Directed Electronics Model 350 Power Amplifier User Manual

Page 9

CROSSOVER SETTINGS AND GAIN ADJUSTMENT

Your Directed Audio power amplifier needs to be adjusted carefully to achieve
maximum performance. These are some guidelines to follow when fine-tuning
the amplifier.

• For normal complete system applications, the crossover selection switches should be

set to "HPF".

• The crossover frequency controls need to be adjusted to suit your particular system.

For subwoofer applications, try and keep the setting low enough to prevent image
smearing (you should not be able to hear male voices from the subwoofer) but not so
low as to create a gap between the subwoofer and the mid-bass/midrange speakers.
For mid-bass/midrange settings, try to keep the frequency low enough to keep your
sound stage in front of you, without overdriving the speaker. It will be to your advan-
tage to spend some extra time with these adjustments, listening to familiar music or
system set-up discs to achieve the kind of musical reproduction that you prefer.

• The gain adjustments allow you to set proper signal match for clean, quiet amplifier

operation. For full-range and simultaneous stereo/mono bass applications, start by
playing some music you are familiar with. With the gain adjustments on the amplifier
in the middle of their rotation, bring up the volume on your head unit to the 3/4
volume setting or until you start to hear distortion or clipping. If you hear distortion
before you reach the 3/4 volume setting of your head unit, reduce the gain settings
on the amplifier and start to raise the head unit volume again. When you can listen
to the music at or slightly above 3/4 on your head unit without audible distortion,
slowly raise the gain of the amplifier until distortion is heard, then back off the gain
until the distortion is not audible. This setting will allow you to reach full output with
all but the quietest of source material, while avoiding excessive noise in the system.
You may need to set the rear channels gain control lower to maintain a good sound
stage.

• The same procedure should be used for adjusting the amplifier when the on board

crossover is set to LPF or FLAT, but you will also have to take into consideration the
effect that gain adjustment has on system frequency response and imaging. Again,
plan on spending some time with music that you know getting the gain and crossover
settings the way you like. Test discs and analyzers may help with this process, but in
the end it's your ears that count - listen to the music !