Anyone modded a Glockenklang 2-band onboard pre-amp?

[JapanAxe]

I have a Sandberg bass factory-fitted with an onboard 2-band pre-amp. I have noticed that the treble control does not give the same amount of cut as on a passive P-bass, regardless of whether the Sandy's controls are set to active or passive. I am guessing this is some sort of compromise to make the control effecrive in both modes.

I am therefore wondering about increasing the cap value on the treble control, although I realise this may screw with its performance in other (unpredictable) ways. If I can identify the right cap, I can just experiment by solder-tacking a succession of different caps in parallel with it, until I get the result I want. However, I would prefer to know what I am doing from the start!

So... Does anyone have a schematic for the Glockenklang 2-band? Anyone tried this or other mods? Any other words of wisdom (other than 'don't do it, you'll break it')?

[EBS_freak]

In short, you can't make one solution fit all where std passive/active circuity is involved. Everything you do is a comprimise. It wouldn't surprise me if the current preamp is already set at that perfect comprimise point.

I'd never buy an active bass wanting a quality passive mode... the two are mutually exclusive. Short of having two sets of wiring looms and controls in there, one for passive, one for active, I think you are a bit stuck.

[JapanAxe]

Aha! But such a thing does exist - my G&L has passive tone controls plus a switchable pre-amp, perhaps not quite what you were thinking of, but still...

Anyway I will be experimenting when I have a couple of hours spare. Would still appreciate a look at the schematic mind!