The Eat at Joe's Kawai K5000 Message Board Digest
Displaying Waveforms from the Harmonic Series
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System Exclusive and the K500
Thursday, 09-Jul-98 16:49:49
209.160.126.84 writes:
I just finished the first version of a program for the Atari ST that calculates
different waveforms using leiter's and Jens Groh's equations (and a couple of mine
as well). The program shows you all the amplitude settings for each harmonic and
will draw a waveform for you to see what the wave looks like (kinda slow
though). I just learned how to send all this info to my K5 via midi. Adapting the
calculations for the K5000 is easy; I just change one number in Jens' famous
equation. Getting the data to the K5000 is another matter.
Here's an example of the kind of info I need:
F0,40,00,10,00,02,04,28,00,00,F7 -sets the K5's harmonic number
F0,40,00,10,00,02,04,29,00,00,F7 -sets the level value
This is for the K5. Does anyone know the equivalant is for the K5000?
I don't want to step on any toes here, so I would want to get leiter's and Jens'
perrmission before releasing anything (they're probably working on something
much better anyway), and hopefully have them double check my work.
For those of you who don't have an Atari, there is a fantastic emulator for the
PC by Frederic Gidouin called PaCifiST. Check it out!
Leslie
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Re: System Exclusive and the K500
Thursday, 09-Jul-98 17:37:17
192.28.2.16 writes:
What phases do you use for the harmonics when you display the waveform?
There are an infinite number of possibilities, but there are four "natural" choices,
each of which is useful sometimes. You can take the absolute value of the
harmonic amplitudes before calculating the waveform display, or not, and you
can apply the amplitudes to a series of sine wave harmonics or a series of
cosine wave harmonics. Some waves will only look like they "should" under one of
the four possibilities; e.g. a pulse only looks like a pulse if you construct it
out of cosines and don't take the absolute values of the amplitudes. It's only a
matter of viewing the wave, though; it generally sounds the same whatever the
phase relation. As they emerge from the K5k, all waveforms are made up of sine
wave harmonics that are essentially in phase and have the same polarity
(i.e., take the absolute value).
[P.S. Don't worry from me about stepping on toes. Anything posted here would
probably be considered published, so it couldn't be patented by anyone in
most of the world. The main exception is the US, where you have up to a year
after a publication to file. If there's any commercial interest out there, better
contact us soon!]
leiter
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Re: Re: System Exclusive and the K500
Thursday, 09-Jul-98 18:56:42
209.160.126.97 writes:
I don't take the absolute value of the amplitudes. All of the sines are in phase
(actually I'm not sure I know how to calculate them any other way). I've always
found a saw wave going down to be more aesthetically pleasing (visually), so I
invert the phase before displaying the waveform. I use the sine function
instead of the cosine. I may need to take a look at using the cosine for the
pulse waves. The square wave and the very narrow waves look like they should,
but some of the ones in between have a staircase look to them. Maybe you've
explained it.
These are the following waveforms the program will calculate:
Saw
Pulse
Triangle
Saw+Pulse (mine!)
Pulse+Pulse (mine too!)
Pluck
E. Guitar (pluck and pickup formula)
I may still implement some others, so if you have any favorites, pass them on.
Leslie
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Re: Re: Re: System Exclusive and the K500
Thursday, 09-Jul-98 20:45:04
199.86.40.85 writes:
>I may need to take a look at using the cosine for the pulse waves. The square
>wave and the very narrow waves look like they
>should, but some of the ones in between have a staircase look to them.
Yep, that's it. Also, the "sine view" is an up-and-down pulse (with a staircase),
whereas the "cosine view" is a regular up-only pulse:
_
_| | _
|_|
vs.
_
| |
| |___
Any waveform view constructed of sines has to be symetrical through a
rotation of 180 degrees around some point, like a saw. Any waveform view
constructed of cosines has to be symetrical in reflection across some
vertical line, like a pulse.
I guess none of this is about listening, but it has thrown me off track in
the past.
leiter
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Re: Re: Re: Re: System Exclusive and the K500
Thursday, 09-Jul-98 22:15:34
209.160.126.148 writes:
Oops! I was taking the absolute value. Once I changed this, the triangle came
out looking like a triangle. I used the cosine for the pulse waves. They now
look like real pulse waves. After I changed this, I noticed the square wave
started in the middle of its cycle (I don't know why I was suprised by this). I'm
so used to using the sine function till I forgot about how the cosine works.
But what about the saw+pulse wave? What approach should I take with it?
Leslie
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Re: Re: Re: Re: Re: System Exclusive and the K500
Friday, 10-Jul-98 01:05:36
199.86.40.89 writes:
>But what about the saw+pulse wave? What approach should I take with it?
Depends on what you expect it to look like!
leiter
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Re: Re: Re: Re: Re: System Exclusive and the K500
Friday, 10-Jul-98 02:39:37
153.37.12.138 writes:
Wouldn't the most visually pleasing way be to calculate them using sin and cosine
respectively and then adding the two together?
Kenji
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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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