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Marantz CDR631

CD Recorder By Paul White
Published February 2001

Marantz CDR631

Paul White tests the latest Marantz CD writer, which combines simplicity of operation with technical sophistication.

Unlike cheaper consumer machines that are forced to use more expensive blank media, the 2U CDR631 can use regular data blanks and will record to both CD‑R and CD‑RW discs. The CDR631 also has no truck with SCMS — the copy protection data is stripped from any incoming signals, but can be added back into the recording if desired — either to permit one generation of copying or to prohibit copying altogether. Sample rate conversion is also included to interface the machine digitally with 48kHz sources, though this is automatically bypassed for 44.1kHz inputs with an accuracy of better than 100ppm.

Both balanced and unbalanced analogue I/O is fitted, on XLRs and phonos respectively, switchable to either 0dBu or +22dBu. The one‑bit delta‑sigma input converters have a 20‑bit resolution, while the output converters have a 24‑bit resolution, but incoming analogue signals are truncated to 16‑bit after conversion, rather than dithered, as far as I'm aware. Digital input is provided on both phono (S/PDIF) and XLR (AES‑EBU) while the digital output is on S/PDIF phono and optical only. A further coaxial socket provides an S/PDIF Thru. An infrared remote controller is supplied as standard, though there's also the facility to use an optional hard‑wired remote via the RC5 phono on the rear panel.

The large wheel located to the right of the front panel provides control over both analogue and digital input gain (with ranges of +0dB to ‑63dB and +6 to ‑63dB respectively). The user interface is particularly good, and marshals not only the recording functions, but also comprehensive replay features — programmable play order, random play, repeat play, music scan and all those other things that you find on virtually every consumer machine. It's worth noting, however, that a number of these functions are only accessible using the included remote control.

The CDR631 has four different recording modes, three automatic and one manual. Whichever mode you're in, a three‑second input RAM buffer allows the CDR631 to avoid clipping the starts of tracks. In Record Track mode, recording starts following a Start ID and stops at the next one. In the case of analogue or AES‑EBU sources, the level detection is used to identify track starts, though S/PDIF uses the track start IDs of the original source. Record Disk mode is much the same, but recording stops when the source stops or after a period of silence. The default auto‑stop system used in the CDR631 stops recording after 20 seconds of silence (anything below ‑55dB relative to full scale). When using CD or Minidisc sources, the recorder stops within three frames of the source stopping — though if you're working from a DAT source then you'll still need to use the manual mode if you need to stop recording directly after the last DAT track.

A Make CD mode is optimised for copying complete CDs, transferring all track IDs and finalising the disk automatically upon completion. After recording in any of the other modes, the disc must be finalised manually. In the Manual record mode you can opt to increment tracks manually during recording, or you can set the CDR631 to detect track boundaries from the signal levels. While you can rely on the 20‑second auto‑stop function to terminate recording, if you wish, you do not need to, and this will be handy for recordings of classical music with extended quiet passages, or for 'trick' albums with long recorded pauses. You can also add CD text at the recording stage — for example, song titles.

Final Word

This really is a very simple machine to use, and the built‑in buffer means you can abort a recording within the first three seconds without trashing your blank CD‑R disk. When recording from an analogue source, the sound quality is excellent, while digital recordings are easy to do, given that no level adjustments usually need to be made — of course, if you're one of those people who think that lightly clipped audio sounds better, the digital input trim control will allow you to achieve this. This is a simple, virtually bomb‑proof machine that does exactly what it's supposed to do. For those whose studios aren't based around a computer, the CDR631 could be the perfect unit for backing up rough and master mixes, as well as for creating small runs of audio CDs for demo purposes.


  • Good interfacing facilities.
  • Buffer prevents clipped song starts.
  • Manual stop mode so long periods of silence can be recorded if necessary.
  • Can record CD‑Rs and CD‑RWs.


  • Threshold and shut‑off time for auto stop is not variable.


A sensibly priced CD‑R machine with professional interfacing options.