Synchronizing at high sample rates:
To record more than 12 tracks in the high sample rate mode, simply synchronize two HD24/EC-2 units together by linking them with an ADAT Sync cable (see page 24 of the HD24 manual). Up to five HD24s may be synchronized this way, allowing high-sample rate systems of up to 60 tracks.
Synchronizing two HD24s at different sample rates:
When synchronizing multiple HD24s (or an HD24 with tape-based ADATs) together, it is possible to have an HD24 record and play back a high sample rate Song, while other machines play back a standard sample rate Song.
In this case, the sample rates must be even multiples of each other (44.1 with 88.2 or 48 with 96 kHz).
For example, one HD24 can be running with 24 tracks of instrumental tracks at 48 kHz while a second HD24 records and plays back 12 tracks of vocals and leads at 96 kHz, for a total of 36 tracks simultaneously.
Depending on the software version of your HD24, a warning message may appear or the sample rate indicator may flash indicating the mismatch in rates, but this will not affect operation.
Inputs and Outputs
The inputs and outputs of the HD24/EC-2 are the same basic type as on a “stock” HD24: balanced 1/4” TRS jacks with a nominal +4 dBu level corresponding to –15 dBFS on the HD24’s meter. In most installations, there will be no difference in meter readings or levels after you install the EC-2.
However, there is a slight difference in the balancing circuitry that may affect some installations. The EC-2 features true differential inputs and outputs, with dual drivers on each output instead of the more common (and less expensive) “impedance balanced” (sometimes called “ground compensated”) method of balancing the outputs found on most audio gear (and on the original HD24 boards).
As a result, if you plug the output of the EC-2 into an unbalanced input, the nominal output will be –2 dBu, 6 dB less than if the EC-2 was seeing a true balanced load. This is normal operation and has no effect on the final quality of the sound...it only reduces the readings on the console’s tape return meters. To avoid this 6 dB loss, simply plug the outputs of the HD24/EC-2 into balanced inputs on the console.
