[sdiy] Ele4Music (EFM) VCA 6b issues...

[Julian]

Hello,

I know its a bit late in the day, but i actually still have a stack of Tom's boards left to go...

Todays one is the VCA 6b.

Supprisingly it seems to work, pretty much, without issue, with a couple of exceptions - a 100k resistor has to be added to the AC 
input, as the board is not actually as per the schematic, and there is no resistor between the capacitor and opamp.  Without this 
resistor, the AC and DC input levels are very different.

So, thats that bit, but, where im having issue is the gain.

What im wanting is, with no additional voltage at the CV jacks, the gain to be simply controlled by the VCA level pot, such that, at 
minimum, there is no signal, and, at maximum, there is unity gain.

This isnt the case though, and, unless ive made an error that i havent spotted, theres nowhere near unity gain (the output level is 
a fraction of the input), and im wondering where would be best to alter the values.

Ive just uploaded the schematics to here -

 http://www.zen9084.zen.co.uk/vca_6b.pdf


Should i do R17 / R34, or R7, R24 (or indeed somthing else), and is there any real reason why one, rather than the other?

Thanks, Julian