Document revision 1.1 – Last modification : 27/06/11
Step
Description
9.
Clip LED setup
Warning
: Do not forget to set your 48V phantom switch to OFF.
This setup will be based on voltage levels rather than on actual clipping because, in tube
preamps, the clipping comes in very progressively and it is difficult to hear.
Connect a 1KHz sine source to the input.
You can use your multitrack software loop playing a sine tone like the one that is
downloadable from the “Downloads & Useful links” section on our website. Route the
signal to an audio output and connect your DMM to this output. The DMM is set to AC
Voltage, on a 100 millivolts scale. Adjust the software output level in order to get
100mVAC. Connect this output your micpre input.
Set the gain potentiometer to 0 and the gain switch to High (top position).
Plug in power and wait 30 seconds.
Warning
: Use an insulated screw driver to adjust the trimmers.
Adjust P3 trimmer (Clip1) clockwise until it starts turning the LED red.
Now set the gain switch to Mid (centre position) and the output pad to maximum.
Increase the 1KHz level in software to 0.5V AC.
Set your DMM to a 20VAC scale and connect it on the output of the preamp, between
pins 2 and 3 of the output XLR.
Adjust the Gain potentiometer until you read 12.35V AC on the DMM. This is about
+24dBu.
Adjust P4 trimmer (Clip2) until it starts turning the LED red.
Plug off power.
Discharge capacitors.
10. Congratulations
You're done !
Copyright ©2008 SoundSkulptor
