appendix A • EC-2 96kHz A/D/D/A upgrade
EC-2 Manual A-7

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.