Specifications

Setting Up The Processing

may not be immediately obvious. The HF clipping control (located in the band 4 limiter and clippers menus)

redistributes control of high frequency energy from the band 4 limiter into the following processing stage. For

the FM path this HF energy gets handled by the HF clipper but in the case of the look-ahead limiter this high

frequency energy can modulate the rest of the audio waveform and introduce a pumping type sound. If you are

using the processor to process for DUAL services (FM and digital) then you can use the shelf control to compen-

sate for pre-emphasis. If you are not using pre-emphasis (non FM use) then do check the HF clipping control if

you are experiencing excessive HF energy and/or pumping from the look-ahead limiter.

Composite clipper

The composite clipper in the DSPX's stereo encoder is highly over-sampled and allows you to gain an extra dB

or two of modulation loudness when using the multiplex output to drive your FM transmitter. The range of the

composite clipper is -0.5 to 2dB.

Here at BW we prefer to use the multi-band and final clipper to generate the required amount of loudness

because composite clipping introduces stereo crosstalk. When we do use the composite clipper we prefer to use

small amounts of no more than 1dB. A pilot protection filter is provided which will protect the pilot region from

contamination by composite clipping products.

Auditioning individual stages of the DSPX processing

When setting up the DSPX it is sometimes useful to hear the effects of the adjustments on that particular

processing stage. By setting the other processing blocks up in a certain way you can make it easier to hear the

effects of the one you are adjusting.

For example to listen to just the action of the multi-band limiters force gate the wideband and multi-bands AGC's

and back down the multi-band and final clipper drives. To hear just the clippers do the same but raise the limiter

thresholds to +6dB and back the drive down to -6dB. You can then up the drive into the clippers with the clipper

drive controls and mixer controls.