Adjusting Infinity IRS servo controller


I got a request from @bobterry99 about adjusting Infinity servo controllers.  Inside the controller are 4 pots:

Left side level (amplitude)

Left side DC offset

Right side level (amplitude)

Right side DC offset

See the attached photo.  I used a 2 ch oscilloscope to monitor the input and output while adjusting.  With 4 ch, you could monitor both channels...

 

jtucker

Unity gain seems aesthetically pleasing to me.  I made new measurements. 

For listening I have the LOW FREQ LEVEL control set to around -8.  For new adjustments I set it to zero.  With each channel being driven by 18 mV I measured 21 mV output. 

With the right-channel R30 already dialed fully CCW the only way for me to achieve unity gain was to increase the ovarall amplifier feedback via R23.  Dialing each channel's potentiometer a little clockwise gave me unity.

With this done I still have to set the LOW FREQ LEVEL to around -8 to achieve a flat frequency response as determined by sound pressure readings using an app on my phone.  I think that's odd.  It's as if the woofer towers are vastly more efficient than the high-frequency panels.

Which version of the servo and which speakers?

BTW, I am looking for a reputable shop to go over my spare servo controller (IRS Beta) to make sure its all up to design specs

I had the IRS Gammas.  Sold them back in 2010.  I did a fair amount of work on the my servo controller plus another one (anybody remember Bobby Shred?), but since I am retired now I no longer have access to an electronics lab.

Is there anyone who can provide a copy of the settings/manual for the IRS servo amp. I have a Genesis 2 system and the amp should be checked out to insure it is performing properly. I figure that it may give some insight for myself and others. Does anyone know who made the amps or can service them properly? All help is appreciated.

 

Mark