Re: OT: Apple has a patent on tremolo!
Re: OT: Apple has a patent on tremolo!
- Subject: Re: OT: Apple has a patent on tremolo!
- From: Richard Dobson <email@hidden>
- Date: Fri, 02 Mar 2007 09:26:51 +0000
Ben Cox wrote:
On Mar 1, 2007, at 12:39 PM, Paul Evenblij wrote:
But this is not about sine waves. In my understanding,
the patented method is a way of getting beat
frequencies which are constant along a large range of
main frequencies. I.e. if you have your two
oscillators playing C3, and the beat frequency is 3
Hz, then if you play C4, the beat frequency will be 6
Hz using 'prior art'. Using Apple's method, this beat
frequency will *always" be 3 Hz.
True. But there are still decades of prior art on this one. People
have been doing this with modular synths for a long time, and many
non-modular synths allow you to use fixed-beat type modulation instead
of fixed-ratio.
Unless this patent application was filed a long time ago, or has lots
of other claims in it besides this apparently simple concept, it sounds
hinky to me.
-- Ben
Prior art: this is from the Kurzweil KN2000 manual (around 1992 vintage):
"There’s only one parameter on this control input page that may still be
unfamiliar to you: Fine Hz. We discussed this in Chapter 6. It can tune
the pitch of the waveform in terms of its actual frequency in Hertz, as
opposed to the usual method of tuning by key names. The advantage to
using the Fine Hz parameter is that you can maintain constant beat
frequencies across much of the keyboard when you have a program with
slightly detuned multiple layers (or multiple waveforms in one layer).
"
The net effect of course is still indistinguishable from tremolo, such
that this form of detuning can be said to be a way to get tremolo, in
practice probably fairly subtle, not up to the 100% mod that real AM
could give you.
Thanks again to the Sherlocks on the Csound list for finding this example.
Richard Dobson
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