E-Bow Questions (Uh-Oh!)

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ryangobie
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E-Bow Questions (Uh-Oh!)

Post by ryangobie » Tue Apr 04, 2006 6:38 pm

Well not E-Bows in particular, but that concept in general. I've had some frankensteining ideas. As I understand, and it makes sense, one transducer is used to pickup the signal then it is amplified (LM386 opamp in the one schematic I've found) and then the signal is put back into the string through another transducer. Sympathetic vibrations. Here goes.

Driver circuit. I've dug around archives and google and I heard a complaint with the OpAmp because it can only deliver +/- 4.5 volts whereas a single ended transistor could do +/- 9. How much juice would I need to drive the output transducer?

I've also heard people talk about the importance of position. A unit like the Fernedes system requires that their unit be installed in the neck pickup hole however the E-bow is said to be able to be used anywhere on the strings (although apparently most effective directly over the pickups). Can anyone explain why the location would affect the performance of a unit? How important is it that the unit be magnetically isolated from the existing pickups?

Would a low impedance driver offer better transfer of energy than that of a higher impedance device? More current through the coil would create more of an affect on the strings?

I think that's about it. I know some of it might be a lil heavy but I have trust in you TOMB.
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Post by @?,*???&? » Tue Apr 04, 2006 6:55 pm

Greatest amplitude of strings is directly under the ebow itself. Thus, if it's over the pick up, it's gonna be the loudest.

The guitar player from 10cc years devised a device that would do what the ebow does but for 6 strings.

Wow.

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Re: E-Bow Questions (Uh-Oh!)

Post by Randy » Tue Apr 04, 2006 7:01 pm

ryangobie wrote:I've also heard people talk about the importance of position. A unit like the Fernedes system requires that their unit be installed in the neck pickup hole however the E-bow is said to be able to be used anywhere on the strings (although apparently most effective directly over the pickups). Can anyone explain why the location would affect the performance of a unit? How important is it that the unit be magnetically isolated from the existing pickups?

I don't know much about the other stuff, but when I use the ebow, the sweet spot moves around depending on what fret I'm at. It's always louder over the pickups, but the tone changes as I go up the fret, so I stay away from them unless I want that screechy tone that position gives.
not to worry, just keep tracking....

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Re: E-Bow Questions (Uh-Oh!)

Post by Phiz » Tue Apr 04, 2006 10:13 pm

ryangobie wrote: I heard a complaint with the OpAmp because it can only deliver +/- 4.5 volts whereas a single ended transistor could do +/- 9. How much juice would I need to drive the output transducer?
I know nothing of the specific circuit you are talking about, but generally speaking, an opamp should be able to get you within 0.7 volts of the supply voltages. Many opamp designs can get you even closer. Are they comparing designs with equal voltage rails?

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Post by douglas baldwin » Wed Apr 05, 2006 8:08 am

A unit like the Fernedes system requires that their unit be installed in the neck pickup hole however the E-bow is said to be able to be used anywhere on the strings (although apparently most effective directly over the pickups). Can anyone explain why the location would affect the performance of a unit?
The vibration of the string is greatest (and the amount of energy necessary to put the string in motion is least) at the midpoint of the speaking length of the string. The E-bow generates a LOT of energy, so it will work pretty well along most of the string's length. But if you've ever used one, you'll notice that it gets the string going the easiest at the center of the string. Because the e-bow generates a wave with its peak beneath the e-bow, it will sound loudest when close to a pickup. Again, if you've ever used an e-bow, you'll find that it drives the string so hard that it generates distortion in the pickup, and placing the e-bow directly over the pickup is disasterous. There's a sweet spot about a 1/2 inch away from the pickup where it works best.

The Sustainiac Stealth and Fernandes Sustainer are essentially one and the same unit, as I recall, designed by the same guy who now sells the Sustainiac independently and offers some other cool sustain-heavy options. Go to www.sustainiac.com. Unlike the E-bow, this kind of unit puts out much less power (much "sweeter" sounding, more "organic" like amp/speaker feedback at very loud volume/close proximity to speaker/clean amp setting). And it excites all six strings. You'll find that if you try to play notes on your highest frets, the Sustainiac/Sustainer won't "grab" them as well because the center of the speaking length of the string is somewhere towards the space between the pickups. Furthermore, because the location of the sustain-generating device is stationary, some notes will "bloom" on their fundamental, some will bloom at the octave (first overtone) and some at the octave-plus-fifth (second overtone), depending on where they are fretted. The Sustainiac also has a switchable option that enhances either the lower harmonic(s) or the higher.

IMHO, I couldn't imagine trying to build a device like the Sustainiac from scratch when it can be bought for about $200. I mean, it all depends on your values and all, and I'm a nutty DIY kinda guy myself, so I can understand that you might learn a whole lot by doing this, but in terms of your time and parts you'd have to order, I'd buy two Sustainiacs and tear one apart.

I've used the E-bow for a decade or so. It's a fun little toy, particularly good on acoustic guitars for mad Arabic fiddle tones. But I'm saving up for the Sustainiac Stealth, which I've tried several times. The Stealth totally integrates with conventional guitar technique, sounds more fluid to me, and is far more predictable in its response.

Best of luck and enjoy your journey into infinite string sustain.

dB, coyote frm Long Island

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Post by ryangobie » Wed Apr 05, 2006 8:52 am

douglas baldwin wrote:IMHO, I couldn't imagine trying to build a device like the Sustainiac from scratch when it can be bought for about $200. I mean, it all depends on your values and all, and I'm a nutty DIY kinda guy myself, so I can understand that you might learn a whole lot by doing this, but in terms of your time and parts you'd have to order, I'd buy two Sustainiacs and tear one apart.
Well, my idea was more along the lines of butchering a guitar and rigging an independent system for each string connected to 6 momentaries behind the bridge controlling each. Maybe it's silly but it sounded good in my head.
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Re: E-Bow Questions (Uh-Oh!)

Post by nclayton » Wed Apr 05, 2006 10:25 am

ryangobie wrote: Driver circuit. I've dug around archives and google and I heard a complaint with the OpAmp because it can only deliver +/- 4.5 volts whereas a single ended transistor could do +/- 9.
Hi! This isn't really true. If they're both run from a 9V battery, then neither of them can exceed 9 volts peak to peak by conventional means, but both of them can get pretty close to that. There would be small differences between real peak to peak voltages depending on the opamp used or the way the transistor was biased, but in reality the opamp has the edge because true rail to rail opamps exist, but you can never quite go rail to rail with an SE transistor. Maybe somebody somewhere figured out how to replace an ebow's stock opamp with a transistor and got a bigger output voltage (I sort of doubt it), but if they did it was probably a difference of fractions of volts, not double the voltage.

I guess you could phase invert the signal then drive the transducer with two symetrical out of phase signals both of which were about 9V P-P for an effective driving voltage of 18 volts, but that's a whole nother story since it's a minimum of three transistors with two in push pull, not 1 single ended transistor. Plus you could do the exact same thing with 2 opamps.

Anyway, the point is that you probably don't have to worry about using an opamp if you want to.

Ned

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Post by space_ryerson » Thu Apr 06, 2006 11:07 am

There is a guy on prosoundweb's forums (I think), and the diystompboxes forums, named 'PSW' who has been building a independent sustainer, which can be added to any guitar without modification, and sustains each string separately. This allows for fully sustaining chords and such. He had even gone as far as to come up with sustaining waveforms to make the guitar sound more like a reed instrument, or synth, or whatever.He is intending to develop it to sell. I plan on buying one when he finishes developing it.

I have a guitar with a custom built floyd rose sustainer, and it is not as intense as an ebow, but , like douglas baldwin noted, it is more organic. With a sustainer, you have the added bonus of not having to hold some clunky thing while trying to play.
I had the sustainer built before you could buy the sustainiac and fernandes kits, but if I were to try to buy one now, I would just buy that. I should mention that installing the sustainer involved me pretty much building a guitar around the sustainer, since it involves a circuit board about the size of a post-it note with two switches on it, two 9v batteries, and whatever 'normal' electronics you might have in an electric guitar.

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Post by BrianK » Mon May 08, 2006 6:46 pm

Keep that Ebow away from the pickups!!!

It is a powerful demagnetizer. The Ebow people don't want to admit it for fear of lawsuits. But it does EXACTLY what a demagnetizer does. Only stronger. I've seen it ruin all three pickups on an old Strat. Takes time, but it works....
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Post by foodforthemoon » Thu May 11, 2006 1:52 pm

Jeff Robinson wrote:Greatest amplitude of strings is directly under the ebow itself. Thus, if it's over the pick up, it's gonna be the loudest.

The guitar player from 10cc years devised a device that would do what the ebow does but for 6 strings.

Wow.
That would be the gizmotron. It was not electromagnetic in nature but rather used a system of wheels that 'bowed' the strings continuously.

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