Variable Series/Parallel with a Pot?

[strangeloop]

I'm preparing to rewire a Les Paul with Seth Lovers. Series and parallel switching is something I'd like, although even better would be using a pot to continuously fade between series and parallel coils. Is this possible? Can I just take the usual DPDT switch wiring and translate it to the lugs on a dual ganged pot?


In case it's relevant, I'm planning on having a master volume and replacing the 3 way toggle with a blend pot to adjust the balance between pickups. I'm still undecided on the other controls. The pickup blend knob will be a push pull that inverts the polarity of one pickup. The two tone controls would ideally be the series/parallel fade, with the remaining knob being possibly a master tone or some other master filter. Or possibly individual concentric pots with a tone stack and series/parallel fade per pickup.

 

[GuitarDoc]

Re: Variable Series/Parallel with a Pot?

The simple answer is "NO". Because you have to ground different wires for each mode...this can't be done variably. It's either grounded or it isn't.

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

But you'd be adjusting the resistance to ground via the pot?

 

[Jocelyn]

Re: Variable Series/Parallel with a Pot?

1) Seth Lovers come stock with single conductor cable. You need 4 conductor cable that might be possible with floor shop custom order.
2) You need a switch not possible with a pot, with a pot you can shut of one coil / split to one coil. Resistance to ground is shutting of the signal.

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

Yes, I'd be ordering the 4 conductor version.
Would varying the resistance to ground through the pot not do exactly what I'm asking?

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

No. Standard wiring has your hot (black) wire soldered to the input, two wires soldered together for a series link (red and white), and the negative wire (green) grounded. For parallel, you would need to need to separate the series link, ground the white wire, and introduce the red wire to the input. This is simply not possible with a normal variable resistor. Period. You'd need to completely change the signal path at three points to get parallel wiring. You need a switch, potentiometers will NOT do the function you want.

 

[Edgecrusher]

Re: Variable Series/Parallel with a Pot?

Yeah sorry some basic understanding of electronics is missing in this idea... its just not gonna work how you want it to

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

I'm admittedly lacking in understanding of analogue circuits.

Say hypothetically I had 3 pots, one between the two coils, and then one between the output of the first coil and the output, as well as one between ground and the input of the second coil. Say all the pots are set to some arbitrary 50% value. Would this not produce a semi parallel sound? 50% of the second coil's input would be the output from the first coil, the other half would be direct from ground. The other 50% of the first coil's output would be summed with the output of the second coil.

I know this is probably a simplistic view of the signal flow but maybe someone can explain the flaw in my reasoning.

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

It is possible with three pots, but it would be overly complicated, have a very narrow/useless blend taper, and put a load down on all of the pickup leads. There is no benefit to using 3 pots over one switch.

Those extra knobs could be used for much more useful applications, such as bass cut, treble cut, spin-a-split, volumes, etc. Or other switches to fill the holes, like phase switching. Three knobs just to switch one pickup from series to parallel just sounds like a bad idea to me.

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

Yes, I wouldn't actually use 3 pots, I was just trying to break things down to a simple form. In practical application, it would be a ganged pot connected to a single knob.

Could the taper issue not be addressed? Either via the choice of pot or addition of resistors or caps across the lugs?

I think being able to get in-between tones would be worth the extra trouble. Not just for the static tone, but for the ability to fade between the two options in real time. I'm already trying to capitalize on the other options. The push pull switch on the pickup blend knob will flip the polarity of one of the pickups, the blend itself would adjust balance between the pickups. This serial/parallel would adjust the tonal character of each pickup. Phase, serial/parallel and volume are the 3 primary adjustments you can make in terms of tone. Phase flipping individual coils wouldn't be strictly useful because they'd cancel each other out too much. The other option I'd consider is parallel/series between the pickups themselves vs the individual coils. Any remaining room I have will be dedicated to some sort of tone stack. Given the choice between changing the tone at the pickup or changing it at a pot, I'd opt for getting it at the source. I can always add an EQ down the chain if I want to filter frequencies. I can't put a pickup into parallel after the fact.

 

[Artie]

Re: Variable Series/Parallel with a Pot?

Actually, you can do this, but not very well. I tried it once. I believe, (if memory serves me correct), the only pot that would do this is a center-detented blend-pot. But here's the problem, you don't fade from series to parallel. You fade from series to off to parallel. I played with it for a minute or two, then replaced the pot with a switch. There is no fading from series to parallel.

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

Just use a push/pull pot if you don't like the looks of a toggle switch.

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

If it is a blend control for each coil while in parallel you want, then you'll need a 4PDT switch and two spare pots.

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

I don't want parallel blend or series/parallel switching with a pushpull or a switch. I want continuous adjustment between parallel and series so I can get in between tones and be able to adjust continuously between them instead of only having discrete, static options of parallel or series.

But here's the problem, you don't fade from series to parallel. You fade from series to off to parallel. I played with it for a minute or two, then replaced the pot with a switch. There is no fading from series to parallel.

That's unfortunate. Was that just due to how you had them wired? My hypothetical scenario above with 3 pots set to 50% of their resistance wouldn't result in silence would it?

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

Not possible. With two coils, you're either in series or you're parallel. Period. What you want is physically impossible.

 

[AlexR]

Re: Variable Series/Parallel with a Pot?

I think spin a split is going to be the closest you'll get.

 

[Artie]

Re: Variable Series/Parallel with a Pot?

I don't want parallel blend or series/parallel switching with a pushpull or a switch. I want continuous adjustment between parallel and series so I can get in between tones and be able to adjust continuously between them instead of only having discrete, static options of parallel or series.


That's unfortunate. Was that just due to how you had them wired? My hypothetical scenario above with 3 pots set to 50% of their resistance wouldn't result in silence would it?

You realize, of course, that I probably won't get any sleep tonight because I'll go back to the drawing board and see if I can make this happen.

Not only that, but kramersteen is going to kick your arse because I'm supposed to be working on his diagram. :werd:

 

[strangeloop]

Re: Variable Series/Parallel with a Pot?

You realize, of course, that I probably won't get any sleep tonight because I'll go back to the drawing board and see if I can make this happen.

Not only that, but kramersteen is going to kick your arse because I'm supposed to be working on his diagram. :werd:

Haha well it would be very much appreciated if you did figure out a way to crack this nut. I understand digital signal processing well, but when it comes to analogue I suck. I know this isn't strictly impossible. Impractical maybe but I'd at least like to know the compromises before giving up.

I keep looking at the 50% scenario because that would be the point of failure. Essentially you've got the usual parallel situation but the direct output from the first coil is half as strong. The output of the second coil is also cut in half but it has some of the output of the first coil bled into it.

Would something like this work? The three pots would actually be one triple ganged pot.

 

[Myaccount876]

Re: Variable Series/Parallel with a Pot?

I'll refer to the pots in your diagram as:

.......1.......
................
................
...2 ......3...

Pot 1 would just be putting a resistor of the value of the pot between the series link. This does not break the series link.

Pot 2 would ground the white wire, which would start to work towards putting the pickup in parallel, except the wire is either grounded or not. Otherwise you're just putting the first end of a resistor on the series link, with the second end of the resistor on nothing - i.e. the resistor is out of the circuit/does nothing. Again, the wire is either grounded or it's not.

Pot 3 has the exact same funtion as pot 2, just replace the word "ground" with the word "input".

This diagram will only switch the pickup between series and parallel, with no real in-between sounds. Because again, the two coils are either in series, or they are in parallel. Period.

Here's an analogy for what I mean: Saying you want an in-between sound of series and parallel is like saying you want your car to drive between the first and second gear. You're either in neutral, first gear, or second gear. There's no way around that. You can switch gears, but you can't be in both gears. It's not physically possible. You can only rev the engine to the gear's max RPM (volume knob at 10), or you decrease the RPM until you're just idling (volume knob at 0).

All anyone and myself can do for you at this point is tell you that what you want is not possible.

 

[scarr]

Re: Variable Series/Parallel with a Pot?

I know this isn't strictly impossible.

How do you know this?

Imagine a pickup as an A coil and a B coil. Series means you put the output of the A coil into the input of the B coil, as a chain. Parallel means you connect the outputs of the A and B coils together.

Now think about what that means if you try to combine those two ideas. It would mean you're connecting the output of A to the input and the output of the B coil. That means you've just shorted out the B coil.

In that sense (and I think it follows for tone and output), the mid-point between series and parallel is a single coil.