Hi,  In regards to David Repanshek's post: Wurlitzer trombones speak
at the 8' pitch.  That is from C below middle C and up.

Wooden trombones in Wurlitzers are mitered 90 degree with no ill effect
on the pipes.  The problem you might run into with voicing reeds is
that the tuning or voicing wire is not separate from the resonator as
far as voicing goes.  Shortening the speaking length of the reed by
tapping down the wire is going to cause the pipe to get higher, but
there is a point where the pipe will seem to choke if you get it too
high.  The best thing to do is to get the exact measurements for the
trombone pipes, reed and shallot lengths and start from known
dimensions.

There are a lot of factors governing tone quality in a pipe and it has
to do with the cubic area in the resonator of a reed and how the pipe
is shaped.  A long taper on a pipe is going to give you a different
sound than a short quick taper.

Reeds are a certain thickness and they are curved for a certain wind
pressure.  They are also curved starting at a certain point for tone
quality.  Reed voicing is a science all itself and, while it has been
done by people with no formal training in it, I would say for the
aggravation factor that I would take them to a local church pipe organ
service man.

The bigger shops have a pipe voicing chest.  Tell them what pressure
(8"?) and what notes the pipe you have are to speak, and if the other
dimensions are what Wurlitzer had, and you will have some pretty decent
sounding pipes.

There is a mistaken notion that flue pipes or open pipes speak out of
their tops.  While there is a certain amount of residual sound that
comes out of the top from the vibrating air column, the actual sound is
produced and heard at the mouth.  Only in a reed does the sound
actually come from the end of the resonator.  The fact that a flue pipe
is open or stopped has to do with the quality of sound that is desired.

It is almost always more desirable to make 45 degree turns in any pipe
instead of 90 degree miters in order to offer the least impediment to
the vibrating air column and to avoid the creation of nodes.  (I'm
paraphrasing Audsley's "Art of Organ Building" here, pg. 494 volume 2.)
Stopped pipes are not as affected as open pipes by mitering.  In any
case, in band organs there isn't much choice.

Tony Marsico