The Eat at Joe's K5000 Wav Resynthesis Project
Guitar
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The gap between theory and reality
Saturday, 07-Mar-98 15:27:58
130.67.2.99 writes:
Someone please explain to me why any attempt to translate bookish knowledge
into sound seems to backfire on this synth. For instance, I have tried to
emulate the behavior of a string plucked at 1/4 of its length. For the first
24 harmonics I have used these levels:
127, 115, 102, 0, 90, 90, 82, 0, 76, 78, 72, 0, 68, 70, 64, 0, 62, 64, 59,
0, 57, 60, 55, 0
Getting the attack right is a problem, of course. But it seems that no matter
what sort of attack I use, whether or not I let the high harmonics decay faster
than the low ones, etc., I am still miles away from the sound of a real string
being plucked.
In particular, I am worried about the murky sound I get with series of harmonics
like the one above. It reminds me of the sound you get if you play a
guitar where part of the wrapping on the wound strings is loose, if you have
ever tried such a thing. I wonder if any of you understand precisely when and
why this murkiness comes about.
Could this have any connection with the incorrect phases that result when we
enter absolute values for the levels? The series above is calculated using the
amplitude formula sin(PI/4 * n)/n^2 - where n is the harmonic number - which
is alternately positive and negative. The complete formula is:
127 + 8 * ln abs(sin(PI/4 * n)/n^2/sin(PI/4)))/ln2
Negative values do not have logarithms, so I have to use that abs() function.
But how does this affect the composite wave function? It seems to me that a
sum of positive terms and a sum of alternately positive and negative terms
ought to add up to two different waves, but I am probably wrong here since
everyone, it seems, is doing it this way. If any of you Fourier experts out
there know the deeper reason for why the abs() values can be used, I would
like to hear more about it.
In any case, the murkiness is there, and the only cure that I have found is
to avoid sustained sounds with many neighboring harmonics of comparable
amplitude. Fortunately, this cure is at least POSSIBLE on the K5000, which is
not the case with a number of other synths. But it would still be nice to get
some sort of theoretical handle on sound formation on this machine.
I hope everyone will share their thoughts and experiences with the K5000 on
this board. It would be interesting to see more people telling about their
work with sound formation, both the positive and negative aspect of it.
Tore
tl001@online.no
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Re: The gap between theory and reality
Sunday, 08-Mar-98 03:15:16
199.86.33.43 writes:
I don't recognise the formula, but the series of harmonics looks like a 25% pulse.
The amplitude of harmonic n for a 25% pulse should be:
A=abs(sin(.25*Pi*n))/n
This looks like part of your formula, but I don't recognise the rest. (Although
it doesn't mean much that I don't).
I got the theory to work on a few things, though. The 127-8logA formula posted
here is very accurate. The most geometrically perfect saw I've seen
from any of the machines I have is by applying that formula and using all
128 harmonics. 65-128 actually make a big difference! I'll post more on that
later.
leiter@skypoint.com
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Re: Re: The gap between theory and reality
Sunday, 08-Mar-98 10:07:32
130.67.65.106 writes:
It may well be that the 25% pulse and a string plucked at 1/4 of its length have
something in common. I presume that you mean to use amplitudes relative
to the max amplitude, which makes it necessary to divide by sin(PI/4*1).
The formula for A/Amax for a 25% pulse would then be
abs(sin(PI/4*n)/n/sin(PI/4)). The only difference from the plucked string
formula here is that n is not squared.
If anyone wonders about the meaning of these formulas, it may help to to
consider the terms A and Amax separately before they are entered into Jens'
formula for the Level:
Level = 127 + 8 * log2(A/Amax)
I tried your pulse 25% for 128 harmonics, and the upper 64 harmonics do make
a difference in the bass. This is not the case, however, for the plucked
string sound, where the upper levels are very feeble due to that n^2 term.
The plucked string formula may be correct for the sustain phase of that sound.
But one probably needs a bunch of loud high harmonics that decay quickly
in the attack phase.
Tore
tl001@online.no
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Re: Re: Re: The gap between theory and reality
Sunday, 08-Mar-98 19:24:30
199.86.33.82 writes:
QUOTE
I presume that you mean to use amplitudes relative to the max amplitude, which
makes it necessary to divide by sin(PI/4*1). The formula for A/Amax for
a 25% pulse would then be abs(sin(PI/4*n)/n/sin(PI/4)).
UNQUOTE
That gives the amplitude relative to the first harmonic, but the first isn't
the max in a 25% pulse, the second is. As pulses get narrower, the amplitude of
the fundamental approaches zero.
QUOTE
The plucked string formula may be correct for the sustain phase of that sound.
UNQUOTE
Now that I think of it, narrower pulses can sound a lot like harpsichords. They
also sound a lot like reed instruments.
leiter@skypoint.com
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Pulses & Plucked Strings
Monday, 09-Mar-98 04:23:25
130.67.2.210 writes:
QUOTE
The formula for A/Amax for a 25% pulse would then be abs(sin(PI/4*n)/n/sin(PI/4)).
UNQUOTE
QUOTE
That gives the amplitude relative to the first harmonic, but the first isn't the
max in a 25% pulse, the second is.
QUOTE
According to my calculator:
sin (PI/4*1)/1 = 0.707 (maximum)
sin (PI/4*2)/2 = 0.5
sin (PI/4*3)/3 = 0.236
There has GOT to be some misunderstanding here.
+-+-+-+
QUOTE
Now that I think of it, narrower pulses can sound a lot like harpsichords.
UNQUOTE
The plucked string formula presupposes that you start the vibration by pulling
the string to one side and then let go of it. Needless to say, this is not a
realistic picture of what happens, even on instruments that are literally "plucked".
I'd like to know more about what the actual sound event looks like in detail.
Unfortunately, even the SHARC database does not seem to have that sort
of data in it. Maybe some of you know other web sites that have raw data on
acoustic sounds of the sort that would be of interest to K5K users.
Tore
tl001@online.no
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Re: Pulses & Plucked Strings
Monday, 09-Mar-98 11:37:22
192.28.2.19 writes:
QUOTE
According to my calculator:
sin (PI/4*1)/1 = 0.707 (maximum)
sin (PI/4*2)/2 = 0.5
sin (PI/4*3)/3 = 0.236
There has GOT to be some misunderstanding here.
UNQUOTE
Oops, I left out the 1/n; I was just thinking about the sin(Pi/4*n) part. If you
go out to a 10% pulse or a 5% pulse--the first harmonic is still biggest. How
'bout that. Learn something new everyday. I guess the sin(Pi/4*n) part never
overcomes the 1/n part.
leiter@skypoint.com
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Re: The gap between theory and reality
Sunday, 08-Mar-98 22:15:32
199.86.33.82 writes:
QUOTE
Negative values do not have logarithms, so I have to use that abs() function.
But how does this affect the composite wave function? It seems to me that a
sum of positive terms and a sum of alternately positive and negative terms
ought to add up to two different waves, but I am probably wrong here since
everyone, it seems, is doing it this way.
UNQUOTE
With a triangle wave, which also has a 1/n^2 amplitude profile, every other
harmonic is supposed to be negative phase. If you leave them positive phase,
the resulting wave form is like a sine that bulges out on the sides instead of
being flattened on the sides. But--it sounds the same. (At least by itself; there
are probably some subtle differences when you combine waves.)
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Re: Re: The gap between theory and reality
Tuesday, 10-Mar-98 05:43:28
130.67.66.36 writes:
Leafing through some books, I find that already Helmholtz asserted that we are
not able to hear phase, so I guess this is an established fact since it has
survived for more than a century.
But I would like to know more about those "subtle effects". Some of you may
have found that additive organ tones can be a strain on the K5000. (They
can, in fact, be a strain on humans too.) I wonder if this is a matter of
sustained amplitude only or whether the phase issue could have something to do
with it.
Tore
tl001@onlin.no
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Re: Re: Re: The gap between theory and reality
Tuesday, 10-Mar-98 11:41:15
192.28.2.19 writes:
I don't know how you could hear the phase of a single harmonic, but with two
identical harmonics the phase determines whether they cancel or reinforce.
By subtle effects I meant the way, say, two notes in an interval interact:
some pairs of harmonics cancel when others reinforce and vice versa.
As far as ear strain, BBE makes an "enhancer" box that corrects for the phase
shifts caused by electronic circuits like amplifiers. It definitely sweetens the
sound. (Some Aiwa home stereos have this curcuit now, too.) The "enhancer" in
the effects section of the K5k is supposed to be like the BBE box; I
haven't tried it much yet. (The "exciter" is different, it's supposed to add
soft distortion to the high frequency portion of the signal to generate high
frequency even harmonics.)
leiter@skypoint.com
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Re: The gap between theory and reality
Monday, 09-Mar-98 07:23:09
12.68.130.71 writes:
I think it is extremely cool that folks are really trying to use additive
synthesis for what it is and not being scared by theory!
The plucked string, like all continuous musical events is a hard equation to
formulate because there are really several "time blocks" of events which
occurr. The pluck of the string itself is a deformation of the music wire which
travels down the wire in opposite directions, reflects, passes through itself
(adding or subtracting due to a linear domain here) until we arrive at steady
state. The moment that is in question is actually quite fleeting --- consider that
the attack of a violin is very different than its' steady state...the same for
the piano...The piano undergoes a very large relative decay within 50mS of its
attack--steady state is radically different than the first 50mS of "attack"
(where a lot of stuff is happening to the string and it is "sorting out" to steady
state")
In other words, the plucked string may be correct, its placement in the whole
scheme of the patch may be treating it as the wrong part of the steady state
in the time domain analysis.
ALSO- The division you are plucking at, lets say 1/5 of the strings length will
supress the n=5 harmonic in the Fourier Analysis coefficients.
I would try Morph Mode and making the pluck a transient event that melts into a
simple 7 or 9 harmonic saw or square to see if it gets you closer. Also
don't forget that the soundboard of a real instrument alters everything the
books say about spectra of the source due to the coupling between the source
(wire) and the amplifier (soundboard).
For those who care try this book for a reference:
"The Physics of Musical Instruments" by N. Fletcher and T. Rossing published
by Springer-Verlag. (2 ISBN's???) - ISBN 0-387-94151-7 and ISBN 3-540-94151-7
Myself-I just figured out that all my "loud spectra" are too soft (my El_Piano
patch is wicked guilty of this fault).
Pete
favant@worldnet.att.net
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Re: "The Physics of Musical Instruments" and Plucked Strings
Tuesday, 10-Mar-98 23:56:35
199.86.33.88 writes:
QUOTE
For those who care try this book for a reference: "The Physics of Musical
Instruments" by N. Fletcher and T. Rossing published by Springer-Verlag. (2
ISBN's???) - ISBN 0-387-94151-7 and ISBN 3-540-94151-7
UNQUOTE
Excellent book. I'm sending in an Accoustic Guitar Patch based on the
information in the book and Jens' Formula.
leiter@skypoint.com
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Re: New website - new downloads
Sunday, 15-Mar-98 13:42:50
193.172.21.195 writes:
I like the new layout of your page very much! I only found one bug. When i click
on the k5000 link there opens a panel at the left. On my 15 inch monitor i
can't see the message digest knob. I know it's there but i can't see it. Just
want to let you know.
About the patches, the Zamber patch is routed to the individual out port. I
didn't hear anything when i tried the patch. After looking in the patch data i've
changed the out part and i could play with the patch.
The acoustic guitar patch works fine. I think Leiter really succeeded in programming
the harmonics of a guitar. It's only working right in the middle section of
my keyboard. When i play on the lower part of my keyboard, the harmonics sounding
different. Maybe Leiter can explain why the k5k is behaving that way
with his patch. I don't really understand this.
Quiffy
tcoh@hotmail.com
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Re: Re: New website - new downloads
Sunday, 15-Mar-98 15:15:05
199.86.40.85 writes:
QUOTE
The acoustic guitar patch works fine. I think Leiter really succeeded in programming
the harmonics of a guitar. It's only working right in the middle section of
my keyboard. When i play on the lower part of my keyboard, the harmonics sounding
different. Maybe Leiter can explain why the k5k is behaving that way
with his patch. I don't really understand this.
UNQUOTE
Thanks. The usual guitar range is E2 up to about E5, although I think this patch
gets too "tight" above A5. The harmonics that come through the FF are
different for every note, e.g., around G2 and G3 the fundamental booms a bit.
What ranges do you mean?
leiter@skypoint.com
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Re: Re: K5000X discontinued
Saturday, 21-Mar-98 04:43:48
153.34.231.34 writes:
Maybe they are still in "selling a piano" marketing mode, and they think that the
hardware is the selling point. I wonder if the marketing is more aggressive in
Japan? Since we haven't heard from any Japanese users here (I have seen a link
to my site from the Japanese page) I don't really know how popular the
instrument is over there.
I agree that it's very interesting how they describe the instrument - the formant
filter particularly - in terms of how it can be used to synthesize acoustic
instruments, and then none of the patches do just that.
Here's a quote from their website:
"This new Formant Filter can be used to simulate naturally occurring tonal
characteristics (such as the tube of a clarinet or the body of an acoustic guitar)."
Hmmmm... I haven't gotten my K5000 back to look at the patch yet, but is this
what Leiter's acoustic guitar patch does?
-Kenji
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Leiter's acoustic guitar patch
Saturday, 21-Mar-98 08:29:40
130.67.2.235 writes:
Leiter employs the formant filter very actively in that patch. In fact, rather
too actively IMO, because there are sudden changes in the amplitude in the middle
of the keyboard. I wonder about his rationale for doing that.
I have some issues of "Journal of Guitar Acoustics" - in fact, I might have all
the issues of this short-lived (?) journal. I could probably get a lot of relevant
information out of them, I just haven't got around to it yet. Frequency response
is one of the few things that are properly discussed from several angles in that
magazine. The information that is sorely missing here and elsewhere (at SHARC
e.g.) is a thorough discussion of onset transients, which are crucial for getting
the right sound color.
Leiter's patch seems to use the same harmonics that I had tried when I complained
about "The gap between theory and reality". I found out afterward that I
could improve the sound by cleaning up my envelopes. Having done this, it sounds
a lot like a lute or classical guitar. That's OK in a way, but I would like to
have a steel string guitar, and there is no way I can make it resemble a steel
string just be choosing another PCM attack. Also, the "classical guitar" I get has
gut strings all over. How to get the sound of wound strings is beyond me at present.
Getting a good steel string guitar might be a suitable warming up exercise to
the challenge of piano and harpsichord sounds, which are probably the hardest
types of acoustic sound we could try for.
Meanwhile, I am looking into FFT theory. I hope to make a program that extracts
information from .WAV files and stuffs it directly into K5K patches. We'll
see.
Tore
tl001@online.no
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Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 12:41:13
199.86.33.77 writes:
QUOTE
Leiter employs the formant filter very actively in that patch. In fact, rather
too actively IMO, because there are sudden changes in the amplitude in the middle
of the keyboard. I wonder about his rationale for doing that.
UNQUOTE
I was following the chart on p.223 of Fletcher & Rossing. Some notes on a guitar
boom a bit, for others the higher harmonics come through better, so it
sounded natural enough.
Looking through Fletcher and Rossing, it seems like many acoustic instruments
have similar body resonances, with a few large spikes and valleys in the
fundamental range and shallower, closer peaks further up the scale. See pp. 268,
303.
QUOTE
Leiter's patch seems to use the same harmonics that I had tried when I complained
about "The gap between theory and reality".
UNQUOTE
Yes, that was the right formula: A=sin(20%*Pi*n)/n^2. (Fletcher & Rossing p. 42).
The waveform that amplitude profile creates is supposed to resemble the
shape of the string before it's released, i.e. an unequal triangle. (It's the
deriviative of a 20% pulse, sloping up for 20% of the cycle and sloping down for
80%.)
F&R at p. 61 (sorry for all the cites, but it's a great book!) discusses
vibrations in strings that have stiffness, which is a major difference between
steel and gut strings. With stiffer strings, the upper harmonics are "stretched"
upward in pitch. It says this is one reason why stretch tuning is used on a piano,
so the harmonics of lower strings don't beat with the upper strings.
Unfortunately this can't be done continuously on the K5k, only stepwise, using
another ADD for each step. I'll stop typing and give it a try.
P.S. Long live the K5k!
leiter@skypoint.com
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Re: Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 13:00:44
199.86.33.77 writes:
QUOTE
(It's the deriviative of a 20% pulse, sloping up for 20% of the cycle and sloping
down for 80%.)
UNQUOTE
Ooops; integral, not derivative.
leiter@skypoint.com
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Re: Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 15:50:52
130.67.2.249 writes:
QUOTE
Looking through Fletcher and Rossing, it seems like many acoustic instruments
have similar body resonances, with a few large spikes and valleys in the
fundamental range and shallower, closer peaks further up the scale. See pp. 268,
303.
UNQUOTE
Come to think of it, we probably accept many such irregularities on "face value"
without thinking about it whenever we actually hold and play a guitar. Maybe
we are more disposed to hearing them when we get the same sound out of a
keyboard, which is supposed to be more even in its response.
Tore
tl001@online.no
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Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 15:27:35
153.34.205.186 writes:
For a "natural" sounding guitar, the additive sources would also need to change
with the B String (or the D String for some guitars I guess) to simulate the
transition between wound strings and nylon or steel strings - right? It seems to me
(just from listening closely) that it's not only the attack transient that differs,
but the harmonic series seems brighter for the unwound steel strings as opposed to
the wound ones. What do the books say?
Also, the attack "transients" on the unwound strings seem to take quite a long
time to die out. My strings start out with a subtle, almost buzzing sound which
takes a few seconds to decay (but still decays before the rest of the tone). The
wound strings do not seem to have this characteristic. Then again, I have a
slightly unusual sounding acoustic guitar.
Again, this is just from listening, so I don't know how accurate I am.
-Kenji
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Re: Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 15:50:07
130.67.2.249 writes:
QUOTE
For a "natural" sounding guitar, the additive sources would also need to change
with the B String (or the D String for some guitars I guess) to simulate the
transition between wound strings and nylon or steel strings - right?
UNQUOTE
Right. Personally I don't care whether or not I manage to program such subtleties
in a guitar sound, but it will a problem to get this right in a piano sound. I
wish Kawai had given us four sets of harmonics, i.e. low/soft, low/loud, high/soft
high/loud, with seamless cross-fading between all four of them. I guess the
solution is to use two or more sources.
Tore
tl001@online.no
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Re: Re: Leiter's acoustic guitar patch
Saturday, 21-Mar-98 18:11:44
199.86.40.85 writes:
Yep, synths never know what "string" you're playing on. It makes the most
difference with a 12-string patch, where the first four strings are tuned in octaves
and the last two are in unison. Let's call it a "feature" instead of a "bug".
I'm sending a Folk Guitar patch that's similar to the Acoustic (gut-string) Guitar
patch. It uses three ADD's (instead of one) for the string, seperating low, mid,
and high harmonics to shift their pitch and "flange" them off each other. It uses
three PCM's (instead of one) for the attack, one set on "Folk Guitar Attack",
one to add more body on the fundamental, and one to add a metalic transient.
leiter@skypoint.com
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Plucked Strings
Wednesday, 01-Jul-98 17:29:23
209.160.126.144 writes:
Do I understand correctly that if a string, on a guitar for example, is plucked
at a particular node, that harmonic will not sound? I measured the string length
of the second string of my Les Paul (24.75 inches). I then measured the
approximate point where the string would be plucked (3.5 inches). Dividing these
two numbers, I got 7.07. Does this mean that the 7th harmonic will not sound?
What about those one octave or more above it?
Leslie
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Re: Plucked Strings
Thursday, 02-Jul-98 01:12:31
199.86.40.75 writes:
>Do I understand correctly that if a string, on a guitar for example, is plucked
>at a particular node, that harmonic will not sound?
Yep.
>I measured the string length of the second string of my Les Paul (24.75 inches).
>I then measured the approximate point where the string would be plucked
>(3.5 inches). Dividing these two numbers, I got 7.07. Does this mean that the
>7th harmonic will not sound? What about those one octave or more above it?
Every seventh harmonic will be missing; 7, 14, 21, etc.
Theoretically, the force the plucked string exerts against the bridge follows a
pulse wave. If you pluck it at 1/7 of it's length from the bridge, it's a 1/7th
(14.3%) pulse. For anything natural sounding, though, you usually have to tone
down the high end.
leiter
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Re: Re: Plucked Strings
Thursday, 02-Jul-98 14:55:48
209.160.126.138 writes:
While we are on the subject, I know that a string is intially sharp after it's been
plucked. Generally speaking, is there more to it than that? Does the string go
flat at all after the attack?
Leslie
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Re: Re: Re: Plucked Strings
Friday, 03-Jul-98 05:17:06
194.172.230.108 writes:
Generally speaking, is there more to it than that?
Yes. The wave that propagates along the string loses energy. The biggest energy
loss occurs each time the wave is reflected at the bridge. The further way of
this energy portion is: guitar body movement and then: sound. What makes it
complicated (and pleasing to the ear) is that the energy transfer (and its overall
decay) is frequency-dependent and that the body has resonances.
Most people are here to talk about the K5000, so let's apply that theory to the K.
For a good guitar emulation you need that 1/7th (or whatever) pulse
wave spectrum, the harmonic envelopes set to a faster decay for the higher harmonics
and a formant filter tuned to the correct resonances. Exact values can
probably be found in the literature - I am sure someone has measured it all. I
think Leiter mentioned a book...
Jens Groh
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Re: Re: Re: Re: Plucked Strings
Friday, 03-Jul-98 13:26:13
209.160.126.93 writes:
Since the Les Paul I mentioned is a solid body electric guitar, I wonder if body
resonaces play a lesser role than with acoustic guitars. This might make the
waves an electric guitar produces closer to theory than their acoustic counterparts.
When I create a plucked sound, I use a pitch envelope to sharpen the sound at the
onset. I was wondering what approach some of you take with the attack.
Leslie
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Re: Re: Re: Re: Re: Plucked Strings
Saturday, 04-Jul-98 20:03:57
199.86.40.88 writes:
>Since the Les Paul I mentioned is a solid body electric guitar, I wonder if
>body resonaces play a lesser role than with acoustic guitars. This might make the
>waves an electric guitar produces closer to theory than their acoustic counterparts.
The body still matters, but it's a lot more subtle. Some guitar players say they
know whether they'll like a solid guitar's sound by playing it acoustically, before
they plug it in.
The pickups are more important; using the formant filter to model the pickup's
frequency response would be a good idea. (And since you own an LP you
know how important the amp is.)
The position of the pickup must cancel harmonics just like the position that you
pluck: harmonics with nodes directly over the pickup shouldn't be picked up;
harmonics with maxima over the pickup are enhanced. This probably matters less
with an LP becuase you have a two-coil humbucker pickup; one is picking
up some of what the other misses.
I think the pickup sees a different kind of pulse than the bridge, but I've gotta
think about that.
>When I create a plucked sound, I use a pitch envelope to sharpen the sound at
>the onset. I was wondering what approach some of you take with the
>attack.
Same, or else a very quick /\_ . (i.e. starting from zero and quickly going sharp
and then back.) I don't remember why I did the second one!
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Re: Re: Re: Re: Re: Re: Plucked Strings
Saturday, 04-Jul-98 21:00:26
209.160.126.111 writes:
On the subject of attacks: In a book I have, called "A Synthesis Guide To Acoustic
Instruments", the authors talked about the "thud" you hear in the attack
of acoustic guitars. They put its frequency at around 100hz. I remember trying
to recreate this by centering some inharmonic partials at 100hz and giving
them a fast decay. I fixed the pitch of the "thud" so it would stay the same
regardless of what key was played. I also rate scaled the amplitude so it wouldn't
be as loud in the upper ranges. Layering this sound with the rest of my guitar patch
made it sound much more realistic. The trick was to balance the sound so
it wouldn't get to "boomy".
Leslie
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Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Saturday, 04-Jul-98 22:56:10
199.86.40.89 writes:
More on the waveform: I think a guitar pickup responds to the _velocity_ of the
string, since it takes motion to induce a current. In that case, the pickup sees
a positive pulse, then zero, then a negative pulse, then zero. Here's the formula:
A(n)=(1/n)*(sin(Pi*n*X%))*(sin(Pi*n*Y%))
where X% is the position that you pluck the string (as a percent of the whole
length of the string) and Y% is the position of the pickup.
leiter
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Re: Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Sunday, 05-Jul-98 01:24:46
209.160.126.137 writes:
I measured the length of the lead pickup (since that's the one I use most of the
time) and got 1.5 inches from its center to where the second string meets the
bridge. So far that makes:
24.75 inches-total length of the second string
3.5 inches-plucking position
1.5 inches-center of lead pickup to bridge
I'll plug these numbers into you're equations and see what I get. I put the
finishing touches on my "Les Paul" guitar patch and it sounded pretty good,
especially in the mid-range. It will be interesting to see how the new numbers work.
"A Synthesist's Guide to Acoustic Instruments" is by Howard Massey with Alex Noyes
and Daniel Shklair. It was published in 1987 by Amsco Publications
(I don't know if it's still in print). It shows how to emulate various instruments
with analog, phase distortion, and FM synthesis. There's enough general info to
make it useful for additive synthesis. It's not really a rigoruos treatement of
the subject, but more of a practical guide to synthesis.
Leslie
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Re: Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Sunday, 05-Jul-98 06:07:54
209.160.126.149 writes:
Well folks, I just got through doing the calcultions using leiter's equations
combining the pluck position with the pickup position (actually I wrote a program
for my old Atari St to do the calculations for me). To say I was amazed at the
results would be an understatement. Once I finished entering all the numbers
and adjusting the envelopes, I had a "Les Paul" sound that rivals a sample (I
should know because I've sampled my LP several times). This is with an old K5
keyboard to; just think what you can do with your K5000!
By the way, the position of the Rhythem pickup is 5.5 inches from the bridge. I'm
going to do that sound next.
Leslie
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Re: Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Sunday, 05-Jul-98 10:52:05
195.232.55.162 writes:
You can get the string velocity by taking the derivative of the string
displacement. Shouldn't the 1/n term vanish then?
Jens Groh
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Re: Re: Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Sunday, 05-Jul-98 13:41:55
199.86.33.43 writes:
The motion above the pickup is a trapezoidal pulse, (1/n^2)(sinX%)(sinY%). As you
approach the bridge, Y goes to 0 and the waveform approaches a
rectangular pulse. There's no string motion at the bridge, but the force on the
bridge is proportional to the angle the string makes as it inserts at the bridge.
leiter
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Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Plucked Strings
Sunday, 05-Jul-98 15:41:45
199.86.33.43 writes:
> The motion above the pickup is a trapezoidal pulse, (1/n^2)(sinX%)(sinY%). As
> you approach the bridge, Y goes to 0 and the waveform approaches a
> rectangular pulse. There's no string motion at the bridge, but the force on the
> bridge is proportional to the angle the string makes as it inserts at the bridge.
Come to think of it, that would be the natural way to roll off the high end for
an accoustic guitar; instead of (1/n)(sin~15%), use (1/n^2)(sin~15%)(sin~4%).
But I think for an electric it's still (1/n)(sin~15%)(sin~21% or ~8%)
leiter
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Re: Re: Re: Re: Re: Re: System Exclusive and the K500
Friday, 10-Jul-98 03:12:43
209.160.126.94 writes:
Sounds like a good idea to me; I'll try it.
By the way leiter, have you created any sounds with the equation you came up
with for the electric guitar? I'm still amazed at how that Les Paul patch
sounded. One thing I noticed is that by setting the pluck position at 50% and
the pickup position at 33% you get an almost bell like tone. Using the setings
40% and 33% gives a sort of soft jazz guitar sound. Amazing.
Leslie
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Two Electric Guitar Patches
Friday, 10-Jul-98 22:28:02
199.86.40.86 writes:
I'm sending two electric guitar patches:
Jangle: Rickenbacker 12-string electric emulation
Twang: Telecaster lead pickup emulation
All of the guitar emulations I've done so far have a drawback: they sound too
harsh above about an A4. That's at least partly because the waveform is made
on the assumption that you're plucking the string at about 1/6th its length.
But as you play up the neck, you're plucking nearer and nearer the center of the
vibrating string. You could put in a second ADD for plucking at about 1/3d the
length and split the keyboard, but I haven't bothered yet.
The FF in both of these patches is supposed to reflect the characteristics of
the pickup. Generally, guitar pickups act like lowpass filters with a resonant
peak. There's some good
information on various types of pickups at:
http://www.seymourduncan.com/tonechart.html
leiter
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And One More
Friday, 10-Jul-98 22:58:55
199.86.40.86 writes:
Here's one more:
Jangle18: Identical to "Jangle", except it adds one more ADD detuned from the
other two, so it's like an 18-string electric guitar.
_This_ is what the K5k is for! :-)
leiter
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