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PostPosted: Fri Jun 16, 2017 4:34 pm 
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Koa
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Has anyone dabbled with multichannel pickups? I'm wanting to play around with it for a 5 string bass. If anyone has any experience with such a thing and have an advice or two, that would be super helpful. I'm not sure what dimensions I need to go for or the amount of windings for each individual pickup. Planning for passive, not active. I've heard with passive there can be some crosstalk between the pickups but if it's minor I can live with it. Spacing is further with bass so it already shouldn't be as bad as with guitars. I may also try the steel plate between each or even see if shielding tape helps. Will probably go with one multichannel bridge pickup and one normal Jazz Bass esque neck pickup.

Let me know any thoughts you guys may have.

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PostPosted: Sun Sep 17, 2017 3:32 pm 
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You could try Mu-Metal between each coil, it will block most of the magnetic field.
https://en.wikipedia.org/wiki/Mu-metal


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PostPosted: Mon Sep 18, 2017 1:31 pm 
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If you are just going to play around with it your good. In production though, there is much to consider, as there is all the additional gear and differences in signal processing involved, adding greatly to the cost of ownership of such an instrument.

As far as the number of windings: First of all there is a lot of snake oil in pickup design already, like "advantages of tall pickup designs" even though the detectable field of a vibrating string only reaches the top 1/3 of the coil in most conventional pickups, not the entire coil where the bottom 2/3ds are nearly inactive, and only add resistance. You will of course have a larger effective field with increase of string gauge (mass), so in effect, with separate cols for each string, you may want to have different number of windings and possibly differing magnetic poles for each coil. Now consider that a string resonates as a longitudinal wave, and excites the pickup where it crosses over the magnetic pole is a sweeping motion from side to side. The part of the winding in front and in the back of the pickup also have less to do with the field than the sides, so coil and magnetic pole shape manipulation come to mind. a rectangular or oval configuration with less windings will prove better than a round design with more as far as tonally. In the end as even with conventional pickup design there are many variables to work with, every one making one difference or another, and no set or best formula when human hearing and personal preference enters the equation. Experimentation will have to be your best friend there, although I can say that a ball park figure to start at would be to up the coil wire length of a regular pickup (which can vary quite a bit) and at least double it or more, then divide it by 5 (in your case). Taking it from there you will get acceptable results, and a good starting point to further exploration to further mold the output and it's sound.

As to cross talk: It is not necessarily that big of an issue in general, as the separation itself within the small magnetic field of induction is going to make a huge difference already in separating the signal and cutting down on accumulative wave distortion, and the tiny amount of cross talk is not going to be a major issue in the grand scheme of things.

The largest factor (the biggest difference achievable) in the sound of an instrument with magnetic pickups is not coil windings or magnetic field properties, but pickup placement, IOW Where the pickup resides within the usable space of the scale length. That is where you will find the most variance to work with, and with a separate coil for each string, the most room to work with.

So without giving you a 25 page essay with all of the mathematical formulas, only to have you find out that it does not jive with human hearing in the end, and is still only a starting point destined to not work out as planned, I hope this is of help.

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These users thanked the author Guitarizzmo for the post: Hesh (Mon Sep 18, 2017 2:31 pm)
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PostPosted: Tue Sep 19, 2017 9:01 pm 
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Cocobolo
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I have been experimenting with multi-channel pickups for quite a while. My focus is electric guitar first, but the same principles and designs apply to electric bass.

I would highly recommend trying a moving coil design, where the string is the coil. This way you get no crosstalk. There is a fantastic thread about this type of pickup design here: http://music-electronics-forum.com/t14952-4/#post448104

The concept is very simple: the strings must be electrically separated at one end, say the bridge, and can have common ground at the other, say the nut with the signal routed back through the neck through the metal truss rod. Magnets under the strings induce a small current in each string as they vibrate. A transformer is applied to each string in the control cavity to boost the signal to something usable to output to a mixer.

Expect a more acoustic-style sound from such a design because the pickup aperture usually includes all of the available area between the end of the fretboard and the bridge, instead of the much narrower sensing area of traditional magnetic pickup designs.


All that said, I've also tried about 5 different single-string magnetic pickups with varying degrees of output and crosstalk problems. I don't know if string bending is a priority for you as a bass player but if it is then beware of the problem of bending strings in the higher positions and using single-string pickups in the neck position - funny things happen to the output levels as the strings are bent out of the magnetic field!

My most successful traditional single string design was a simple two coil humbucker for each string with the coils wired in a balanced output scheme as described by David King in this post: http://music-electronics-forum.com/t7646/#post200817

Super clean output. I positioned the treble-string pickup at the neck and the bass-string pickup at the bridge with the rest staggered in a straight line between them from bridge to neck - very balanced tone-wise: mellowing out the treble strings and brightening up the bass strings. 100% in agreement with Guitarizzmo that pickup placement is the most powerful determinant of tone color for traditional magnetic pickups.


All that said, just buy some of these: https://www.cycfi-research.com/product/nu-module/

Leo



These users thanked the author Durero for the post: Guitarizzmo (Tue Sep 19, 2017 10:59 pm)
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PostPosted: Tue Sep 19, 2017 11:18 pm 
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Durero wrote:
All that said, just buy some of these:


Yep, figured out a long time ago that I can't possibly do it all, and get it all done too, let alone spend good money on more equipment taking up more space, potentially ending up unused. There are lots of people out there that are specialized in just that, and have been for a long time. To add another monumental task to ones already overflowing to do list, when someone else is already way ahead with it, makes little sense practically or fiscally. On the other hand you may want to make that your calling, but in order to succeed, may have to drop something (everything) else in order to git r' done.

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These users thanked the author Guitarizzmo for the post: Durero (Wed Sep 20, 2017 2:06 pm)
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PostPosted: Wed Sep 20, 2017 2:13 pm 
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Cocobolo
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Guitarizzmo wrote:
let alone spend good money on more equipment taking up more space, potentially ending up unused.

[uncle] That sentence is a painfully accurate description of me and my shop! :oops: :lol:


Absolutely agree with you again. If you can find a component that fits don't waste time reinventing it.


I forgot to explain in my earlier post that the Cycfi single string pickups didn't exist yet when I began my search and various DIY attempts. The Cycfi pickups are fantastic, both the single string ones and the traditional passive and active designs.


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PostPosted: Wed Sep 20, 2017 7:39 pm 
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Yeah, I still get asked why I don't wind my own pickups... [xx(]

Oh, and those relentless "Pickup changers" those players that just have to try every latest and greatest pickup out there to get one single iota of improvement: One of my clients afflicted by it was selling a guitar and wanted it fully functional to get the best price, but the bridge pickup was dead. He allowed me to put one in that someone had me order, and never came back for the repair (stiffed me essentially). When he heard the 1999 SD Super distortion, he fell back in love with the guitar and was having second thoughts on selling it. I also had to remind him that he had me replace a set of them years back. He had to admit, he should have just given them a better chance in the first place. [headinwall]

I know for a fact that some companies discontinue stuff, only to re-brand it at a later date as the "Newest thing". The fashion industry are the worst: The DKNY "happy peach" blouse your wife just bought, is identical to the DKNY "Young tangerine" one she bought 2 years ago. laughing6-hehe

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These users thanked the author Guitarizzmo for the post: Durero (Fri Sep 22, 2017 1:12 pm)
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