Alesis ADAT-XT manual Combining XTS and Adats, XT Transport Speed, Sample Rate VS. Pitch Control

Multiple ADAT-XT Operation: Chapter 5

COMBINING XTS AND ADATS

XT TRANSPORT SPEED

The XT’s transport speed has been improved to be four times faster in engaged mode than the original ADAT. Because of this and other unique features, it is recommended that you make the XT the master (ID 1) in your system and your ADAT(s) should be the slave(s). Until you need more than 8 tracks, you may want to avoid inserting tape(s) into the slave unit(s). This is because when locating, the ADATs will move slower than the XT. The result is the XT will locate to a specific tape position, stop and wait for the ADAT(s) to get there before going into play.

SAMPLE RATE VS. PITCH CONTROL

The Clock Select function on the XT is another addition not found on the original ADAT. This function allows you to instantly choose between 48 kHz or 44.1 kHz sampling rates, as well as lets you select a digital clock for applications involving the recording of digital audio from a non-ADAT source). The XT also writes sample rate information when formatting a tape. This way, the XT automatically knows which sample rate a tape was formatted with although either sample rate may be used.

Example: When playing back a tape that was formatted at 48 kHz and the Clock is set to 44.1 kHz, the 44.1K icon will flash, to indicate that you are using 44.1 kHz but it isn’t the original sample rate used when the tape was formatted. The same goes when you playback a tape formatted using 44.1 kHz with the Clock set to 48 kHz; the 48K icon will flash.

It is important to remember that on the XT, the Pitch Controls are supplemental to sample rate selection. With the original ADAT, you had to pitch down a tape in order to playback at a 44.1 kHz sample rate. This is no longer necessary on the XT due to the addition of the Clock Select function.

If you play back a tape that was formatted on an original ADAT, it will not have any sample rate information written on it (since this is a new feature not found in the original ADAT). The XT will automatically select the 48 kHz setting in this case. Therefore, if you had been pitching-down such a tape to play at 44.1 kHz, you must press the [CLOCK SELECT] button to manually change the XT’s Clock to 44.1 kHz.

INPUT MONITORING

The original ADAT was designed so that when you were monitoring a track’s input signal, what you heard was the actual analog input being fed directly to the analog output—the signal did not pass through the A/D and D/A converters. There was an advanced feature whereby, if you held [SET LOCATE] and pressed [ALL INPUT], it would then allow you to monitor the input after the converters, so as to hear exactly how the signal would sound when played back from tape.

The ADAT XT lets you monitor the input signals through the converters at all times. Because of this, there is an extremely minimal delay as the digital audio passes through the converters’ buffers. If you were to listen to both the original signal on your mixer and the tape return of the same signal coming back from the XT, the delay of the signal coming from the XT would cause some phase cancellation when combined with the original signal. Therefore, it is important that you either monitor the original signal or the tape’s input signal on your mixer, but not both.

ADAT XT Reference Manual 63