Alesis ALESIS M20 TUTORIAL 4: COMBINING M20S AND ADATS

Tutorials and Applications, Chapter 15

TUTORIAL 4: COMBINING M20S AND ADATS

M20 TRANSPORT SPEED

The M20’s transport speed is much faster in engaged mode than the original ADAT. Because

of this and other unique features, make the M20 the master (ID 1) and any ADAT(s) should

be the slave(s).

When locating, the M20 will locate to a specific tape position, stop, and wait for the ADAT(s)

to catch up. Therefore, until you need more than 8 tracks, don’t put any tape(s) into the slave

unit(s) so that the M20 won’t have to wait for the slave(s) to locate.

The M20’s Sample Rate function, which allows choosing between 48 kHz or 44.1 kHz

sampling rates, was not directly available on the original ADAT. This function also allows

selecting a digital clock for applications involving the recording of digital audio from a non-

ADAT source.

The M20 writes sample rate information when formatting a tape, so that it automatically

knows a formatted tape’s sample rate (even though either rate may be used).

Example: When playing back a tape formatted at 48 kHz with the sample rate set to 44.1 kHz,

the 44.1 indicator 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 play back a tape

formatted using 44.1 kHz with the sample rate set to 48 kHz; the 48 kHz indicator will flash.

The M20 Pitch Controls supplement the sample rate selection. With the original ADAT, you

had to pitch down a tape to play back at a 44.1 kHz sample rate. If you play back a tape that

was formatted on an original ADAT, it will not have any sample rate information written on

it. The M20 will automatically select the 48 kHz setting. If you had been pitching-down such

a tape to play at 44.1 kHz, you must press the Sample Rate button to manually change the

M20’s sample rate to 44.1 kHz.

The original ADAT was designed so that when monitoring a track’s input signal, you heard

the actual analog input ó the signal did not pass through the A/D and D/A converters.

There was an advanced feature, accessed by holding Set Locate and pressing All Input, that

allowed monitoring after the converters. This allowed hearing exactly how the signal would

sound when played back from tape.

The M20 monitors the input signals through the converters at all times (unless overridden as

described in section 8.6d). This creates a minuscule 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 M20, the M20’s delay 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.