How difficult to add an active/passive switch

[markdavid]

Hi guys and girls ,

I want to add a passive/active switch to my Ibanez SR900 as I would like to be able to use my bass without a battery and would also like to get a more old school passive tone sometimes , I want the switch so that when I switch to passive the active eq is completely bypassed but not the volume and pickup blend , I will be getting a local luthier to do this work for me , how difficult will this be to do ?

[Spartacus]

Heres a wiring diagram for the SR900


The pickups are buffered, the blend is after the buffers and 25k volume is after the preamp which makes it a bit more dificult to do if yiu want to keep existig preamp. the pot values are too low for the pickups to work properly in a passive setup. They might sound a lot quieter with no treble.

Edited July 10, 2009 by Spartacus

[markdavid]

[quote name='Spartacus' post='537035' date='Jul 10 2009, 09:22 AM']Heres a wiring diagram for the SR900


The pickups are buffered, the blend is after the buffers and 25k volume is after the preamp which makes it a bit more dificult to do if yiu want to keep existig preamp. the pot values are too low for the pickups to work properly in a passive setup. They might sound a lot quieter with no treble.[/quote]

Thanks for the help , obviously with what you have said regarding the pot values it may be better to add a switch that completely bypasses the tone and volume controls do you think this would be a difficult task?

[Spartacus]

[quote name='markdavid' post='537191' date='Jul 10 2009, 01:16 PM']Thanks for the help , obviously with what you have said regarding the pot values it may be better to add a switch that completely bypasses the tone and volume controls do you think this would be a difficult task?[/quote]

The sort of active/ passive switch youre looking at would bypass the tone controls anyway. it would be easy to add a switch that bypasses them but in passive setups the pickups need a decent resistance across them otherwise theyll have low volume and no presence. All of the pots seem post-gain so none are suited to connect directly to your pickups in a passive configuraton because their resistance is too low. One way to do it is to get your tech to rewire so the pups go straight into a 250k or 500k blend and THEN into the preamp buffer stage, remove the existibg blend pot, and install a SPDT switch to switch between output of the preamp and the output of the new blend pot.