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Need help wiring a BTB w/ EQ bypass

K

Kermin VH

Aug 21, 2006
91
1
43
www.myspace.com
#1
Hi all!

I'm trying to figure out how to wire my Ibanez BTB675 with an EQ bypass switch (run it passive, in other words). I'd prefer not to have to drill any new holes in my bass, so I wanna use a push/pull pot if at all possible. I'd like to have the master volume and blend knob intact when bypassing the EQ.

Here's the link to the stock wiring diagram:

[Invalid or Expired Link Removed]

Also, would I need to change any of the pots to adjust for when I run it in passive mode?

Thanks! -Joe
 
#4
Hey Pollinator, I guess I should mention that this is my first wiring mod. I don't really understand how to use the diagram you posted. :( I'd really appreciate it if you (or anyone, for that matter) could help me figure out how to kinda "combine" the diagrams. I found that diagram in my own travels, but I'm completely ignorant of how to apply it. :help:
 
#5
The layout on the Ibanez website is quite chaotic, [DEL]but if I'm understanding it right you might have to put the balance control before the EQ, which might change the sound a little bit.[/DEL] OK, I was reading it the wrong way round :scowl: . I'll try to make a diagram for you with a simpler block representation (a rectangle that says EQ that includes all those pot, etc). It's almost like Ibanez doesn't want people to meddle with the wiring, but I'll try to post it sometime tomorrow if nobody else gets here faster.
 
#6
Poll.....

I'd like to do the same on an Ibanez SR400. The EQ circuit appears to be a bit different from the link, but if you post the wiring diagram For Kermin I can probably figure it out.

Thanks in advance

Jeff
 
#7
I don't know about turning push/pull volume knob to active/passive switch but I know how you can turn your ibanez bass to passive without any soldering. Only downside of this is you'll lose the tone control. (not a big deal if you like flat eq on the bass)

If you look at the blend pot, on the top left connector is the output of the two pickups. And if you look at the volume pot, on the right connector is the output coming from the preamp. Unplug these wires at the preamp and hook them together, your bass will become 100% passive.

Now you can make customization to have switches that can move these two wires around to achieve passive/active mode. But, I don't know if its possible to have the tone control to work once the preamp is bypassed since they are in different resistance.
 
#8
I haven't found a wiring diagram on the Ibanez site for your bass or my 2012 SR300, which appears to have the same config as the BTB. I used this diagram to convert mine. It's the closest I could find. The wires from the volume and balance pots are the only ones that count. ID them and you are all set.

SR300 Wiring Before-After.jpg
 
#9
Joe, a balance with 25k value is a sign of two things, one the pups are active (put the diagram doesn't show any connection to the batt for the pups), two the pups are wired to a buffer (which on the diagram looks like the way it is. Pups connected to board and than a blend after the buffer).

Going passive here is not a good idea…

IMO

M

ps: jc522 that's a different layout/pre
 
#10
Oh, maurilio is right. I didn't see that the pickups are going into the preamp first then goes through the balancer. That's not a good sign...
Your only choice for getting active/passive here will be buying a new preamp that has the bypass switch.

jc522's circuit seems sound since his pickups are going to blend first.
 
#11
Check my old thread, it might help you out: www.talkbass.com/forum/f38/bypassing-active-eq-spector-euro-906716/#post13021678

Basically follow the schematic i've drawn in Paint (the colors are random)

EDIT: If the volume pot is AFTER the preamp, you can still send the signal from the pups to a switch - which then will send it straight to the pre or straight to the jack, but in that case you'll lose volume and balance control.
 
#13
Don't mean to hijack this thread from Joe, but I have a question related to my mod.

I did the mod on my 2012 SR300. It's a different model than the SR300 in these wiring diagrams (has 3 tone pots), but the volume, balance and jack were originally wired as in the Switched diagram if you follow the Active path. The signal path is pup-balancer-preamp-volume-jack. The mod works very well.

My other bass, a 2010 SR300, is wired exactly as in the Before diagram. The signal path is different from the 2012 model. It is pup-balancer-volume-preamp-jack.

The Switched diagram changes that path to the same as the first instrument, pup-balancer-preamp-volume-jack.

Is there any concern that the volume pot on the 2010 model, which used to handle just the pickup voltage, might not be designed to handle the preamp output voltage?
I don't know if the volume pots are the same on both basses.
 
#14
Hey guys! Sorry I've been in absentia from my own thread, I've been bogged down with other responsibilities for a while.

Maurilio, according to the Ibanez website, they're passive Bartolini humbuckers. So unless Ibanez has the wrong info up there, they should be passive, and I should, somehow, be able to wire this thing up the way I want. I just have no idea how. :hmm: I read a blurb somewhere (that I unfortunately cannot locate now) talking about having to replace some of the pots to accommodate for running one in passive mode. That's where I got that in my head. Is there a value for the balance pot that would make the circuit happy regardless of whether I'm running active or passive?

Eukatheude, I really don't want to lose the volume and balance controls. If there is no way to do this mod without losing them, I'd rather just not do it, honestly. I feel like it kinda defeats the point of what I'm trying to achieve.

tjlee87, you bring up a very interesting point. Does anyone know of any preamps I could install that already have the EQ bypass feature built in? I'm not dead set on keeping the factory pre, I just want to be able to turn it off. I guess I should mention that I want to stick with a 3 band EQ.

Thanks to everyone for replying to this thread! Keep the ideas coming, please! Help my boneheaded self to find a solution to this problem...
 
#15
maurilio said:
Joe, a balance with 25k value is a sign of two things,

1- one the pups are active (put the diagram doesn't show any connection to the batt for the pups), Which means they are not active


OR/AND (I should have been more clear)



2- two the pups are wired to a buffer (which on the diagram looks like the way it is. Pups connected to board and than a blend after the buffer).

Going passive here is not a good idea…

IMO

M

ps: jc522 that's a different layout/pre
Click to expand...

I would not try to modify the OEM pre, not worth it.

3 band pre Aguilar Pope Bartolini Nordstrand… all can be configured with an active/passive ctrl
 
#17
Ah, ok! I see what you meant there, Maurilio.

Thanks, everyone! I think I may just invest in a new preamp. After taking into consideration massive amount of PITA I'm going to run into trying to get the stock pre to do what I want, I think it might be more economical to just bite the bullet and get a pre that's meant to do the active/passive thing. It certainly seems like the better way to keep my sanity intact! ;)

Thanks again to everyone for all the advice! I'll post about what I get when I install whichever pre I decide on.
 
#18
This is a bit of a stretch for me but....couldn't Joe use a 3P2T on-on toggle switch to route from pup to balance to volume as in the attached pic? My concern would be with teeing into the pup and balance outputs without isolating them from the pre-amp. Maybe not a concern? Or, with a 4P2T switch the battery could be disconnected, if necessary.

switched.jpg
 
#19
Now that I've modified both of my basses I noticed that the Groveline G104 has the same control configuration as mine, as well as Joe's BTB, with the addition of an EQ Bypass switch. Anyone know what that preamp package lists for at the Ibanez parts department? The part number is 3EQ2SC0004. It includes the pots which I'd guess might be fairly good quality considering the $3000 list for the G104.
 
#20
jc522 said:
This is a bit of a stretch for me but....couldn't Joe use a 3P2T on-on toggle switch to route from pup to balance to volume as in the attached pic? My concern would be with teeing into the pup and balance outputs without isolating them from the pre-amp. Maybe not a concern? Or, with a 4P2T switch the battery could be disconnected, if necessary.

View attachment 291656
Click to expand...

with a 25k blend those pups will sound very dark and low volume at the same time if you install a 250k the buffer will not work properly….

you can always try, if you really want….
 

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