Mixing Hot Rails & Strat pickups creates problems.

[wolf]

I am attempting to install a Super Seven Switching
www.1728.com/guitar6.htm
in a ninth guitar and this is the first time I've had any problem with it.
Basically, the circuit is designed for two humbuckers and the guitar I'm rewiring has 2 humbuckers which consist of 1 Hot Rails and 2 Strat pickups, one of which has RWRP.
I can get one half of the Hot Rails to match up with one of the Strat pickups. When I change to a different pickup, it should only lose humcancelling but instead it goes out of phase.
The only thing I can figure is that the Hot Rails are magnetized horizontally whereas the Strat pickups magnets have the North - South axis in a vertical direction.
I'm sure you will want more information but I've typed enough to get this topic started.

[ashcatlt]

Jun 13, 2010 4:32:10 GMT -5 wolf said:

The only thing I can figure is that the Hot Rails are magnetized horizontally whereas the Strat pickups magnets have the North - South axis in a vertical direction.

I'm not completely sure what you mean here, don't think it's quite possible, and am pretty sure that it wouldn't make a difference anyway.

If each "HB" is in fact cancelling hum and producing anything better than a thin nasty mess then the two coils must have the same string-sensing polarity. If you've wired it so that the two HBs are sensing in the same direction, then all 4 coils must have the same string-sensing polarity and I don't really think it matters why.

As hard as it is to believe from an old pro like you, the only answer that makes sense (to me, maybe I'm overlooking something) is that you've made some silly mistake in the wiring.

[newey]

The only thing I can figure is that the Hot Rails are magnetized horizontally whereas the Strat pickups magnets have the North - South axis in a vertical direction.

Are these the real SD Hot Rails™? And are the SCs Fender SCs?

There are many pickups with the dual rails format. I've never heard of any being magnetized "sideways", but who knows?

Seymour Duncan advises that, in general, their pickups are magnetized opposite of Fender SCs, although they note that Fender has changed their magnetic polarity several times over the years, so it depends on which Fender SCs one has.

But if this is the case with your pickups, it could explain the anomaly.

I can get one half of the Hot Rails to match up with one of the Strat pickups. When I change to a different pickup, it should only lose humcancelling but instead it goes out of phase.

Do you mean that when you change which SC is combined with the one coil off the Hot Rails, you observe this? Are both coils split from the Hot Rails in your scheme, or only one?

One of your SCs is RWRP with respect to the other. One of the Hot Rails coils is likewise RWRP with respect to the other. If the Hot Rails is of opposite magnetic polarity with respect to both SCs, we would expect that the RWRP Hot Rail would be OOP when combined with the RWRP SC (since the windings would be the same but the magnet reversed in the SD.)

The "regular" SC would then be also out of phase with the RWRP Hot Rails coil, since although the winding was opposite, the magnetic polarity would be the same.

If you are splitting both coils individually from the Hot Rails, you should notice the same results with the other SC if the other Hot rails coil is selected. And there should be some "phasiness" when the full Hot Rails is combined with either SC, although that may be tougher to notice.

But if it's only the one position that has a problem, the opposite polarity issue can't be the culprit.

EDIT: Ninja'd by Ash here, but I think we're both essentially saying the same thing.

[wolf]

Well, I figured that sooner or later, a visual aid would be required:

(Sorry for that smudgy .jpg image)
Looking at the bottom 2 drawings of that graphic, when I talk about the magnets being polarized differently, I mean for the SD Hot Rails, polarization is along the "x-axis". However, the "Strat" magnets are probably polarized vertically (along the Y axis).
Newey, the pickups are not genuine Seymour Duncan ones. They are the Duncan Designed brand.

[sumgai]

wolf,

Be thankful that ChrisK isn't here to castigate you.

A magnetic field shares at least one common property as our beloved coils - markings or designations thereupon are relative, and not absolute. A magnetic field is circular (when viewed from a given angle), it is never linear. It does "distort" into an elliptical shape, along at least one plane, if the basic magnet's shape is not a perfect sphere.

That ellipse can be oriented more strongly in any one plane, but for the most part, we don't care if the field is stronger in one direction or the other, so long as it works to sense the vibrating string. And you've got to admit, the pickup works, so really, who cares if the magnet(s) might be more powerful in some other direction, eh?

Given all that, I think you're chasing phantoms with this line of reasoning. Not to mention that myriad other players (or more properly speaking, their guitars) have successfully combined these two pickups without issue, albeit perhaps in a more simple arrangement.

I'll not go out on a limb and guess what's wrong in your case, because after all, you've done eight more of these than I have! But I'll gently remind you that when the stinky stuff makes forceful contact with the rotating ventilator, it's time to go back to basics. In your case, rather than starting over from the beginning, I think I'd start by removing those things that could produce the effect you're noticing. Take notes as you go, and don't backtrack just because something you tried didn't solve your problem. Work in a logical and linear fashion, because nine times out of ten, jumping around just delays success.

HTH




sumgai

[wolf]

sumgai
To tell you the truth, I have just a very fundamental understanding of magnetic fields. In fact, I keep thinking of those magnets you see in the 4th grade with N and S clearly marked, leading you to think there is no magnetism outside of that horizontal field.

Another problem might be the fact that a Hot Rails and a Strat pickup are very dissimilar and this might cause problems in getting a combination of the two to behave as if they were perfectly matched coils.

You mentioned that other people have used Hot Rails and Strat pickups with no problems but as you said, never in such a complicated setup.

[newey]

Did you check the resistance of the pups before installing?

Usually, a coil either works or it doesn't, but a bad coil might be a thought here. And the resistance measurements will/would be handy in sorting this out anyway.

[wolf]

Yes, all four coils are working. As I said I think the problem is that the coils may be too dissimilar to each other.

[sumgai]

wolf,

I think the only question that's left here is, do the two pickups have such disparate impedance values that connecting them together causes a drastic change in the total impedance (as you select some particular combo). I can see where if one pup "dominates" the other in this fashion, then you might get a "half-phase" sound, just like the series-with-capacitor circuit we sometimes talk about.

I think some 5Spice modeling is in order here, but the first question will be, what are the impedance specs for these devices.....


HTH



sumgai

[wolf]

Good point Sumgai

As you thought, there is a bit of a difference in the DC resistance between the two. (I don't have the impedance figures).
The Hot Rails have a DC resistance of 13.6 K each and the Strat type single coils are 6 K each.

So, basically, the Hot Rails have more than double the resistance of the Strat coils.

[ChristoMephisto]

Even with 13.6k, thats two SC in series each with about 7.8k
Even with that, the DC resistance doesn't describe the characteristic of the pup.

Have you tried other pickups?

[chuck]

the Hotrails is simply two single coils ... so what you have are 4 SC pickups that you want to use in various combinations.

they will work like a charm if they are wired correctly.

troubles like this are usually due to a simple oversight ... recheck everything and i bet you will find the problem

[wolf]

Oh I've rechecked everything and I'm at the point where all pickup wires are disconnected from the switching. So, if I want to test how 2 coils sound, it's now a matter of twisting wires and connecting with alligator clips.

I've done this wiring 8 times before and I'll admit I have messed it up a few times previously but I've always managed to track down the problem.

Oh and I have taken the Seymour Duncan wire colors into account because I usually wire DiMarzio pickups.

[chuck]

you should have it ironed out in no time