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Help With Complex Wiring Idea


verhoevenc

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So I've figured out how to do the following idea with the 2-pickup combos in parallel... However, as you'll see below that's not the best idea since parallel wiring with a high output and low output pickup will lead to a fairly large volume and resistance drop between settings.

The idea: I want to put a Humbucker in the bridge position and then one of those split-coil single coils in the neck (aka one coil each for the top 3 and bottom 3 strings to make a humbucking single coil). Here's the trick: in positions that combine the two pickups I want to have a pot that allows you to bias to each coil of the single coil to accentuate either the lower or higher strings. All the way clockwise would be just the low 3 strings, all the way counter just the 3 high strings, and in the center it'd be the standard neck pickups.

5-way switch settings would be something like this:

1- bridge humbucker

2- bridge humbucker and neck pickup normal

3- bridge humbucker and neck pickup with "variable coil" pot included

4- bridge coil tapped and neck pickup with "variable coil" pot included

5- neck pickup normal

When I manage to find the diagram I drew up that manages to do this in parallel I'll include it. But I'll be mesmerized by your technical prowess if you can figure this out so, at minimum, positions 3 and 4 are in series!

Best,

Chris

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Can't be done using off-the-shelf parts. Too many options for one 5-way switch to achieve. I can do everything except the humbucker coil tap with a 5-way 4-pole Oak Grigsby Super Switch.

Could be done if you could get your hands on a 5-way 5-position switch (unlikely).

Could be done if you can live with a blend function that wouldn't go to absolute zero at either extreme.

Could be done if your blend pot only faded in one coil while the other remains at 100% all the time.

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The area I'm most concerned with is getting the "one coil or the other" portion of the circuit to work in series with the bridge pickup. I thought I had the idea working here in parallel... But as you'll see with the output matrices to the left... Series would be much nicer!

image.jpeg

Chris

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Are those pickup resistance values known or assumed? 9K seems low for a typical humbucker...

Low resistance doesn't always equal non-optimum output or behavior. Assuming your single coil values of 5K are typical (I have no idea off the top of my head), positions 2 and 4 on a Strat should yield 2.5K, which seems pretty low but that shouldn't be cause for alarm.

I guess the other thing to consider is what that scheme wired as parallel-only sounds like? Parallel makes your wiring scheme viable with the parts you have available, whereas mixed series/parallel complicates things a lot. Is parallel-only wiring off the cards solely because the maths says it looks odd?

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I went with a vintage-style wind. So let's say the SD Pearly Gates: 8.21k. So 9 isn't hugely off base. One thing you've missed though is taller could on SCs allow for more wore and more DCR per coil. I say that the neck pickup, made up of two coils, is 5k EACH. So if played in series it's 10k. That's why in the "series" matrix where the full, non-variable neck is paired with the bridge it's 19k; 5+5+9k.

but no, my main concern isn't low output= bad. My main concern is drastic volume drops between switch positions. In parallel your largest differences are 10 to 2.37 (about a quarter). In series it's 19 to 9.5 (about a half).

Differences are my fear, not absolute values.

Chris

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DC resistance by itself isn't a measure of a pickup's output, only an indicator. The full story is down to the proximity of the pickup to the strings, how far along the string's length the pickup is placed, the number of turns on each coil, the strength of the magnets, the inductance of each coil, the type of magnet used etc etc. A low resistance pickup might be louder than a high resistance pickup owing to its physical position and electrical/mechanical properties.

I'd still suggest wiring it up and trying it out before writing it off based on the calcuated resistances. Either way, I reckon it's an interesting-looking circuit that would be fun to experiment with.

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  • 2 months later...

Looks like this has been sitting here a while, but did you get this figured out, Chris?  The blend on the split neck looks interesting, but are you trying to actually capture bass vs treble strings in that blend, or bass vs treble frequencies?  If it's the former, then yes, a blend pot could do that for you.  If it's the latter, then a Fender TBX tone control could do that.

If you were going to just select one coil or the other of the neck pickup in position 3 and 4, then I think you'd need a Super Switch.  I'm building an 8-string with one bridge humbucker straight to volume, no tone, and I've been sketching out different sound combinations of just two coils (series, parallel, cut, caps in series and parallel) on a Super Switch diagram.  Soooo many ways to wire up those babies.

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