Peterson 490ST Strobe tuner....good?

[David Ilvedson]

Thanks Richard,

That is enlightening for me...

David I.




----- Original message ---------------------------------------->
From: Richard Brekne <richard.brekne@grieg.uib.no>
To: PTG <pianotech@ptg.org>
Received: Mon, 01 Jul 2002 23:05:18 +0200
Subject: Re: Peterson 490ST Strobe tuner....good?

>The best lesson I can suggest is by taking Tunelab 97 and do the following
>simple exercise.

>Tune A4 (1) to 440. Then set the tuning partial to read the 3rd partial, and
>while playing the A4 adjust the offset on Tunelab so that the phase display
>stops. Note the frequency in Hz on a piece of paper. Then tune A3 so that it
>stops the dial. This gives you a perfect 6:3 octave type. Now set Tunelab to
>read the 3rd partial of A3 and adjust the offset while playing A3 til the
>display stops again, and note this frequency down as well. It will be
>approximately half of the first frequency you noted.

>Now divide the frequency for A4(3)  by that of A3(3). This will yeild a number
>just a tad over 2... somthing like 2.00582... or whatever... just barely over
>2. This represents the inharmonicity spread for the 3rd partials of these two
>notes with same tuned as a perfect 6:3 octave type.

>Take the 12th root of this number. Then starting with A3 (3) mulitiply the
>frequency times this 12th root of just over 2 to find the frequency for the
>next note up. Continue such until you reach A4 again.

>The resulting curve is a linear perfectly spaced division of the 3rd partials
>of all the notes from A3 to A4. And as a temperament octave it actually works
>quite well most often.

>Ok... this is the basic curve... and things get a bit more complicated after
>that as we actually have several things to take regard to... several partials
>each with there own theoretical curves that dont match up neccessarilly so well
>when we tune to just one... and well a whole bunch of other things we try to
>compromise together to come up with a "best" solution.

>But this is as good a place as any to start learning about how RCT, SAT, and to
>some degree Tunelab work. I would suggest you do this a few times...and use
>Tunelabs numerical editor to accompish the same thing as manually finding the
>12th root of 2(+ the spread) to get all the frequencies for the temperament
>octave.

>When you have a good feel this much start asking more questions. We have
>several enthusiasts here and I am sure between us you will find some good
>answers to most of your questions as you find out more.

>Cheers

>RicB


> Charles Neuman wrote:

>>Richard, or anyone,
>>
>>I'm curious what algorithms are used to calculate a tuning curve based on
>>harmonic measurements of 1 or more notes. Is that information available?
>>
>>I'd like to try to do this manually sometime: I'd measure the offsets of
>>each harmonic of the test note(s) (using an ETD) and then use that info to
>>calculate the tuning curve. I'd like to try different methods.
>>
>>I suppose I could come up with a way to do this, but I'm sure people have
>>spent a good deal of time thinking this through thoroughly. Anyone know if
>>these algorithms are published anywhere?
>>
>>Charles Neuman


>Richard Brekne
>RPT NPTF
>Griegakadamiet UiB