P-rail switching scheme dwg file, ChrisK?

[ew57]

Greetings, I have a potential issue concerning wiring a P-rails set & I wondered if it was possible to have the .dwg file made available so I can correctly diagram my intentions without re-inventing the wheel. Thanks & take care.

[newey]

ew57-

Hello and Welcome!

ChrisK posted this.

If you need more specifics, I'd suggest PM'ing ChrisK. Chris freely shares his work so long as it's credited to him and not used for commercial exploits.

And, please share your plans for the P-Rails, we've had a bit of interest in those pups lately.

[ew57]

Greetings, I may have made myself unclear, I'd like to get a copy of the cad file itself so I can make some revisions of my own & then post the image file for clarification.

Regarding the wiring I'd like to do, I need to rewind a bit: I happen to be in the midst of a tele build using a Seymour Duncan p-rail pickup set & my intention was to use a 4P5T strat super switch for each pickup to access the following selection (single coil, P-90, humbucker parallel, humbucker series, off) and then a volume & tone for each pickup much like a gibson, but instead of a gibson style selector (neck,neck/bridge,bridge) the pickups/tone/volume circuits would then be wired in parallel (neck & bridge on) permanently, since each Super Switch would have its own "off" position.

The biggest potential for issue I see is dealing with the interaction between the individual volume/tone circuits. I've briefly discussed different buffer arrangements with JohnH & am leaning towards installing an additional Gibson style selector switch, although I'm open to persuasion.

This is completely non-commercial, as I've come to the conclusion that I'd never be able to recoup the build costs let alone factor in any of the time involved....

[newey]

and then a volume & tone for each pickup much like a gibson

Is this a regular Tele or a Tele Custom? If it's a regular tele, are you using concentric pots?

my intention was to use a 4P5T strat super switch for each pickup

Have you fitted these 2 superswitches in your Tele? You may have some fitment issues . . .

There may well be easier ways to accomplish this rather than with 2 superswitches.

[ew57]

This will be a homemade tele body, hopefully using a modified traditional tele control plate, but with the cavity routed from the backside due to clearance/fitment issues. If the super switches are placed back to back, they "should" still poke through a modified control plate alright. Concentric pots are also going to be used to try to maintain the more traditional look.

[ashcatlt]

The switching you're talking about is the same thing I did x 3 in my Behringer strat. I've got no pots, but that's easy enough to work in. Also, I used rotaries. Not exactly the most convenient way to select different pickup combinations, but I never really do that on the fly. If you're one who likes to switch back and forth mid-flail, you might want to re-think adding a 3-way. Of course, with a 4-way you could get the series combination as well.

If you're going just for the parallel combination between the 2 switches, the 5 ways you've got don't need 4 poles. It's basically the old Tele 4-way trick. Here's sumgai's version, which eliminates the hanging hot from the more traditional version.

In my implementation I had to short across each of the coils in the off position to get them to go all the way off. In my mini-strat, I found that this caused a dead spot when I turned one of the rotaries off and then flipped the S/P toggle to series mode. Pretty sure you could avoid that with 4 poles.

[ChrisK]

The format that the file is in is AutoCADLT2005 .dwg

Switching the two coils for the P-Rail pickups should only take two or three poles of the 4P5T, depending on how you do the unconnected coil (hanging, shunting, or neither). This leaves at least one pole free on each for disconnecting and/or arbitrating volume/tone structures.

[ew57]

Chrisk, 2005lt.dwg would be fine, if it was 09 I'd have issues. I appreciate it! I know its a tall order, but what are the pros & cons to the hanging and shunting topologies you eluded to?

Ashcatlt, I follow the diagram you posted up until position #4, could you enlighten me as to what's going on there?

Thanks guys! I'm learning enough to realize how little I know!

[ChrisK]

The CAD files were emailed to you.

A shunted (shorted) coil, which is a coil terminated in the lowest possible impedance (its internal impedance) will draw the most energy from a vibrating string.

Since nothing is free, the energy comes from somewhere, and in this case, it's from the string. It will reduce the sustain of the note.

A hanging coil, or one that is connected to a signal output point by only one of its two leads, will, in theory, couple signal (good or bad) into said signal output point thru capacitive and inductive coupling which completes the circuit.


Several tests have been conducted to analyze the effect of both, to incomplete results.

The only valid way to test for the effect of these wiring practices is to have an A/B switch that adds/removes EACH effect individually. A recording device must be triggered and a note plucked. The A/B switch should rapidly be toggled (perhaps 1 sec on/2 sec off) and the difference listened to.

Any method that does not use the same signal event will be inconclusive, since the signal events are generated by humans.


Those that prefer a very clean sound will notice the effect of a shorted coil (I test all guitars thru the same PA system), which has effect on the harmonics of the vibrating string, while those that use a fair amount of distortion may notice the effect of coupled noise due to the non-linear active circuit response, as well as not hearing the difference in sustain since clipping of any sort tends to limit the signal amplitude and hence, creates artificial sustain.


In position #4, since the neck coil is hanging, it is shorted to eliminate the effects of a hanging coil while incurring the effects of a shorted coil.

[ew57]

Thanks for the info guys! I finally got a chance to get back to this build!! ChrisK, if the coil is completely removed from the circuit, does it still have an effect on the string(s)? Thanks!

[ChrisK]

No, it shouldn't present any load to the strings other than the effect of the magnetic pull (which is always there anyway).

[ew57]

Thanks for the quick reply! So if a guy was to use a transistor (or two) , then he could remove the coil from the circuit without the ill effects of hanging or shorted coils, or are the effects of said coils too minor to deal with such foolishness?

[sumgai]

May 7, 2009 13:18:26 GMT -5 ew57 said:

So if a guy was to use a transistor (or two) , then he could remove the coil from the circuit without the ill effects of hanging or shorted coils

Errr, not quite. An active circuit (one or more transistors) will not change the net effect of hanging, shorting or whatnot, because it acts equally on all signals put into it. If there's a buzz from a hanging hot, it'll get amplifed too. If your harmonics suffer from the short, they'll still suffer, perhaps even more noticibly.

The only way to cure either/both ill(s) is to use another pole on the selector switch to fully disengage the + line from the "off" pickup. This goes beyond the standart 2P4T switch shown above, as found on different model Telecasters - your 4P5T 'superswitch' will be necessary for that functionality. Which of course gives you your desired "Off" position as well, thus fulfilling your stated requirements.

Where you might revisit the schematic above is when considering the pickup selector scenario. You've said "I'll just do a permanently parallel thing....", and that's fine, but...... You might want to experiment with both pickups on in series, with the various possible coil combinations in each pickup. You don't need four switch positions to do this, obviously, you can do it all with a toggle, slide, rotary, push-pull, or what have you, choose your favorite form factor. Electrically, the switch would need only to be a DPDT, and that'd let you open up a world of tones that you were otherwise going to never experience.

Or so it seems to me, anyways.


(Me? I'd use two Tele switches as above, one for each pickup. Then I'd use a superswitch as a pickup selector, wired so as to cure all ills. Not incidentally, I'd now have only one "Off" position instead of two, which some folks would consider a good thing. But that's just me. )

.... or are the effects of said coils too minor to deal with such foolishness?

As noted by Chris above, these effects have been tested, but only in an anecdotal manner (not scientifically in any way, shape or form). Some members here, speaking both for themselves and repeating what they've seen/heard/read from other sources, state that these effects can be easily heard, although they usually admit that this is only when conditions are optimal for doing so (IOW, not in a live performance environment). Others tend to poo-poo the very idea, which really means that they haven't taken the time to test for themselves, they're just parroting thier beliefs-of-the-day. I'm more in the first camp, but I have to disclose that my hearing is pretty much shot, and even in a quiet studio I don't hear any differences worth talking about. But others swear that they can hear 'em, and that's good enough for me to say "well, then let's deal with that little issue".

All in all, you're on the right track (to Nuttiness, of nothing else! ;D). Please remember to post images of your drawings when you're done.

HTH




sumgai


EDITed to add:

Watch, Chris will come back with

So if a guy was to use a transistor (or two) , then he could remove the coil from the circuit without the ill effects of hanging or shorted coils

The answer is yes, of course. Err, you are referring to a digital switching scheme, aren't you?

[ew57]

Thanks for your reply! To clarify, I've sketched out that I can do the following with just two of the four poles of the superswitch, much like the tele 4 way example:

1. P-90
2. Parallel P-90 & rail
3. Series P-90 & rail
4. rail
5. off

With the third pole, I figured I could use the 9v from the buffer circuit I intend to use to put voltage on the gate of a jfet that would be in series with the positive of the neck coil & also the negative of the bridge coil (following the tele 4 way example again) at the appropriate positions to simulating open, thus removing the coil from the circuit. An application similar to what I’m trying to describe was found here:

www.allaboutcircuits.com/vol_3/chpt_5/2.html

I’m interested in keeping one pole of the super switch free for control of the buffer circuit, but that’s a whole other story.

I’m no EE for sure, just hacking my way through life!

[sumgai]

ew,

Well Hell's Bells, but you are indeed talking about a digital switching scheme...... albeit a bit out of the ordinary, but I digress.

This would work, with suitable design specs, but it's still overkill. Worse, one (that would be you, in this case) needs to consider how the FET under consideration will affect the tone coming out of the pickup, and through the turned-on device. Not all FET's are create to be 100% transparent to an audio-spectrum signal, though most can do a decent job of it.

And for the final straw, you are now draining a battery, thus creating work in the future tense (changing batteries), and this drain does not even contribute directly to the sound/tone/level of the signal going out the jack. That's a pretty meager ROI, IMHO of course.

Until you do some experimenting, I wouldn't bank on talking to any patent attorneys. But by all means, such experiments are cheap (wallet-wise), fun, and most importantly, instructive. Please, have at it, and keep us posted on what you find. Or ask questions here, as the case may be.

HTH




sumgai

[ew57]

Actually, Gibson has a WAY complicated circuit that is somewhat similar (and patented) patent #5,136,919. I love patent searches!

ChrisK, didnt you say "If'n it ain't for commercial uses, SWIPE good ideas. (Steal With Integrity, Pride, and Enthusiasm.)" ? ;D

[newey]

The only valid way to test for the effect of these wiring practices is to have an A/B switch that adds/removes EACH effect individually. A recording device must be triggered and a note plucked. The A/B switch should rapidly be toggled (perhaps 1 sec on/2 sec off) and the difference listened to.

Any method that does not use the same signal event will be inconclusive, since the signal events are generated by humans.

It seems to me we have been having this debate for far too long. As ChrisK would say "Empirical is!"

I envision a test mule guitar, 2 SC pickups (SCs would presumably accentuate any noise issues more than HBs), with one of the two pickups wired with a DPDT switch across it so as to take it completely out of circuit. This would be followed by another DPDT, with one pole shorting the pickup and the other pole leaving it hanging. The other pickup would be always on.

One could then test along the lines Chris suggests, toggling between hanging/shorted/out of circuit, and posting audio and visual results.

One could of course put this all on a single switch, but I figure one is more likely to have spare DPDTs lying about than more complex types.

I'm willing to take this on, but it would have to await completing several other projects- too many half-assembled guitars around the place tends to draw the stink-eye from the wife.

So, if anyone else has the time, guitar and inclination, the gauntlet has been thrown down, so to speak.

[ChrisK]

Not all FET's are create to be 100% transparent to an audio-spectrum signal, though most can do a decent job of it.

Yep. That's why we invented analog multiplexers (aka analog switches).


Come on now, post the linky.
www.google.com/patents?id=7q0eAAAAEBAJ&printsec=abstract&zoom=4&dq=5,136,919
This patent expires this summer.

As I had posted a ways back in unk's "Brian May Trilogy",

I did develop a much easier way of doing this a few years back (2002). A$$uming that the phase switches are separate from the combo switches, it takes three SPDT center off switches, a GAL (a ultra-low standby current/input threshold activated CMOS Generic Array Logic IC), 8 SPST analog switches, a few resistors, an optional OPAMP buffer, a voltage regulator, and oh yeah, a 9 volt battery. I'd also included active tone controls.

Note that I'd also included CMOS switching of phase and humbucker splitting. BTW, it's only easier since you use a PCB to do the wiring, program the GAL to do the switching logic, and use active stuff to save a whole bunch of money. This can be done for about $20 to $30 in volume.
i37.photobucket.com/albums/e84/cekikta/Wiring/P-CADCore2-Sheet5.jpg

There are folks selling a microprocessor/LCD-based thingy that does this with relays (for "vintage tone").

A person is allowed under U.S. Patent Law to make a copy of any invention for their own non-commercial use.

(Steal With Integrity, Pride, and Enthusiasm.)