Input Signal to BJT VCR for EF

[Rayman]

I'm using the PAIA 2720-3B circuit for a VCF (slightly adjusted for 9v power supply).  I'm using a BJT as a VCR to control the filter.  In order for the circuit to work properly, I need my input to the VCR to vary between .5v and 1.5v.  This seems right in line with a guitar signal, but I was wondering if there is a way to amplify a signal then attenuate it so no matter what the input is (guitar etc) the signal feeding the VCR will always be between .5v and 1.5v.

Any suggestions?