What The PAQRAT Is

Technically, the PAQRAT is called the RC 24A or the RC 24T, depending on which MDM format you're using. It is a Black Box that takes in a digital stereo signal (both AES/EBU and SP/DIF formats are provided for) and converts it into the appropriate MDM format. In my case, that's ADAT and the output is optical, which is sent to the ADAT for recording. Upon playback, the ADAT optical signal is sent back to the PAQRAT, where it is reassembled into an AES/EBU signal and presented to the AES/EBU output.

It is (almost - see the sidebar) that simple and straightforward!

How It Works

In Principle

It takes four MDM tracks to store a stereo 20-bit signal. In fact, the PAQRAT will handle a 24-bit signal. The 16 most significant bits (MSBs) of each channel of the stereo signal are sent to the odd channels of the MDM set, and the remaining 8 least significant bits (LSBs) plus a -20 dB reference tone are sent to the even channels.

There is a switch to select whether you record on channels 1-4 or 5-8 or both (for a safety copy if you are archiving - a truly nice touch!). Naturally, you can select playback of either 1-4 or 5-8.

The only other control is a switch to select re-dithering, so that if you are recording the output of the PAQRAT to a normal 16-bit system, the device will properly dither the signal at the 16th bit, heading off possible problems with an un-dithered signal.

In Practice

You patch the AES/EBU or SPDIF output from your A/D converter or other digital source into the PAQRAT, and select that format on the front panel. You patch optical lines from the PAQRAT to the ADAT and back (with the DA-88 you patch word clock and multi-pin connector). You verify that you are getting 16-bit or greater words, verify the language and the sample rate (all displayed on the PAQRAT). On the ADAT you select Digital In. On the PAQRAT you select whether you are going to record on tracks 1-4, 5-8 or both. Arm the ADAT, verify you have levels (all the armed even-numbered tracks will show a -20 dB level on input), hit record 'n play and you're in business.

To play back, you simply rewind the ADAT, select which four tracks you want to play (1-4 or 5-8), patch the PAQRAT AES/EBU digital out to your converter or whatever, select 16-bit re-dither if you want it (see below), and hit play.

It's that simple.

A minor limitation: don't get tempted to try to use your PAQRAT with ADAT as a 4-track. You can only record or play back two tracks at a time through the PAQRAT from an ADAT. This is not, to my way of thinking, a problem.

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