Audio Equipment

R-DAT

The R-DAT (Rotary-head Digital Audio Tape) format, while quite popular in the mid 1990s, is slowly disappearing from the marketplace. Very similar in design to a VCR (video cassette recorder), only much smaller, this device uses a R-DAT cassette tape which measures 2 7/8" x 2 1/16" x 3/8". A variety of lengths are available which permit continuous recording or playback for up to two hours. This linear PCM-based (uncompressed data) recording system offers very ultra-low distortion levels and is immune to speed errors, tape noise (hiss), and nonlinear frequency anomalies (within its usable bandwidth) which is typically 20Hz-22kHz.

Portable R-DAT recorders are small and relatively lightweight making them very easy to carry around in the field. Features include real-time tape counters, the ability to stamp the current date and time on the tape automatically (available on certain models only), and a built-in indexing system which allows the operator to mark and quickly access the starting points of up to 99 selections. Professional models also offer low frequency filters, 48-volt phantom powering for microphones, and incorporate high-quality microphone preamps.

Although it appears from the above information that R-DAT is the answer to all field recording problems and needs, there are problems and pitfalls that one should consider before purchasing an R-DAT machine.

1. Most of the inexpensive digital recorders being sold today do not allow off-tape monitoring (the ability to monitor a recording as it is being created). Read-after-write, or confidence playback heads, are not commonplace. Therefore recording problems cannot be detected during the recording process.
2. R-DAT is not a very robust tape format. R-DAT systems utilize a very narrow tape that is only 3.81 mm wide. Their extremely slow linear tape speed coupled with a rapidly spinning head assembly writes the data on the tape in a very compact form. Dirt, dust, or foreign debris that migrate into the machine can potentially cause recording problems. The R-DAT recorder has built-in error correction circuitry that does help offset many recording errors. However, very large errors can cause signal drop-outs or complete mutes. Needless to say, these problems could render a recording useless.
3. R-DAT recorders are not the most reliable units for operation in very high humidity (condensing) environments. Most R-DAT recorders have a "dew" or humidity sensor built in which shuts the machine down whenever high humidity is detected. Recording in the tropics or rainforest could therefore render the machine useless unless proper precautions are taken.
4. Some R-DAT machines utilize non-standard rechargeable NiCad or NiMH batteries. The typical recorder will operate for approximately two hours per battery charge. This means many rechargeable packs must be carried and kept charged to allow for lengthy recording trips. Other possible means of powering are available from sealed rechargeable lead-acid batteries (described in a later section), or standard drycell packs which can be adapted to work on certain machines.

Nonetheless, the features of the R-DAT recording systems are simply too great to be ignored.

The price range on currently manufactured portable R-DAT machines is between $795 and $3,390. Listed below are the units we have field-tested.

• HHB PDR-1000 PORTADAT   $2,790 (production discontinued 10/2000)
  This rugged professional machine offers read-after-write capability, date and time stamping, low frequency filters, phantom powering, and an internal playback speaker. High resolution backlit metering is provided. Professional 3-pin XLR-style connectors are utilized for microphone inputs and RCA phono jacks are used for outputs. Digital input and output capabilities are provided. Field powering is accomplished by proprietary, internal, rechargeable NiMH batteries, or via 12-volt DC external supply. A standard 4-pin XLR power connector is provided.
• Tascam DA-P1   $1,638
  This is the lowest priced professional recorder built for serious fieldwork. It does not offer read-after-write capabilities or low frequency filters; however, it does provide 48-volt phantom powering for microphones. A good high-resolution backlit meter is provided. Input connectors are professional 3-pin XLR-style, and RCA phono jacks are used for the outputs. Digital input and output capabilities are also provided. Field powering is accomplished by proprietary, internal, rechargeable NiCad batteries, or via DC external supply. A special power connector is required.
• Sony TCD-D10ProII   $3,390
  This rugged machine does not offer read-after-write capabilities, low frequency filters, or phantom power. It does offer excellent backlit metering as well as date and time stamping on the tape. A small internal speaker is also provided. Input connectors are professional 3-pin XLR-style, and RCA phono jacks are used for the outputs. Digital input and output capabilities are provided but require an optional specialized cable assembly. Field powering is accomplished by proprietary, internal, rechargeable NiCad batteries, or via DC external supply. A special power connector is required.
• Sony PCM-M1 $795
  This small pocket sized recorder is a pro/consumer device that was not designed for the daily rigors of field use, but will perform well in the field if handled with proper care. It does not offer read-after-write capability, low frequency filters, or phantom powering. Input and output connectors are 3.5 mm stereo mini-jacks that are not very robust. Backlit metering and automatic date-stamping on tape are provided. No internal speaker is provided so all monitoring must be done via headphones. Digital input and output capabilities are provided but require an optional specialized cable assembly. Field powering is accomplished by AA batteries, or via DC external supply. A special power connector is required.