Q: Transformers in feedback loops?

[Sam]

Being the noise addicted individual I am I used my headphones to got nice feedback tones from my guitar by moving them close to the pickups. Naturally there was a massive amount of feedback in certain positions while other positions gave a whole new dimension to my old DD-3 Delay.

I then did some experimenting with a normal feedback loop but the nice "rounded" and controllable feedback couldn't be retained. Is if possible to use a transformer to simulate the "headphone speaker to guitarpickup" kind of feedback (like one is used in the Deluxe Bazz Fuss to simulate passive pickups)? I that case, wouldn't it be nice to have an expression pedal emulating the moving of headphones?

[brett]

Is this any better than feedback from an amp?
If I were doing this with a pedal, I'd control the feedback with a pot in series with either the transformer primary or secondary.  
Alternatively, use a wah pedal and have a coil in the base and another under the pedal.  I't might be more controllable that way, too.
cheers

[toneman]

how were U doing the "feedback"??
were the headphones on a table?, the floor? or your head??
"feedback" happens from the strings.
When energy is coupled to the strings, *in phase, reinforcing*,
the strings don't dampen naturally....they continue to ring.
i remember, wayyyyy back,  the Paia Infinity Plus.
The IP was a incandesent bulb-based sustainer/compressor.
When a college buddy bought a kit & assembled it, i was there
when he first powered it up (must have been bout 1976).
It was *amazing*....hey, it  *was* a few years ago....  
U could hold one note forever.....no kidding.
No distortion, no fuzz, just one singing note...!
Worked 4 chords 2!!
Is that what U R trying 2 do??
staysustained
tone

[Sam]

Is this any better than feedback from an amp?

No. I might have been a bit unclear as to my intentions: The "headphone loop" gave the digital delay a cool "flying saucer" (or analog delay) type of feedback. I plucked a string muted and let the delay repeat a coulpe of times and the slowly moved one headphone closer to the pickup on the guitar. As soon as the feedback became too intence I could simply move the headphone to stop it or make it "softer".

I really liked this dynamic way of controlling the feedback and the way it sounded and thought I could be a way of using a transformer and an expression pedal to "emulate" this setup.

[Sam]

how were U doing the "feedback"??
were the headphones on a table?, the floor? or your head??
"feedback" happens from the strings.
When energy is coupled to the strings, *in phase, reinforcing*,
the strings don't dampen naturally....they continue to ring.
i remember, wayyyyy back,  the Paia Infinity Plus.
The IP was a incandesent bulb-based sustainer/compressor.
When a college buddy bought a kit & assembled it, i was there
when he first powered it up (must have been bout 1976).
It was *amazing*....hey, it  *was* a few years ago....  
U could hold one note forever.....no kidding.
No distortion, no fuzz, just one singing note...!
Worked 4 chords 2!!
Is that what U R trying 2 do??
staysustained
tone

Well. I'm quite familiar with "normal" amp (or in this case headphone) feedback and the nice endless sustain. This setup sent the delay bounces from the headphones, back into the pickups and created this "analog type fifties Sci-Fi sounds". No strings where involved since they where muted.

Cheers!

[octafish]

Sounds at first like either you're are using a piezo or mic based pickup or you have a real loose coil in your pickup. If that was the case you would get a microphonic squeal that I think nobody would enjoy no matter how much a noise freak they are. However maybe what was happening was the pickup was picking up the EMF from the drivers in the headphones. I kinda sounds like a quasi ebow thingy happening. Do you know about the ebow? If not google it.  There is an ebow like sustainer circuit around here somewhere. I think you might be able to adapt something using that circuit and mount it in something you could hold in your picking hand.

BTW the classic howling amp feedback is definitely from vibrating strings so you're doing something different here if the strings are muted.