How to add passive tone control to active/passive bass??

[keytthom]

Hey, given this diagram...
[url]http://purgatoryshift.com/wc/WindowClippings_d394ef55bff146ccb7607d6e41376e6c.p ng
Do you know how i could add a passive tone control to it, after installing an active passive switch like this...



Any help appreciated

[line6man]

You can run it parallel to the output of the blend pot.

That is not the proper way to wire an active/passive switch.
Do it like this.

[keytthom]

Hey, Im useless as far as electronics go

Could you give me more of a guide on how to do it?

[SGD Lutherie]

You can't install an active passive switch like that because the volume control is 25K and wont work with the passive pickups.

So you need to replace the volume control with a higher value, like 250K or 500K, but that might not work well with the preamp.

The best solution is to wire the blend control to a 250K or 500K volume pot, and then to the input of the preamp. Take the output of the preamp and run it to the active passive switch, and not to a volume pot.

The passive tone control would wire up to the new volume pot, or at the output of the blend control.

Also that active passive switch you have is wrong. What you want to do is take the wire from the blend/new volume pot and switch it from the input of the preamp to the output jack. At the same time disconnect the output of the preamp from the output jack. It's also a good idea to switch the input of the preamp to ground when switching to passive.

Before you do all that you should make sure you actually like the sound of the pickups passive. So temporarily disconnect the output from the blend to directly to the jack (with the preamp disconnected from the jack). Then you will hear what the pickups sound like passive. Passive is not always better.

[line6man]

Originally Posted by SGD Lutherie

Also that active passive switch you have is wrong.

Exactly.

That switching will not work in any bass, because the volume pot is after the switch. Because of the impedance differences between the active and passive modes, either the volume will have no effect in active mode until the end of the rotation, or the passive mode will have very little output, depending on whether the pot value is high or low.

For proper active/passive switching, you need a pot value appropriate for the higher impedance passive pickup signal ran before the switch and input of the preamp.

[keytthom]

hey, i have the active/passive switch wired up how it is in the picture in the 1st post, and it seems to work ok :S

is it dangerous? or just not meant to work like that

sorry for my ignorance

[keytthom]

Oh, sorry just saw what Line6man put. and thinking about it, it is pretty quiet in passive.

Could, when you have time, you try and draw up a wiring diagram of what you are saying i should do?

im not sure i understand :S

sorry to be of bother.

[line6man]

Originally Posted by keytthom

Oh, sorry just saw what Line6man put. and thinking about it, it is pretty quiet in passive.

Could, when you have time, you try and draw up a wiring diagram of what you are saying i should do?

im not sure i understand :S

sorry to be of bother.

I can't see your original diagram any longer, the link is broken.

What you want is a simple volume-blend-tone setup with an active/passive switch, right?

[line6man]

Here is a VBT active/passive diagram, if this is what you wanted.

[SGD Lutherie]

Originally Posted by line6man

Exactly.

That switching will not work in any bass, because the volume pot is after the switch. Because of the impedance differences between the active and passive modes, either the volume will have no effect in active mode until the end of the rotation, or the passive mode will have very little output, depending on whether the pot value is high or low.

For proper active/passive switching, you need a pot value appropriate for the higher impedance passive pickup signal ran before the switch and input of the preamp.

I started writing my reply, got sidetracked emailing my wife her shopping list she left on the table here (smart phones are wonderful!) and then you come along with your one thousand and one wiring diagrams, just as I hoped you would.

You have quite a nice collection there.

[line6man]

Originally Posted by SGD Lutherie

I started writing my reply, got sidetracked emailing my wife her shopping list she left on the table here (smart phones are wonderful!) and then you come along with your one thousand and one wiring diagrams, just as I hoped you would.

You have quite a nice collection there.

189, currently.

Thanks.

[jesterbass]

Hey guyz, the last diagram is very informative. I have a question though, my bass has active pickups and both volume and blend are 25k. Should I use 25k as well for the passive tone pot?