QSC Audio DSP-3 Manuel D’Utilisation

There are two audio channels each with two input connectors, a

balanced 3-pin ‘euro’ terminal block jack and an electronically

balanced DataPort input. The inputs are protected with a filter that

prevents radio frequency interference.   The inputs have software-

selectable full scale input level sensitivity;   this is the level at which

the analog to digital converters reach their full scale digital value.

Refer to the 

Specifications section for full details. The DataPort is

scaled to clip with a full scale digital input if the DSP-3 does not

change gain structure.  Each CODEC input is diode protected to

prevent any large signal from destroying its inputs.

The first stage the audio passes through is an inverting gain stage.

The second stage is a second order Butterworth low pass filter that

removes high frequency sampling artifacts. The signal is then sent

out of the DSP-3 through the DataPort or the output ‘Euro’ connec-

tors. The output level is selectable in software.

No external power supply is needed for use with the CX, DCA and

PL2 two-channel, 2 RU series amplifiers produced with  date-codes

of August, 1999 or later. With these models, the DSP-3 is supplied

power from the  amplifier  via the DataPort (HD-15) connection.  CX,

requiring the use of the same type of external DC supply as

used with Powerlight amplifiers.  The amps in question will have a

serial number PRIOR to 0899XXXXX, where the first four digits of

the serial number are the MMYY datecode.  Again, the modules

WILL work with these amps just fine, but will require the use of our

external power supply. External power is not required for all other

directly-mounted-to-amplifier situations.

When used with the Powerlight series of amplifiers (or 3 RU & 4-

channel amps), the DSP-3 requires use of the accessory external

supply. The accessory external supply is also used when connecting

to non-QSC amplifiers (or any amplifier that does not have a

DataPort). External power is provided by the accessory power

supply  (“wall wart”) via a coaxial power cord jack on the back of the

DSP-3.

The DSP-3 samples the I

MON

 and V

MON

 (current and voltage monitor-

ing from the amplifier) lines of QSC amplifiers (via the DataPort) in

order to perform dynamics (limiter, compressor, etc.) processing.

The four inputs (I

MON

 and V

MON

 for both channels) are continuously

sampled by a four channel ADC. When used with non-QSC

relies upon amplifier current and voltage feedback. The

DSP-3 will also not be able to monitor the protect or power status

of the amplifier as these features require amplifier data via a

DataPort connection.

One contact closure input is provided.  It uses pin 9 of the RS-232

DB-9 connector (not normally used for RS-232).  Shorting this pin to

ground with a maximum impedance of 1.3 kOhms will cause a

general purpose I/O pin of the DSP to be pulled to  a logic low.  The

current release of Signal Manager software uses this input to allow

switched gain functions. Each of the Switched Gain blocks will be

switched simultaneously by the single contact closure (switch).

Each Switched Gain block has a two gain settings; one for open and

one for closed switch conditions.