Hi!
Following the experiment on
http://www.youtube.com/watch?v=ntPblldKpBwlast night it occurs to me that in my experiment whilst two notes coming through one speaker were no different to the individual notes coming through individual speakers we all know that in practice big electronic organs with multiple speakers sound better. Why?
Pondering on this I wonder if it is a matter of dynamic range. In the experiments, all the speakers were being driven in safe regions of linearity. But when we put together an "organ", we vastly exceed just two "pipes", and whilst one added to another might be fine but another 80 and then another 150 sounding on top all at once may be a different matter not merely of sheer complexity but simply of dynamic range within linearity.
Could putting the whole of an organ sound of many thousands of pipes
at realistic volume through a cylindrical hole perhaps 8 inches in diameter, or two such holes, upset our assumptions about the linearity of air compressivity?
The following file
http://www.jungleboffin.com/mp4/organ/h ... beware.mp3may be capable of testing the dynamic range of speakers if played at a realistic volume.
Please
take care: this file is s
peaker dynamite and may
destroy inadequate speakers at a realistic volume and, most certainly, if it does not
cause you to jump out of your skin or induce a heart attack, your speakers may simply not be hi-fi.
(The recording was made at our first concert to bring familiarity of the organ to new audiences, before I had heard of Hauptwerk on the unaltered, unimproved virgin 3 manual ex-Londonderry Cathedral instrument. No doubt it may illustrate how Hauptwerk is superior. Nevertheless I hope that you enjoy the fun as the audience did. The project to put the organ repertoire onto this concert platform owes a deep debt to the great organists who have enjoined with enthusiasm to make this possible, and thanks to Hugh Potton on this occasion. All organists are welcome)Reverting to the concept of realism, should not the area of speaker cones in use be related to the total area of all speaking pipe diameters? In areas of speaker design requiring slots or reductions of openings from the cone, from memory the general rule is that a compression ratio exceeding 4:1 introduces distortion from non-linear air compression. So this might be a good point from which to work in relating organs to speakers.
Of course this is irrelevant to home reproduction systems where air shifting required to produce a "realistic" sound pressure is on a different scale to that required to be done by an instrument in its native building.
On this basis, taking a 1:1 pipe area to speaker area ratio an 8 inch unit might be capable of representing a dozen gamba and dulciana pipes, a tenor Diapason note played with a triad above middle C, but not more, one pedal Ophicleide, a myriad of mixture pipes, etc. One simply needs as many speakers as necessary to equate with the areas of speaking pipes, although physics can provide ways of defying this law.
In a smaller environment one can probably take the ratio up to 4:1 without undue effects, but in a church or auditorium greater than 1:1 is overkill.
This may be a reason in addition to my voicing observations recently why electronic organs have failed to measure up on full organ tuttis.
Best wishes
David P