arp avatar and 4075 filter probem

[steven thomas]

Hi everyone,
                   I recently  got an arp avatar that hasn't been used for 
almost 20 years (from a guitar player..no surprise there!)
Its working (well after having to replace  a CA3080 in the vca ) but I found 
that the filter's feed through is incredibly sensistive to the front panel 
freq slider, so making manual filter sweeps is almost impossible. I have read 
that there is a problem with sensistivity of the  sliders on Odysseys (recall 
the avatar contains the Odyssey  BII and CII oscillator/filter boards with 
4075 4-pole filter). Does anyone 
know a mod that can bring better resolution for the freq slider and 4075 
filter? As part of my plans to
mod the avatar (and make it patchable) , I have  build and installed  the 
truly excellent 40235 filter designed by Joachim Verghese at Arptech ..and it 
works really well (The '4023' part of this filter is stunning!)  But I also 
like the sound of the  4075 so I have kept that on the filter board and 
installed a three way slide switch on the front panel to switch between  the 
4075/4023/4035 filters. I guess I could play around with adding additional 
resistors to the freq slider when it feeds the 4075..but I am wondering if its 
as simple as that ..or is it a design problem with the 4075 itself? Have any  
Odyssey owners out there (with 4075 filter)  had similar problems?
Any help much appreciated !
 
cheers steve thomas

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