guitar feedback

[coreybox]

I was wondering if anyone can guide me to a way to make guitar instantly feedback, but in a controllable sort of way. Im about put a new pickup in a guitar of mine, and i thought it would be cool to wire this sort of thing directly into the guitar. it can be an effect  or any other kinda way(not sure what other way there would be though). anyways thanks


corey

[petemoore]

For 'regular' feedback, the speaker, air, pickup and amp all create a 'filtered' loop...the speaker shakes the string, the string wiggles electrons in the pickup, the amp amps that signal, speaker moves air, air moves string/guitar body....that's how that works.
  There have been designs that use a speaker mounted 'in' the guitar that directly 'power's the feedback loop into the strings.
  Big [define] amps and solid body guitars have a long popularity for their feedback properties. Adding Distortion [harmonics] may further 'refine' the sustain properties.
  Here's what I use to get 'controllable' feedback...
 Guitar with HB
 Saturated Distorter
 Reverb
 "Big' amp
 2 or 4 'quality' speakers.
 Are you talking about something 'in' the guitar that will make sustain by itself? Or are you talking about an effect that will 'refine' the feedback characteristics of guitar>amp?

[coreybox]

in the guitar. maybe mounting a small speaker or somehting? i dont know how to do this though

[vseriesamps]

So much about feedback seems to depend on the entire rig. Hard to say what an individual guitar will do with any of the thousand amps designs out there

When I wanted screeching distortion before I slammed a chord,  I used to use a Boss CS-3 compressor and just turn it up all the way. Compression will give you instant feedback when prodigously applied.

Otherwise it's all about gain. Oh and phase--a phase switch can do a lot to encourage or discourage feedback with a given setup.

And where you're standing. And how resonant the room you're in is. And whether the headstock might be touching the amp, or the floor.

and and and and and and and and and
K

PS didn't Boss also make an orange distortion/feedbacker pedal. How did that work?

[Hal]

pump the amp, and stand in front of it.  Turn the gain  up all the way.  Especially on solid state amps, it sometimes works to walk up to the amp, hold the chord with your left hand, and increase the volume with your right until it feeds back.  Edge it back down when you want...

[smoguzbenjamin]

The Boss distortion/feedbacker didn't really feedback anything. It was a synth which sampled the frequency of the note and then played around with it to get a sound that resembled feedback when you held the pedal down. I haven't played with it, but from what I've heard it was interesting, but standing in front of a big amp and waving your guitar around had a much better effect to it

[StephenGiles]

You really don't need any effects at all, although some sort of booster on the amp input may help. After seeing Eric Clapton in John Mayall's Bluesbreakers in 1965, I managed to get superb feedback just by standing at the right angle near to the amps I was using at the time. Of course the amps were up very loud - we were a trio, and the angle really depended on the room, number of people in the room, all sorts of things. It's no good facing the amp because all you get is squealing.
Stephen

[coreybox]

thanks for all who replied, but yes i to know how to get feedback using a guitar and amp. my question was weither there is some sort of effect that i could add into my guitar to acheive feedback with out pumping the amp up and have it sort of at my fingertips. maybe some sort of boost..but iwth a master volume sort of thing. any more replies would be thanked

corey

[petemoore]

"Live Wire" Theatrics'''
 Sometimes I'd have trouble getting the right harmonic [or any] to reliably sustain on a certain AC/DC song, a C note [last note of the lead sustains for a 'minute'] during the solo to refrain transition.
 For this I discovered a trick that allowed me to do it very reliably and at much lower volume levels than what it would 'normally' take to cause the right harmonic to sustain.
 Amp should be at least a little more than quiet, and distortion helps, take the head of the guitar, and try to 'screw' it into the cabinet...try different angles...then bend the note by 'leaning' on the guitar head and flexing it...sometimes just a little pitch bend [light string bending] causes the string to 'catch the wave' as the notes wavelength 'speeds past itself'...because what you [and the guitar] are 'hearing' out of the amp is delayed...
 Math time...OT
 I'm not so good at applied math as to figure out whether what I hear [when standing say 4' from an amp] is how much of a delay, I think I read it's something in the order of a slight phase shift.
LP + 2 or more speakers + 22watts or more has been a traditional method of obtaining 'sustain', at a point, sustain cannot be the only issue...if a note sustained at full volume, a second note would be much les percievable.
 }}}"Sustain' by itself means what:
 1 How long it takes a given note to decay
 2 The shifting harmonics that make leads Houwll and 'talk'
  }}}To You?
 With no amp: Hard surfaces with high mass [like frets nuts bridges] and attached mass [guitar body] will determine to a large degree how long a note plays [and what the decay rates are] , by not absorbing [dampening] the strings kinetic energy [the 'vibrational' inertia it has after being struck]. FOr this reason, unamplified accoustics tend to not sustain as long as electrics.
 Sympathetic vibration...the woods themselves may 'vibrate' at certain freqs or dampen certain frequencies more than others. This sympathetic vibration is what is heard as 'accoustic feedback' when an accoustic is amplified high enough ...Eqing can change the pitch of it sometimes, it is a rather nasty sound that can be hard to get rid of 'at volume' [try 'stuffing the accoustic guitar with newspaper or...].
  This is why LOUD PLAYERS generally don't use accoustics. {Ted Nugent in the "Birdland days used to get some HUGE feedback sustain at eardrum shattering volume levels...he used earplugs].
 Temperature, humidity, barometric pressure, and pollution can affect sustain. What type of solids, liquids, and atmosphere the waveforms are 'forced' through or reflected off of, or absorbed by...etc.
 I've never seen stats or notes about laquer influencing sustain properties, but I would think even laquer influences sustain.
 Raising the pickup...Speaker frequency response...only about a million things may influence sustain.
 For talking sustain purposes:
 ...there Should be 'coast' sustain...where you initiate a string vibration and measure the rate at which it diminishes [like an unamped accousitic works].
 And "Powered' sustain...a sympathetic vibration 'amplooped' [String>pickup>amp>speaker>air>wood>Metal>string>pickup etc] to 'induce' 'itself' to sustain harmonic or harmonics.

[Mike Burgundy]

I agree on the laquer thing. The hype about quality instruments having thin layers on them is justified to an extent. I think everyone can wrap their mind around the idea that 1/8" of poly laquer has some effect on an instruments resonance. I'm exagerating here. Settle down. I do believe that two layers of different mass and stiffnes (and hence different resonance) hinder each other more when they're actually close in response. I think Parker works the other way 'round - a *very* hard outer shell (carbon fibre - very light though) with a soft core for resonance (boxwood/balsa I think). Stiff, but very free because of the reduced weight.
Ramming your guitar's head into a speaker cab increases the physical connection between speakers and instrument, so it's logical you'd be able to get more sustain/feedback at lower levels. This is the rough'n'tumble version of the small speaker connected to your headstock method. Hey, Hendrix did it, although why he needed it at his levels...

[runmikeyrun]

I think one of the coolest feedback sounds comes from two guitars feeding back on the same note (or in harmony) and bending one of the necks slightly to bring the note in and out of tune with the other guitar...

What about a small switched vibrating motor powered by a 9V battery (then if you have active electronics you can run it off of that) that keeps the strings vibrating while the guitar is turned down or off.  If you have a note feeding back, you could switch on the motor, keeping the string resonating at the same frequency, then turn off the guitar or tune, or whatever, then when you bring up the guitar volume again (in theory) the string will still be resonating.  I would attach the motor's casing to the bridge inside the guitar cavity.  Toss a spst toggle or pbno switch on there and you got it.

Since we're all adults here who don't make wild judgements, I say this with confidence.  I think a good source of a motor would be from a vibrator.  They are small with a little offset weight on the output shaft to create a vibration.  Most run on 3 or 4.5vdc.   The soft silicone, um, shell could be easily cut away to access the motor.  You can get a cheap vibrator for about $10 in the seedier parts of town... just be sure to hide the remants from your wife/parents!!

However, i will echo what was said before about leanin the guitar neck onto the speaker cab, it would yield the same effect (a good way to test my theory too).

hth.
Mike

[coreybox]

thats interesting? a motor just anywere on the cavity might produce this effect?

[Paul Marossy]

Here's something to try that I learned as an unwilling student:

If you have a pedalboard with a common power supply provided by a wall wart, and a wah pedal, place the wall wart close to the wah shell and it will cause feedback to occur. Not too close or you will get really obvious 60hz hum, but at the right distance, it will cause your rig to have massive feedback with a high gain pedal like a Boss Metal Zone. You will still hesr some hum at first, but once it starts to feedback, it gets drowned out by feedback.

From what I can surmise, the inductor in the wah picks up the 60 cycle hum radiated by the wall wart. In combination with a high gain pedal, you get lots of feedback. From what I can tell, it causes oscillation to occur. You can control it fairly well with a volume pedal. The only drawback to that scenario is that it makes your wah pretty useless otherwise. But, perhaps in a recording situation, it could be the ticket to what you want.

A motor may have a similar effect since it would create a magnetic field around it that the guitar pickups would react to.

There is also this schematic that Ansil drew up that I think may have something like the effect that you want: http://www.projectguitar.com/tut/sustainer.htm
I don't know if anyone has built this, but if you do, please report back to us on its performance!

[coreybox]

yes yes that looks like what i want! problem is though im not sure exactly how to build it off that diagram. the pickups and the switch are a little ambiguous. Do i just choose what pickup to run through the circut? are both merged together and running through the circut? also the piezo speaker.  do i put that out to the output? basically i dont knwo how to do this except just the circut part, which does not have a capacitor value?

can anyone help clear this up?

thanks

corey

[StephenGiles]

At a pinch, you could always borrow your wife's/girlfriend's vibrator and adapt that!
Stephen

[petemoore]

Electric "STring Whacker'
 DC motor with fishing line or wig strands on it's rotor drive, when spun becomes a 'string wheel like a weed whacker.
 Radiused Half Track...a 'snow mobile' rear end drive system with 'strands' coming off it...matched shape to the radius of the fretboard...
 Violin Bow...as we know J.P. used this trick to attain great musical and theatrical advantages.
 Bridge Hammer...similar to what's used in school bells to indicate period changes...try 'knuckle on the body', or tapping something on the bridge for 'relative example of the attack, hammering the bridge at a 'high' frequency [say 400 HPM, hammers per minute] in combination with 'powered sustain' [amp] would probably get some interesting results.
Problem with this is School bells I think use solanoids, but something with a motor/cam could probably be hacked together. It' could be made I think to easily start/sustain any note not dampened.

[DDD]

An ultimate answer is here:
http://www.sustainiac.com/index.htm

[Johnny Guitar]

Something I've been considering is putting a speaker and a piezo PU in a (well) tuned autoharp. I think by using a few stomp box kinds of things and a few synth circuits (like a VCA) you could get some pretty useful feedback sounds at somewhat low volume. I think there would need to be a lot of experimentation though.

From my experience the most important thing to get feedback in a loud situation is the distance in front of the speaker. When I used to play out (in the height of my Townshend, Hedrix, Belew noise style) I would find out where different notes would happen and mark the stage for these different notes, a la Belew.

It's worth it to try experimenting hitting a note, facing the amp, and slowly move further away from your amp (or closer to it) to find the distance where that note will feedback for you -- diferent notes will have different distances in most cases. Note: this "practice" session will not make you a lot of friends with your neighbors or room-mates.

John

[petemoore]

Something I've been considering is putting a speaker and a piezo PU in a (well) tuned autoharp. I think by using a few stomp box kinds of things and a few synth circuits (like a VCA) you could get some pretty useful feedback sounds at somewhat low volume. I think there would need to be a lot of experimentation though.

From my experience the most important thing to get feedback in a loud situation is the distance in front of the speaker. When I used to play out (in the height of my Townshend, Hedrix, Belew noise style) I would find out where different notes would happen and mark the stage for these different notes, a la Belew.

It's worth it to try experimenting hitting a note, facing the amp, and slowly move further away from your amp (or closer to it) to find the distance where that note will feedback for you -- diferent notes will have different distances in most cases. Note: this "practice" session will not make you a lot of friends with your neighbors or room-mates.
 >>>I'd like to add 'angle' to the equation...if anyone saw Fripp on Saturday Night Live [very clearly] demonstrating how just turning/twisting  the guitar can cause harmonic pitch shift in the feedback...he must have done 'some' tuning to get his rig to respond like that...lol...great show !!!

John

[coreybox]

alright:

http://www.projectguitar.com/tut/sustainer.htm

can yall help clear that up?

this seems to be what i want but i dont fully understand what it is saying to do.  I dont really understand what the switch is doing. does it matter wha pickup is run through the circut or does it have to be both or what? also with the piezo speaker....is that what sends output to the amp?

thanks again

corey