Standard DPDT Switching -- BTB Pickup Wiring Help

[benjaminr]

Hi everyone!

I just dreamed up this wiring schematic for a BTB pickup set up on a Jazzmaster and was wondering if I could bounce it off a few of you.  Disclaimer: I have no idea what I'm doing.

The idea is that when the upper DPDT switch is in the 'down' position, the rhythm and lead pickups function normally using the master volume and tone controls.  In the 'up' position, the rhythm and lead pickups still function normally with their own dedicated volume and tone controls, and the BTB pickup is engaged with dedicated volume and tone controls as well.  This way, I can either get only the BTB pickup to function by rolling down the lead volume of the normal circuit, or I can blend all three pickups by adjusting each of their respective volumes and tones.

I know that was long-winded, but this is my first attempt at something like this, and based upon my marginal knowledge of switching and circuits, this schematic *appears* like it would work as described above.

Here it is:



Thanks everyone!

 

[Jumble Jumble]

It'll work, yep. The only thing I would say is that the orange wire from the lower volume and the blue wire from the jack are always connected - so no need to run both of them all the way up to the upper switch. Connect the volume straight to the jack, and then run one wire from the jack up to the upper switch the switch that other circuit in.

 

[line6man]

There are two problems.

Firstly, the switching is way too complicated. All you need is a single pole and throw to switch in the lipstick pickup.

Second, the way you have the lipstick pickup's tone control wired, there can be no isolation. It will function as a master tone control when the lipstick pickup is on, regardless of the other pickups' volume setting.

As a side note, you might consider switching the lipstick pickup before it goes into a volume pot, so that the load on the rest of the circuit when the lipstick pickup is at a low volume does not change as much when switching.

 

[benjaminr]

There are two problems.

Firstly, the switching is way too complicated. All you need is a single pole and throw to switch in the lipstick pickup.

Second, the way you have the lipstick pickup's tone control wired, there can be no isolation. It will function as a master tone control when the lipstick pickup is on, regardless of the other pickups' volume setting.

As a side note, you might consider switching the lipstick pickup before it goes into a volume pot, so that the load on the rest of the circuit when the lipstick pickup is at a low volume does not change as much when switching.

Thanks for the tips, I really appreciate it.  I literally have never done this before, so I need all the help I can get.  Can you suggest an alternate wiring solution?  How would a SPST fit into the picture instead of the DPDT?  Or at least an alternative to the tone control so it will function as desired? 

EDIT*

I'm working on a new schematic with SPST switching--I see where you're coming from.  Still not sure how to rewire the tone control to make it function as desired.

EDIT 2*

Here is a quick re-write.  Still unsure about upper volume/tone controls.  Looks closer though.

 

[benjaminr]

It'll work, yep. The only thing I would say is that the orange wire from the lower volume and the blue wire from the jack are always connected - so no need to run both of them all the way up to the upper switch. Connect the volume straight to the jack, and then run one wire from the jack up to the upper switch the switch that other circuit in.

Thanks--so it's not a big deal to have two wires connected to the output jack? 

 

[Jumble Jumble]

Not a big deal at all - but if it's awkward to physically do for any reason, then your long wire to the upper switch could just go to the middle terminal on the lower volume control instead.

 

[line6man]

There are two problems.

Firstly, the switching is way too complicated. All you need is a single pole and throw to switch in the lipstick pickup.

Second, the way you have the lipstick pickup's tone control wired, there can be no isolation. It will function as a master tone control when the lipstick pickup is on, regardless of the other pickups' volume setting.

As a side note, you might consider switching the lipstick pickup before it goes into a volume pot, so that the load on the rest of the circuit when the lipstick pickup is at a low volume does not change as much when switching.

Thanks for the tips, I really appreciate it.  I literally have never done this before, so I need all the help I can get.  Can you suggest an alternate wiring solution?  How would a SPST fit into the picture instead of the DPDT?  Or at least an alternative to the tone control so it will function as desired? 

EDIT*

I'm working on a new schematic with SPST switching--I see where you're coming from.  Still not sure how to rewire the tone control to make it function as desired.

EDIT 2*

Here is a quick re-write.  Still unsure about upper volume/tone controls.  Looks closer though.

The tone control should be parallel to the lipstick pickup. The output of the lipstick pickup will then go to the switch, and the switch will then go to the volume pot.

 

[line6man]

It'll work, yep. The only thing I would say is that the orange wire from the lower volume and the blue wire from the jack are always connected - so no need to run both of them all the way up to the upper switch. Connect the volume straight to the jack, and then run one wire from the jack up to the upper switch the switch that other circuit in.

Thanks--so it's not a big deal to have two wires connected to the output jack?

That depends on what you want from your tone controls. If you want isolation, resistors would be necessary to isolate the signal paths before they sum at the jack.

 

[benjaminr]

It'll work, yep. The only thing I would say is that the orange wire from the lower volume and the blue wire from the jack are always connected - so no need to run both of them all the way up to the upper switch. Connect the volume straight to the jack, and then run one wire from the jack up to the upper switch the switch that other circuit in.

Thanks--so it's not a big deal to have two wires connected to the output jack?

That depends on what you want from your tone controls. If you want isolation, resistors would be necessary to isolate the signal paths before they sum at the jack.

Would you mind elaborating a little?  I really am new to this, and I want to try to get this right the first time.  What resistors and where would they go?

Thanks!

EDIT*

So I think I've updated the schematic properly except for the resistors you mentioned.

 

[drewfx]

If you have two tone controls for different PU's and there is no resistance then when both PU's are turned on either tone control affects both PU's. A Les Paul is this way with the switch in the middle position and both volumes turned all the way up - either tone equally affects both PU's.

Some people find this confusing and/or upsetting for some reason and thus conclude that having two tones wired this way is "bad".

 

[benjaminr]

If you have two tone controls for different PU's and there is no resistance then when both PU's are turned on either tone control affects both PU's. A Les Paul is this way with the switch in the middle position and both volumes turned all the way up - either tone equally affects both PU's.

Some people find this confusing and/or upsetting for some reason and thus conclude that having two tones wired this way is "bad".

Ah, this makes sense.  So where in the circuit would a resistor or resistors need to be placed to prevent this?

 

[line6man]

It'll work, yep. The only thing I would say is that the orange wire from the lower volume and the blue wire from the jack are always connected - so no need to run both of them all the way up to the upper switch. Connect the volume straight to the jack, and then run one wire from the jack up to the upper switch the switch that other circuit in.

Thanks--so it's not a big deal to have two wires connected to the output jack?

That depends on what you want from your tone controls. If you want isolation, resistors would be necessary to isolate the signal paths before they sum at the jack.

Would you mind elaborating a little?  I really am new to this, and I want to try to get this right the first time.  What resistors and where would they go?

Thanks!

EDIT*

So I think I've updated the schematic properly except for the resistors you mentioned.

Your diagram is still incorrect.

Firstly, you need to connect the signal to the middle terminal of the volume pot, with the first terminal wired as an output. This is because you have a circuit where more than one signal is going to the output jack, so you cannot allow the output impedance of the instrument to approach zero if the lipstick pickup's volume is being reduced, or else it will also reduce the volume of the regular pickups.  Note that the wiring of the regular pickups' volume pot can remain the way it is, because there is not any situation in which the lipstick pickup would be used alone. Additionally, it is actually preferable to leave it the way it is, because the taper will typically be better that way.

Second, the volume pot should come after the switch, so that its resistance will still load the circuit in the same fashion, when the lipstick pickup is muted. On the other hand, you can consider switching the volume pot out of the circuit when the lipstick pickup is muted, if you find it desirable for the tone to be slightly brighter when the lipstick pickup is muted. I suppose it is a personal preference.

Regarding tone control isolation, I explained this rather recently in a private message, so I'm just going to paste my message below. Note that in your case, all of this will probably just lead to overthinking something that doesn't matter to a lot of people, so take it with a grain of salt.

Tone controls do not operate independently of each other in any standard wiring scheme.* This is because they are wired parallel to the signal path. Usually, there is a pickup selector switch that allows the tone controls to only be in the circuit when the pickups they are meant for are selected. If you have two pickups on, the tone controls will either both be doing the same thing, or both be working over the entire signal path. Some people are in disbelief of this, because they swear that their Les Pauls have independent controls. This arises from a confusion over what the controls really do. If there are two tone controls and two capacitors, using them both together when both pickups are on will mean that the two controls will combine to do something different than if either were used alone. If there are two different capacitances, each tone control will also be affecting a different range of frequencies. So while they may sound different, or have a noticeable effect when used together, they both apply to the same signal, rather than the individual signals from each pickup.

*There are four exceptions. The first is when you have a guitar with two volume pots, and the volume pots are rolled down a bit. This allows the tone controls to work independently of each other, because the volume pots place a resistance between the pickups and the output, that prevents each pickup's tone control from affecting the other pickup.

The second solution is to place resistors in series with each signal path, before they come together at the output jack, or master volume pot. This was the way that 1960-1961 (IIRC) stacked-knob Jazz basses were wired. It works, but it also has a major disadvantage. The resistors cause a drop in volume, since they are resisting the flow of electrons from the pickups to the output. The value that Fender choose for Jazz basses was 220k Ohms, which is quite high for the impedance of the pickups on those basses, but some people have had luck with values as low as 80k. (Depending on the impedance of their pickups.) In a setup like this, the best thing to do is use a trimmer pot to fine tune the resistance for the best compromise between tone control isolation and loss of output.

The third solution is that if you have an instrument with an A/C taper blend pot, the blend will provide some isolation for the tone controls, since there is always some amount of resistance in series with at least one pickup. Aside from the fact that blend pots are rather uncommon on guitars, I have seen few people satisfied with the behavior of A/C taper pots, for various reasons. (M/N taper blends, which only provide resistance in series with one pickup at any given point in the rotation of the pot, are much more desirable to most people.)

The fourth solution is active buffering. This is the way that mixing consoles work. An opamp or JFET transistor can be used to provide isolation between signal paths, but it requires a battery, and comes with its own set of drawbacks that are too complicated to get into right now. I'll explain it later, if you are interested.

With all of that being said, the tone controls will always remain independent if the pickups are soloed. So you can decide for yourself what's practical, as far as tone control usage goes.

 

[benjaminr]

That is awesome info--thanks for your time and patience.  So more along the lines of something like this:

 

[line6man]

That is awesome info--thanks for your time and patience.  So more along the lines of something like this:

Yes, that will work.

 

[benjaminr]

You have been super helpful--I really appreciate your time.