OK Electro-twinks - what the hell IS a sustainer, anyway?

[stubhead]

Indisputably, a "Fernandes Sustainer",  a "Sustainiac" or an "EBow" are: a pickup; powered by a 9v battery; powered backwards, using the battery current to twitch the string, instead of twitching the string to make a current come out of the pickup. So: what's the rest? An amplifier/transformer. umm... I know shielding is a big deal-issue-problem. And it seems that getting it to work evenly is a big big problem, notes upon strings apparently get “excited” at vastly different rates, depending on what node, harmonic or lack thereof your exciter is acting upon, which makes sense.

I HAVE a pickup, and I HAVE a 9v battery, and I sure DON'T have $249.95 to give to Fernandes or Sustainiac

I've been digging through "home-made Ebow" and "home-made sustainaic" stuff.

http://www.projectguitar.com/tut/sustainer.htm
http://projectguitar.ibforums.com/topic/7512-sustainer-ideas/
http://diy-fever.com/misc/diy-sustainer/

What keeps coming up is a “Ruby amplifer” made from a 386 chip. I don't really understand this. What I want to do is take a  line out from a mini-mixer – the “effects send” TS jack, then to... what?


This last runs you through the patents of the sustainer-type devices, the text is Dutch:

http://logosfoundation.org/kursus/4047.html


Dat een elektrische gitaar aangehouden tonen kan produceren wanneer we maar dicht genoeg bij de luidspreker staan opgesteld en die van voldoende volume voorzien is genoegzaam bekend.
Ook zonder deze nogal brutale techniek is het evenwel mogelijk aangehouden noten te spelen op snaarinstrumenten met ferromagnetische snaren. Daarvoor is sedert vele jaren een hulpmiddel op de markt dat luistert naar de naam ebow. Anders dan wat door de fabrikant wordt beweerd, is dit geen originele uitvinding, want het werd reeds in de eerste helft van de 20e eeuw toegepast op sommige pianos om lang aangehouden tonen mogelijk te maken en zo een orgel-achtig effekt te verkrijgen..
We geven hierbij de volledige tekst en tekeningen van het originele ebow patent.
Dutch-to-Engrish -
Held that an electric guitar tones can produce whenever we close enough to the speaker stand up and provide sufficient volume is well known. Even without this rather brutal technique is, however, possible to play on stringed instruments with ferromagnetic strings. Sustained notes This is a tool for many years on the market that listens to the name Ebow. Contrary to what is claimed by the manufacturer, this is not an original invention, because it was used as early as the first half of the 20th century some pianos to make long sustained tones possible to obtain an organ-like effect ..

Cool. But what am I supposed to DO? The mini-mixers have powered mic inputs, if that helps...

 

[Cagey]

I don't think it's the kind of thing you want to try making yourself. While they're fairly simple devices, I suspect there has been a great deal of trial-and-error involved in getting the working models to actually work. But, I could be wrong. I've never paid much attention to the things, lumping them in with things like rice cookers and electric knives.

Anyway, basically what I think they're doing is using a coil wrapped around a ferrous core to make an electromagnet that will oscillate at whatever frequency you switch power to it. At the same time, they have a coil wrapped around a magnet to sense the movement of a ferrous material in the magnetic field - a version of a guitar pickup, in other words.

So, you get a string vibrating somehow, the sustainer pickup senses it, the electronics use that signal to switch a transistor that'll switch power to the electromagnet at the frequency it sees. If that electromagnet is in close proximity to a ferrous material like a string, the string will be attracted/repulsed at that frequency. In other words, you will have created a feedback loop out of magnetism. String vibrations are used to switch the exciter to make string vibrations. Sustain amungo. Put wheels on it! Ship it! Get it outa here!

But, you would run into problems with the sustainer sensing itself, so you have to play games with spacing, magnetic shielding, phasing, etc. That's where it all gets pretty tricky, at least in my head. Also, since there are inductors involved, you get into frequency response issues that are probably a thinker, too.

Why they cost so much is anybody's guess, but I imagine it's an economies-of-scale thing. Demand's too low. Possibly some patent carve-outs. Why do Earvana nuts cost so much? They should be $5, tops.

 

[Dan025]

i'm guessing that it's an amplifier but it may not be a basic pickup. it might be tuned differently and there would be no need for magnets. there may need to be a compressor to get the proper signal strength without excess feedback and there might need to be a certain phase shift and equalization. like cagey i think it needs a lot of testing to find exactly how to tune the thing.

but maybe they can just play some noise through it and excite the strings which just resonate at there own frequency. it might work with a square wave signal generator at a high frequency that wont make it through the tone circuit and amplifier. i guess you'd want to start simple and add parts as you go to overcome annoying artifacts.

 

[Cagey]

You'd need mechanical contact with the strings for a piezo pickup to work, so that's kinda out. You could do it with light, but for simplicity's sake, that sorta leaves the Hall effect, which means you need a magnet. Then, in order to create sustain, you have to put energy back into the string - again without touching it. The simplest way is with a varying magnetic field. You'll notice the Ebow won't work with nylon strings - which means the ferrous quality of steel strings is important. Hence, the switched electromagnet.

But, I'm just theorizing.

 

[Dan025]

i meant no permanent magnet. surely you need an electro magnet (or piezo crystal under the bridge, that's mot such a bad idea either) but i was thinking simple modified pickup as the device to drive the strings, but use the other pickup for the signal. so yes there would be a magnet somewhere in most cases....

 

[DavyDave53]

I HAVE a pickup, and I HAVE a 9v battery, and I sure DON'T have $249.95 to give to Fernandes or Sustainiac

You could just save up and give Mr. Keeley $259, and drop one of the these puppies on you pedal-board?

http://www.sweetwater.com/store/detail/K4Comp/

Just a thought...

 

[stubhead]

When you hit a chord hard into a overwound pickup, you generate about one volt or so. The "phantom power" microphone outs on a mixer are 48 volts - so the juice is there. I'm just gonna have to try some stuff. I'm pretty sure that if you just took an extension chord and plugged a guitar pickup right into the 120 volt wall socket, it might be too much juice.  But a pickup/9v matchup is easy, as is the 48 volts from the mixers. I wonder what makes it "phantom?"

You could alternately try mounting a piezo transducer under the bridge on a hollowbody, but that's a separate issue.

 

[Dan025]

you have to isolate the dc from the coil in most cases, the wire on a pickup is very fine and wont carry much current, i dont know how much it will take to burn it up. that means being series with a capacitor or using an isolation transformer. what signal you feed into the sustainer is still a bit of a mystery to me. it could be a constant noise that gets filtered out that just excites the strings or it might be an amplified signal from the other pickup.

 

[Patrick from Davis]

Phantom Power on a mic is easy.  Mics are wired like AC: hot, neutral, and ground.  If the mic needs power to run, like a condenser mic, you put 48 volts DC across the hot and neutral to power it.  The AC sound signal generated by the mic uses the same wires, but there is a cap to separate the two.  Since it is a signal wire, the power across the same lines was considered "Phantom" because it doesn't effect the sound, but uses the same wires.  I am sure that there was some sort of marketing guy mixed in there at some point as well.
Patrick

 

[stubhead]

I don't know how familiar y'all are with the Alumitone pickup - I love them on steel guitars, and they're supposedly great bass pickups too - flat, loud & clean. "Flat" meaning NOT a huge mid-range boost, meaning that as 87.5% of all guitar amplifiers are made to work best WITH huge mid-rangey boosty pickups, umm. It seems to take some getting used to in a typical guitar rig. ??? :icon_scratch: :sad: :dontknow:

But the thing uses the aluminum frame as ONE SINGLE BIGASS WIRE, and it's got a little integral transformer tucked away inside. SO: I e-mailed Lace (who makes them) and asked, re: using an Alumitone as a sustainer driver:

Do you have any experience with this kind of thing, good or bad?
Do you have advice with this kind of thing, good or bad?
Have you ever run an Alumitone backward to make music?
What's the worse that could happen if you really goosed the pickup with like, 12 or 18 volts?

And the response, from consumer rep Reggie Ashley, was pretty much "bombs away!":

I really don’t know if the Alumitone pups will do what you are asking. The Alumitone pickup is a transformer, however we have not explored any of the four questions you are asking. In theory it should work, however we have no idea of what result you will get. It’s worth a try, and I would be curious to learn of the outcome of your experiment. Please keep me posted.

I happen to have a steel/bass-sized one around here somewhere....

If it's as simple as running a few AA batteries through it to irritate a few strings, whew.... arty07:

 

[Cagey]

If you just run batteries through it, all you'll get is dead batteries. Fast. Unless they can source enough current to burn open the winding on the transformer or pickup coil. Rechargeables can supply some pretty wicked short-circuit currents, if you just want to let the smoke out. But, if the coils don't open, all the DC through a coil will get you is an electromagnet (until the batteries die a minute or so later). Not sure what you could use that for on an instrument.

If you want to stimulate something into vibrating, you'll need to make the current oscillate. That'll make the magnetic field grow and shrink, which will make anything sensitive to magnetism be attracted and released at the frequency of the oscillations. That's more along the lines of what you're looking for.

Also, in order to be useful, you'll need to be able to vary the frequency of the oscillations. Otherwise, you'll be stuck with a one-note instrument. Kinda like a snare drummer in a marching band, or one of those "occupy [wherever]" dingbats.

 

[Dan025]

I don't know how familiar y'all are with the Alumitone pickup - I love them on steel guitars, and they're supposedly great bass pickups too - flat, loud & clean. "Flat" meaning NOT a huge mid-range boost, meaning that as 87.5% of all guitar amplifiers are made to work best WITH huge mid-rangey boosty pickups, umm. It seems to take some getting used to in a typical guitar rig. ??? :icon_scratch: :sad: :dontknow:

But the thing uses the aluminum frame as ONE SINGLE BIGASS WIRE, and it's got a little integral transformer tucked away inside. SO: I e-mailed Lace (who makes them) and asked, re: using an Alumitone as a sustainer driver:

Do you have any experience with this kind of thing, good or bad?
Do you have advice with this kind of thing, good or bad?
Have you ever run an Alumitone backward to make music?
What's the worse that could happen if you really goosed the pickup with like, 12 or 18 volts?

And the response, from consumer rep Reggie Ashley, was pretty much "bombs away!":

I really don’t know if the Alumitone pups will do what you are asking. The Alumitone pickup is a transformer, however we have not explored any of the four questions you are asking. In theory it should work, however we have no idea of what result you will get. It’s worth a try, and I would be curious to learn of the outcome of your experiment. Please keep me posted.

I happen to have a steel/bass-sized one around here somewhere....

If it's as simple as running a few AA batteries through it to irritate a few strings, whew.... arty07:

nah you need an oscillating signal to drive it. you would need some type of small amplifier and i don't know if they use a standard harmonic rich signal from a simple oscillator then filter that out, or if it's feedback driven as in it takes the guitars own signal and drives the strings with it. i have no idea of how good an alumitone works as an electromagnet. just because it's an adequate reciever doesn't mean it's a good driver. pickups drive a pretty low load so they don't need to have a strong coupling to the strings to generate voltage. using volltage to make the strings move on the other hand may work ok with a normal pickup but i would think the alumatones have a really low impedance and use that little transformer to turn current into voltage. getting enough current through it the other way to wiggle the strings may be difficult.

i think you over estimate how simple the device is. i'm sure it's not a complicated schematic on the scale of amplifier schematics. but it's definately not a matter of charging an electromagnet with dc that can damage the pickup or transformer. dc through an electromagnet would only pull down on the strings and if it was strong enough would create a harmonic like touching the string with your finger. ever hear of "stratitis" when the neck pickup is too high? that's because the magnetism from the focused field that rod magnet pickups create effectively pinches the string at the 24th fret harmonic. you want to wiggle the strings, not pull on them..

also if the impedance of the "coil" on the alumatones is as low as i think it is it would probably make the battery explode with dc tied right to it.

 

[DustyCat]

Its an eBow built into your guitar. I needs another pickup though.

 

[Dan025]

somehow my eyes skipped over your research. the lm386 is a small all in one amplifyer, you could use other active circuits but these chips are used to power speakers directly so that suggests you need a good amount of power. they are used in cigarette box amps and similar things. i think i've also seen them in fuzz pedals.

what i am seeing is that there is ALWAYS a pickup AND a device to move the strings. you can use any pickup and you can move the strings with direct contact through piezo (piezo works both ways, something about compressing the crystal squeezes out electrons, but pump in electrons a certain way and the crystal grows, pretty cool!) or with an electromagnet. for the electromagnet version you need a ferrous core or core with a high permeability. maybe a full sized humbucker with very thick rails rather than pole pieces like an x2n or something, the magnet can be removed. the hand held "e-bow" uses transformers with a "full iron core" the core is important in it's ability to be a good pulling magnet.

the circuit using the string vibrations to feedback into the electromagnet and keep the strings moving. it gets that signal from the other pickup. it may be difficult to use just one pickup for this because the coils may couple together and have an annoying feedback, you can filter that out but depending on how things are phased it may not work as desired. if you want just one pickup you may want to use piezo for one of the transducers. you could possibly use a normal piezo bridge, minus the amplifyier as the e-bow with your normal pickups as the pickups. or maybe you can hook up the output of an active piezo bridge to a dimarzio x2n with the magnet reomved.

one of the things you might need to figure out is capacitor choice. all these circuits have ouput and sometimes input capacitors. this can be for phase shift, filtering, or isolation. if you use the wrong capacitors you might not get as much sustain, you might start striking harmonics instead of sustaining the fundamental sustained note may start squeeling, or it may break something (well that's more if you leave them out entirely).

 

[Patrick from Davis]

So looking at some of the links, the Fetzer/Ruby amp is just that, an amp.  Tiny little thing built on a bread board, or something similar.  Your guitar signal goes into this.  This is used to amp up the guitar's signal, to a reasonable energy into the pickup, modified to be a magnet driver for the strings.  That way the frequencies you are playing are always the ones that the magnet emphasizes for sustaining.  It appears that they want to use a piezo to get your guitar signal, then it's amplified, and then that is used to drive the electromagnet/pickup in reverse.

Using an Alumintone pickup to do this is the part I can't really say much about.  If it works in one direction to make an electrical signal for the amp, it should work the opposite way to make a magnetic signal to sustain the speakers.  But how well it does it?  Dunno.
Patrick

 

[Pelagaard]

Slight tangent, but they guys over at Electrical Guitar Company posted a pic on their instagram feed two weeks ago of a Sustainiac with the caption "Lap steel bound." And then, on Friday, posted this...