Rewiring active to passive

[alittlebitrobot]

Hi,

I've got a [url="http://www.dv247.com/assets/products/51326_l.jpg"]V940FL[/url]. It's active but I never boost the tone. I like active on fretted basses but not fretless.The tone knobs have a centre detente and that's exactly where I keep them, which raises some questions.
Q1: Are the pickups themselves active? If you look at the attached image, the pickups (thick white and thick purple) come to the balance pot (bottom left) first and then a couple of smaller wires go to the preamp so I assume the pickups will work without a battery. Is that right?
[attachment=147227:940wiring.jpg]

Q2: With so many wires in such a small space, it's difficult to know exactly what each wire is doing. I know there's no standardised wiring diagram really but, in theory, how does one "de-active" an active Eq? What I mean is, what's the least amount I can do to disengage the battery but still have the bass work? I'm just worried that if I desolder every wire associated with the preamp, it'd be a pain to reinstall if I need to one day.
Having said that, I really like this bass but they don't sell for much second hand so I'm not too worried if this is effectively a permanent change, as long as it works

Q3: This might be the most important one. Will doing this [i]necessarily [/i]leave me with that tone that I like? It seems reasonable to me that if I have the knobs set to zero, I'm bypassing the preamp (although it's still using the battery), so rewiring the battery out of the system should leave me with that tone. .....yes? ...I could well be wrong.

ANY help is appreciated. I will gladly accept links to old threads where this is dealt with instead of new replies, I just couldn't find any that were useful to me. If more photos would help, I'll take more tomorrow with my SLR instead of my crappy phone cam.

thanks

[LiamPodmore]

De solder the pickups, remove the entire thing, and then throw in one of KiOgons solderless looms. That way you can just pull it out and throw the active EQ back in if needs be. That's the simplest way of doing things, and what i did with my Ibanez.

Liam

Edited October 30, 2013 by LiamPodmore

[BigRedX]

1. Probably not. Very few pickups themselves are active (EMGs are the most common and even not all of them are), and although people make a big deal about active pickups, they are essentially normal coils and magnets pickups with a pre-amp/buffer circuit stuck to the bottom.

2. Your best bet is to follow the advice in LiamPodmore's post above and remove everything and replace it with a standard passive volume and tone pot for each pickup. IMO having an individual passive tone control on each pickup gives you more versatility than a cheap active on-board pre-amp that will just be doing what the controls on your amp should be doing, but not as well. If you remove the whole circuit and make a note of which wire from the pickups went where, replacing it at a later date will be fairly simple.

3. No, not necessarily. There is no guarantee that the centre dent point on any of the pots is actually "flat". It's just the centre point. Cheap pre-amps like the one on this bass will tend to colour the sound to some extent even if you do find the point on each control where the cut or boost is at a minimum. Even on high-quality units like the John East pre-amps there is a certain amount of colouration that occurs simply because the signal is passing through extra circuitry. Of course the same is true for passive as well. Wiring a pickup directly to the otput jack does not give the same sound as having it go via volume and tone control even if they are set for maximum volume and minimum treble cut. The extra circuitry in there always has some effect on the sound.

[BassBunny]

[quote name='LiamPodmore' timestamp='1383092825' post='2260227']
De solder the pickups, remove the entire thing, and then throw in one of KiOgons solderless looms. That way you can just pull it out and throw the active EQ back in if needs be. That's the simplest way of doing things, and what i did with my Ibanez.

Liam
[/quote]
Beat me to it.
+1 for this way forward.

[alittlebitrobot]

Ok, nice one. That all sounds pretty sensible, then. Thanks very much for your replies!

[Ghost_Bass]

Check the two fat wires commingfrom the pickups (purple and white) and check if there's any red wire coming from them and connecting to the red wire coming either from the battery or the preamp.

If there's no wire doing this then your pickups are passive. I can't say for sure from the picture you posted.

[alittlebitrobot]

Thanks, Ghostie. In that case, they're definitely passive.

update: currently in talks with KiOgon. Thanks for the tip, LiamPodmore.

Edited October 30, 2013 by alittlebitrobot

[alittlebitrobot]

Ok, so my once-active V940fl is now passive, thanks to KiOgon.
..and thanks to the previous posters in this thread for pointing me that way.

It's taught me a bit about electronics too. The new passive eq hasn't fundamentally altered the sound. The guitar still has the tone I really liked, but it's even a bit nicer.
Well happy.

[Myke]

Awesome

[alittlebitrobot]

Having said that, I then took the old active EQ and put it into my old Peavey 6 string.
That did NOT work.
So it's back it's old Peavey self.
Still, it was an educational failure.

[BigRedX]

It didn't work because you got no sound, or because you couldn't get any sounds you liked out of it?

[alittlebitrobot]

It made a sound but it was a weird sound. It was very quiet but also... hard to describe. It was what you might get if you just pressed a microphone against the body and played unplugged, rather than the pickups doing their thing.
It was hard to compare the two basses. The Peavey has a volume and tone for each pickup. The V940 had both pickups wired to the 'blend' knob. The V940 pickups had two wires each, a ground and output. The Peavey had 5(!). A ground wire, a thin black one, a thin red one and then a thin green and thin white wire that were soldered to each other and then taped back out of the way. I didn't understand that at all, but that left me with three wires in play; the ground, the black and the red. I treated the ground and thin black as two grounds (because they're both black) and the red as signal. That's when I plugged it in and it made the sound I described earlier.

So, I just panicked and ran away.
Then I returned and resoldered the old Peavey eq into place.

[mcnach]

[quote name='alittlebitrobot' timestamp='1383089941' post='2260209']
Q3: This might be the most important one. Will doing this [i]necessarily [/i]leave me with that tone that I like? It seems reasonable to me that if I have the knobs set to zero, I'm bypassing the preamp (although it's still using the battery), so rewiring the battery out of the system should leave me with that tone. .....yes? ...I could well be wrong.
[/quote]

Many preamps are not flat at all even when the knobs are at the detent points... so check that first. Wire the output of the balance knob to an output jack and see what it sounds like. If you like it... great! Remove the preamp and install passive controls.

[Ghost_Bass]

[quote name='alittlebitrobot' timestamp='1383849261' post='2270013']
It made a sound but it was a weird sound. It was very quiet but also... hard to describe. It was what you might get if you just pressed a microphone against the body and played unplugged, rather than the pickups doing their thing.
It was hard to compare the two basses. The Peavey has a volume and tone for each pickup. The V940 had both pickups wired to the 'blend' knob. The V940 pickups had two wires each, a ground and output. The Peavey had 5(!). A ground wire, a thin black one, a thin red one and then a thin green and thin white wire that were soldered to each other and then taped back out of the way. I didn't understand that at all, but that left me with three wires in play; the ground, the black and the red. I treated the ground and thin black as two grounds (because they're both black) and the red as signal. That's when I plugged it in and it made the sound I described earlier.

So, I just panicked and ran away.
Then I returned and resoldered the old Peavey eq into place.
[/quote]

You got those wirings wrong. If you can post some pics of both the Peavey's wires and the EQ you got from your V490 we can try to help you hook it up the right way.

Cheers

[alittlebitrobot]

[quote name='Ghost_Bass' timestamp='1383923745' post='2270894']
You got those wirings wrong. If you can post some pics of both the Peavey's wires and the EQ you got from your V490 we can try to help you hook it up the right way.

Cheers
[/quote]

Thanks! It looks like a mess in photos so I made a diagram, as unambiguous as I could, for both basses.
The Peavey is a passive 6 string with soapbars.

The V940 is (was) an active 4 string with PJ pickups.


I'm not sure if you'll actually be able to tell from this what I should do. If you can, that'd be AMAZING. If not, no big deal. I'm pretty happy with the sound of all my basses now, I just wanted to learn a little bit more about modification and how tone circuits work.
Cheers.