and test/comparison to DAT. What a interesting medium of recording. I will be doing a test soon comparing DCC digital pre recorded tapes,cd to DCC tape , vinyl to DCC tape , analog played on DCC to MD.
www.marantzphilips.nl The Philips Digital Compact Cassette was introduced in 1992 at the same time as the Sony MiniDisc.
The sales and marketing hype was that it was backwards compatible with the popular and established analogue cassette tape. Although the two types of cassette construction where very different, the basic physical size was similar allowing the DCC player mechanism to accommodate the older analogue cassette for playing in the DCC players.
The DCC system had a very impressive technical specification and provided CD audio quality recording and playback. But the public expected "instant audio track access" on high technology digital products (as the optical CD and MD) and the DCC "tape format" was seen as past and outdated technology and had very poor general customer appeal.
It was Philips plan for DCC to be the successor for the 1964 analogue cassette tape, but it turned out to be a multi million pound blunder, but a great lessons learned for the whole audio industry.
Production of the DCC machines ceased on the 31st October 1996 when Philips finally accepted that this digital tape format had no hope of success just four years its introduction.
DCC175, portable recorder, can be connected to a PC's parallel port with the DCC-link cable. Only sold in The Netherlands. It looks very similar to the DCC-170 but internally it is very different.
Pure, portable digital sound with Bitstream 18-bit resolution. Also makes superb digital recordings on DCC cassettes. Fitted with multimedia plug for connection to PC as storage/backup medium.
* Studio Recording Quality from digital or analogue sources
* Unified input jack for coaxial/optical digital, microphone and line sources
* Multimedia plug connects to parallel port of PC
* Plays analog cassettes with Dolby B
* DCC text display with scroll
* Track selection by title
* Remote control in headphone cord
* Dynamic Bass Boost
* Optical digital output for connection to HiFi system
* Rechargeable NiCd battery pack
* Also supplied with AC/DC adapter, coaxial digital cable, HiFi cable and carrying case
DCC RECORDERS - Frequently Asked Questions
Does DCC Sound as good as DAT ?
We're in the realms of subjectivity here. Because the new generation of DCC machines utilises 18 bit recording the dynamic range is greater than that of DAT or CD. Most aficionados agree that DCC sounds as good as sub £1000 DAT machines, and many say that the overall sound isn't as brittle - its more natural and "analogue-y". We are biased (of course), but from the thousands of units we've sold we've only ever had one complaint about the sound quality, and countless numbers of people contacting us saying that they can't believe how good DCC sounds.
Comparative tests with MiniDisc have repeatedly shown that DCC sounds better.
Don't however compare the 18-bit machines (DCC730/951/170) with the earlier DCC machines which do not sound as good.
Why is DCC so cheap?
DCC uses a fixed head mechanism - like a cassette recorder - as opposed to DAT which uses a helically scanning head system - like a video recorder. Consequently the mechanics of the DCC's transport is much simpler, and therefore less expensive to manufacture.
What's the difference between the DCC951 and the DCC730?
Very little apart from styling. The 951 is designed to match the 900-Series of Philips audio components, and incorporates an additional bus for communicating to other 900 series units - but for 95% of users this is of no use. Otherwise the performance of the 730 and 951 is identical.
Are DCC units reliable?
Because they are mechanically so simple, there is relatively little to go wrong and they have proved to be very reliable.
Is it better to buy a portable (170) or a mains powered unit (730/951)?
If you want to go on location and/or collect samples, then the 170 is the best bet, otherwise get a mains powered unit. These have much bigger buttons, faster rewind, infra-red remote, and titling, and for studio use are much easier to use day-on-day. The portables though have stereo mic inputs and are very sexy.
REVIEWS OF DCC PRODUCTS
Paul White - 'Sound On Sound'
'.... now that the supply of cheap DAT machines is drying up, a great many home studio owners are wondering which way to turn for mastering. Furthermore, certain very cheap DAT machines have gained reputations for unreliability.... it [ DCC ] seems now almost certain to become a significant player in the private studio market.'
'.... It would seem then that DCC is the perfect answer for those looking for a low-cost means of recording high quality stereo masters..'
'To confirm that the machine was compatible with DAT, I cloned a tape I'd made in the studio and had no trouble with this procedure at all. When the two recordings were compared by switching from the original to the copy during replay, a difference in sound was just evident, but it was subjectively no greater than the difference between one make of DAT machine and another.... Test recordings made via the analogue inputs also showed the recording quality to be excellent.'
'Also reassuring is the fact that the digital I/O's seem happy enough talking to DAT machines and that bodes well for those who want to download their finished mixes into digital editing systems or make DAT clones. In fact, you have the advantage that the sample rate of DCC conforms to the pro. 44.1 khz. rather than the 48 khz. standard adopted by most budget DAT recorders.'
'At its current RRP of under £250 including VAT, free tape and inclusive remote control, the DCC730 is a superb budget mastering machine.... At this price, DCC is currently the only low cost option for high quality stereo mastering.'
'.... the recording quality is to all intents and purposes indistinguishable from DAT or CD. Indeed, if you're using the analogue input, you'll actually get a little more dynamic range than you would with a DAT machine.'
'.... for those looking for an affordable, high quality mastering system that maintains a high degree of compatibility with existing equipment, I have no hesitation in saying that the DCC730 represents an excellent way of spending £250.'
'What Hi-Fi'
The verdict from the above publication gave 19 stars from a maximum of 20 based on the four criteria of sound, build, facilities and value.
'And let it be said that the DCC is very, very good.'
'.... the improved dynamics of the 18 bit system are again apparent.... certainly there's no feeling that this is CD's poor relation'
'.... the DCC deck really shines: it makes stunning recordings from analogue sources, such as radio tuners. Hooked to the superb Audiolab 8000T tuned in to a variety of Radio 3 concerts, it's capable of making recordings that sound just as good as the off-air signal.'
'The digital format ensures solid pitch stability, even with demanding solo instruments such as flute, violin or piano, and you can set levels conservatively for the loudest passages confident of no tape hiss even in quiet sections.'
'.... it's easy to forget you're listening to tape and not a silver disc.'
'Record digitally from CD and the deck sounds good....but of course, you're not going to get 18 bit resolution from such recordings, since the source material - the CD - is only 16 bit.... With this new deck Philips has moved on from the simple ability to tape CD's well. Whether you play the new 18 bit pre-recorded tapes or make recordings from analogue sources, the DCC has a role of its own.'
'Hi-Fi World'
'I've used a good quality DAT machine for years and am no stranger to the way digital tape can render analogue sound dry and antiseptic. But the Philips simply wouldn't entertain the possibility, giving a surprisingly warm and fulsome rendition. The bass was particularly well-rounded and lacked the sense of sterility so common with digital. There was no trace of hardness higher up the frequency range - the drum kit was crisply captured and ride cymbals showed neither imprecision nor hardness.'
'All in all, I was seriously impressed with the DCC.'
'The Mix' (DCC170 portable)
'Fortunately, Philips have included a digital output on the DCC, which really does expand its horizons significantly, especially if you're in the market for squeaky-clean samples, digital editing or just plain tape cloning.'
'All DCC recorders will accept a digital input at all three popular sample rates (32, 44.1 & 48khz ), which is good news for anyone who wants to transfer a DAT collection to DCC. DCC's ability to handle any sampling rate you can throw at it might even precipitate a glut of second-hand DAT machines!'
'So Philips have produced an 18 bit portable DCC for 250 quid. Sounds too good to be true doesn't it? Nevertheless it's here, and the lessons of of price and consumer willingness to invest in a new format have been well and truly learned by their marketing team. The major record companies have already given the format a vote of confidence with pre-recorded tapes.'
'.... you can't ignore the fact that this is a portable digital recorder at a previously unheard of price....'
'I invited several people to listen to both the [Sony] minidisc MZ-R2 and the DCC170. Digital transfers of recordings to both formats were played back, and blindfold listening tests were carried out using four different sized speakers in different environments. It has to be said that it was pretty close, but the DCC170 seemed to win the day. Words such as "spacey", "airy" and "more exciting" were used to describe the DCC170 sound, and the MZ-R2 did seem to lose some of the recordings ambience and presence. On smaller speakers, the detail of sparkling percussion appeared more defined on the DCC.... the stereo image was narrower and the bass fainter than the DCC'
'Last but not least, is the appealing ability of the DCC system to play existing analogue tapes.... the DCC brings out the best in any tape.'
'Hi-Fi Choice' (DCC170 Portable)
The comparative test from the above publication gave the DCC170 a maximum 5 stars for both sound quality and overall verdict against 3 for Sharps' MD-M11and 4 for Sony's MZ-R2 minidisc systems.
'.... If I wanted to bootleg an essential concert this [DCC170] is the one I would choose.'
DCC TAPE INFORMATION excellent
Tapes
Is pre-recorded software available for DCC? Not anymore. There used to be some prerecorded tapes but they're sold out everywhere as far as I know (even the Philips shop doesn't carry them anymore). Anyway it seems that at least here in the Netherlands there were never any prerecorded MD's either.
What are the advantages of pre-recorded DCC software? There are three kinds of DCC: prerecorded tapes, user tapes and super-user tapes. With prerecorded tapes, the subcode track on the tape carries a continuously repeated stream of data with tape title, song titles and artist names and (possibly) lyrics. User tapes (which are the tapes that are made by recorders that don't support text such as the DCC-900) don't contain any text data (just markers), and super user tapes may contain text data attached to each track-starter mark.
That means with prerecorded tapes you can search by title, because the player can retrieve the entire list of titles from everywhere on the tape. By contrast, super-user tapes cannot be searched by title because the recorder can only retrieve the title of each song at the start of that particular song. Also, as far as I know, the tape title and artist name cannot be recorded by any current recorder except the DCC175 (and only if you connect it to a PC, and the DCC175 can't display text data on super user tapes) and most recorders have limitations on the characters you can enter for the song title (for example, only capital A-Z, 0-9, + - and *). The limit of the song title, artist name and tape title is 40 characters each.
Can I record "pre-recorded" software on my own deck? No. Even the DCC175 attached to a PC records super-user tapes only, although you don't need to make a separate pass through the tape to record the text data: it can be recorded on-the-fly while recording audio from harddisk.
Is it possible to use analog tapes as DCC tapes? This is probably the most frequently touched subject on DCC-L. Lots of people tried drilling holes in analog tapes to turn them into DCC tapes, with varying rates of success. In theory, it's just not supposed to work: the data rate for PASC is 384kbits/sec, which results in a 48kHz frequency range per head, and analog tapes are just not designed to take that amount of data. That is why Philips decided to use the same tape as in video cassettes, in addition to improving the mechanical properties of both cassette and head assembly (see the Philips DCC page)
If you want to try it yourself in spite of this, here are some tips:
* Use a chrome tape; the Magneto-Resistive heads can't record well on metal tape, how unlikely this may seem. Fuji and TDK SA-X give the best results according to those who have tried.
* Use a new cassette if possible; an old tape may have been damaged or stretched slightly by a bad analog recorder.
* Drill the holes (you need at least two) in such a way that no debris ends up inside the cassette. Use a piercer instead of a drill, and/or hold the cassette upside down while you're doing it.
* Remember that the recording-blocking taps work reversely for DCC: hole=record; tap=protect.
* Don't record anything valuable on a fake DCC: even if you don't get drop-outs right away, the recording may deteriorate rapidly for various reasons: tape quality (mechanical as well as magnetic), cassette quality (mostly the pressure pad behind the tape), recorder state (dirty heads) etc.
Are there any cleaning tapes? Philips used to have a DCC cleaning cassette as SBC3500 which was also included with the DCC824 car stereo. It works with 5 pads and 2 bristles that clean the capstans, pressure rollers and heads with propyl alcohol. However it is probably sold out by now.
If you want to clean the heads of your stationary recorder, you'll have to open it up (unless it's a portable where the heads are easily accessible) and clean them carefully with a soft cloth and a bit of alcohol. Don't use a swab or spirit because that may leave more dirt behind than it cleans up.
PHILIPS ORIGINAL WEB PAGE on DCC TAPE PHILIPS DCC web page NOTICE:
The page below this notice is a copy (by kind permission of Philips Sound & Vision) of the DCC page that appeared on the Philips website until November 1997. I did not change any text and don't intend to do so: everything below this note is Copyright © 1996 Philips Electronics N.V. and is subject to the Philips terms and conditions. The page is not officially part of the DCC-FAQ and the DCC-FAQ's legal section does not apply here!
Thanks (again) to Monique Verbeek of S&V for taking the trouble of digging up the page and the graphics and sending them to me.
Jac Goudsmit
(end of notice)
Digital Compact Cassette
DCC is a medium on which audio information is digitally encoded and which reproduces CD quality sound. Since it uses the standardised format of analogue cassettes, it is completely compatible with analogue cassette decks.
Text mode allows a DCC deck to display support information (eg track title, artist name) in several different languages, about the recordings on the tape. The styling has been improved: the DCC tape has a slide off cover which makes access easier, plus the front is completely smooth and suitable for album art. The DCC cassette is protected from dirt and wear by a sliding door, so that the cassette will not easily become jammed or tangled.
DCC introduces a real breakthrough: PASC. PASC is precise and efficient. It compresses the data so that it can be accommodated on standard length audio tape. PASC ensures only sounds within the hearing threshold and takes into account the fact that loud sounds mask soft ones.
DCC tape frames contain PASC information in a checkerboard pattern, which stops drop-outs impairing the quality of the sound performance. DCC has all of the error correction possibilities of compact disc.
Azimuth is the position and angle of the tape in relation to the head. In conjunction with the Fixed Azimuth Tape Guidance (FATG) mechanism fitted to the DCC head assembly, the Azimuth Locking Pins (ALPs) ensure not only improved wrap-around tape-to-head contact, but also consistent azimuth alignment.
To play back information in the DCC miniature track dimensions, DCC uses magneto-resistive (MR) technology. MR technology is a major advance in the thin-film head for digital playback. MR's high-read sensitivity allows narrower tracks to be used for digital coding, so that overall tape data density is increased.
DCC takes the best of years of analogue cassette development, and adds the perfect sound of digital technology.
Introduction
In the Eighties, a Philips invention captured the limelight. Compact Disc opened a new era of digital, perfect sound. Digital audio in the CD format offers high dynamic range and very low noise, as well as low distortion, wide channel separation and total absence of wow and flutter: in a word, natural sound. Digital audio also offers extra user convenience with fast track access and programming. The error correction process in the CD player corrects any mistakes from slightly soiled or damaged CDs, so that the recordings retain their original purity. Consumers recognise this and the CD has become overwhelmingly accepted.
Yet in the Nineties another Philips invention has centre-stage: Digital Compact Cassette, (DCC). DCC is the marriage of compact cassette to Digital Audio, forming a union that combines perfect sound and high convenience with even greater versatility.
With the latest advances in digital audio technology, it has become possible to record digital-quality sound on a new type of audio cassette, which runs at normal compact cassette speed. With its revolutionary and extremely efficient PASC coding (see below), DCC achieves up to 18-bit resolution, producing superb digital sound of Compact Disc quality. DCC uses digital technology to produce digital quality on tape. And DCC will playback standard analogue tapes. In this chapter, we will look at several aspects of DCC and we will examine PASC coding. We will also look into the new head assembly which is a key to the DCC design. Finally, we will discuss the mechanical parts of the DCC cassette.
Important aspects of DCC
DCC operating convenience is well up to CD standards, especially with pre-recorded cassettes.
A number of features has been incorporated in DCC tapes and decks.
Track and time codes are on the tape. These codes, combined with autoreverse, make track access effortless and fast. DCC decks can locate a chosen track on either side of the tape.
A brand new feature of pre-recorded DCC is text mode. Text mode allows cassette decks to display support information about the recordings on the tape, such as album title, a complete list of track titles, names of the artists on each track, and lyrics (displayed in sync with the music). Television screens or remote control units can be connected to the cassette deck to display more extensive information. Text can be written on the tape in up to seven languages.
The well-known durability of cassettes is enhanced in DCC by digital error correction, improved mechanical design and built-in tape protection. As for styling, the new DCC design, which is smoother and slimmer, features an integral cover design, which has more visual appeal, and is easier to handle, carry and store.
In addition, DCC decks have a unique and practical advantage: they are compatible with their analogue predecessor. Customers can play their current analogue cassette collection on their DCC deck. DCC is available to the customer as a total system package, including decks from a range of manufacturers, and blank cassettes as well as cassettes pre-recorded on leading music labels.
Numerous digital first generation copies on to DCC blank tape can be made from an original, pre-recorded DCC. But, any further copies (ie 2nd, 3rd etc generation) made from the first generation copy will not be digital.
[Figure]
Figure 2 Only one generation of digital to digital copying is permitted
Autoreverse is a standard feature of DCC decks, which allows continuous listening to both sides of an analogue or a DCC tape.
All these factors make DCC the logical, digital successor to Compact Cassette. It meets higher demands for sound quality, durability and style. It is designed for the new generation of music lovers in a new digital age.
DCC Cassette
A number of design features of the DCC cassette improve upon its analogue predecessor.
The cassette is smooth on the top side, which can now be used for artwork or information. This is because the drive hub openings are only needed on one side of the cassette (as autoreverse is standard on DCC).
The tape and tape drive wheels, which are exposed in the analogue version, are concealed in DCC cassettes by a metal sliding panel called a slider. This slider, which is pushed aside automatically when the cassette is loaded, also locks the tape hubs. This means that:
* the tape is protected against soiling and scratches
* the tape does not tangle, unwind or jam
* cassettes can be carried around safely without their cases.
DCC cassettes are provided with cases, which provide additional protection for the cassette and space for extra information such as a booklet. The case is in the form of a slide-out sleeve which allows the smooth side of the tape to be visible (eg to display artwork) and facilitates easy access to the cassette.
The DCC cassette is made of new materials which are specified for use over a wider temperature range than those of the analogue cassette. The length of a blank DCC cassette can be indicated by holes in the rear of the housing. These enable DCC decks to calculate and to display the time on the cassette. Accidentally writing over a recording can be prevented by a record protection switch.
The tape is a standard videochrome tape: chromium dioxide- or cobalt- doped ferric-oxide, 3-4 µm thick in a total tape thickness of 12 µm. As in analogue cassettes, the tape is 3.78 mm wide, and is bi-directional. This format reduces access time, since less tape needs to be wound. It also allows continuous repeat playback.
DCC coding
DCC uses PASC (Precision Adaptive Sub-band Coding), a newly developed system which compresses the audio information so that it will fit on an audiotape and produce CD sound quality.
How does PASC do this? PASC concentrates on maximising the efficiency of the digital coding, by taking into account two factors not previously considered in digital audio:
1. The ear hears only sounds above a certain loudness (dB) level, called the hearing threshold. The threshold of hearing depends on the frequency of the sound (since the ear is more sensitive to mid- range frequencies) and on the individual. Consequently, it is only necessary to record sound above the hearing threshold, provided that the threshold is taken as the reference for both recording and playback.
[Figure]
Figure 4 The ear hears only sounds above a certain level, called hearing threshold.
2. Louder sounds hide (mask) softer sounds. A whisper, perfectly audible in a quiet room, will not be heard in a busy street. In fact, louder sounds dynamically adjust the threshold of hearing. With computer techniques, it is possible to track this threshold adjustment, making it necessary for only the sounds above this dynamic threshold to be recorded. Of course, this applies to both recording and playback.
[Figure]
Figure 5 Louder sounds mask softer sounds.
PASC achieves very efficient sound recording indeed. It needs only one quarter of the bit rate of PCM (of CD). This level of efficiency creates adequate room for precise recording of what the ear actually hears. The sound quality of DCC is in every way comparable with Compact Disc.
More information on how PASC coding works can be found in the Appendix.
Tracks and tape frames
DCC signals are recorded on nine parallel tracks on the cassette tape. Eight "Main Data" tracks contain all the PASC data, error correction data and system information. The ninth, "Auxiliary Data" track holds mainly track and time information, similar to compact disc, with extra tape markers for easier operation. Start markers, for example, make track access easy, while reverse markers are used to initiate auto reverse. The auxiliary data can be scanned during high-speed search, making operation faster and more straightforward.
All the DCC data on tape is grouped into self-contained tape frames, separated by InterFrame Gaps (IFGs). To accommodate small deviations in the sampling frequency during recording, IFGs can vary slightly in length. They also help to locate the start points of the tape frames.
Each DCC tape frame contains 12,288 bytes of information (not including synchronisation). This is composed of: 8,192 bytes of PASC data, 128 bytes of system information (data for text-mode displays and information such as copyright and tape type), and 3968 bytes of error detection and correction information.
The PASC data is spread across the tape frame in a checkerboard pattern which stops drop- outs (missing signal on the tape due to damage of the magnetic layer), influencing the quality of the audio performance. Even large drop-outs will not impair sound quality (see figure 7.6). This can be compared to interleaving used in CD players, which compensates for any interruptions to the signal caused, for example, by dirt or grease.
[Figure]
Figure 6 The PASC data is spread across the tape frame in a checkerboard pattern.
A Cross Interleaved Reed Solomon Code (CIRC) protects the main data against random and burst errors. The two layers of CIRC data are spread across the eight main data tracks. This powerful error correction code allows for correction of drop-outs even up to 1.45mm in diameter. It can even compensate for a drop-out bigger than a completely missing data track.
In support of the revolutionary PASC, all the techniques which have made compact disc synonymous with audio excellence are applied to DCC. All are closely integrated, and optimised for the tape medium. They are fundamental to the extreme reliability and quality of this new digital audio system.
Azimuth
In audio terminology, azimuth is the position and angle of the recording or playback head in relation to the tape. Azimuth alignment is the position of the head gap in relation to the position and direction of the tape. Azimuth difference is a slight discrepancy between the position of the recording head gap and the position of the playback head gap. Azimuth error refers to problems in playback that arise because of azimuth differences. If the azimuth is not adjusted well, the head will not be in the best position to read the information on the tape and the sound will be negatively affected.
DCC has incorporated an important advance to ensure azimuth alignment and prevent azimuth differences and errors: Azimuth Locking Pins (ALPs). In conjunction with the Fixed Azimuth Tape Guidance (FATG) mechanism fitted to the head assembly, the ALPs ensure not only improved wrap-around tape- to-head contact (see left inset of figure 7), but also consistent azimuth alignment (see right inset of figure 7).
The ALPs improve the wrap-around angle of the tape against the head. This extends the tape-head contact area and optimises the physical conditions for signal recording and reading. The exclusion of gaps in the head mechanism means less friction and so less wear on the tape (which will therefore last longer). The tape is also stiffened in this crucial tape guidance area, and this contributes to the high accuracy of the FATG mechanism.
[Figure]
Figure 7 ALPs and FATG
In the FATG mechanism, special slots are mounted either side of the head assembly. The two top edges of the slots are reference surfaces to align the tape with the head. Meanwhile, the sloping profiles of the lower ports of the slots gently force the stiffened tape upwards against both reference surfaces. This simple device eliminates azimuth error.
The ALPs/FATG design requires no complicated mechanisms or close tolerances. Its very simplicity ensures permanently accurate tape-head alignment.
Magneto-resistive
The DCC sound signal is recorded on eight parallel tracks, each 185 µm wide. The track width required for playback, on the other hand, is only 70 µm wide. This width factor helps to reduce the sensitivity to azimuth error. An additional track carries control and display subcode information.
To achieve these miniature dimensions, the DCC record/playback head assembly calls on the advanced thin-film head technology already well proven in multichannel professional recording. In one single head element, three sets of head elements are combined:
* Nine Integrated Recording Heads (IRHs) for digital recording
* Nine Magneto-Resistive Heads (MRHs) for digital playback; and
* Two Magneto-Resistive Heads for analogue playback.
[Figure]
Figure 8 Magneto-resistive technology is a major advance in the thin-film head for digital playback. Magneto-resistive (MR) technology is a major advance in the thin-film head for digital playback. MR's high-read sensitivity allows narrower tracks to be used for digital coding, so that overall tape data density is increased. In addition, MR player output is independent of tape speed. So the problem of varying output levels with varying tape speeds, inherent in previous magnetic head designs, is eliminated.
The digital heads occupy one half of the head surface, while the analogue heads occupy the other half. So both digital and analogue tapes can be handled by the autoreverse head assembly.
In an integrated recording head (one head assembly with recording and playback functions), the signal current conductor is surrounded by a flux guide which concentrates the magnetic field into the recording gap in conventional fashion. The Magneto Resistive Head (MRH) playback head, on the other hand, features an advanced magneto-resistive element whose resistance varies with the magnetic field impressed on it from the tape, via the flux guide. A constant current is fed through the element, so that the voltage across it varies with the magnetic field on the tape. Magneto-resistive heads are excellent for reading DCC bit transition.
For analogue playback, the high stability and absence of noise of magneto-resistive heads also ensure top quality.
Basic structure
Figure 9 shows the basic structure of a digital compact cassette deck. [Figure]
Figure 9 Blockdiagram: DCC.
The recording process begins when the L and R channels from the microphone enter the A-D converter (from left to right in figure 9). The signal to be recorded then passes through PASC coding, error correction and channel modulation/demodulation, before reaching the head amplifiers. After the head amplifiers, the signal goes to the head itself, where it is recorded on the tape.
Playback runs the opposite way, from right to left in figure 9. After PASC coding and each of the steps between it and the head, the signal to be played back goes to the DAC and then to the L and R channels for amplification and reproduction. Digital in/out is used for input from and output to other digital sources, such as a CD player.
Most frequently asked questions about DCC
Q. What tapes will DCC decks play and record?
A. The decks will record and play back DCC tapes and play back analogue
cassettes.
Q. What is the purpose of the metal "slider"?
A. The slider protects the tape and locks the hubs.
Q. What is the formulation of the tape?
A. The tape is either chromium dioxide or cobalt-doped ferric oxide,
similar to video tape.
Q. What sampling rates can DCC use?
A. 32 kHz, 44.1 kHz or 48 kHz.
Q. Why do the DCC decks have Dolby B and C noise reduction?
A. Dolby B and C noise reduction is for playback of analogue cassettes.
It is not used for either record or playback of DCC cassettes.
Q. Will all DCC decks feature autoreverse?
A. Yes, autoreverse is part of the DCC standard that all manufacturers
of DCC hardware must follow.
Copyright © 1996 Philips Electronics N.V. All rights reserved.
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I had the Philips DCC 175 recorder hate to say it, but mines was junk, had alot of problems with it, didn't sound as good as one might Presume it would, Presumably the fixed assembly for portable recorders was more difficult to make and gave lesser sound quality (especially dynamic range) when playing analog cassettes and had alot of mechanical problems, I had mine fixed three times on the third time eat my favorite tape, well it learn how to fly, just didn't teach it how to land!! ended up replacing it with a sharp MD recorder MD-MS722 which was much better and now also own SONY MZ-N910 Net-MD, which record directly from USB using Sony Sonic Stage software. "Wish I didn't destroy that DCC recorder at the time I was just fed up with it I never could get it to work right"If you needed something small to take to class at the time to record, MD recorder was the way to go, first gen had problems with compression software but they fixed with the second and later generations, at the time and you get way better battery life to.
Of Philips portable DCC models the DCC 175 was by far the most complex mechanically and electronically. Not surprised it was not very reliable sorry to hear had such problems. Today it is a very rare unit to find or own. Too bad you did toss it even if only had for display. The cable that connects it to the computer is totally not available now so if you find one make sure it comes with that unique cable. Very state of the art for its time. Panasonic to my knowledge only made the one DCC model that I have. Also believe the Philips DCC 175 was only portable model to link to a PC directly.
Info on the DCC 175
DCC175, portable recorder, can be connected to a PC's parallel port with the DCC-link cable. Only sold in The Netherlands. It looks very similar to the DCC-170 but internally it is very different.
Pure, portable digital sound with Bitstream 18-bit resolution. Also makes superb digital recordings on DCC cassettes. Fitted with multimedia plug for connection to PC as storage/backup medium.
* Studio Recording Quality from digital or analogue sources
* Unified input jack for coaxial/optical digital, microphone and line sources
* Multimedia plug connects to parallel port of PC
* Plays analog cassettes with Dolby B
* DCC text display with scroll
* Track selection by title
* Remote control in headphone cord
* Dynamic Bass Boost
* Optical digital output for connection to HiFi system
* Rechargeable NiCd battery pack
* Also supplied with AC/DC adapter, coaxial digital cable, HiFi cable and carrying case
Did get another one in mint condition with box and everything a couple of weeks ago off craiglists for $45 bucks, comes with the parallel cable to hook up to computer. this one doesn't want to engaged the gear won't play. Don't think it was ever used stickers and paper still on recorder, it problem is because it wasn't used, I think a gear is stuck. Open it up this weekend relube all the gears and check to see why it not playing, sound like it want to work maybe out of alignment?
