help with bass wiring

[some.guy]

hi all,

i've made a crude diagram for a passive wiring set up for my IB-6S kit utilizing all 5 pots, i wonder first if it could be verified whether or not this will indeed produce sound (at least theoretically) and second i figured i would post it here to possibly assist anyone who buys a similar kit in the future.

i had to think outside the box a bit or this, and i may need to work through a few different capacitors to get the desired effect, but i think this could work. essentially 2 volume, master tone, bass cut and treble cut... could get some nice tones this way i reckon.



thanks, and i hope this ends up helping someone

i'd like to try a .033 micro farad cap on the treble pot and a .0022 on the bass

[wokkaboy]

Hi Some Guy,
sure the resident wiring guru Weirdbits will see this post and let you know if it looks like it will work.
Sounds like you know a fair bit about electronics to cook up the diagrams !

[WeirdBits]

When you asked about passive IB-6 wiring one of the first ideas I had was to include a G&L style passive bass cut on some of the designs. The layouts I was going to suggest were:
1) Master volume, 2 volume, 2 tone.
2) Master volume, 2 volume, master tone, master bass cut.
3) 2 volume, 2 tone, master bass cut.
etc.

Note: I'm assuming your diagram is showing the back of the pots.

For the volumes on a bass, typically you wire the 'input' (pickup) to the middle lug and the output on the left lug (as you have drawn them). That allows you to effectively ground a pickup to mute it without affecting the output from the other pup.

The G&L L-series basses used a 0.0022uF cap on their bass cut, but given the range of the 6 string bass I'd probably tend towards a 0047 or even 0068 cap. I've seen a rule of thumb suggesting a bass cut cap should start at 10% of your tone cap value, ie. 0.068uF tone cap would use a 0.0068uF bass cut. Ideally, you would want a revese audio taper 'C' pot for the bass cut so it would work in the same direction as a tone pot, 10 no cut, 0 max cut, and the wiring would be as you've drawn it. You could use a linear 'B' pot, but may be too 'all or nothing' to be useable. If you use a standard audio taper 'A' pot, you'll need to wire the cap and connections between the middle and right lugs, and it will work the opposite way to a tone pot works... in this case, 0 no cut, 10 max cut.

What effect are you trying to achieve with the 'master tone' and 'treble cut' combo? to generally drop some mid to top end with a medium value cap on the master tone and then cut the upper highs further with a smaller value cap treble cut? You would want the treble cut to be wired the same as your master tone between the middle and right lugs, unless you're using a linear or reverse taper pot. There's a chance you won't have fine enough control with both the master tone and treble cut and could double-dip too much with the high end making it too dark, but that's something for your ears to determine.

Instead of using separate tone and treble cut pots you could maybe have one tone pot and use the other pot to sweep between two cap values giving you a variale top end filter for your master tone.

[wokkaboy]

glad you are the pro Weirdy, most of that went about 6 miles over my head !

[some.guy]

thanks for the reply weirdbits, some good knowledge there.

i think a trip to the electronics store will be in order before i heat up the iron, i'll purchase a few caps of different styles and values as well as a few nicer pots, set up the caps on some cardboard and alligator clip them into the circuit and test out what i think flavours the signal the most pleasing.

i thought with some experimentation the master tone could be a pretty drastic filter with the treble cut being a bit more subtle. i was also toying with the idea of adding an active mid boost circuit or some kind of voltage controlled filter instead of the master tone or a few more outlandish set ups but the idea of an all passive system is appealing to me, both to save routing a battery cavity and because i've always found active systems reduce the dynamics of my playing, even if only to a very small degree.

in the mean time i might use the time it takes me to source some new components to refinish the back of the body, i had gone for an all natural finish but seeing it done up i think it would look nice if i sanded back only the back and sides of the body, did some more grain filling work, and added a black stain to the very back (leaving the sides natural) it would look really nice, i'll try get hold of a camera oneday soon to share my project with everyone...

cheers

[WeirdBits]

Here's the quick diagram I did when you first asked about the wiring. It's just a finger sketch on my iPad so it's a bit rough, but you get the idea. Master Volume, Neck Volume, Bridge Volume, Master Tone and Master Bass Cut:


I was thinking to use the two linear 'B' pots for the individual volumes, and the three 'A' pots for the master controls etc.

Your plan to experiment with the cap values is the way to go, you could even wire in a couple of sockets on the pots so that you can swap caps with the circuit in place.

[WeirdBits]

I been thinking about your Tone and Treble Cut combo, and there's a chance that the double-dipping could mean that each time you adjust the tone you may also have to tweak the treble cut setting. So... what if reducing the tone also decreased the effect of the treble cut?

If you link the treble cut pot to one end of the tone pot and the tone cap on the other end it should produce this effect. With the tone on 10 the treble cut pot will have full effect at your preferred setting (with whatever cap you choose, I just picked the 015), then as you wind the tone back towards 0 it should also decrease the effect of the treble cut pot. This should reduce the double-dipping and hopefully lessen the need to tweak both pots whenever you change the tone. Of course, it could make the treble cut too subtle and/or ineffective as you start to wind the tone back... it's just an idea, haven't tried it.

[some.guy]

thanks for all the help weirdbits,

after giving your posts some consideration, i realized a master tone and treble cut combo probably was a bit unnecessary. looking through some old magazines and articles i'd saved i came across the idea of a kind of mild overdrive circuit some people had been using in place of a tone knob consisting of 2 diodes in series wired in opposite polarities, and i came up with this.



i've used your diagrams as a kind of template to make pretty certain this would be correct, if you give me the go ahead i think this is the setup i'll use, after a quick trip to the electronics store of course. i know the passive OD circuit isn't good for too much, but it does flavour the tone in a pretty interesting way and i think combined with the bass and treble cuts there'll be some pretty interesting tones to be had...

thanks agaim

[WeirdBits]

Your green wire should connect to the middle lug of the OD pot (along with the blue connection) and run to the middle lug of the TC pot, rather than the left lugs as you've drawn it. Connecting the green wire to the left lug of the OD pot would decrease your tone control's effect as the distortion is increased, which is not what you want... if that makes sense.

With 'A' type pots and the way you have them wired above, the OD will be at full distortion at 0 and minimum distortion at 10, same as a standard tone control, and your BC pot will be the opposite with minimum cut at 0 and max cut at 10 (which is what you want with audio tapers).

Never really messed with black ice mods myself, good luck I hope you get the sound you're aiming for.

[some.guy]

quick trip to the electrical shop and a bit more thinking later, and i've changed it it again just a little, drawing from all previous ideas.

i've had to draw this version as a more formal schematic just because im more used to doing things that way, point to point diagrams hurt my brain after a while.

last couple coats of clear in the next few days then i'll be ready to wire 'er up. i'll be sure to post some sound samples, that's a lot easier for me than photos lol.

this time 'round i've made the diode circuit a full wave rectifier with a small crap across the negative input and output, to hopefully get a bit more crunch and the more i turn the more treble cut off i get, to keep the tone smooth, if that makes sense at all... combined with master tone control and bass cut. also, cap values are going to be experimented with, whats written is just an example as weirdbits had suggested for a previous incarnation.



cheers