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Sustainer/stopper Combo?


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hello again, since my last thread/idea flopped, ill try another!

If i was looking at making some sort of pickup that would cancel a string's vibrations like in a moog guitar. how would i do this? i understand how a sustainer causes the string to vibrate, but how would i make it NOT vibrate.

if someone could give me a general idea of how to do it, i could probably make the actual circuit.

any help is appreciated.

oh yeah, as far as experience:

-been building pedals about a year now

-very comfortable doing any and all routing id need

-can read through just about any clear schem for guitars/pedals you could toss at me

hopefully im good enough :D

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The principle is simple, the practice is not. First, all must be hexaphonic. There must be 6 single-string pickups placed as close as possible to the drivers. If the signals are cophasal the sustainer drives the string, if they are counter-phasal the signal stops vibrations. The problem is it's not that trivial to obtain strict phasing on different frequencies because of inductive and capacitive reactance. So there must be a filter that compensates the pickup/driver phase shifts. It may be non-trivial. Besides, the vibrations are polarized, in general it's an elliptical polarization that rotates in time, differently for different harmonics. So, for best result there must be a "stereo" pickup and driver, that operates in 2D, in a plane, perpendicular to the string. Besides, if so happens that your driver is placed exactly at the knot of the standing wave in the string (which is very possible), it won't affect that very harmonic at all. So, it must be localized and distributed along the entire string -- at the same time!!!

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I'm not sure about that...but one wonders why?

for far less hassle than you can make a sustainer you could just put a mute on the bridge like the old fender jazz and/or jags used to have...quite simple. For bonus points...have you ever bent a paperclip so that it just touches the string a little in front of the bridge saddle just right...a very convincing sitar effect. My old guitar teacher did a TV add once and showed us how he got the sound he used...threaded tin foil between the strings near the bridge for an faux banjo effect.

All of these strategies are easier and get better results than a reversed sustainer could do.

There is of course technique...the exact same thing can be produced with damping with palm, fretted fingers and spare picking hand fingers. These things are honed to a high degree with great slide players, but are fairly crucial for sustainer or just very loud guitar playing. With practice you can get a damped muted like sound with no mods at all!

on an "effect box" application...I bought but have yet to make it, some kit called a "twanger" or something. Basically, has a half wave rectified preamp (so you only get the top or bottom of the wave through)...not quite damping, but it does produce a sound a little reminiscent of a resonator guitar in a pedal.

Occasionally I have produced the effect with some experimental drivers, but more unwanted fluke than design. In general, reversing the polarity creates the harmonic effect. If power is not a consideration, a really strong pull on the strings by magnetic force would likely cause something like this effect and likely how moog do it with a hex driver and pickups...but I am very wary of moog claims. I have yet to find anyone that has played one, the clips are all hype, and there appears to be a lot unsaid about real performance. There is no technical data available so it is impossible at this stage to know...but I do suspect that the "mute" thing largely is a product of a magnetic dampening action for that "banjo" like effect. I am led to believe that in one mode, possibly the more effective mode, the hex drivers work effectively as one and so very similar to conventional sustainer performance. But as I say, haven't seen one and at the cost of the things, likely never will!

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