DGT coil split resistor question

Random Gecko

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I have a 2009 PRS DGT that doesn't have the resistors on the coil split circuit to bleed in a little of the other coil to add some fatness when they're split. I was thinking of doing it myself and seeing what happened but had a few questions about the wiring of it.

PRS' schematic states that they use a 2.2k resistor on the bridge and 1.1k resistor on the neck. Is it the higher the value the more of the other coil is let through or visa versa? For example, if I used a 3k resistor, would it let more of the coil through, or less?

Any help would be great. Thanks.
 
The lower the value the less of the other coil will come through. What happens with the split coil is that you are grounding the coil that isn't used. When you put a resistor in between the splitted coil and ground, you are grounding it less, so the higher the value, the less you are grounding that coil. So 3k would be more humbucker/less single coil than 2.2k that's more than 1k, or 0k what is effectively what you're having now.
 
The lower the value the less of the other coil will come through. What happens with the split coil is that you are grounding the coil that isn't used. When you put a resistor in between the splitted coil and ground, you are grounding it less, so the higher the value, the less you are grounding that coil. So 3k would be more humbucker/less single coil than 2.2k that's more than 1k, or 0k what is effectively what you're having now.

I'm so confused! I posted this over at The Gear Page too and got he exact opposite response?!
 
Ok, here's what I would do. Buy some resistors, maybe 0.5k, 1k, 2.2k and 3k. Costs almost nothing. Then also buy 2 leads with crocodile clips in both ends so that you can hook in the different resistors you want to try easily and then just try the different values. You can easily see if I'm right or not (not that that really matters), and if you prefer PRS stock values or something else before soldering them in.
 
But if we just want to look at the diagram - I hope you can see that one end of the resistor is connected to the ground? So you are putting in resistance between the other end of resistor and ground, make sense? And obviously when something is grounded, it makes no sound. So less resistance means less sound and more resistance makes more sound. No resistance means no sound.

Your current wiring is probably like this: https://www.prsguitars.com/csc/schematics/schem08/dgt.pdf.

You can see that there's a wire between something and ground in the push pull pot. A wire means no resistance and therefore no so sound. Which makes perfect sense, you pull it and the splitted coils makes no sound. And this leads back - if you where to add in resistance, it means it's less grounded and less grounded would be more sound. So the higher the value, the more resistance between itself and ground and the more sound will come through the splitted coil.

But again, I'd get some crocodile clip wires and resistors and try myself what value you want.
 
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Right, gotcha. So the bridge humbucker is seeing more of the second coil right? Presumably to make it fatter and more Tele?
 
Also, does that mean a 1.1k resistor is gonna be brighter and thinner than a 2.2k for example?
 
Exactly. If you consider that a typical DGT bridge pickup is around 8.8K, that means that each coil is 4.4K. That's the value the split pickup would have without the resistor. If you add in the resistor, 2.2K of the grounded coil is retained, giving a value of 6.6K, which is much closer to the value of a hottish single coil.

The neck pickup is normally around 7.3K. Half of that (3.65K) is a pretty weak single coil. However, with a 1.1K resistor that gives a value of 4.75K.
 
Makes sense.

So to be sure - if you were to put a 2.2k resister on the neck rather than a 1.1k, you'd probably get a hotter output, and more of a traditional humbucker sound - so less highs, and fatter - than the 1.1k which should sound more 'single coil'?
 
I think I am going to try this. I always think the standard coil split is too weak. One question though. When looking at the DGT diagram, it appears that the resistor for the bridge pickup is grounded on the right lug of the push/pull pot. Are both resistors grounded this way? From the drawing, you can't tell if the neck resistor is grounded in the same place.

Thanks
 
The diagram simply shows the route to ground, but you don't have to connect the resistor to the lug directly. The right lug grounds the casing. As long as the resistors are connected to the casing, that grounds them both.
 
Exactly. If you consider that a typical DGT bridge pickup is around 8.8K, that means that each coil is 4.4K. That's the value the split pickup would have without the resistor. If you add in the resistor, 2.2K of the grounded coil is retained, giving a value of 6.6K, which is much closer to the value of a hottish single coil.

The neck pickup is normally around 7.3K. Half of that (3.65K) is a pretty weak single coil. However, with a 1.1K resistor that gives a value of 4.75K.

I'm sorry, but these calculations can't possibly be correct. Maybe they are ok approximations, but certainly not correct. If you add a 10K resistor instead, by this calculation the 8.8K humbucker would be 14.4K when split (8.8/2 + 10), and that's just not going to happen. If you add infinate resistance, i.e. disconnect the resistor, you get 4.4K on each coil, or 8.8K for both so that's the maximum you can ever achieve. I'm not sure about the calculation but it must be some form of sliding scale between 0 resistance (0K output) and infinite resistance (4.4K) output for the split coil but a simple addition of the resistance is not going to give the correct result.

Best way is probably to just test anyway. When I've used the default PRS values though, I've gotten excellent results.
 
I could be wrong, but that's the way I understand it. If you used a 10K resistor, as you suggest, I think it would have little or no impact on the sound as it would, by my understanding at least, allow the full 4.4K of the "grounded" coil to remain in play. As long as the value of the resistor is greater than the resistance of the split coil, then it will do nothing. I must take some measurements and compare my theoretical figures with real values.
 
if you want to fine tune your single coil sound use a mini trim pots of say 3k3 value instead of a fixed value resistor then adjust to taste ;-)
 
The problem with resistors is they need current flowing to work, as per Ohms law
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there's not a lot of voltage or current flowing in a pick up circuit. I've tried this tweak on more than one occasion and, if I'm honest, I don't find it makes a whole lot of difference. I know people say it does make a difference but I'm yet to be convinced.
 
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... I know people say it does make a difference but I'm yet to be convinced.
It depends on the application. On high gain rigs, the difference is less apparent. Similar to the differences noticed in Cu24s with 57/08s vs. HFS/VB pickups. There's a huge resistance difference but at high gain, that translates into other factors (like clarity and frequency response). But on certain setups, like mine, the difference is very readily noticed. It's wonderful, if it fits your tastes and application.
 
I think that we may have jumped the tracks here. Sooo... It's true that the measured DC resistance of a pickup is an indication of how much output it can generate. But the higher measured DC resistance is an effect of a higher output pickup, not a cause. More windings around the bobbin means more output for a given disturbance of the magnetic field from the strings. And more wire means more DC resistance through the wire. But it's not the resistance itself generating the output. The DC resistance measurement is simply telling you that you likely have more windings. If you had some sort of super duper low resistance 43 gauge wire, you'd actually get more output. Adding a resistor in a passive circuit can't possibly generate more output. Depending on where you add it, it can certainly change frequency response (and tone) but it won't give you a "hotter" output.
 
It depends on the application. On high gain rigs, the difference is less apparent
That's a good point and, if designed properly rather than just throwing a resistor in line it should work wherever you use it.
Depending on where you add it, it can certainly change frequency response (and tone)
I'd much prefer to see somebody clever design a proper discrete circuit to cater for AC resistance (impedance 'Z') changes in load and voltage in coil tapped pick ups and then you may have something to work with, the resistor alone isn't the answer IMHO.
 
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