Humbucker in parallel

[jeff]

I've read that when two coils are in parallel that each coil loads down the other. That's why pos. 2 and 4 on a strat sound darker than 1,3 & 5. I like the single coil tap sound on my humbucker guitar but don't like the single coil hum. I'm thinking using mixing resistors would still eliminate the hum but not load each coil down, retaining the single coil sound. Just as in a guitar amp that has two inputs,
68K resistors isolate one guitars pickups from the others.

Has anyone tried using mixing resistors, a resistor in series with each coil? How did it sound vs pure parallel vs single coil and what value did you use?

[jojokeo]

I will simply run the humbucker in "dual sound" mode as what it's called going way back to DiMarzio's labeling and one of the first pickups to be able to be modified for running humbuckers in parallel or series modes. Dual sound mode = parallel mode. This way you get single coil type of sound but w/out the humm of actual single coil mode.

By saying "darker" sound are you implying "less output" level? Typically the more turns that a pickup has the more output you get but at the expense of high end which to me, is a "darker sound".

[jeff]

 It's hard to put sounds into words but if you play a strat on the bridge or mid it sounds "brighter" than the bridge/mid position. Know what I mean? It, to me, doesn't sound just like a reduction in volume but "darker", like the tone knob is turned down a little. It doesn't sound like a blend of each sound but a different, parallel, sound. As opposed to bridge being brightest, mid/bridge less bright mid even less bright. The mid alone to me seems brighter than bridge and mid combined which isn't what I'd expect if mid/bridge is a combonation of the mid and bridge sounds.

I don't know if that makes sense???

[jojokeo]

yep, I understand what you mean. That's when it's great to have a no-load tone pot

[HotBluePlates]

I've read that when two coils are in parallel that each coil loads down the other. That's why pos. 2 and 4 on a strat sound darker than 1,3 & 5. I like the single coil tap sound on my humbucker guitar but don't like the single coil hum.

Don't use mixing resistors. Use the proper parallel wiring for your humbucker's coils. I don't have much proof of my opinion here beyond a little experience with series/parallel wiring of humbuckers.

However, I believe that the "odd sound" of the in-between positions on a Strat is due to the distance between the coils being used. Because the pickups are sensing different portions of the string then mixing the resulting signals, we might guess the two signals have slightly different phase and harmonic content. Once mixed by being placed in parallel, the phase difference results in some elements of the sound being reinforced while others are minimized, and a new sound that is not simply adding both.

For what it's worth, when you select both humbuckers on a two-humbucker guitar, they are in parallel, and we don't worry about loading or a darker sound. I'd also contend that the neck/middle position on a Strat is brighter (but different) than the neck position, and the middle/bridge position is brighter than the middle-only position. I've added a bridge-pickup-on switch to a Strat before, and played neck/bridge. It was a lot more like having the neck/bridge setting on a Tele; brighter but not the clucky in-between Strat sound.

A long while back, I had a Les Paul with push-pull volume controls to select series/parallel wiring of the pickups. Parallel wiring gives the expected brighter and lower output sound while killing buzz. So no mixing resistors needed.

[jjasilli]

Guitarnuts.com  addresses this issue.  It's a wiring thing. LP wiring tends to place the vol pots so they isolate the PU's to reduce loading.  Fender wiring does not do this.  Using the Rule of 10's, a series resistor 1/10th the pot value, or less, in the positive PU leads, will isolate the PU's, but not matrially affect the overall circuit.  You might try it and see.

[jojokeo]

I sort of agree HBP on what you're saying about cancellations and such. But w/out overanalyzing everything, parallel wiring results in less resistance. Less resistance means lower output. I think the "perceived" lower output volume tricks the ear into thinking that there's also less trebles and/or highs.

I have an '82 anniversary LP that I installed Seymour Duncan triple shot mounting rings onto and they're pretty cool. Without any modifications I can switch any pickup configuration that's desired - series/parallel or any single coil. They're very easy to install and not to much $$ either. I rather like the parallel mode as it helps give a nice little subtle brightening to an otherwise dark sounding guitar in general. My fav or usual is running the neck paralleled w/ the bridge pu in series.

[G._Hoffman]

That's not why humbuckers are darker - or at least, it is not the only reason.  At least as important, probably more so, is the length of string that the pickup "sees."  When you have a longer string, you get multiple cycles of longer wavelengths (i.e., lower overtones), and if they aren't in phase (and most of them won't be) they will start to comb filter each other out.  This is why a stacked humbucker the size of a single coil will never sound like a full sized humbucker, a P-90 doesn't sound like a Strat, and a mini-humbucker doesn't sound like a Full sized humbucker.  The size of the pickup window is a huge piece of a pickup's sound, and changing the load on the pickup will never allow it to get around the acoustic comb filtering that is going on. 


Gabriel

[jojokeo]

The size of the pickup window is a huge piece of a pickup's sound

Yes, you're right - the "pick up window" is only part of it which yields the type of sound, quality, and volume that you hear.

You mean to say the total string area passing over the total area of a given pickup. But there's many other factors like string mass, string composition, string proximity, vibrating over the coil's (size, type, and length of coil wire) magnetic field (type, size, composition, properties) of magnetic material being used...and this is not all of the factors that goes into it either. However, I don't think we're trying to go into a thesis of pickup making here or an expose' on why an electric guitar sounds the way it does as compared to another. The shark is being jumped here now.

[jeff]

Thanks for the thoughts guys.

 That makes sense to me now that the position of the pickup will pickup the srtings vibrations at that point and some of the signal will be boosted an some cancelled. For some reason I thought that the "problem" with parallel pickups was each pickups DC resistance and the impedance of the coil. The way I was thinking was this: I read that a 1M vol pot will be brighter than a 250K volume pot. Imagine you have a single coil and a 250K vol on full. Now add another coil(and for the sake of argument let's ignore what it's picking up, let's imagine it's connected to the jack but not in the guitar) Now that first pickup on full vol has 6K to ground not 250K, isn't that like using a 6K volume pot on full? I thought that was the "promlem", that you're loading each pickup down because of the DC resistance of the other's coil. Plus, you now have a coil to ground, the impedance of having a coil to ground will kill highs, right? I thought isotating resistors would lessen these effects. Now I have to figure out which came first the chicken or my head- I need to think less, play more!

LP wiring tends to place the vol pots so they isolate the PU's to reduce loading.  Fender wiring does not do this.  Using the Rule of 10's, a series resistor 1/10th the pot value, or less, in the positive PU leads, will isolate the PU's, but not matrially affect the overall circuit.  You might try it and see.

Great Idea, but I don't even have to do that. You've given me an insperation for an experiment. The way a LP is wired(at least mine, i've seen schematics for "backwards pots"), The vol wiper of each is connected when both PUs are on. So basically when full on the pickups are in parallel with 250K(2X500K) to ground. So by turning each vol down a little, it's like each pickup has a isolating resistor. 50K isolating resistor and 225K to ground vs no i-resistors and 250K to ground.

[jojokeo]

I would like to suggest turning your tone pots into "no-load" pots or buying no-load pots. Also, if you have the covers on your humbuckers, remove them. These two things will make a difference in brightening up and taking the blanket off a dark sounding guitar. Plus the no-load pots gives you a slightly higher gain out of them too. It's a nice improvement and if you want the "before" mod sound, just slightly turn the pots down to ~8 or 9 on the dial and they're back to stock sounding. I've "no-loaded" many guitars and it always gives a pleasant result, it's just one more option available like another switch or setting to be had and that's never a bad thing.