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Permalink Reply by Blues Frog on September 16, 2016 at 4:54pm

it keeps the strings high off the pickups. the higher they are the less the coils willpick up the sound.

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Permalink Reply by Ron "Oily" Sprague on September 16, 2016 at 7:24pm

Ok, that will work. Barely. Two major problems, one of which was mentioned, and another of which wasn't. The first problem is that a mag pup works by primarily string vibration distorting the mag field over each cylindrical mag core, which causes a small current to flow in the copper wire coils surrounding the magnets. That current goes through all the wiring to the jack, through a guitar cable, and to an amplifier. Along the way, there is a loss of current due to resistance and dispersion. What current arrives at the amp is so small, it needs to be boosted, so as to ultimately drive a speaker to transmit sound. The amplifier takes that current, and boosts, or amplifies (hence the name) it enough so as to be able to drive the magnetic coil in a speaker; the vibration of the speaker pushes air,mwhich your ears receive and your brain translates as sound. Yes, placing a bridge on a mag pup will transmit vibrations to the coil of the pup, causing a current flow by distorting the mag field around the cylindrical magnetic cores. Do an experiment: plug in a standard mag pup, and rap it sharply with your hand or other blunt instrument. Ther will be the sound of a dull thud transmitted. But, the current generated from the string vibration transmitted through a bridge to a pup is likely to be even smaller than that generated by string vibration in a magnetic field alone, due to dampening from the bridge itself, unless it is made from something extremely dense like titanium.

The second problem is related to the first. Strings are "attached," for all practical purposes, at the bridge, and the nut. Those two points are called nodes. Those nodes are zones of almost no vibration on a string; not none,me cause there is some, but almost none. Strings vibrate in a sigmoidal, or S-shaped, pattern, along their length, when plucked or strummed. The harder you strike the string, the larger the vibration (to a point: you can break a string by exceeding the material's willingness to vibrate and deform). Putting this vibration of the string inside a magnetic field is what you want to do with a mag pup. By locating the bridge atop, but just behind, the cylindrical magnetic pole pieces of the pup, you are getting much smaller amplitudes or excursions of string vibration, than locating the pup closer to the halfway point between bridge and nut, wher string vibration is greatest ( and which, by the way. Is at the twelfth fret, by definition. Which also gives me an excellent idea...). This is why, on a Strat for example, you get warmer deeper tones on a neck pickup, and brighter higher tones on a bridge pickup: you've changed the character of the string vibration's amplitude, and thus the sound transmitted by the current generated in the pup, by moving the pup forward or backward between bridge and nut.

So, this setup will work, but will be both low volume and quite trebly.

As for my excellent idea, surely someone has done this already with a standard mag pup, but using an induction pickup, or a Thinbucker / Flat Cat humbucker, at the twelfth fret, could give rise to a different CBG tone altogether. Elmar? Dan Sleep? Wayfinder? Turkeychicken? Any others with the equipment to test my idea?

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Permalink Reply by Paul Craig on September 16, 2016 at 8:17pm

The new Taylor T5Z guitar has a humbucking pickup buried in the neck joint and it works and sounds awesome.So your idea of a pickup in the 12th fret area is intriguing.

It would need to be a pickup that wouldn't get all muddy sounding that far up. Most likely a ceramic magnet or a neodymium magnet pickup with low output.

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Permalink Reply by Fomhorach on September 17, 2016 at 5:31am

How did the embedded piezos sound?

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Permalink Reply by Danny B. on September 18, 2016 at 5:47am

Can I see what an embedded piezo looks like, Wayfinder?

I already dremmel a slot under my bridges and set the piezo bar in there, trying to make sure the bridge is pulling down hard on it, but is there a better way?

I've been wondering why not make the slot even bigger and epoxy the thing up in there, maximum vibration transfer to the bar?

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Permalink Reply by Danny B. on September 19, 2016 at 4:01am

Thanks Wayfinder this will be helpful!

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Permalink Reply by Fomhorach on September 17, 2016 at 5:39am

Oh and it's not a dead zone, it's just a nodal point of the strings 2nd 4th etc.. harmonic. The orig tone and 3rd 5th 7th etc are all at the highest point there.
For some reason the 1st is the orig tone.

It's all powers of 1 2 3 etc and a bit mathmathingy.

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Permalink Reply by Ron "Oily" Sprague on September 17, 2016 at 5:46am

One pretty nicely-done version of how vibrating strings have nodes and antinodes:

https://newt.phys.unsw.edu.au/jw/strings.html

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Permalink Reply by Paul Craig on September 16, 2016 at 8:26pm

I'm sure this works, but I'm of the opinion that it would be better if the pickup was further away from the bridge.

In the pic, it looks like the strings are in between the poles. This  works by microphonics in the pickup picking up the vibrations through the pickup's body and CBG body, but not using the pickups full potential.

So I would recommend moving the pickup forward towards the neck and placing it so the strings go over the poles.

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Permalink Reply by Fomhorach on September 16, 2016 at 8:31pm

I think it could be quite interesting. As Ron said, you do get noise from a pickup if you knock it with your hand.

How does it sound Danny?

Of course everyone is correct about getting it under the strings for volume and tone.

Speaking about nodes and pickup placements, there are a few harmonic spots along a string (the 12th for example on an open string). You can select the opposite of these nodes (anti-node??) for pickup placement to enhance desired frequencies depending on the notes and chords you want to play. 

Say you have a signature chord in one of your songs that you need to rip out in an exact frequency, eg The Who - won't get fooled again, you could find the anti-node points for that chord and by placing a pickup or two at these points and by raising or lowering the pole peices depending on the string you want to enhance you 'frequency drive' that particular instrument.

I would be interested to hear the results of a pickup under the bridge, it might sound like a strange piezo. And in guitar building, anything with a unique sound is desirable.

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Permalink Reply by Danny B. on September 17, 2016 at 12:35am

I should have clarified - this is just a picture I found on the internet that I'm curious about.

I wonder if this is one of those cases of an excellent craftsman with little musical knowledge making a guitar that looks great but may not sound very good.

The raised brass tacks for fret markers are nice looking but practically questionable as well. Maybe it's a wall hanger!

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Permalink Reply by Ron "Oily" Sprague on September 17, 2016 at 12:46am

Danny,
Whew! Thought it was an "innovation" you were developing. However, it did give me an idea...and another variant: what if your 12th fret was a rail type mag pup, instead of 6 individual pole pieces?

That would be kewl...

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