Vol pots for coil tap

[Hotrock]

AAAAhhhhhhhhh electronics has always wound me up.

Can someone answer the following:

1) I'm building a double cutaway LP with two coil tapped humbuckers, two tone and two volume. I know I need 250K Log pots for the tone controls but what should I use for the vol pots. Melvin Hiscock rekons that it's 250K for single coils and 500K for a humbucker, but doesn't mention what to use if you coil tap.

2) I thought that if you coil tapped a humbucker you could select three options. Front only, front and back or back only. Now I'm begining to think that you can select the front and back option and EITHER front or back coil alone. Which is correct and which one is usually used?

3) I am thinking of using a balance controler instead of a selector switch, is it worth it? I play live so I figure a balance controller is OK as I don't need to switch configurations quickly. If I do this what value pot will I need?

4) I'm going to buy some Ceramic Disk Capacitors for the electrical gubbins ranging from 0.001mfd to 0.01mfd and have a bit of an experiment. Should I buy 16V or 50V capacitors?

5) When I route for the control cavity, how much wood should I leave for the tone controls to stick through the top? The knobs that I already have attach to the shaft with a grub screw (if it's any help)

Cheers guys, even the slightest bit of help will be appreciated.

[Snork]

i dont even know what a coil tap is )-:

[Snork]

i mean i've heard of it a lot i've just never asked what it meant.........................

[Hotrock]

A humbucker has two coils, with coil tapping you can select it so that both coils are on (humbucker) or a single coil is on (normal pup). So you get single coil sound or humbucker sound from the same pup.

While I'm on the subject on further to the previous questions:

6) Will it make a difference if I use a push/pull tone pot over a push/pull volume pot? Or will it depend on the circuit?

[Snork]

oh i knew that........ lol. thanks!

[fidgec94]

6) Will it make a difference if I use a push/pull tone pot over a push/pull volume pot? Or will it depend on the circuit?

To the best of my knowledge, i dont think thats would make any different. The push/pull pot is just a DPDT incorporated onto a pot to save routing a new hole. The pots would still have their inherent linear or logarithmic taper, but also able to open close a switch as well. I think the Jimmy Page wiring schematic has push/pull pots left, right and centre....

[fidgec94]

1) I'm building a double cutaway LP with two coil tapped humbuckers, two tone and two volume.  I know I need 250K Log pots for the tone controls but what should I use for the vol pots.  Melvin Hiscock rekons that it's 250K for single coils and 500K for a humbucker, but doesn't mention what to use if you coil tap. 

The 500k are supposed to give a brighter sound are they not? I think it'd be down to personal preference really. My guitar used to have 3 single-coil pickups in it, but still used 500k pots. Odd The pickups were crap so the sound wasnt all that good. Now i have H/S/S, but i have rail type single coil sized humbuckers, so i really have H/H/H configuration. I use 500k volume and 500k tone, sounds maybe abit too bright. Maybe i shouldve used a 250k pot somewhere, or maybe i need as bit more bass in my sound.

2) I thought that if you coil tapped a humbucker you could select three options.  Front only, front and back or back only.  Now I'm begining to think that you can select the front and back option and EITHER front or back coil alone. Which is correct and which one is usually used?

Im sure you can do what you originally thought...i have schematics back at home i can check later.

edit: I found it (3rd pic down on the left)

4) I'm going to buy some Ceramic Disk Capacitors for the electrical gubbins ranging from 0.001mfd to 0.01mfd and have a bit of an experiment.  Should I buy 16V or 50V capacitors?

I dont think there will be any benefit from using 50v caps....you can use a really high value cap to protect yourself from faulty valve amps (and that connected between signal ground and actual jack-ground) but as far as normalguitar wiring, the current and volatge is quite low

5) When I route for the control cavity, how much wood should I leave for the tone controls to stick through the top?  The knobs that I already have attach to the shaft with a grub screw (if it's any help)

I think people leave about 1/4" or if using a figured top or want more than 1/4" thickness, longer shaft pots are used.

[lovekraft]

Two things -first, to avoid loss of high end, you'll want to use the same value for volume and tone pots, so if you want a brighter sound don't use 250K tone pots with 500K volume pots. Second, for quieter and more high fidelity response, use poly caps instead of ceramic discs - voltage rating is immaterial in small signal apps, unless you're using a cap to isolate the string ground - then 500 volt or better. Older humbucking Gibsons generally use 500k pots with a .02uF cap for the tone, but in the '70s they got kinda crazy, using 250k tone pots with .047uf or .02uF caps with 500k volume pots. I've seen tone caps as high as .1uF and as low as .001uF. Play with it, caps are dirt cheap, you can buy a box full for what those fancy switch pots cost.

[aMpaGe]

Those diagrams pasted above, taken from guitarelectronics.com ... If you were holding a DPDT pot in your hands and trying to coordinate it to those diagrams, which way is the actual POT facing? UP or DOWN?

For instance, the series/parallel mod, 3rd one down, right hand side. If one wanted to be in series with the pot DOWN and parallel with the pot UP, what is the proper way to wire?

My switch lugs are not labeled, so I don't know where 1 2 3 4 5 6 is... I assume it runs 1 2 3 down left side and 4 5 6 down right side?

Those diagrams never show the actual pot portion of the diagram.

I'm using allparts EPP280 dpdt pots. Thanks very much.

[lovekraft]

In the diagram you're talking about, the top two leads in the picture correspond to the top two leads (ie, closest to the pot) on the switch. For a visual, imagine that the pot is above the switch leads shown.

[aMpaGe]

So the pot is pointing UP?

[lovekraft]

Yeah, like this:

SHAFT

*POT*

o o o

SWITCH

o o

o o

o o

[aMpaGe]

Thanks.. After comparing duncan and the guitarelec diagrams that's the conclusion I came to..

When wanting to wire 2 pickups to the same DPDT switch, can you use the left side for one pickup, and the right side for another??

I suppose the way to do it would be to run the hot output of each pup to the middle lug on either side and then to switch?

Turns out I had a faulty pickup anyways, that threw me for a major loop and caused me a lot of grief. It was supposed to be a duncan hotrail but it was actually an ESP pickup.. Grrrrrr...

So how do you go about wiring 2 pickups to one push pull so they both go series/parallel, but not all be turned on at the same time?

[lovekraft]

You don't - you'll need a separate DPDT switch for each pickup.

[Hotrock]

Right then, I've decided to use 2 tone and 2 volume controls with a selector switch.

So:

2 Push/pull 500k pots

2 Normal 500k pots

Bucket full of capacitors (Poly cap)

Selector switch

Jack socket

The knobs that I have are held on the shaft by a grub screw. Do I want split shafts?

Right I think thats it, sound ok to someone that knows?

[noname]

The knobs that I have are held on the shaft by a grub screw. Do I want split shafts?

Right I think thats it, sound ok to someone that knows?

Doesn't matter what shaft.

Sounds good

for the tone I would sugges .22 uF capactitors.

[lovekraft]

Right then,  I've decided to use 2 tone and 2 volume controls with a selector switch.

So:

2 Push/pull 500k pots

2 Normal 500k pots

Bucket full of capacitors (Poly cap)

Selector switch

Jack socket

Right, sounds correct.

for the tone I would sugges .22 uF capactitors.

That's gonna make the tone awfully dark, but give it a shot if you like - you can always change it. BTW, the parallel pickup is going to be less powerful than series because the two coils load each other. I'm working on a way around that, I'll let you know if it works.