RCT

[Richard Brekne]

Roger Jolly wrote:

> Hi Frank,
>                A little light or perhaps, or mud on the subject. Re
> inharmonicity, my current passion and night mares.
>  Lets assume a reasonable curve has been calculated of equal quality, by
> any of the three major ET's.
>  Point 2 we are dealing with a well scaled piano but the voicing is a
> little uneven.
>  For simplicities sake we will look at octave 5 upwards.
>  In this register upwards we are tuning to the second partial aurally, as
> with the ET.
>  If you have a very bright note the 2nd is almost non existent and the
> inharmonicity also increases.Aurally your brain reverts to the fundamental.
> so in the next octave you compound the error, and so on up the scale..........

Ok guys.... (Roger...grin.. thanks for the continuing supply of mud.. )

What I am not clear over is this buisness of calculated scales vs realtime
measurements. I wrote in a post a bit back that I had done this little experiment
with Tune Lab. I tuned  A-3 and A-4 as a 4:2 octave and verified this with Tune
Lab. Then I figured my own temperement by dividing the real time frequency of A-4
by that of A-3, took the 12th root of that and arrived at frequencies for all the
inbetween notes. Since I was useing the frequencies (A-3 and A-4) of the 5th
partial of each, and then the 4th partial of each I had two sets of equally
spaced frequencies for the 5th and 4th partial of each note inbetween the 2 A's.
I tuned each of the inbetween notes to the 5th partial frequencies and checked
them against the 4th partial frequencies (didnt have to change anything really on
the check round). This gave me a really nice temperament with very evenly spaced
thirds.

Ok... after doing that I tuned the rest of the piano using Tune Lab as I use my
ear. That is to say I directly referenced the partial of the note I was going to
use as a reference note by zeroing in on the frequency of its partial and locking
the setting on that, then tuned the notes corresponding partial to that setting.
For example take A2... I set Tune Lab to read the 3rd partial of A3, adjusted the
offset til the display stayed still, and locked onto this setting. Then I tuned
A2's 6th partial to this setting. I used standard appropriate octave types for
each register of the piano, but tuned the entire piano in this fashion. The
result was an extremely evenly tuned piano. Thirds, tenths and seventeenths
progressed very evenly indeed.

What I liked about the experiment, was that I used the computer and Tune Lab to
make sure that what I try to do with my ear was like dead on. This took all the
calculation (with the exception of the temperatment itself) out of the picture.
What I did not like about it was that it was a bit time consuming. (took over 2
hours to do). I figure tho that as I am new to ETD's I could improve on the time
after a bit, and that I could get good at adjusting for and neccessary changes
with regards to stretch and partial problems underways.

Now I have used RCT a bit more, and what I like about it is that I get better
speed, but I find that I am not always happy with the amount of stretch (tho it
is always very even), and I feel kinda like I am out on a limb trusting that this
"calculated tuning" is going to be good enough. Again, I figure that given time I
will be able to merge the RCT with what my ear wants (in general from a tuning)
and get a good result.

My "question" is then, (given your statements about inharmonicity, strength of
partials, and how these change under conditions such as those voiceing can
present) Which ones of these two methods is really the most dependable, or shall
I say will result in the most "correct" tuning ? (I assume here that both RCT and
Tune Lab are equals when it comes to measuring accuracy) If you have an opinion
on this, I would also like to hear (as in depth as you can get inspired enough to
write.. grin) your reasoning.

Thanks..

Richard Brekne
I.C.P.T.G.  N.P.T.F.
Bergen, Norway