ST Audio DSP24 ADAT, Manual

ST A

UDIO

 DSP24 ADAT 

- 27 - 

The 

Clock And Sample Rates (Hertz)

 section allows you to select the source of the 

clock for the DSP24 card. You can select between 

Internal Master Clock

 and 

External Master Clock

. Make sure to select 

External Master Clock

only

 if you are 

recording or monitoring from the ADAT or S/PDIF input of the card. In that case, 
the device that is connected to the input will supply the clock for all operations you 
perform with the card. If you select 

Internal Master Clock

 (default), the clock 

generator on the card will generate the samplerate. You will have problems with 
noise and clicks in your audio signal if you have selected external clock without an 
active device (DAT, MD, digital mixer, etc.) on the digital input. Also you will 
have similar problems when you want to record a signal from the digital input with 
the card set to internal clock. 

The section of the 

H/W Settings

 dialog also shows the current sample rate of the 

card, which has been set by your application software. The samplerate selected here 
will be used for all functions of the card. This includes the digital output, so if you 
sync an external device (MD, DAT, digital mixer, etc.) to the DSP24 card, it will 
use the clock that is selected here. The 

Rate Locked

 option is used to force the card 

to a specific samplerate. It is disabled by default (which is also our recomendation) 
which automatically allows your application software access to all supported 
samplerates. When the option is enabled, your software will only work with the 
selected sample rate. This means that any application that attempts to use the driver 
at a different sample rate will show an error message. 

Reset Rate After Play

 should 

be selected when you want the sample rate to return to a specific setting after 
software has finished using the card for playback and/or recording. This is 
especially important if your external device that is connected to the digital output of 
the card, is synced to the DSP24 card. If you just use the analog outputs, the 
selected samplerate and the 

Reset Rate After Play

 option are not important when 

the card is not used by your software at the moment. 

Keep in mind that the ADAT protocol does not support higher sample rates than 
48kHz. This means that you can only select 88.2 and 96kHz when you are working 
with S/PDIF signals. 

Device Settings 

The 

Device Settings

 tab controls the 

options needed for playback and 
recording.  

Under 

Waveout Driver

 you can 

select the 

MME/ASIO

 buffer size 

(latency). The smaller the selected 
value is, the smaller the resulting