This two-channel VU meter was made using the VUM-2 module and a PSU-12 module. It includes a front panel calibration control.

It was housed in an aluminium frame enclosure half a rack width and 2RU high. I used a 2RU aluminium panel cut in half to make the front and rear panels. The rear panel has two channels of input and output XLR sockets (the inputs are bridged directly to the outputs) allowing it to be placed inline with the output bus. An internal mains power supply using a PSU-12 module was used.

VU Meter front panel  A single stereo balanced input and meter driver module is used. The VU meter driver module consists of a variable gain amplifier (to allow input signal calibration) driving a current amplifier which drives the meter. The capacitor on the base of the drive transistor allows adjustment of the display ballistics a little.  


Two large Kyoritsu VU meters (with internal rectifiers) were using for this unit, however any VU meter should suffice. These did not have internal lamps so I added 4 yellow LEDs to provide some scale illumination. They are not high-brightness LEDs since the objective was to provide soft illumination for use in dimly lit situations.

 

VUM-2 Circuit (pdf) VUM-1 BOM (pdf)
VUM-2 PCB (pdf)  

 

Once the unit was assembled and tested, a simple timber sleeve was used to complete the housing.

VU Meter unit

 

 

 

 

 

 

 

 

 

 

 

Front of assembled unit

VU Meter rear panel

 

 

 

 

 

 

 

 

 

 

 

Rear panel