Using Stand-alone CD Recorders

Philips CRD 870 recorder

This revised page (2001) is still for people who want to make CDs as simply as possible, but it now makes no attempt to describe and illustrate the ever-growing range of CD-R units available to the home consumer. These remain affordably priced, easy to use and have feature sets not so different from the early Philips CRD 870, which is taken as representative. .

General Information

Stand-alone CD recorders have been available to the home consumer at high street prices from 1997. They cost about the same as a good video recorder. Most machines are intended for transferring existing recordings, analogue or digital, to CD. They copy material of up to 74 minutes 59 seconds to a 650Mb CD-R or CD-RW, and higher capacity discs can contain up to 80 minutes of material. The machines usually record in real time; recent units may offer higher duplication speeds of CD-sourced material.

Editing, even on current machines, often remains limited to track marking and single Undo. Whilst some machines have a dedicated microphone input and adjustment of channel balance, most do not. (External equipment can be used between microphone and recorder to give a suitable signal for live recording.)

Stand-alone recorders do not make conventional silver CDs. They use CD-R (recordable CD ) blanks. The newer machines can also use CD-RW (rewritable CD) blanks. After recording, discs must be 'finalised' before they will play on other decks.

CD-R discs are then compatible with most CD players. CD-RW discs are compatible with fewer. Older CD players are particularly likely to give problems. There is greater compatibility with the CD-RW units of computers. The blanks are not the same as those used for CD-R and CD-RW in computer drives: they must carry an electronic tag which enables the recording deck. Suitable blanks are identified as 'CD Audio'. The units will, however, play audio discs which have been recorded by computer, and conventional CD.

Increasingly, DVD players are used to play audio CDs. Not all DVD players are compatible with recordable CD discs of either type. It is worth checking compatibility before buying a DVD player.


Opinion

"The dream of affordable digital copying for personal use has finally been brought to fruition. There is clearly great potential in this machine and signs of what will come in the next millennium." - AudioFile

"The CDR870 performs as competently as any CD player in its price range, with smooth tonal characteristics, and well-paced and balanced delivery neither too aggressive or laidback. Sonically, it would appear to offer the best of different worlds, without getting in the way of the music. Which, despite the marked lightness of the lower frequencies that discerning audiophiles might target for criticism, is quite in keeping with the spirit of things. Recorded discs reflected these sonic traits it is only when you scrutinise the copies, using the originals as a direct reference, and playing back the same discs on a top-notch system like the Audiolab 8000CDM/8000DAC, that some inherent flaws are magnified. Inherent, but not detracting." - Sujesh Pavithran, AudioFile Review

For further details, see the review of the CDR 870.

Applications

No opinion is expressed or implied about the legality of the uses described here.

  • Exact duplication of an existing CD for personal listening. Making a duplicate can be useful insurance against theft, particularly from cars and second homes, and against damage. It adds about 25% to the cost of the purchase of a full-price CD. Of course, it is nearly as expensive as buying two copies of a budget-price issue.
  • Making personal compilation albums, for 'easy listening' or for study.
  • Copying analogue recordings from all sources. These can be given the convenience of full track marking. The sound quality can be enhanced before the recording stage with ancillary equipment. Other editing is best done before recording too. For extensive editing and refurbishment it is better to use a computer with sound processing software and a CD-writing drive, rather than a stand-alone recorder.
  • Live recording. See the notes in Introduction above. There is a choice to be made in recording live material. For the very best quality a digital signal should be recorded, to bypass the unit's A/D converters. However, the recording will be marked with SCMS tags, and so cannot be used as a master for further digital copying. (The great advantage of making copies digitally is that track information is preserved.) Conversely, live recordings made through the analogue circuits must pass through A/D conversion, and may be less perfect, but they will not carry SCMS and therefore can be used to master further copies made digitally.
  • Supply on demand copying. Though these machines are impracticable for mass duplication, they are ideal for making a few copies as and when needed. (For longer runs, there are many firms offering CD cutting - or pressing, or burning - and they usually offer full production services. 500 copies is a sensible figure to work from, though some will make shorter runs.)

For more uses, see MiniDisc page.

Archiving

Archive recordings are usually made on CD-R for cost and convenience. CD-R discs are much cheaper than CD-RW and are compatible with most players. CD-R is strictly a record-once medium. Anything which goes wrong stays wrong. This unforgiving nature is most problematical when recordings are made from analogue sources. Pending a fuller account of 'archiving the vinyl', here are some suggestions for getting the results you want.

Auto Track Increment

This does not always work as expected when a recording is made from an analogue source. The machine has to detect a silence of 3 seconds before the track number is incremented.

Missed track marks are often caused because the silence is not so silent after all. Many things can affect it, and they may not be apparent when listening to the source. Tape hiss; surface noise; pops, clicks and scratches; ambient hall or audience noise; low frequency recorded mains hum; high frequency pilot tones and 'birdies' can rise above the level preset in manufacture as 'silence'.

Extra track marks can occur when there is an expressive pause in the source which is faithfully marked as a new track by the recorder. They can also happen between movements when a short signal like a cough triggers them.

It may be better to use manual track marking for serious archiving. This also allows additional track marks to be inserted, and gives more control over the length of a silence. (See your manual for details.) The downside is that you have to monitor the recording while it is being made, and any marks missed through lapses in concentration cannot be inserted subsequently. You may also misjudge the split second for inserting a track mark. It is a good idea to listen to the source before making the recording, estimating and noting exactly when to press the marking control. You will usually find that you can make the marks more positively if you use the control on the machine, rather than on the remote.

Recording time

If you are compiling a disc from several recordings, you have to be sure that they will fit! You can determine the approximate length of the recordings by timing them, or by adding up the printed timings - if any. (These are rarely given for gramophone records, either on sleeve or label.) But do not rely too much on your figures. Record turntables and tape decks often show small but significant long-term speed variationsYou cannot reliably determine the overall timing to within seconds, even when you make the recording immediately afterwards. Leave a sensible margin for error.

Compiling a CD for equipment testing

With a CD recorder, it is easy to compile your own test CD from other CD test recordings, and it will be accurate enough to be useful. (Recording a test signal via an analogue chain cannot be accurate: it merely gives a snapshot of your equipment and the level is at the mercy of you and your gain control.) The advantage of making such a compilation is that you can determine the order and duration of the items. This can save a lot of attention-destroying effort on disc changing and juggling with the repeat button. You should, however, plan the recording with the original recording's warnings about exposing your ears and your equipment to prolonged test signals in mind. You can incorporate tests from analogue sources on the same CD (for example, you may have LP test records with 'quad' decoding tests, etc.), but identify them clearly as being analogue and less accurate.

Review (Philips CDR 870)

Philips CDR 870

CD-Rewritable/CD-Recorder

It's here at last, and it works extremely well. The Philips CDR 870 is the world's first machine offering consumers a CD recorder that can erase previously made recordings and re-record "many hundreds of times over". Although eclipsed by the blanket media coverage of DVD, the catch-all high-density 5in disc system finally poised for launch this spring, the CD-RW (ReWritable) disc has been quietly taking shape. The CDR 870 costs 499.00 complete with a starter pack of four blank CD-R discs and one CD-RW disc, as I was able to confirm by briefly visiting the distributor's website to find a six-page description. Of primary interest for its unique ability to handle CD-RW discs, the CDR 870 in a way resembles a Russian doll: wrapped up in its surprisingly slim-line chassis (only 75mm high) are two generations of backwards compatibility. It works equally well with standard CD-R (Write Once Read Many times) discs, greatly undercutting the selling price of rival CDR machines, and of course it does duty as a high-specification CD-Audio player.

At least to begin with, blank CD-RW discs are rather expensive at about 18 each and are perhaps best seen as an efficient short-term storage medium. At one time CD-R discs used to cost this much but have worked their way down towards 3, making them a cheaper option for permanent collections compiled from favourite CD tracks or other audio material. CD-Rs also have the advantage that, once 'finalized' with a Table of Contents, they will play on any conventional CD player, whereas CD-RW discs, because of their lower reflectance, can be played only on CD-RW machines. However, Philips says it will integrate full CD-RW playback capability in future generation CD players, and they expect other manufacturers to follow suit.

The designers have been at pains to make the CDR 870 extremely easy to use, and it is certainly not necessary to have a deep understanding of how these miracle new discs actually work. However, a few words of description are surely in order.

The good old CD-Audio, now celebrating its 15th birthday, has a simple spiral track of digital 'pits' pressed into the upper surface of a transparent polycarbonate substrate. This is overlaid with a metal reflecting coating and a protective lacquer. The pits are 'read' by a sharply focused laser beam: the pits modulate the reflected light to reproduce, after decoding, the original bitstream of the digital music signal. All that is then needed is a digital-to-analogue converter to supply a suitable audio signal for connection to a hi-fl amplifier and loudspeakers.

Both the CD-R disc, which has been around for only about six years (see, for example, our review of the Meridian CDR recorder in the May 1992 issue) and the new CD-RW disc are somewhat more complicated. There is an extra area prior to the usual lead-in, comprising a Program Memory Area to store the track numbers of the recorded items and their respective start and stop points, and a Program Calibration Area to allow a brief trial recording to be made for Optimum Power Calibration (OPC) each time the disc is loaded. In fact, the required laser energy is constantly optimized by running OPCs during recording to deal with dust, scratches, etc.

The CD-R disc has a gold coloured dye-based recording layer with a reflectivity of 40-70%. The CD-RW uses a reflective aluminium phase-change recording layer with a reflectivity of 15-25 per cent. The colour difference helps with the very necessary business of recognizing which disc type is being used, and Philips have devised very different labels and liner card designs for each, as well as CD/Recordable/Professional and CD-ROM variants, to try to avoid any confusion.

Both types of disk are 'pregrooved' during manufacture to ensure that the recorder follows the same spiral pattern as an ordinary CD, with ideantical track width and spacing. In addition there is a superimposed sinusoidal excursion at 22.05kHz to control the linear speed and provide an absolute time reference. For CD-R recording, the laser beam 'burns' pits in the recording layer by momentarily heating it to 2500C. This causes tiny areas of the layer to melt, reducing its volume, and allows the substrate to expand to fill the space. The recording layer in a CD-RW disc consists of an alloy which is normally in a polycrystalline state. Heating impulses from the laser change the material into a non-crystalline amorphous state which has a much lower reflectance than that of the 'land' between the pits. The resulting track can produce a readout signal similar to that from a standard CD and is equally robust.

The CD-RW process is reversible and so the recording can be erased using an annealing treatment to return the alloy to the crystalline state, by heating it to a temperature of about 2000C for an extended period. This may take up to 37 minutes for a complete disc but there is a faster 'on the fly' erasing facility to eliminate the last recorded item by simply erasing its subcode reference. Alternatively, there is an overwrite procedure which combines the write and erase techniques. This burns in new 'pits' as required while applying a lower-energy non-pulsed laser beam to write new crystalline 'lands' with any previous data erased.

Construction

The CDR 870 thus comprises three different functional elements. First there is the playback path which routes the digital signal data either through the D/A converter and error correction, where necessary, to a standard pair of analogue output sockets, or direct to a digital outlet (both coaxial and optical outlets are fitted) for connection to an external DIA converter or digital recorder. Analogue and digital connecting leads are supplied.

Second comes the recording path which begins with either the conventional pair of analogue input sockets feeding an AID converter or a choice of coaxial or optical inlets bypassing the AID. A built-in sampling rate converter accepts digital signals with any sampling frequency in the range 15-56k Hz, including the standard rates 32, 44.l and 48kHz, and converts them to the CD standard 44.l kHz.

Third is the CD-R/CD-RW mechanism employing a high-power laser source to provide the special write and erase functions, with very precise tracking capability and extra electronics to respond to the preformed spiral track control signals. Attention has been given to the need to prevent unauthorized copying (as demanded by the music industry). As well as the familiar SCMS (Serial Copy Management System) fitted in all consumer digital recording media (DAT, DCC and MD) to inhibit copying of a copy, the CDR 870 has RID (Recorder Unique Identifier) which records a 97-bit code every 100 frames identifying the brand name, type and drive number of the machine used to record the disc.

The recording procedure is basically the same for both the CD-R and CD-RW discs, which are recognized and displayed as "Recordable" or "Rewritable" as soon as the disc is loaded. The display also indicates the number of tracks and total duration of any previous recordings. Pressing Record shifts the head to the end of the last recorded item, displays the new track number and enters the Reoord Standby mode. A touch on the Play button starts the recording.

An Input button toggles between the analogue and coaxial or optical digital input sockets. A digital source is to be preferred, for example the digital outlet now found on many CD players, not only because there is then no need to set recording level but because track numbering can be automatically entered from the digital source material. If required, however, Manual track numbering can be selected instead, and requires a tap on the Record or Track button at each new track location. The Stop button will stop the recording, or recording stops automatically if a 20-second silence in the source material is detected. Pressing Display at any time will show how much recording timc is left.

Recording from the analogue input requires the playing of the source material briefly in the Record Standby mode while adjusting the Record level knob for peaks just short of the 0dB meter reading. This is normally a short exercise, and indeed the chosen setting will normally remain valid for all subsequent recordings from that source. The music to be recorded can then be cued up as necessary, and the recording started as described above. Auto or manual track numbering are again options but, paradoxically, auto numbering can be a nuisance when recording classical music from an analogue source because any very quiet passages lasting more than three seconds will be interpreted as a track change and given the next number in the sequence. To avoid this, manual keying in of incremental numbers can be used as the recording proceeds.

A CDSYNC feature provides one-button synchronized start of a recording from a digital source, either of a single track or all tracks. When either a CD-R or CD-RW disc is fully recorded, a process known as Finalizing must be performed, by pressing Finalize followed by Record, when the approximate time needed for finalizing is displayed. Once a CD-R disc has been finalized, it can be played on any CD player but no further recording on that disc is possible. A finalized CD-RW disc can be played only on a CD-RW machine and must be completely erased before re-recording.

Playback procedures are standard for all three types of disc, and made even more user-friendly by the remote control which duplicates all the above-mentioned functions such as Track lncrement and Finalize, and additionally provides direct access to individual tracks from the numbered keyboard. Pressing the Display button switches from Track number and elapsed time to Track time remaining, Total time remaining or Level Meter off. Fast search can be at twice or eight times normal speed; Repeat Play applies to a single track or the whole disc or programmed sequence (up to 20 tracks); and the Recording mode can be used for up to 99 individual tracks.

 

Performance

Having the Gramophone Awards cover CD to hand, I began to evaluate the CDR 870's performance as a straightforward CD deck. Of course I was already very familiar with the opening track, an excerpt from Dyson's The Canterbury Pilgrims (Chandos 0 CHAN9531, 7/97) as I remembered agonizing over comparisons of this recording with the other excellent short-listed CDs in our run-up to selecting it for this year's Engineering Award. The Philips machine produced excellent sound quality with very wide frequency response and true-to-life dynamics: so much so that I again ran through the original two-CD set as well as the other, equally revealing tracks on the sampler disc.

In fact, Philips claim to have employed a state-of-the-art CD mechanism including a die-cast transport, their latest one-bit SAA7366 MD converter and, unlike DCC and MD, no data compression. I can certainly state from extended listening that the unit performs the CD player role handsomely, and this was confirmed by test measurements. Response from 20Hz to 20kHz was virtually flat, though with an insignificant rise to about +0~5dB from 6kHz upwards, and playback signal-to-noise ratio was 105dB as claimed.

I then played the sampler CD and others on a high-quality CD deck connected into the CDR 870 both as an analogue and a digital source. A note with the review machine advises new users to make their first recordings with a re-usable CD-RW disc. I was happy to follow this advice because, of course, it allows one to become proficient at the admittedly simple operations - and rub out any mistakes afterwards. This is in marked contrast to the CD-R system which is very unforgiving of operational hiccups that remain on the disc to haunt you evermore.

I am bound to say that recording on to both disc types came as near to sonic cloning as makes no difference. Strictly speaking, there was a suspicion of a less spacious quality and less bite from the analogue-sourced recordings, but the difference was tiny and doubtless a function of my input equipment. Transcriptions I made from good quality LP records and off-air were very successful and virtually impossible to distinguish from the original. Again interestingly, the tiny high-frequency rise I had measured on CD playback was identically mirrored on record/replay for both CD-R and CD-RW discs.

This leaves me to conclude that Philips are offering a powerful recording facility to domestic consumers. The machine is moderately expensive but not unduly so for anyone seeking this menu of options: it will play CDs to more than acceptable standards; tidily recorded CD-R discs can add, at little expense, one's own choice of programme material from any source to place alongside a collection of CDs; the CD-RW discs offer operational flexibility and re-recordability, but at a price and of course cannot be played on ordinary CD players.

There remains the question of timing: has this versatile deck and the whole CD-RW idea come too late (except perhaps in the computer context)? I have a sneaking feeling that if affordable CD-R and CD-RW had surfaced a few years ago, the DCC and MD formats would never have seen the light of day. As it is, consumers have been made chary of investing in new media and DVD now seems likely to burst forth, though initially as a high-density video medium, any month now. In-fighting is still taking place as regards a final DVD-Audio specification, and this might delay its appearance for a year or two. Still, CD-RW has this media uncertainty to deal with, and I wish it luck.

John Borwick's Review of CDR 870, Gramophone, January 1998, pp.118-22.

(A short specification table is omitted.)