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WIGGLING 'LITE' IN GUEST MODE

Reverse engineer this:
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Reverse engineer this:
electricanada
From: https://somasynths.com/dvina/

“A key feature of DVINA and its sound is that there is no pickup inside. Instead, I take the electric signal DIRECTLY from the strings that vibrate in the strong magnetic field of a neodymium magnet, hidden in the neck. Further, a weak signal from the strings is amplified by a custom-made transformer built into the body of Dvina to a standard level. So Dvina’s high output is ready to be directly connected to stomp boxes, guitar amps or an audio interface.”

How the heck do you take the signal from the string? Just wire the string into the transformer? Where does the magnet get involved? So confused....
jrhillma
Guitar and bass pickups only have magnets in them to magnetize the strings. The waggling magnetic field created by the vibrating string(s) then interacts with the coils to induce voltage. A pickup doesn't need magnets in it at all, as long as the strings are magnetized. Once the strings lose their magnetization, though, there's no way to induce voltage in the coil, and no signal. Pole pieces in modern guitar pickups aren't there for any reason, really, other than to ensure the strings are magnetized.

(so sayeth Seth Lover back in the late '70s, near as I recall; think it was in Guitar magazine or maybe Guitar Player)
SlightlyNasty
It's pretty straightforward - the string is a wire moving in a magnetic field, which will generate a current in that wire. Then they're using a transformer to convert that current into a useable voltage for interfacing with traditional guitar equipment.

Essentially the string is acting like the winding in a generator, just not er... wound.
EATyourGUITAR
there is nothing that needs to be reverse engineered here. he gave you all the information %100. you only need to sort out how many turns and what thickness enamel coated copper wire was used in the "transformer". although I think it is technically half of a transformer unless it is a humbucker. I don't think there is an iron or magnetic core since that is placed further up the neck already. it would be redundant in the main pickup.
JimY
I think it's a bit like a ribbon microphone. The metal ribbon sits in a magnetic field and its ends connect to the primary winding of an audio transformer. That transformer has a large step-up ratio to boost the tiny signal current in the ribbon.
I can imagine there is a big hum pickup using guitar string as the ribbon, but if there is an even number of strings, it's possible to arrange a humbucking effect by alternating the polarity of the transformers. Or run all the strings in series with half connected in the opposite direction for only one transformer. The transformers are not an easily found type since the primary impedance is really low, 1ohm or less, though it can probably be higher if it works with all the strings in series.
JimY
More thinking, all the strings can connect zig-zag in series. Up the low-E back down the A and so on. A difference amp can be used to pick up the signal instead of a transformer, but a transformer could make it a passive instrument. That thing only has 2 strings but does use a "custom transformer". In the back view, I think I can see a piece of copper tape connecting the tuners.
electricanada
So, I stick a magnet under the strings. Then I wire the strings into a transformer, and out into my fuzz box?

Why haven’t others used this approach? Got to be some kind of caveat that I’m not seeing....
SlightlyNasty
Because you're essentially creating a pickup with less than a single winding, which means the output is going to be truly miniscule unless you use an extremely powerful magnetic field (hence the neodymium magnet). In turn, using a powerful magnet means more string pull (where the magnet tends to deaden the oscillations of the string directly above it, leading to reduced sustain and a shift in the harmonic profile of the sound). It also requires a custom-wound transformer which is either time-consuming or expensive to make.
electricanada
SlightlyNasty wrote:
Because you're essentially creating a pickup with less than a single winding, which means the output is going to be truly miniscule unless you use an extremely powerful magnetic field (hence the neodymium magnet). In turn, using a powerful magnet means more string pull (where the magnet tends to deaden the oscillations of the string directly above it, leading to reduced sustain and a shift in the harmonic profile of the sound). It also requires a custom-wound transformer which is either time-consuming or expensive to make.


Presumably the bowed strings would be less troubled by magnet pull than plucked strings. Yet I’ve heard that bowed strings don’t do well with guitar pickups, but I don’t know why.

Then there is still the transformer cost. What could the advantage be to this method that caused Vlad to choose it? Does it sound that much better than the piezos?
NV
electricanada wrote:
Presumably the bowed strings would be less troubled by magnet pull than plucked strings. Yet I’ve heard that bowed strings don’t do well with guitar pickups, but I don’t know why.


It's more to do with the construction. Guitars have flat bridges and boards, so reaching the inside strings with a bow becomes "bow smash, big noise." You can put a magnetic pickup on an electric violin as long as the strings are steel cored, but the curved shape generally makes piezos an easier solution.


Quote:
Why haven’t others used this approach? Got to be some kind of caveat that I’m not seeing....


They have, it's just not as practical as other approaches. The StringAmp is a pickup made for violin/cello/etc that generates current within the strings via fingerboard magnets, and has been around 20-some years. People still tend to prefer piezos and mics though - cheaper and easier by a wide margin, and they've been pretty well refined over the years.
EATyourGUITAR
older fender guitars have more rounded necks. this means a smaller radius. the pickups have 6 individual pole pieces. the G string pole is always pushed up close to the strings because the G string is the least loudest string on a guitar. so we already sorted out the tech that could be used on a 4 string violin years ago. but this 2 string violin needs nothing. you could have a pickup made for a 1 string guitar and it would still work for two strings if it was placed in the right spot. you will never have an arc of strings in a two stringed instrument even if the fretboard has an extremely small radius.
NV
EATyourGUITAR wrote:
older fender guitars have more rounded necks. this means a smaller radius. the pickups have 6 individual pole pieces. the G string pole is always pushed up close to the strings because the G string is the least loudest string on a guitar. so we already sorted out the tech that could be used on a 4 string violin years ago. but this 2 string violin needs nothing. you could have a pickup made for a 1 string guitar and it would still work for two strings if it was placed in the right spot. you will never have an arc of strings in a two stringed instrument even if the fretboard has an extremely small radius.


Magnetic pickups are used in bowed instruments just fine, they look like this:



The issue with bowing guitar pickups isn't the magnet, it's the fingerboard. Vintage Fenders have radii of about 7.25" compared to modern fretboards of 9.5" with some even higher. The radius on a viola is about 1.5". Even the massive double bass radius is 3.5", and the strings on those are an inch apart at the bridge. You're going to need a Fender so vintage it's made by Stradivari if you want to bow all 6 strings, but a magnet will grab it all just fine.
JimY
SlightlyNasty wrote:
Because you're essentially creating a pickup with less than a single winding, which means the output is going to be truly miniscule unless you use an extremely powerful magnetic field (hence the neodymium magnet). In turn, using a powerful magnet means more string pull (where the magnet tends to deaden the oscillations of the string directly above it, leading to reduced sustain and a shift in the harmonic profile of the sound). It also requires a custom-wound transformer which is either time-consuming or expensive to make.


You might find a suitable transformer from an old Ribbon Mic. The old "Beatle Mic" Reslosound (the ones that screw on top of micstand) are usually beyond restoration if you find one now (and were never much good anyway). Working, good quality, Ribbon Mic's are high-value these days, so gutting one just for the transformer would be a brave thing to do.


For experiment, the operating coils of miniature relays with a neo magnet stuck on can make a rough and ready magnetic pickup. Operating coils for 24v to 110v have winding impedance similar to guitar pickups.
JimY
You can buy ribbon mic transformers...
https://www.bumblebeepro.com/shop/rtp-35-ribbon-mic-output-transformer  /
Expensive!
SlightlyNasty
electricanada wrote:
What could the advantage be to this method that caused Vlad to choose it? Does it sound that much better than the piezos?


Well, I don't want to speak for Vlad, but I'm sure a big part of it is just the fact that it's an interesting, rarely-used approach that will have its own sonic characteristics. The SOMA stuff is all about alternative approaches.
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