guitar feedback

[petemoore]

AG...just enough spark to light the candle to start the fuze that lights the charge that blows my mind into back to idle curiosity.
 Partials...
 Looks like he's taking a signal from the pickup[s?] feeding a 386 to drive a peizo...if 'I' saw one work or understood it better, I'd add a whole lot of related [relevant?] information. An before building get more reference info.
 Is the peizo directly vibrating the pickup?
 Are there noise issues?
 Do you have to dig a bigger hole in the guitar to install it?
 If I knew more I could probably ask even more questions.
 If I had a peizo, and a pickup, and enough will, I'd get a string/pickup going
  tack a bridge and nut [anything that the string would have to 'go over']on a 2x4, get the pickup by the string I'd used some kind of wedge technology [screw] to tension the string, then try 'adding' the peizo to the equationz in somehows'z.
 I've built some nogoes using Partial schematics, very similar looking to this one. This looks a little 'teasy' to me, but if you have the parts it's not an 'all day-er' either...at least to run initial tests on it.

[coreybox]

ya this looks nice, but i dont know how to go about doing it.

[Johnny Guitar]

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

Not a real clear description of what they're trying to do but it looks like a great idea! Glue a small piezo to the back of one of the pickups. You need an amplifier to power the little speaker (that's what the 386 does). The input to the amp is just the output of the guitar. The switch appears to just turn the feedback amp on and off.

BTW, I saw Trey Gunn (in King Crimson) a few years ago using a device which he plugged into one of the outputs of his Warr touch guitar and held it in front of the neck and behind the neck to get some very interesting feed back like sounds. I've never seen a device like that before or since but it looked like some kind of elaborate E-Bow device.

John

[puretube]

http://www.amptone.com/fernandessustainer.htm
http://www.guitarshop.net/fernandesdragonflypro.htm

[Paul Marossy]

Someone correct me if I'm wrong, but I believe that the little piezo speaker attached to the back of the pickup is acting like a transducer, and by adding that to the signal from a hot output pickup (like a humbucker)increases the output more, causing feedback to happen "more readily".

I still want to know if anyone has built it and what the results were...

Also, do some research on Frank Zappa's guitars. He had a guy who wired up his guitars somehow so that he could get feedback in any venue. It was in a Guitar Player issue around the time after Zappa's death.

[petemoore]

Adding delay to the piezo signal [or any feedback system that partially depends on sympathetic vibration] could cause 'selective harmonics' to be accented or dampened to the point of greater control over the feedback pitches...the relationship of the pitch of the note being 'pushed' or 'pulled' more at a certain point [like when you go high on a swingset by pulling your weight foreward/backward at just the right time] could make for a more interesting project...I'd save all that for after preliminary testing of the 'peizo feedback driver' function, or whatever we're calling it.

[nightingale]

in my experience~
the mkII tonebender will slip away into feedback very easisly with all sorts of guitar/amp combos.
fuzz on,

[brett]

Try the RM Axis fuzz turned up, with almost any tube amp (pref. 50W up).  Easy, quality feedback with any guitar.

[Paul Marossy]

OK, here's the Zappa feedback thing, from the Oct. 1995 issue of Guitar Player:

In virtually every guitar that Zappa played, were "identical parametric filters...One of the filters was set for the bass frequencies from about 50Hz up to 20kHz. The filters had a variable resonant frequency ("Q") independent from the EQ gain. You could find a tone and get right on top of it, and nail it" says Sloatman (who worked on Zappa's guitars).The Q ranged from 0.7 to 10, or a very wide dynamic range to a very narrow one, and was adjustable via a 1/4" screwdriver notch on the face of the guitar. This allowed Frank to control the feedback characteritics in any hall. He could basically tune his guitar to the room, find out how the room responded to the amplifier, and dial it up so he could have maximum control of the feedback. That was the whole point behind the equalizers."

Since reading this, I've always thought this was an interesting approach. Although I think Zappa wanted to have the maximum volume levels possible without feedback problems, I think that it could be used to also dial in on the spot where you can easily get it. My wah thing described earlier post seems to be partly similar to what is described above.

[petemoore]

I definitely overstate the obvious here: I like having wood, metals, and fancy cardboard as part of the feedback loop...I guess I'm just conventional that way, having N/P getting cool, fun playing feedbacks with a tube amp and Fuzzerz.
 I'ts cool that this thread has taken the interesting turns it has.
 The F.Z. feedback parametric sounds interesting enough to do some investigating into, maybe we'll see some interesting feedback about the peizo feedback driver !!!
 I saw Frank Zappa in the 80's...what a show...there was a 15 min. Guitar/Drums session Frank participated in...Super Duper, also had another black guy that was over the top talented, and allowed 'showspace' enough to really demonstrate how he could shine .

[Paul Marossy]

From listening to the three CD set "Shut Up and Play Yer Guitar", Zappa seemed to be a master of feedback, very evident on a couple of those tunes...

[coreybox]

Well back to the 'schematic'.  what do i do with the green wire from the speaker. where do i put the negative end of the 9v? what capicitor should i use?

ya zappa is pretty sweet.

[Paul Marossy]

what do i do with the green wire from the speaker. where do i put the negative end of the 9v? what capicitor should i use?

Green wire from speaker would go to ground. Negative of battery goes to ground. The only part I'm not sure of is the size of the capacitor - probably depends on the piezo speaker's characteristics. I'm thinking probably a 10uF or so for starters.

[coreybox]

what would no cap do?

[John Egerton]

Here we go...

I've been looking at this circuit and have been asking ansil questions about it....

The capacitor is for bass response.... Adjust it to taste....

The speaker isn't actually a piezo speaker... Aparrantley he just jotted this down quickly... I believe that this is a regular speaker... much like the one used in the smokey amps... or jus the smallest speaker you can find that isnt piezo...

I have a cordless phone that has a speaker in it, i'm not sure what it is but it works well.. You'll find out why next...

If you want a really easy example of how this thing wourks then do the following...

1) Turn on your amp and wire your guitar
2) Set your amp to your usual playing volume
3) Take a mobile(cell) phone and check your voicemail, get a friend to talk to you etc while holding your phones speaker to th pickup on your guitar that has been selected.

Hey Presto... You can hear everyhting through your amp...

The speaker works in exactly the same way... you play a note and there is a separate 'cranked' amp speaker behind your pickups to let your notes sing. What is actually happening is that your pickups are detecting the sound fromt he speaker, much like the sound picked up from te speaker of your phone....

I am going to build this thing today.. I'll let you know how it goes...

[DDD]

Hi men,
Could you please explain why the speaker should be placed UNDER pickup? It seems that the speaker should shake the string instead of uselessly shaking the pickup.
So I think the speaker should be placed as close as possible to the strings, say side by side with the PU but not under it.
Also, small piezo speakers don't reproduce frequency lower than 400-800 Hz, so how it will sustain lower tones?

[Doug_H]

;lkj

[Paul Marossy]

Darn it!! I'm going to end up building this thing...  :roll:  

[David]

Darn it!! I'm going to end up building this thing...  :roll:  

If you don't, Paul, I might!

Hey, here's another idea!  I don't know if any of you guys have ever seen this, but back in the spring, I found an article on making a piezo pickup for acoustic guitar.  It actually worked very well -- of course, I needed to do a better soldering job on it, but that's another story.   :oops:

Anyway, I wonder if such a piezo pickup couldn't be fastened to the pick guard or bridge as a contact mike?  With the signal level that thing kicked out with my acoustic, there'd be plenty of juice available for the chosen feedback mechanism!

[Eric H]

A few years ago in one of Aron's older forums, someone built a homebrew sustainiac kind of thing.  IIRC, it was kind of similar to Ansil's idea, with a little speaker attached to the headstock or something. He posted a couple clips and it was very impressive, ethereal clean chord swells and etc. I thought it sounded a lot better than the sustainiac clips, which IMO are not that impressive. But that could just be the clips they have, which just sound like normal loud high-gain guitar feedback to me.

In any case, don't know if there's anything about this in the archives or not. Might be worth a search.

Doug

Yeah, Doug probably 4-5 years ago. It was the endlessly creative (and currently MIA) Frank Clarke. It's been a large part of my live sound ever since.

-Eric