Article by Al Self 1/21/00
(By permission. Copright reserved)

Regulating Tibia trebles may be as simple as using a toe cone to close down
the "screeching" offenders. That is the easy part. The hard part and the
part that requires the most time is identifying how to proceed and how much
more quiet you want the trebles to be. The scaling and the cutup are set at
the factory so these pipes were meant to get out and fill the theatre. The
toe can only be closed down so far then the pipe begins to sound asthmatic.
Normally you can get the pipes down to where they won't stick out of a large
ensemble which includes the 2-2/3' and the 1-3/5' pitches. There are many
tricks you can do but I would *not* want to see them done unless the person
doing them is properly trained. Manipulating the windway by closing it a bit
is one trick amateur weekend jackknife voicers should *not* try. It usually
requires moving the languid and the upper lip too. You then end up with four
mysterious variables and one screwed up pipe needing revoicing.

Process wise, you need a trained ear at the console to listen for loud and
soft pipes and a technician in the chamber who knows your signals and has
impeccable technique. The console job is not easy when you consider how poor
the ear is at determining volume levels. The human ear detects changes in
volume when it doubles or halves (3dB steps). So the best work is done with
comparison chords and octaves until you have determined what needs to come
down or up in volume. A sheet of paper with the pipes written across
representing the top 3 octaves is a starting point. Randomly play each of
the highest 4 Cs at the console with your eyes shut. Do they sound about
equal? How about the 3 C#s? Do they sound about equal? The rest of the
notes? Yes, go up and down the 3 octaves playing a C major chord. Do they
sound about equal? Do the same with a D major and so on. What you are doing
is listening for any outstanding loudness. Note it on the paper. Why don't
I recommend a sound level meter? They don't hear the harmonic content which
can give a false reading. Your ear will hear the overall effect of the pipe
and you will mentally assign a value to the whole. e.g.: A 16' Metal
Diaphone is less loud than a 16" Tibia but sounds louder because of harmonic
content. Once you have recorded your tone sensation levels on paper you
might be surprised. The top octaves may not need any work at all but were
voiced and regulated loud just like the rest of the rank. If they do stand
out then a very very very light coning of the toes is the best place to begin
for your chamber man. Small changes are the rule. Start with the lowest
note that is objectionable then have the chamber man cone it down just a
touch (it may even be down in the woods). Play down the keyboard to check
against the new level and make sure there is no step. Sounds OK then go up
one, etc. The process is slow and you want random checking to make sure that
you are achieving blending and smoothness. Slowing down the process further
is that with each change in volume the pipe must be tuned again. While
holding the pipe to work on it your hand's heat will transfer and tuning will
be altered. There is a whole ballet of pipe manipulation that one must learn
to avoid some not too apparent side effects (thin strings require the best

For a home installation of a theatre organ you may never get the trebles down
to where they don't take the top of your head off. What I have done for my
clients with home installations of higher pressure instruments is to make a
new set of trebles from an old Principal with a lower cutup (I would never
lower the cutup of a valuable original TO rank). You can then cone the new
octave(s) down to the operating pressure where they blend in without the
screech. Should the organ ever go back into a theatre, the original top
octave(s) that are labeled, stored in the chamber, and boxed well can be used.

Tools you will require: A good ear, a good chamber tech, a small toe cone, a
tiny scratch awl or machinists pick with long tapered shaft to reopen a toe
hole that you might have closed too much, a set of tuning forks to tune the
organ before you start, a windgauge to check your pressures, a tuning knife,
hearing protectors for the chamber man, a knowledge of work code (e.g.: 2
short taps on a primary valve to get a note to play means, "Try it and how's
that?"), food to keep you going, and a pint to wash it down with. Just
kidding about the pint.

This is how I was trained and I would like to hear from others if there are
better methods, shortcuts, and tricks about which I need to be enlightened.
I am sure since it is late that there are many things I have forgotten.

Al Sefl