Craig Brougher has stirred up a great discussion on one of my old
favorite topics.  He says:

> That is a very interesting and helpful letter from Richard Schneider

That's for sure!  I wish I could have "talked" with professional organ
builders like this back in my college days!

> Those four characteristics I mentioned seemed to be predominant in my
> ability to notice and to name the ones that were surely made of wood.

Craig, I learned the hard way (well, it was fun!) that pipe sounds
which you would swear are wooden can come from metal stopped pipes.

I was enjoying a "wooden" stop at a recital once, when I realized it
was coming from an exposed set of metal Rohrfloeten [rohr flutes]
(Chimney Flutes), which look like sawed-off Diapasons with a smaller
metal tube out the top.  The metal stopper fits snugly over the metal
pipe much like a modern tuning slide on an open metal pipe.  But, boy,
do they sound hollow and wooden.

In earlier organs Rohrfloeten were usually wood, with the chimney bored
through the stopper handle.  Recent church organs seem to be built with
more nearly exclusively metal pipes.  Just as outdoor organs (monkey-,
band-, fair-) are mostly wood pipes, then and now.  I suspect all organ
builders like to use the same material, wood or metal, throughout an
organ, to match their own skills and to help the different ranks stay
in tune with weather changes.  There are good reasons to stick with
wood in the portable instruments that we love to crank, but they aren't
tonal.

> Excessive speech problem may be called chiff, but normal speech still
> has it.  It just isn't easily noticeable anymore, so it isn't called
> chiff, but it still doesn't turn on like a frequency generator.  It
> still has a start-up sound.  That's the characteristic I speak of.

Right.  Let's call this the "attack".  You're right, it's VERY
important.

> It takes a moment to establish the air curtain and get it stabilized.
> That isn't called chiff.  That's a characteristic of this or that
> kind of pipe, and when you hear a song being played, that character-
> istic is going to color the sound you hear to a great extent, but
> that characteristic isn't measured or evaluated scientifically.
> It is discounted.  That -- I am saying- - is a basic mistake called
> "very typical." It's what I have learned to expect.

You're right, but scientists no longer discount this.  Sometime ago
tests showed that given a set of bright instruments (say trumpet, oboe,
and sax) or mellow instruments (flute, clarinet), listeners could no
longer tell them apart when the experimenters edited tape recordings
to eliminate the initial attack on each note.  The test subjects heard
only the steady-state tones, and could no longer tell a sax from a
trumpet.  So the experts have caught up with reality here.  Craig has
done us valuable service by pointing out how the attack determines our
perceptions of any instrument.

>  When either pipe starts to blow, or when it is cut off, its
>  physical response has to be different because of the different
>  flow characteristics between those types of pipes.

Air flow does not cease instantly, due to (1) pressurized air trapped
in the wind chest key channel and the pipe foot, and (2) momentum of
that air in motion.  Air is hardly compressed at organ pressures, so
(1) is probably not as important as (2).  I grant that a wooden pipe's
long stem might build up more momentum in its narrow air flow, but I'll
see what the organ builders say.

Don't forget that the vibrations have their own inertia, without the
air jet.  Slap your palm against the open end of a piece of pipe to
hear its stopped pitch.

> Next option -- we could just faux grain a metal pipe with paint and
> stains and tell everyone those are wooden pipes.  Just let their
> imagination do the rest.  (Having some fun -- not sarcastic).

Imagination is very powerful, and it cuts both ways.  Mormons have fun
too -- the 32 foot pedal diapasons in their Tabernacle organ are really
wooden, but are planed round at the corners and painted faux gold to
look like metal!  Not that anyone can hear the difference at those low
pitches, but it's fun!  Some fairground organs seem to have wooden
pipes made to look metallic too.

> Regarding sympathetic vibration within a rank, I still think that
> has some bearing and do not believe that metal pipes are nearly as
> affected, but I don't know for sure.

I took Richard's posting to imply that the air coupling between mouths
and open ends was much more significant than coupling through the pipe
walls, but ...

> If the distance between the vibrating bodies is very close, and the
> transducers are large and flat, the effects will be more pronounced
> than if they are tubular and further apart

This makes good intuitive sense, but let's ask this:

Some monkey organs were made with the front rank of wooden pipes
all sharing a common front and back slab of wood, and with only one
side wall piece between adjacent notes.  Has anyone noticed coupling
problems with this?  I know this form of construction is not popular,
probably because it's a pain to repair.  Of course this does not change
coupling between different ranks, so may be irrelevant.

Wooden pipes are more likely in monkey and band organs, where there is
big pressure to cram the ranks close together, thus asking for sympa-
thetic coupling problems -- but again, the mouth coupling probably
overshadows anything through the walls.

> If you were standing in front of a Loesch or Weber with those great
> wooden violin pipes playing, you might answer that you were hearing
> a violinist.  It is to say that in the last 100 years to my knowledge,
> such metal pipes are not generally available, while wooden ones are.

This may be sociological:  Builders of church organs, who used mostly
metal pipes, were less interested in getting an exact violin imitation,
leaving this to the orchestrion builders, who preferred wooden pipes.
Theatre organs did go for a true string tone, but I'm pretty sure they
used metal.

In fact, I was just as shocked to find "nasty" wooden violin pipes in
barrel organs as to find "woody" metal flutes in church instruments.
Maybe another reason for such good string tone from wooden pipes, is
that the bridge or frein or beard is made adjustable by screws on
wooden pipes, but is soldered in place on metal pipes.  A voicer or
even a savvy owner can tweak his wooden string ranks to perfection more
easily than a metal set.

I hope I've added more to this discussion than noise and confusion!

Mike Knudsen