Installation manual

Instructions for setting the Threshold control of the compressor.

The compressor’s threshold control is relatively easy to set as long as one understands

the various electronic “blocks” involved. Please read the following text carefully.

RA can be considered simply as a pre-amplifier, with variable gain (the front panel volume

control) and a compressor circuit whose threshold has nothing to do with the amplifier

which drives the sub woofers or where the gain setting is on the amplifier. The threshold

control’s setting is entirely dependent on the output level of the head unit (HU). It is not

affected by the volume control of RA.

In this example setting the volume level on the HU to some arbitrary level will send a

signal of say 0.4v on musical peaks from the HU to RA. Whether the Sub Harmonic

Synthesizer is used or not does not affect this example. RA will amplify this signal by

12dB (4 times) to a level of 1.6v peak. The compressor’s threshold control now uses this

1.6v peak signal to activate the compression system and the threshold control simply acts

as a “volume” control for the compressor. It takes the 1.6v signal and depending on the

setting of the threshold control instructs the compressor to activate and begin

compressing the signal. Only when the on the front panel turns on does

compression begin. The volume control on the front panel simply controls the output level

of RA.

Now we must set the amplifier’s level control so that all the parts work together.

All Zed amplifiers have LEDs on their front panel to indicate that the amplifier channel is

clipping. Our mono blocks have four LEDs set at 0dB (rated power), -3dB (half rated

power), -6dB (one quarter rated power and -9dB (one eighth rated power).

In our example we have decided to have the compressor come in at say -3dB. How do we

set up the various controls....easy!

With NO compression set the Hu’s volume control to the highest level you are comfortable

with (suggestion about 85% of the maximum). Do the same with the volume control on

RA. Now set the level control on the Zed mono block to a level where the -3dB LED is just

lighting on the loudest musical peaks of your favourite bass CD. Now set the threshold

control that the on the front panel turns on at these loudest musical peaks. If

you want some extra compression (tighter bass) advance the threshold control so that the

LED lights more often or even stays solidly lit (lots of compression).

If you set the level control on the amplifier so that the 0dB LED lights and you use the

compressor, the net result is twofold, you have compression and you prevent the amplifier

from clipping.

RED LED

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