I had a guitar vision...

[spook]

I've been poking through this forum a bit, and I'm very impressed by the amount of knowledge flying around here. Unfortunately, it also really confuses me. Since I'm definitley more of a musician than a tech, I was hoping some of you might answer a few questions. Mostly out of curiosity, than wanting to actually mod my guitar.

So, last night I fell asleep listening to "Queen II" the album by, well, Queen. It must have been Brian May's wonderful Red Special that inspired it, but I had a bit of an odd dream.

I own a Jay Turser 134, which is a semi-hollow Les Paul style body.



Except she's black, cream trim, chrome hardware and I but a bigsby on her.

Anyway, in what I remember of this dream, the controls on my guitar were a little switched around.

In the place of the pickup selector there was a master tone/volume cocentric knob, controlling the whole output of the guitar. Three of the four volume tone knobs were again cocentric pots.

But this time, the top knob was a in/out phase knob, and the bottom was an on/off knob. I guess the second is really the same as a volume knob though.

The fourth knob was controlling a piezo bridge in the tune-o-matic.

The thing that confuses me, is that there were only two pickups on the guitar, but I was manipulating and combining three. This leads me to two conclusions.

1)As usual, my dreams make no sense, and there was supposed to be a third pickup.

2)there were two single coil pickups inside one of the humbucker cases.

Now, the second one is really intriguing to me, personally.

And I thought this was an interesting (even if probaly not completely original) concept that could make for a lot of really cool sounds. Since you can combine all thre pickups, at different volume levels each, with different phase adjustments, and then still adjust the tone. I'm wondering how the piezo could figure into all this though...

Fascinating, I think, and I was just wondering if anyone could give me some input or point me towards some reading material, I'm not looking for schematics or anything...

Thanks!

[UnklMickey]

spook said:

...This leads me to two conclusions.

1)As usual, my dreams make no sense, and there was supposed to be a third pickup.

2)there were two single coil pickups inside one of the humbucker cases...

hi Spook,

Welcome to Guitarnuts2.


i can't help you with conclusion #1.

your dreams / nightmares / fantasies / etc. are between you and your shrink.

.:lol:.


but in regards to conclusion # 2:

there ARE 2 single coil pickups in EVERY humbucker.




unk

[spook]

unklmickey said:

spook said:

...This leads me to two conclusions.

1)As usual, my dreams make no sense, and there was supposed to be a third pickup.

2)there were two single coil pickups inside one of the humbucker cases...

hi Spook,

Welcome to Guitarnuts2.


i can't help you with conclusion #1.

your dreams / nightmares / fantasies / etc. are between you and your shrink.

.:lol:.


but in regards to conclusion # 2:

there ARE 2 single coil pickups in EVERY humbucker.




unk

Thanks, that's what I figured, but I never knew if they could be wired in such a way as to be controlled individually, so that they can be individual pickups, or put together to 'make a humbucker'.

And yes, conclusion one is, well,

[UnklMickey]

if a HB has 4 wires coming to the outside world it can be treated as 2 separate coils, with all the commensurate switching and controls.

if it doesn't have 4 separate wires, but is an uncovered unit, it can easily be rewired to 4 separate wires.

if it is a wax-potted covered HB, it will be more difficult, but still possible to rewire.

if it is an epoxy-potted covered HB........................good luck with that!


unk




EDIT:


hey gang,

there was also mention of piezos in the first post of this thread.

so, who's our resident expert on that?

[spook]

So, assuming that my pickups do have 4 wires each, I could have one cocentric phase/volume for each coil?

What I'm wondering is, how is a volume knob different from an 'on/off' switch in this situation? Would it work much the same, or would it have some different effects?

Also, what difference would a phase knob, rather than an in/out phase switch make? I've seen a unit in a recording studio that allows a 180* arc of phase switching, rather than the o with the x through it for a 18-* flip. Is this rather the same?

And I've been looking at piezo tune-o-matics, and I've seen a couple interesting things. One (GHOST) that was supposed to be really swank and work with some MIDI stuff, but in my experience stuff that awesome rarely works out.

It's all so fascinating, and I'm so new to it, that I'd love any bones to be thrown to help me out!

And unklemickey, thank you for your input already!

[UnklMickey]

spook said:

...One (GHOST) that was supposed to be really swank and work with some MIDI stuff, but in my experience stuff that awesome rarely works out. ...

maybe, but with a screen-name like Spook, i'm sure a product named Ghost must be intriguing!


LSH....



changing phase in a continuously variable fashion in a passive circuit would be impractical.

by using delay, you could alter the phase relationship, but that would change according to frequency.

so, mostly it make sense to think of changing phase, only in terms of switching connections.

the simple things to deal with on pickups in passive circuits are:

In-phase or OoP (Out-of-Phase)

series or parallel

overall amplitude (volume) or relative volume (blending)

filtering (high-cut, low-cut, or mid-cut)



unk

[ashcatlt]

As for the phase shift deal: I think the box you have seen was probably the Little Labs IBP (In Between Phase), or something similar. I couldn't find a schematic, but according to the manual it uses a pair of (passive?) all-pass filters. The active electronics are all buffers and makeup amps. I don't know much about it, but you might be able to build something similar inside a guitar...

That being said, I'd like to point out that the effect of a "phase knob" would only be noticeable when you have 2 or more pickups combined.

To the rest of your dream. It is concievably possible to have an individual volume knob for each of the (4) coils in your guitar.

A little bit of info regarding the humbuckers. Every humbucker combines two single coils. One of these will be both Electrically and Magnetically 180 degrees out of phase with the other. This way when the two are mixed together in equal proportion, the signal induced by the strings will add together, while the hum caused by EM radiation cancels out. The hum is "bucked".

The two coils are so close to the same physical point on the string that selecting between the two will have no audible effect.

Humbuckers come from the factory with the two coils wired in series with one another. This is part of what creates that distinctive HB sound. If you leave it wired in series with itself and put a volume pot on each of the coils, each one of these pots will act as a master volume for both coils. That is, turning either one all the way down will turn the entire HB off. This setup would give you more "fine" control of the volume, but would probably have limited practical use.

On the other hand, you could wire the two coils in parallel with each other. This will produce a sound which is much closer to that of a single coil pickup, but just a little louder. In this case, the individual knob will affect only its assigned coil. Turning down one of these will reduce the overall volume of the pair to something a bit more than half. At the same time, the proportion of hum in the signal will increase.

[UnklMickey]

hi Ashcatlt,

nice link!

i always enjoy seeing what people are doing in the audio / studio world.

interesting concept, all-pass filtering to affect only the phase of the signals.

don't let the term all-pass mislead you. these are no-doubt active filters.

pass in this case refers to "throughput", not the lack of active devices.

ie: high-cut, high-pass as being two complementary types of filters

neat stuff that, although $600 per channel does put it out of reach of most average folks. (but then even average folks dream about stuff that is out of their budget range.)



it is good that you are putting so much thought into how pickups interact.

there aren't that many of us who spend the time, to look at the deeper aspects of the physics and electronics.

The two coils are so close to the same physical point on the string that selecting between the two will have no audible effect.

that is definitely a true statement.

going a bit deeper, the coils are so close to one another that when used together, they have a small, but finite temporal difference.

summing the 2 signals together after buffering with active preamps would result in a sound that would be similar to a single coil, yet the slight gap between them causes a slight phase shift. (comb filtering.)

when we put the 2 coils together in either series or parallel (without buffering), we create a further divergence from the sound of a SC. the doubling (or halving) of the internal inductance alters the frequency response.



If you leave it wired in series with itself and put a volume pot on each of the coils, each one of these pots will act as a master volume for both coils.

take a look at the ToneMonster2.

JohnH does some nice work there with his blender, to adjust the relative volume of coils, both in parallel AND in series.

the same principles involved there, can also be applied to the 2 coils of a HB.


as you mentioned, decreasing the amplitude of the signal from one of the coils will dramatically affect the hum-canceling, as well as the tonality.




unk