2 Single Coils, 4-way switch, with Phase

[Samuel Hartpence]

Hello,

Inspired by the Improving the Telecaster Thread, I'm hoping to drop in the maximum amount of versatility I can without getting as complicated as a Brian May or a Jazzmaster, and preserving the looks of a standard tele. I haven't found a wiring diagram for this, and am new two wiring. I'm assuming Greg can help me out with this but here's the basics:

Two traditional telecaster pickups (Golden Age pickups from the auction)
I'd like a 4-way switch for series and parallel outputs when both pickups are on (Not difficult)
I'd also like a push-pull pot for a phase shift if possible

The Seymour Duncan site has diagrams for both individually, but not the two options combined (and again I'm new to this so I don't know how to merge the two). I've also heard that there are pot manufactures that by-pass the pots completely (a relative 11 if you will). Does anyone have any information on those pots, how they perform and where I can get my hands on them?

Thanks!

[Mark Swanson]

That is actually pretty easy. First, use the regular diagram that you have for the 4 way switch and the series/parallel wiring- don't think about the phasing yet. After that's all set, then all you need to do is connect the push/pull switch to reverse the polarity of one of the pickups, which will put it out of phase with the other in one position.
To do a series connection, you will need to separate the grounded cover on the front pickup and/or separate the grounded plate on the bridge pickup from the coils and run it to ground independently. Otherwise in one of the positions, as you flip the phase of the pickup, the ground side (either the front pickup cover or the string ground itself) will switch to the hot side of the circuit, that won't make it at all.

[Samuel Hartpence]

Do you know anything about the bi-pass pots?

[Mark Swanson]

No, and I'd be skeptical as to any difference it would make.

[Greg Robinson]

Samuel, Mark covered how to wire up the 4 way switch well, thanks Mark! If you need any further help with that we'd be happy to oblige.

Regarding the "No load" pots, I haven't used them myself, but from a theoretical standpoint, they would have an impact on the frequency response of the instrument, but I doubt it would be significant enough to justify the added cost of such components.
I'll see about simulating it a bit later to observe the effect, it's something I haven't done before and I'd be interested to see the results myself.

[Greg Robinson]

Ok, I've had a chance to simulate the frequency response of a pickup both with, and without a no-load tone pot.
I'm using LTSpice, available for free from the Linear Technologies website.
The model I'm using is that developed by Terry Downs, and is explained in detail on his website.

The circuit approximates the frequency response of a Telecaster bridge pickup, with standard 250k volume and tone pots, and includes a treble bypass cap on the volume control, which is fairly common. There is also a delay line to simulate a 20' cable, and the first stage of a tube amp.

You'll see that in one schematic, the tone control is connected as normal, while in the other, it is completely disconnected from the circuit, as would be the case with a no load pot.

The following are the standard circuit and frequency response:

[Greg Robinson]

And here is the no-load circuit and frequency response:

[Greg Robinson]

Both the frequency plots have been scaled the same.
You can see that with the no-load pot, it allows much more of the resonant peak through, around 5dB more! That's a much more significant difference than I was expecting. But, it doesn't do anything for the rest of the frequency range, and i might expect that it might tend towards a more nasal sound. It might turn out to be really good for lead work, but without actually trying it for myself, I'm undecided, this just goes to show that it does actually make a difference.

[Mark Swanson]

I can say that I play a telecaster all the time, and long ago I have been leaving off the tone control, I run volume only and I do hear a difference that I like. To me a tone control is useless.
One alternative to the expensive no-load pots would be to use two push/pull pots in your guitar. One would change the phase as you wish, and the other could switch out the tone pot- or if you wanted, it could switch out everything and just provide a direct run from the pickups to the output jack, bypassing everything.

[Samuel Hartpence]

I like that idea Mark. Thanks.

[Greg Robinson]

Bypassing the volume control as well as the tone makes the effect even more dramatic, and also slightly raises the resonant peak.
Being that you can't use the no-load pots as volume controls (it would turn the guitar off when you turn to 10), Mark's idea of using push-pull pots is great.
I personally prefer push-push pots, as you can use whatever knobs you like without having to worry about being able to get a grip. Allparts has push-push pots.

[Samuel Hartpence]

As I get closer to getting to that point (I'm currently laid up from a leg surgery a few weeks ago and have a couple of weeks before I get back to my projects), I'll PM you two for the details. Again I'm a novice and haven't used my soldering iron since I was an undergraduate research assistant.

The project is inspired by a challenge from one of my musician friends who loves his Highway 1 Tele for live shows, but almost records exclusively with a Vintage Jazz Master. He's always complained that the Jazz Master is too complicated for live shows, too valuable for live shows, and not stable enough for live shows (Particularly when he attacks it playing Dire Straights and SRV). He loves his Tele, but gets frustrated because it's not quite sonically versatile enough for everything he plays (the guy plays it all; Jazz, Blues, Country, Pop, Praise and Worship and is a fairly sought after session musician in the region), so consequently carries around way too many guitars to his gigs. Now we'll have to do some soul-searching and decide how much complication is too much complication.