Active /Passive bass bypass switch Help needed!

[lowergroove]

I've found a few different schematics and write ups about an active /passive bypass switch but even the SD one on the web site isn't what I'm really looking for.

I am using SD 67/70 passive basslines pickups and STC-3P pre-amp.

I want to install either a DPDT or SPDT on/on switch (whichever works best) for the active /passive option on this bass.

It's a custom build and I want it true bypass so the preamp is completely out of the circuit when it's in passive mode.

Does anyone have a complete drawing, preferably in color of how to accomplish this with the SD parts I specified.

I can solder quite well but I'm more of a wood whiz, though I'm trying to delve more into electronics with my new company.

Help would be greatly appreciated!

Thanks in advance, Steve

 

[DrNewcenstein]

Re: Active /Passive bass bypass switch Help needed!

So you just want to be able to send the passive pickup to the preamp and then to the output jack with one switch option, and with the other send the passive pickup signal directly to the output jack?

Should be pretty simple - wire the pickup directly to the switch, then the switch's "passive only" side would go straight to the jack and the "active" side would go to the preamp.

If you wish to add passive volume and tone controls for the passive option, you could do that as well.

Since the signal from the pickup is being directed to either option exclusively, it should provide true bypass functionality since you're removing the pickup from either path with the switch.

 

[lowergroove]

Re: Active /Passive bass bypass switch Help needed!

Welcome to the forum.

Pardon my senility but I have never heard of SD Basslines 67/70 pickups.
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=active_passive_switch

Sorry the 67/70 is called the SJ5-67/70 The numbers refer to the width of the string spacing the pickups will accomadate.

The wiring diagram direct from SD (comes with the pre-amp) for the STC-3P does not contain any other info on how to wire in a passive switch for the pre-amp. I've used these on 20 or more basses now and this is the 1st that requires a passive switch installation.

And yes, I am trying to isolate BOTH of the passive pickups from the preamp using a DPDT mini toggle switch.

ON- to pre-amp only
OR
ON- to passive pickups only

I hope I claified, Thanks

 

[lowergroove]

Re: Active /Passive bass bypass switch Help needed!

And the link you supplied I already have but I'm told it's not true bypass, not what I'm looking for but thanks for the help.

It also doesn't tell you how to wire it from the pre-amp or what wires need to be cut or added in the process. It assumes you know what to cut or add etc.

Thanks to all.

 

[DrNewcenstein]

Re: Active /Passive bass bypass switch Help needed!

To get true bypass means you're removing the preamp from the path between the pickups and the jack. If the preamp has integrated volume and tone controls, and these are the only volume and tone controls in the bass, then you will have to wire the pickups to the mini-toggle so they split out one way to the preamp and the other way out to the jack directly.

If the volume and tone are not integrated with the preamp circuit, and the pickups are wired directly to the pots, and then the pots to the preamp, then you would put the wire that goes from the pots to the preamp on the switch, and the other side of the switch would go directly to the jack.

Otherwise you'll have to modify the preamp itself for true bypass.

 

[lowergroove]

Re: Active /Passive bass bypass switch Help needed!

I found an Active/passive wiring diagram on guitarelectronics.com called

WIRING_MOD_SW003

And it seems like exactly what I was looking for. They say it will work for several brands and is a true bypass if wired correctly.

thanks to all for your help, Steve

 

[bobb]

Re: Active /Passive bass bypass switch Help needed!

I found an Active/passive wiring diagram on guitarelectronics.com called

WIRING_MOD_SW003

And it seems like exactly what I was looking for. They say it will work for several brands and is a true bypass if wired correctly.

thanks to all for your help, Steve

I'm new to the site. I'm trying to wire a bypass as well. Did the switch from guitarelectronics.com work? Can you post a diagram of what you did? That would be super helpful. Many thanks, Bob