plans/ schematic for a guitar/ instrument string sustaining

[Sam Waterston]

I'm trying to locate a schematic for a circuit that allows a sustained
resonance of guitar or instrument strings. There is already such a device
called an Ebow, found here:

http://www.ebow.com/ebow/brochure.htm

However, this unit doesn't allow the oscillator to be varied, and I'd like
to vary the string frequency this way.

If anyone knows where I could locate a circuit schematic or plans for either
the above device or something similar, please share it if you would.

Thanks,
Sam

 

[Rich Grise]

On Sat, 23 Oct 2004 00:57:50 +0000, Sam Waterston wrote:

I'm trying to locate a schematic for a circuit that allows a sustained
resonance of guitar or instrument strings. There is already such a device
called an Ebow, found here:

http://www.ebow.com/ebow/brochure.htm

However, this unit doesn't allow the oscillator to be varied, and I'd like
to vary the string frequency this way.

I don't know if I'm way off base here, but from my "knowledge" of the
"basics", I'd say that the string itself determines the frequency.
In other words, I'm sure the box does just what it says - in fact, you
don't even need to spend the big bucks - just add a little feedback in
your pickup preamp.

But for frequency, I'm afraid you have to alter the mechanical properties
of the string, like with one of those bend bar things.

If anyone knows where I could locate a circuit schematic or plans for
either the above device or something similar, please share it if you
would.

The circuit shouldn't be hard - maybe google for "tuning fork oscillator".
If your ax has two pickups, you're already practically there - use one for
pickup and one for driver. That lays the whole loop out in front of you,
and you could even experiment with trying to bend it electrically, maybe
a serrodyne modulation scheme.

Have Fun!

I just tried to type "Good Luck" and "Have Fun" simultaneously. Did you
know that if you superimpose "Luck" on "Fun" you get "FLuunck"? I wonder
if that means something. >;->

Cheers!
Rich

 

[Sam Waterston]

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.23.01.49.17.933631@example.net...

On Sat, 23 Oct 2004 00:57:50 +0000, Sam Waterston wrote:

I'm trying to locate a schematic for a circuit that allows a sustained
resonance of guitar or instrument strings. There is already such a
device
called an Ebow, found here:

http://www.ebow.com/ebow/brochure.htm

However, this unit doesn't allow the oscillator to be varied, and I'd
like
to vary the string frequency this way.

I don't know if I'm way off base here, but from my "knowledge" of the
"basics", I'd say that the string itself determines the frequency.
In other words, I'm sure the box does just what it says - in fact, you
don't even need to spend the big bucks - just add a little feedback in
your pickup preamp.

But for frequency, I'm afraid you have to alter the mechanical properties
of the string, like with one of those bend bar things.

I actually have the aforementioned device... EBow. You don't think if I
tried to alter the device frequency that it would alter the strings? If
not, I have had limited success holding the device over one of the strings
and then adjusting string tension. However, range is limited and I'm afraid
the string will break under too much tension.

If anyone knows where I could locate a circuit schematic or plans for
either the above device or something similar, please share it if you
would.

The circuit shouldn't be hard - maybe google for "tuning fork oscillator".
If your ax has two pickups, you're already practically there - use one for
pickup and one for driver. That lays the whole loop out in front of you,
and you could even experiment with trying to bend it electrically, maybe
a serrodyne modulation scheme.

Is this any relative to the ring modulator? I already have that classic
unit.

Thanks,
Sam

Have Fun!

I just tried to type "Good Luck" and "Have Fun" simultaneously. Did you
know that if you superimpose "Luck" on "Fun" you get "FLuunck"? I wonder
if that means something. >;-

Cheers!
Rich

 

[Clifford Heath]

Sam Waterston wrote:

I'm trying to locate a schematic for a circuit that allows a sustained
resonance of guitar or instrument strings.

The Yahoo "leftbrainluthiers" mailing list has discussed various ways
of exciting guitars and other instruments with a view to measuring the
response characteristics of the strung instrument. Note that the
behaviour of the string is surprisingly strongly affected by the
mechanical impedance and frequency response of the guitar as a whole,
and is *very much affected* by contact with a bow.

There are several accepted methods, each with different drawbacks:

* The "stinger", a modified speaker. Remove most of the cone, leaving
just enough for support, and attach the voice coil to the bridge of
the guitar using a lightweight but stiff straw etc. Note that the mass
of the straw changes the effective mass at the bridge and will lower
the resonant frequencies. This is often used with an FM radio source
for a week or so to "play in" a new guitar.

* Acoustic coupling, using a speaker to feed in sound.

I haven't done either of these, so YMMV. Ask the list members, I'm just
an interested bystander.

Clifford Heath.

 

[Rich Grise]

On Sat, 23 Oct 2004 01:59:31 +0000, Sam Waterston wrote:

"Rich Grise" <rich@example.net> wrote in message
newsan.2004.10.23.01.49.17.933631@example.net...
On Sat, 23 Oct 2004 00:57:50 +0000, Sam Waterston wrote:

I'm trying to locate a schematic for a circuit that allows a
sustained resonance of guitar or instrument strings. There is already
such a
device
called an Ebow, found here:

http://www.ebow.com/ebow/brochure.htm

However, this unit doesn't allow the oscillator to be varied, and I'd
like
to vary the string frequency this way.

I don't know if I'm way off base here, but from my "knowledge" of the
"basics", I'd say that the string itself determines the frequency. In
other words, I'm sure the box does just what it says - in fact, you
don't even need to spend the big bucks - just add a little feedback in
your pickup preamp.

But for frequency, I'm afraid you have to alter the mechanical
properties of the string, like with one of those bend bar things.

I actually have the aforementioned device... EBow. You don't think if I
tried to alter the device frequency that it would alter the strings? If
not, I have had limited success holding the device over one of the strings
and then adjusting string tension. However, range is limited and I'm
afraid the string will break under too much tension.

Yeah! String tension is exactly how it's done! Cool! You Reach!

And if the string breaks, you know you can play around it, and the
audience generally isn't paying any attention anyway. ;-)

I know - I was a wannabe roadie for my brother's band for a number
of years. Our Mom and I trained Dan to ignore the mistakes, just charge
on ahead as if nothing has happened. I've also found that it is
disgustingly easy to deceive people.

it electrically, maybe a serrodyne modulation scheme.

Is this any relative to the ring modulator? I already have that classic
unit.

Nah, it's just a buzzword that I threw in there because the sentence
needed a little more meat. All it is is a varying frequency sawtooth
applied to a frequency modulation input, and the only usage I've seen
for it was in a transponder designed to deceive doppler radar.

It's way cool watching the spectrum while serrodyne modulating - it's
like it spawns a child sideband, that kind of moves across the scale,
like it's budded or something. It's terribly terribly hard to describe,
but way cool to watch, and apparently tells the Doppler that it's
coming at you at 100,000 miles an hour, or something.

Frequency axis ->

^
/ \
/ \
/ \
_____/ \_______________________________________________


^
/ ^
/ \
/ \
_____/ \_______________________________________________

^
/ W\
/ \
/ \
_____/ \______________________________________________

^
/ \ ^
/ V \
/ \
_____/ \_____________________________________________

^
/ \
/ \ ^
/ V \
_____/ \_____________________________________________

^
/ \
/ \ ^
/ \/ \
_____/ \_____________________________________________

^
/ \
/ \ ^
/ \ / \
_____/ V \_____________________________________________

^
/ \
/ \ ^
/ \ / \
_____/ \/ \_____________________________________________
^
/ \
/ \
/ \ /\
_____/ \_/ \_____________________________________________

Oh, come on. Do I have to draw the whole thing? The little
sideband marches to the right, diminishing as it goes.

Thanks!
Rich

 

[Rich Grise]

On Sat, 23 Oct 2004 14:03:58 +0000, justin wrote:

I like the magnetic pick-up-in-reverse idea, interesting, one pick-up
driving the other and creating an electromechanical feedback loop... I
know that loudspeakers make bad microphones, do pick-ups make good
drivers, i.e. will applying certain voltage create enough magnetic flux to
drive the strings?

I haven't actually done it with a real circuit, but conceptually it seems
"intuitively" that it would work. For one, you don't need very much
excitation, since the string is resonating, after all; and for the other,
I think if you're using electronic feedback to phlang a string, it's a
little late to worry about purity of waveform anyway. ;-)

Cheers!
RIch

 

[ChrisGibboGibson]

"Sam Waterston" wrote:

I'm trying to locate a schematic for a circuit that allows a sustained
resonance of guitar or instrument strings. There is already such a device
called an Ebow, found here:

http://www.ebow.com/ebow/brochure.htm

However, this unit doesn't allow the oscillator to be varied, and I'd like
to vary the string frequency this way.

Varying the frequency of the e-bow will not vary the frequency of the string so
the note will remain the same. The tonality will change though.

You have to appreciate how the e-bow works. It is *not* a feedback device. It's
a very fast, very mild plucking device. It's more like *very* quickly plucking
the string with a *very* soft plectrum.

It effectively, magnetically, gives the string a lil gentle thump at a lowish
frequency.

The frequency of the e-bow is *very* carefully chosen. If it's too high it
intermodulates with the strings' natural frequency and produces a disgusting
sounding mess.

If it's too low it sounds like a bee strumming the string. I've changed them
and whatever you do they sound worse. They are more or less as perfect as they
can be as they are.

If anyone knows where I could locate a circuit schematic or plans for either
the above device or something similar, please share it if you would.

I think you want more of a controlled feedback device. If that's the case, this
is how you do it. (I have a box of these somewhere from days gone by).

Get a small relay with a round coil (cube automive relays work well) and remove
the coil. Connect it to a small guitar practice amp speaker output. You need
about 10 to 20 watts. Hold it near the strings just like an e-bow. Dead simple.

Gibbo

 

[ChrisGibboGibson]

"Sam Waterston" wrote:

[snip]

Thanks for this suggestion! However, what am I using for the amp input- the
guitar or can I use a separate oscillator? What will be the effect on the
strings?

Sam

Use the guitar as the amp input. If you use an oscillator you'll find that
certain low frequencies (between 20 to 60 Hz) produce *reasonable* results (but
not brilliant) but it's very unpredictable and anything outside that range
sounds awful.

The advantage with this system over an ebow is that the end sound if *far*
better.

It's basically full feedback but put under control. A compressor (just into the
amp feeding the relay coil - not the one for the sound) helps a lot.

The disadvantages are that A) it's a *hell* of a lot more difficult to control
due to the positive feedback and B) you have wires running to the gadget in
your hand. If you can put up with the wires and practice with it the end result
is well worth it. It sounds fantastic. But you do have to practice a lot.

The e-bow doesn't just fire a signal at the strings. It's a gated oscillator
(ie it's switched on and off at a rapid rate).

Gibbo

 

[ChrisGibboGibson]

And my reader fuc@ed up. That was Rich I was replying to.

 

[Rich Grise]

On Sat, 23 Oct 2004 21:49:07 +0000, ChrisGibboGibson wrote:

And my reader fuc@ed up. That was Rich I was replying to.

Heh. I didn't notice - I saw what I wrote, so didn't bother to check
"$OP wrote". But the questions got answered, so all is well.

Thanks!
Rich

 

[Clifford Heath]

ChrisGibboGibson wrote:

"Behaviour" of a sting is determined by its frequency and amplitude.
This simply isn't true.
Yes. All of which affects the *tonality* of the note to a huge degree.

But also the perceived frequency. Due to string inharmonicity (harmonics
becoming progressively sharper due to string stiffness and aerodynamic
drag), the ear will often "perceive" the frequency to be somewhere above
the actual fundamental as it shows up on an FFT. The higher harmonics
die first, and the string recovers from being stretched (an effect
ignored by the Mersenn equation), which causes both the perceived and
actual fundamental frequency to shift.

You are quite correct in what you say but to say that Justin was wrong is a bit
harsh. Because he wasn't.

Justin was trying to discount the complexities of the motion, and the
effect of the mode of excitation, and in that respect, he was wrong.

 

[Clifford Heath]

Kevin,

Justin was responding to my (now apparently somewhat OT) message
about how the LBLers do this "with a view to measuring the response
characteristics of the strung instrument". So that turned out not
to be what the OP wanted, and Justin returned to the original request.
I guess that was fair enough, but in the process he discounted all I
said on my topic, and I objected - because for the issue I addressed,
it matters. Nuff said.

 

[Rich Grise]

On Mon, 25 Oct 2004 08:17:46 +0000, justin wrote:

In article <417b8e83$0$21752$afc38c87@news.optusnet.com.au>, Clifford
Heath <no@spam.please.net> wrote:

Kevin,

Justin was responding to my (now apparently somewhat OT) message
about how the LBLers do this "with a view to measuring the response
characteristics of the strung instrument". So that turned out not
to be what the OP wanted, and Justin returned to the original request.
I guess that was fair enough, but in the process he discounted all I
said on my topic, and I objected - because for the issue I addressed,
it matters. Nuff said.


Sorry to cause a stir, I am not discounting what you're saying. It is
well known to me that string frequency will vary over the duration of a
note because of a nonlinear mechanics of a string. After all, if it
wasn't for that - a string would be unusable. But this side effect
anomaly is so subtle and irrelevant to a musician that it has only a
theoretical significance, probably only to hair splitting nuts like us


This is the part I was responding to:

behavior of the string is surprisingly strongly affected by the
mechanical impedance and frequency response of the guitar as a whole,

This makes an either very badly formulated or simply _not true_
statement.

About the "behavior" - disregarding the amplitude part because it is
dependent on an exitation, an external factor - and focusing on the
frequency: mechanical /acoustical properties of a guitar have NO effect
on a frequency - the pitch, not the tone - of a string.

You can take the same string from acoustic guitar and put it on an
electric solid body, or strung it between two nails on a marble floor -
it will unconditionally resonate at an exact frequency, i.e. it's
behavior is not affected.

Maybe a more precise way to say what you intended was to restrict that
to: the _tone_ (and tone only) of a string is affected by physical
characteristics of a guitar.

I'd submit that the frequency will be measurably different from an
acoustic than from a string with the exact same bridge and nut, and
exact same tension, mounted on a marble base, because the the top of
the guitar will be part of the resonating mass. And the electric
may very well be somewhere in between.

Cheers!
Rich

 

[Ronald H. Nicholson Jr.]

In article <251020040117453752%justin.c@se.net>,
justin <justi nüc@se.net> wrote:

It is
well known to me that string frequency will vary over the duration of a
note because of a nonlinear mechanics of a string. After all, if it
wasn't for that - a string would be unusable. But this side effect
anomaly is so subtle and irrelevant to a musician ...

Not necessarily true. Ask a musician to play a piano that is perfectly
tuned in equal temperament, rather than "stretch" tuned, as is usually
done to take into account these real physical and inharmonic effects,
and they might think the piano is unpleasantly out-of-tune. Makes it
quite relevant.


IMHO. YMMV.
--
Ron Nicholson rhn AT nicholson DOT com http://www.nicholson.com/rhn/
#include <canonical.disclaimer> // only my own opinions, etc.

 

[ChrisGibboGibson]

(Ronald H. Nicholson Jr.) wrote:

In article <251020040117453752%justin.c@se.net>,
justin <justi nüc@se.net> wrote:
It is
well known to me that string frequency will vary over the duration of a
note because of a nonlinear mechanics of a string. After all, if it
wasn't for that - a string would be unusable. But this side effect
anomaly is so subtle and irrelevant to a musician ...

Not necessarily true. Ask a musician to play a piano that is perfectly
tuned in equal temperament, rather than "stretch" tuned, as is usually
done to take into account these real physical and inharmonic effects,
and they might think the piano is unpleasantly out-of-tune. Makes it
quite relevant.

"Stretch tuning" and "equal temperament" have *nothing* to do with the
phenomena of a string changing pitch throughout the duration of the note and
dependant upon how hard it is plucked or hit.

Equal temperament tuning means quite simply that all semitone intervals on the
keyboard are an equal fraction up on the previous note and all octaves are
exactly double the frequency of the next lower octave.

Stretch tuning is where the top of the keyboard is deliberately made sharp with
respect to the centre and the lower part of the keyboard is deliberately made
flat.

This is to compensate for the way the human ear perceives tone. ie although
4000 Hz is exacty 2 octaves above 1000Hz the human ear will perceive it as
being flat.

Gibbo

 

[Allan Herriman]

On 27 Oct 2004 09:21:17 GMT, chrisgibbogibson@aol.com
(ChrisGibboGibson) wrote:

(Ronald H. Nicholson Jr.) wrote:


In article <251020040117453752%justin.c@se.net>,
justin <justi nüc@se.net> wrote:
It is
well known to me that string frequency will vary over the duration of a
note because of a nonlinear mechanics of a string. After all, if it
wasn't for that - a string would be unusable. But this side effect
anomaly is so subtle and irrelevant to a musician ...

Not necessarily true. Ask a musician to play a piano that is perfectly
tuned in equal temperament, rather than "stretch" tuned, as is usually
done to take into account these real physical and inharmonic effects,
and they might think the piano is unpleasantly out-of-tune. Makes it
quite relevant.


"Stretch tuning" and "equal temperament" have *nothing* to do with the
phenomena of a string changing pitch throughout the duration of the note and
dependant upon how hard it is plucked or hit.

Equal temperament tuning means quite simply that all semitone intervals on the
keyboard are an equal fraction up on the previous note and all octaves are
exactly double the frequency of the next lower octave.

Stretch tuning is where the top of the keyboard is deliberately made sharp with
respect to the centre and the lower part of the keyboard is deliberately made
flat.

This is to compensate for the way the human ear perceives tone. ie although
4000 Hz is exacty 2 octaves above 1000Hz the human ear will perceive it as
being flat.

Oh. I thought it was because the harmonics of a real, physical
instrument aren't exactly at integer multiples of the frequency of the
fundamental - they're a little sharp.
So you make the low notes a little flat, so that their harmonics are
in tune with the middle notes, and you make the high notes a little
sharp, so that they're in tune with the harmonics of the middle notes.

This may be completely wrong.

Regards,
Allan

 

[ChrisGibboGibson]

Allan Herriman wrote:

On 27 Oct 2004 09:21:17 GMT, chrisgibbogibson@aol.com
(ChrisGibboGibson) wrote:

(Ronald H. Nicholson Jr.) wrote:


In article <251020040117453752%justin.c@se.net>,
justin <justi nüc@se.net> wrote:
It is
well known to me that string frequency will vary over the duration of a
note because of a nonlinear mechanics of a string. After all, if it
wasn't for that - a string would be unusable. But this side effect
anomaly is so subtle and irrelevant to a musician ...

Not necessarily true. Ask a musician to play a piano that is perfectly
tuned in equal temperament, rather than "stretch" tuned, as is usually
done to take into account these real physical and inharmonic effects,
and they might think the piano is unpleasantly out-of-tune. Makes it
quite relevant.


"Stretch tuning" and "equal temperament" have *nothing* to do with the
phenomena of a string changing pitch throughout the duration of the note and
dependant upon how hard it is plucked or hit.

Equal temperament tuning means quite simply that all semitone intervals on
the
keyboard are an equal fraction up on the previous note and all octaves are
exactly double the frequency of the next lower octave.

Stretch tuning is where the top of the keyboard is deliberately made sharp
with
respect to the centre and the lower part of the keyboard is deliberately
made
flat.

This is to compensate for the way the human ear perceives tone. ie although
4000 Hz is exacty 2 octaves above 1000Hz the human ear will perceive it as
being flat.

Oh. I thought it was because the harmonics of a real, physical
instrument aren't exactly at integer multiples of the frequency of the
fundamental - they're a little sharp.
So you make the low notes a little flat, so that their harmonics are
in tune with the middle notes, and you make the high notes a little
sharp, so that they're in tune with the harmonics of the middle notes.

This may be completely wrong.

Not really, it's part of the same thing.

We hear the pitch of a note according not only to it's fundamental but also to
it's harmonics. And we also hear a true octave sinewave as being flat.

This is why the "stretch" has to be different for different sounding
instruments.

http://www.rolandus.com/glossary_main.asp

"Stretch tuning
Traditional acoustic piano tuning that slightly sharpens the highest keys and
slightly flattens the lowest keys for psychoacoustic purposes. "

"psychoacoustic purposes"

Gibbo

 

[ChrisGibboGibson]

Boris Mohar wrote:

On 23 Oct 2004 18:10:04 GMT, chrisgibbogibson@aol.com (ChrisGibboGibson)
wrote:

"Sam Waterston" wrote:



I think you want more of a controlled feedback device. If that's the case,
this
is how you do it. (I have a box of these somewhere from days gone by).

Get a small relay with a round coil (cube automive relays work well) and
remove
the coil. Connect it to a small guitar practice amp speaker output. You need
about 10 to 20 watts. Hold it near the strings just like an e-bow. Dead
simple.

Gibbo

How about record or erase head from a tape recorder?

I guess they might work if you can manage to hold one 2 microns from a
vibrating string

Gibbo

 

[ChrisGibboGibson]

"Dan" wrote:

[snip]

Or better yet, a fretboard build into the body and use a compressor and
better pickups. How do you think Carlos gets his sustain?

By distorting the shit out of it so it no longer sounds like a guitar. Which I
suppose does have the advantage that it helps hide the fact that he plays like
somone broke his fingers.

Living on a reputation. That he never earned anyway.

Gibbo

 

[ChrisGibboGibson]

"Kevin Aylward" wrote:

[snip]

The obvious subtlety is that the tension changes a little as the string
moves, so this changes the frequency a little, but this is very minor.
If it were too drastic, guitars would sound out of tune when hit hard.
They don't.

They do if you put poof gauge strings on like .008 s

Gibbo