Deluxe Players Strat switch and blend pot question

[garyb]

I got some new goodies for Christmas which included a new set of 250K CTS pots including a blend pot from Callaham Guitars. There are quite a few variations of wiring for this set up, but one that really plays well for the Deluxe is one I found here www.guitartechcraig.com/techwire/tech01.jpg as it uses the DPDT which is already there for the Players strat.

As I recall from when I put in my Texas Specials, the shield on the pick guard goes around rather than under the spot where this DPDT switch is glued to the pickguard. I don't know if that was for convenience or if that switch can't be grounded for some reason. My challenge now is that I also have a full aluminum shield that I was planning to use and I need to determine if I can attach the switch to that shield, or if I need to cut around it to ensure correct connectivity.

Anybody have an idea there?

I also have a question on blend pots in general. There are at least a couple of varieties. One is the Fender no load pot which is what Callaham is emulating. The diagram that he was promoting is on the Fralin site. The other type is a true blend pot with 6 lugs. That one is easy to understand, but I am not quite clear on what is happening with the first one. I have also seen some diagrams from Kinman recommending the use of standard audio taper pots for blend pots. They seemed to be going for bigger is better because the recommendation was for a 1Meg pot there.
Thanks,
GB

[sumgai]

Hmmmmm........ "Tis the Season to be Blendy, fala lalal la, la la la la."

gary,

Hi, and welcome to the Special Edition of the NutzHouse, as noted above! ;D

No, seriously, many folks here, both new and used, have been asking about blend pots lately. Just check the Index listing of this sub-forum, Electronics and Wiring, you'll see what I mean. But enough of that..... One of your questions is actually new, so you get more than just the standard 'read the rest of the threads' message. Although I gotta admit, I can't understand why the folks at the Fender Community Forums have ignored you for what, a week now.... Well, let's see what we can do about that state of affairs.

To explain the "two terminal control" concept of blending, as versus six terminals, I need only refer to the Player's Strat, as you did. Two of the terminals of a regular pot are used to vary the amount of signal coming from the connected pickup. That variable signal is hooked to the guitar's output in place of the switch on the Player's Strat! This lets you control how loud that pickup is, and when it's at full volume, it should be as loud as the sound coming from the pickup(s) chosen by the the main Selector switch. The main volume control still has the final say as to what's going out of the guitar, this control doesn't over-ride that.

As you might guess, I'm not a fan of doing things this way, but hey!, if it plucks your strings, far be it from me to pee in your Cheerios! ;D


As far as your aluminum shield goes, the only time a shield is cut away from where a control is mounted is when a ground loop problem might/does exist, and there's too much noise in spite of the shield. Other than that, the shield should be used as designed, with all of the mounted controls making mechanical contact (and thus, electrical contact too). Use it like it was intended, and all should be well.

HTH



sumgai

[ChrisK]

As I recall from when I put in my Texas Specials, the shield on the pick guard goes around rather than under the spot where this DPDT switch is glued to the pickguard. I don't know if that was for convenience or if that switch can't be grounded for some reason.

The glue doesn't adhere well to the foil (and, the foil doesn't adhere all that well to the pickguard). Since the switch mounting block is plastic, grounding it is moot anyway.


The 2-terminal method of blending in a pickup (rheostat mode) works best with a reverse audio taper pot. The standard normal audio taper is already up to 100 K at about "8" on a Strat knob, which doesn't give much resolution when backing off from "10".

The easiest way to find such a reverse taper is to use the appropriate element in a pan pot.

The 3 terminal (potentiometer/ratiometric (well for two pots the 6 terminal)) method of blending in pickups works best if you use an actual blend pot. Most pots sold as blend pots ARE NOT SUCH, but are in fact pan pots, designed for use in a stereo or mixer for full total power output (as in the sum of both channels) across the panning range.

Blend and Pan Pots

If you don't want to use a pan pot, you can still use a normal audio taper pot, but you'll have to turn it in the anti-clockwise direction (using the wiper and the other end terminal).

[sumgai]

Chris,

A second, and closer, look at the pot shown on Callaham's website reveals that the normally hot terminal is completely missing. (!) This forces one to use rheostat wiring, in reverse mode, per your suggestion above.



Personally, I find this cumbersome, and not memory-friendly. Training-friendly, perhaps, but I've got enough learning curves in my life already... sheesh! ( ;D)



sumgai

[garyb]

Thanks for the responses guys! And very observant of sumgai to note that this question languishes on the Fender boards. Somebody responeded to another post over there and recommended these boards, so I jumped right in. It was good advice.

I didn't know when I started down this path that it would be so popular. I did a fair amount of reading after I posted (sorry) and have a bit better grasp on this. I am still a bit stuck on the idea of a standard pot being used here verses a no-load pot. I understand the intent of a no load is to remove all resistance from the path when it is on 10, but I am not really sure I understand why that is a good thing in the blend scenario. I got some indication from the Kinman site that in this approach you can get some bleed over between the pickups being blended and think that the no load is used to avoid this?

I am still a little lost on the higher resistance reverse taper approach. Looks like guitar electronics sells a 1M reverse taper if this is the most appropriate for this approach.

On a side note, I emailed Bill C. on the blend pot, first thinking it was damaged, and then realizing it looked that way in the picture. He stated they removed that lug to avoid people reversing it. If all else fails, I may just use it as a tone pot.
The GuitarTechCraig diagram actually uses this lug, which is kind of where my confusion kicked off.

Thanks for the input! I will keep reading and hopefully have this thing figured out soon.
Thanks,
GB

[ChrisK]

I am still a little lost on the higher resistance reverse taper approach. Looks like guitar electronics sells a 1M reverse taper if this is the most appropriate for this approach.

This forces one to use rheostat wiring, in reverse mode,..........

The higher resistance issue is not one of higher pot resistance, but of the resistance change effect of a normal taper audio pot. It has its resistance decrease rapidly since it's down to about 200K from the hot terminal to the wiper at "8" from full-in at "10". What this means is that the blended-out pickup gets blended out much too rapidly.

JohnH has indicated that about 100K is the optimal maximum series resistance beyond which there is little discernible effect. I have found that 200K is my maximum, but I was using Fender Custom Shop SCN Tele pickups thru a very clean amp.

With the aforementioned pot, my maximum effect occurs after just 2 number positions on a normal taper audio taper pot of 500K.

At 250K, one gets down to about "6" from full-in at "10", so this is 4 number positions.

Either way, the change happens rapidly, in the piecewise linear upper section of the pot.


If one had a reverse taper audio pot (as in left-handed), the 200K value would occur at about "1.5" from full-in at "10" on a 250K pot. JohnH's 100K occurs at about "3".

The 200K value would occur at "3" from full-in at "10" on a 500K pot. JohnH's 100K occurs at about "4".

Regardless of range (100K vs 200K), and pot value (250K vs 500K), the reverse taper approach for the above variations still gives a minimum of 60% of rotation for effect, and it gives the gradual blend-out (which is the whole point of not just using a switch).

Just slightly better than the maximum of 40% for the normal taper with normal rotation, eh?

The Blend Pan pot has both the normal and reverse taper elements and is a lot easier to find than a left-handed/reverse taper pot.

So, where does one find a pan pot? Hmmm, Blend and Pan Pots just might help.


Now, one CAN get the proper blending effect if one wires the pot using the normal two terminals used for tone controls (the two remaining terminals on the Callaham pot AND IS WILLING TO TURN IT IN THE OPPOSITE DIRECTION ("0" is full-on and "7" is the 200K point on a 500K pot.

Backwards is.



The Picture Story

Looking at Audio Taper Pots - Not Really, one can see on the right upper graph that the resistance fall-off on curve "A" is very rapid as the rotation goes from the right side of the chart to the left, and then becomes much more gradual once past mid rotation.

On curve "C" the resistance fall-off is gradual as the rotation goes from the right side of the chart to the left, and then becomes much more rapid once past mid rotation. This is the "operator preferred" effect.

Again, the "A" curve can be used, but backwards is as backwards does.


Ok, done is. Go buy a blend pan pot.

The GuitarTechCraig diagram actually uses this lug, which is kind of where my confusion kicked off.

And, since it does, the use of a pan pot with both elements may be of help in this scheme since a pickup is being blended from series to parallel.

While a pot is used for this, no representation is given as to the actual blending effect since he treats the pot simply as a switch in the drawing's realized combination chart. This will have to be analyzed before I can give any meaningful input.

For these types of combos, I prefer the Mike Richardson wiring with phase scheme, since it is excruciating logical in position layout and most easy to drive when one is distracted by actually playing the guitar.

[garyb]

Well ChriisK, this helps out a bunch! The discussion has made me stop an re-evaluate what I am really looking for here and the Mike R diagram pretty much nails it. The blend pot approach all started on a whim as I already had a 7 tone strat in the deluxe. I wanted to see what else I could do with what I had. What got me going on the other diagram initially was the series positions and the phase stuff kind of came along for the ride.

I need to spend some time with this diagram to see if I can determine how to adapt it without the phase switches. The 10 positions in that post would be good for me. Looks like the top diagram is for 2 conductor and the bottom is for 3. Am I reading that right?

Here are a couple of questions that will help me out:

1. Is there any difference between the SuperSwitch and the MegaSwitch version E? (StewMac)
2. Are some SuperSwitches better than others? StewMac, GuitarElectronics, Fender?
3. Should a SuperSwitch go into most strats without modification? (I will measure, but I am sure somebody here will know)
4. Which pickup position is most likely to benefit from a no-load pot? Neck or Bridge (Texas Specials)

Thanks again,
GB

[ChrisK]

Whoa, a possible MR convert, eh?

Looks like the top diagram is for 2 conductor and the bottom is for 3. Am I reading that right?

If you look at the top schematic portion of the drawing, you'll see that there really are just two active wires from each pickup. On the lower left wiring diagram, the "R" is the hot lead and the "G" is the return. The "B" is just the bare frame ground wire from these specific pickups (DiMarzio Virtual Vintage) shown connected to the backs of the pots.

1. Is there any difference between the SuperSwitch and the MegaSwitch version E? (StewMac)

Absolutely! The SuperSwitch is a 4P5T switch and the MegaSwitch E is a custom combination switch (there are two versions afoot a'planet, tho' I don't know if the new one is in the U.S. yet)

2. Are some SuperSwitches better than others? StewMac, GuitarElectronics, Fender?

I like the feel of the Fender ones the best.

3. Should a SuperSwitch go into most strats without modification? (I will measure, but I am sure somebody here will know)

Yes! For a Strat, just make sure that the terminals face in toward the pickups. I have also had some issues with them easily fitting into a Tele.

4. Which pickup position is most likely to benefit from a no-load pot? Neck or Bridge (Texas Specials)

Bridge.

I need to spend some time with this diagram to see if I can determine how to adapt it without the phase switches.

This is excruciatingly easy! The phase switches are modular in nature and are completely "upstream" of the pickup combination switching. As a result, they can be removed/modified independently.

The bridge pickup goes to the BP Tone push pull pot's switch.

The neck pickup goes to the NP Tone push pull pot's switch.

As you look at the two switches, you'll see an "X" of wiring that realizes the DPDT-based phase reversal needed to, uh, reverse the phase. "D" is when the push pull is down (normal phase) and "U" is when the push pull is up (reverse phase). The center switch terminals on each side are the pole commons. If one just makes the connections from the pickups "R" and "G" wires to the connections directly above (the "D" terminals - don't forget to wire in the tone circuits directly across each respective pickup), one can realize the normal phase selections.

WARNING! The out of phase positions are exceedingly useful, especially in the series modes, and I wholeheartedly recommend that they be preserved. If one subsequently doesn't like them, there's no law requiring that a push pull switch actually be switched!

[garyb]

Thanks ChrisK,
This is a plan. I need to order some more parts, but I really look forward to the end result. I looked at this last night a determined how to pull out the phase switches, but thanks for helping me verify that I got it right. I may also take your advice and put them in, but I haven't decided yet. I think I need to get the phase switch working in LP first as I think I fried that one, trying to reuse it one too many times.
Thanks again for all the input!
GB

[ChrisK]

I think I fried that one, trying to reuse it one too many times

In My (not so) Humble Opinion.........

I don't know your (or anyone's) financial state, nor would I want to presume too much, but in my experience, using only new components in every design's final build is the only way that I will do it.

Free time is often the most valuable asset that we have. I have no interest in fixing things that should not be broken in the first place.

It's like spending a lot on a rifle, a scope, and a hunting trip, only to use the cheapest ammo available. Ensurance is.

[garyb]

I hear that man. I just need to keep more stock on hand and it won't be a problem. This particular push pull pot went through alot though so it was kind of an old friend.... ;D I have moved on now though....
Thanks again for all the input!
GB

[garyb]

OK,
I have been looking at this without the phase switches and I wanted to clarify what ChrisK said and what I think that means to my wiring. Just to be really clear, I am doing Mike R wiring on a Deluxe Player's Stratocaster and am utilizing the push button switch to perform the series parallel function, but that will be reversed from what is in the diagram, since down is really active on this switch rather than up. I am eliminating the phase switches on the neck and bridge tone pots (for now) and trying to make sure I make the right connections to the pots and the super switch from there. I am also doing QTB wiring with a common ground with all of this occuring on top of a Callaham full alluminum shield (here's a plug for their bridge blocks which are very cool and toneful ). Now with that out of the way here are the pickup to tone pot to superswitch connections I plan to make.

Neck + goes to the right (pot facing down) terminal on the pot. A wire from that terminal also goes to the super switch 5 position on the middle positve side connection. That wire then bridges positions 4 and 5 on in the first set and position 5 on the 2nd set. I want to run the capcitor to ground here, but the diagram looks like I should be taking these connections through it to the pot terminal. Is that correct? I know I also need to make a connection to this set from the volume pot/switch combo.

Neck - goes to the wiper terminal (center) on the pot. Another wire will connect this terminal to the super switch common terminal opposite the middle negative connection.

The bridge connections basically follow the same process except that the connection to the super switch comes from the positive side for this pickup.

Just one additional clarification, and that is that 'ln' or '1n' shown on the volume pot, I assume to be a treble bleed capacitor (typically .001 uf). I would also assume that any treble bleed combination would work there (cap alone, cap resistor etc.).

My switch should arrive this week and I am going to begin cutting wire today. I will wire everything up on the shield, prior to pulling the pick guard, and then putting the pickups and push button into the circuit, before replacing it all back in the guitar. I am hopeful that I can remove the push button mount from the pickguard without destroying either. We will see how that goes. Can you buy a replacement for this mount anywhere without a special order to Fender?

Thanks again for all the input.
GB