Paul White ponders the benefits of a DAT recorder with a 40kHz audio bandwidth.
You could be forgiven for thinking that one DAT machine is very much like another, but Pioneer's D9601 is not only a fully professional machine with balanced XLR analogue connections, both XLR AES/EBU and coaxial IEC958 digital I/Os and RS422 9‑pin serial interface; it also has the ability to record at twice the standard sample rate, by running the tape and the internal electronics at double speed. DIP switches are provided on the rear panel to allow the user to customise various interfacing parameters and, like some others in the latest generation of DAT machines, the facility is provided to record up to 50 characters of text along with the start ID subcode data so that track titles, for example, can be displayed during playback.
Another benefit of this particular machine is that if you have access to two of them, there's a double speed copy mode that lets you clone standard sample rate DATs from one machine to the other in half the usual time, and in a busy studio environment where you regularly need to backup DAT tapes, this could be a very valuable feature. The digital outputs can either pass on the high sample rate signal or down‑convert to the standard rate, and a user‑selectable copy ID system allows the user to specify whether the tape can be cloned freely, once only or not at all.
Using The D9601
Because the operational and subcode editing aspects of this machine are similar to those of other professional DAT recorders, I'll skip over the obvious stuff and get straight on with the listening tests. When working with a new tape, this should first be initialised to create a lead‑in section around eight seconds long, which allows the machine to build a table of contents, much as you might find on a CD.
In operation, the D9601 behaves much as a conventional DAT recorder, and as with the Tascam DA20, alpha‑numeric data is entered using the infra‑red remote control included. Even at the standard sampling rate of 44.1kHz, the sound quality of this machine is impressive, no doubt due in part to the pulse‑flow single bit D/A converter and the stable clock circuitry. If there's a subjective difference when you switch to the 96kHz sample rate, it's very subtle, especially on routine material. I thought I could detect a tiny difference in the openness of the stereo image, and the overall listening material seemed indefinably more comfortable, but this could simply be a case of the emperor's new clothes: perhaps I heard a difference because I expected one.
In Short...
You've really got to make up your mind why you need a high sample rate DAT recorder before going out of your way to buy one, and one of the best reasons for me is still the practical advantage of being able to make digital clones at twice normal play speed. For routine CD manufacture, I can't see any advantage in recording at the higher rate, though I'll be quite happy to listen to any reasons, either technological or philosophical, that anyone would care to raise.
The bottom line is that the D9601 is a reassuringly solid, friendly DAT machine with professional audio and digital interfacing as well as facilities for hardwire remote control and RS422 interfacing. As to the high sample rate capability, I feel that whatever benefits that might convey will not be fully realised until a high sample rate consumer format is released.
That Increased Bandwidth In Full...
The most interesting feature is obviously the ability to record at twice the usual sample rate, which equates to 88.2kHz or 96kHz as opposed to 44.1/48kHz. This pushes the audio bandwidth up to around 40kHz instead of the usual 20kHz, and though 20kHz is already above the upper hearing limit for most humans, it is generally accepted that if you cut out everything above 20kHz, there is a subjective difference in the way the sound is perceived.
This could simply be due to the way very high frequencies interact with each other to produce signals in the audible band, but other researchers claim that we perceive very high frequency signals in a way that can't can't be explained via conventional wisdom. In the case of digital systems, increasing the audio bandwidth helps avoid the side effects (often related to phase) of the very steep filtering, both analogue and digital, needed to produce a flat frequency response which approaches half the sampling frequency. Whatever the real reason, many of the people who use their ears for a living claim to be able to hear the difference.
At this point, you might reasonably ask why you need double sample rate recording, because ultimately, the results are likely to end up on CD with a standard 44.1kHz sampling rate anyway. If a standard CD is to be the ultimate destination for the recorded material, then I think it's difficult to find a counter‑argument to this. For high‑quality vinyl recordings, however, and for material that may still be needed when the next generation of high sample rate CDs comes along, high sample rate recording is a good idea — though arguably only when working with analogue mixers and multitrack tape machines.
Pros
- Professional balanced audio interfacing plus AES/EBU and co‑axial digital interfacing.
- Good external controllability.
- TOC and alpha‑numeric facilities.
- High sample rate option.
Cons
- Using the high sample rates obviously halves the available recording time from a tape.
Summary
Pioneer build some really nice DAT machines and this one is no exception. This model has an excellent range of facilities, including the ability to record at both standard sample rates and double rate.