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Pedal Acoustic Bass 32

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Barrie Davis:

I have never been totally satisfied with the sound produced by Quinted 32s, often they Quint is derived from the Bourdon which is often far too loud. I recently played a small organ with a synoptic spec as follows; 16, 10.2/3, 8, 5 1/3, 4, all derived from the one Bourdon unit. The 10.2/3 was useless and certainly did not produce a realistic 32 sound.
I have heard of, but never some across, organs which have a 32 the lowest octave being quinted off a seperate octave of Quint pipes, these standing on their own chest and voiced quietly to provided the needed 5th. Does any member know of any places where this has been done?

Best wishes


Colin Pykett:
A resultant bass can never reproduce the effect of a full length pipe, regardless of how you derive the tones.  This is because, with a full length pipe, you have real (and considerable) radiated power in the air at the fundamental frequency.  With a resultant, you only have a beat frequency at the fundamental.  Although they are numerically the same, there is a very important difference - there is no acoustic power whatever in a beat.  Therefore there is also no power at all at the missing fundamental frequency.  (To be rigorous, power at the beat frequency would only arise if the propagating medium (the air) was nonlinear, which it is not.  It could also arise in the ear itself, which is admittedly slightly nonlinear.  But the nonlinearity is nothing like pronounced enough for it to be relevant to this discussion).

Doubters might like to try an experiment.  Try to detect the missing fundamental in the 'resultant bass' created at a higher frequency, by playing middle C and the G above it on an 8 foot flute or diapason.  If the resultant bass idea really does result in a missing fundamental being re-inserted, you should be able to hear a tone at tenor C in the experiment just described.  In practice you will not (unless you are using an electronic organ so awful that it should not be used in the first place.  Either that, or there is something seriously wrong with your ears!).

The only difference between these two situations, i.e. the experiment just described and a conventional resultant bass at lower frequencies, is that in the latter case the beat is slow enough for the ear to follow it, whereas at a higher frequency the beat is far too fast for the ear to follow.

Organ builders, or at least some, love you to believe that you can get more than you pay for.  In fact you cannot.


Colin Pykett


But the fact remains, Colin, that resultant bass does work - not as well as the real thing, granted - but there's not always space for even stopped 16ft pipes.

Maybe the Compton "cube" is a better solution to the space/deep bass problem?

Every Blessing


David Pinnegar:

Tony, I know that there is a hint of an illusion but Colin is quite right - there is simply too much power in the quint tone, causing confusion in the sound and only a hint of really what one's striving for.

The other day I was piano tuning - and in the treble, working with a reference frequency I heard heterodyne frequencies which gave an arpeggio as one moved down the semitones but they failed to be heard on recording -

Acoustic bass can be equally ineffective.

Best wishes

David P

Colin Pykett:
It wasn't my intention to be too pedantic, though re-reading what I said I probably was.  Apologies.  Actually I think we are all correct.  What I said is factually true, in that there is no acoustic power at the fundamental.  However Tony contended that it's better to have half a loaf than nothing at all, and that is often true as well.  The powerful illusion of a slow beat, especially for the lowest few notes of a resultant bass, does underpin to some extent whatever is going on above in favourable circumstances.  Higher in the quinted octave it generally gets less effective, and the 'join' between B (the top note of the resultant octave) and C (the bottom note of the rank) can often be painful!  But these are generalisations, the matter is strongly subjective, and it's perfectly permissible for people to hold differing views.

I guess most will have noticed that electronic organs never have resultant bass stops (at least, I've never seen one that did).  The reason is that they don 't need to unless a customer insisted on it.  Many of them have pathetically inadequate speakers at the lowest frequencies of a 32 foot flue stop so that, as you go down the compass, the fundamental gradually fades out - usually in the bottom octave.  But at the same time the 2nd harmonic of the 32 tone (at 16 foot) and the 3rd (at 10 2/3 foot) will remain, or at least not fade out so rapidly, so you will get a resultant effect automatically which takes over as the real fundamental itself vanishes.  The best of both worlds?  Maybe - it depends on how charitable one is feeling.  I'm feeling very charitable at the moment, having just returned from a walk along the shore at Southsea in gorgeous sunshine, after which we partook of Speckled Hen in a favourite watering hole.

All the best

Colin Pykett


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