Mailbag: “Getting Resultants”

July 6, 2011

Dear Michael,

While listening to this week's program online, I looked at the information on the Wilkes-Barre organ. It raised in me a question I've always wondered about. I noticed that the 32' stop on the pedal is a "resultant." The stoplist suggests that two pitches sound together to "result" in a 32' pitch. This is a nifty trick of physics. My question is, are stopped 32' ranks unsuccessful? I often see "resultant" but not often does a stop list make clear that a 32' rank is 16-foot length and stopped. On the contrary, often there is an apologetic reference, especially with reeds, that "the last __ pipes (fill in the number) are half-length." How effective are "resultant" stops, etc.? I'd think that the effect would be ruined if a nearby rank was a little out of tune, or if either of the paired pipes were out of tune.
So, two or maybe three questions in there somewhere.

Chuck

 

Chuck,

A 32' Resultant pitch is created by combining the pitches of two 16'
registers (preferrably one a bit louder than the other...a 16' Bourdon for the 'tonic' pitch and a 16' lieblich Gedact playing a fifth above...presuming the organ specification already includes these, or their equivalents). Sometimes the resultant is created using the tonic and fifth from a single rank, but in practice the effect usually is somewhat 'quint-heavy' on the note a fifth below the tonic.
In either case, the effect is created without need to built, or pay for, any additional pipes, and the control wiring required to activate this effect is of minimal cost.
Often the 32' pitch is achieved using a stopped 16' pipe, and this is fine, too, though much more costly than the 'resultant'. The most profound 32' pitch effect is created by a full length open (wooden) pipe.
Since large/long pipes generally do not go out of tune (if properly built, and located in an environment with regulated temperature changes), there is no functional challenge to using a 'resultant' pair of pipes/pitches.
Half-length reed resonators are a compromise, too, as there is less fundamental to the sound. It is possible to counteract this loss with higher wind pressures, leathered shallots, etc. Since the low octave of a 32' reed likely is used only in full ensemble, the differences in tone-quality are minimized at the listener's ear, and they can be very effective.
Consider this online forum:
http://www.organforum.com/forums/showthread.php?3861-reed-pipe-resonator-length&s=7f102f39fbca64df064d183f090cae86

Again, it is a matter of cost (a 32' full length anything is hugely more expensive than something smaller) and available space (they are BIG). Life is filled with compromise.

 

jmb

 

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