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Lowest Bass Notes on a Bosendorfer Imperial 290 (Read 2427 times)

Offline octave_revolutionary

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Lowest Bass Notes on a Bosendorfer Imperial 290
« on: May 24, 2016, 11:30:29 PM »
This question is aimed at acoustical engineers and scientists, but I have little doubt that some piano technicians who are familiar with the Bosendorfer Imperial might be able to help me here.

As everybody knows, the lower limit of human hearing is around 20 Hz. But I can hear, perfectly well, the bottom C on the Bosie Imperial in this video:




............or can I?

Could it be that I can simply FEEL the fundamental tone, and HEAR the overtones, which impart to the note its particular timbre? How else, if we proceed from the principle that noone can hear frequencies below 20 Hz, than I can hear the low D and C in this video?! or is the lower limit of human hearing really closer to 16 Hz? And if it is, then why can I hear the lowest pipe in a 64-foot organ reed stop, which pounds out vibrations at only 8 Hz a second??!! Or does the same apply here?

Octave

Offline georgey

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Re: Lowest Bass Notes on a Bosendorfer Imperial 290
«Reply #1 on: May 25, 2016, 12:32:37 AM »
I just read this now.  The frequency of the fundamental tone of the C you are referring to is

440*2^(-53/12) = 20.6 > 20 Hz

OOPS

440*2^(-57/12) = 16.4 < 20 Hz

if I am doing the calc correctly. This S/B in your hearing range.  Someone check me.  I only have a math background.

^ - to the power of

(EDIT to help georgey remember: all the C's Hz are slightly more than powers of 2: 8Hz, 16, 32, 64, 128, 256, 512Hz, etc. Length of organ pipes in feet for C's are also roughly powers of 2: 64', 32',... 1/2' , etc)  ;)

I guess I could just google the answer:
The low end of the audible spectrum is generally said to be somewhere between 15 and 20 Hz. Now, the lowest A on the modern piano is about 27.5 Hz, which is getting close to the edge of our ability to hear. Adding nine notes on the biggest Bösendorfer gets the lowest note down to 16.5 Hz, which can be barely heard if at all by most people.

In the very low notes, most (if not all) of what can be heard is actually the overtones of the note. That's why they sound a bit "muddy". The existence of lower notes than are generally used adds to the resonance of higher notes, so that's also one of the reasons that we have them.


Offline iansinclair

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Re: Lowest Bass Notes on a Bosendorfer Imperial 290
«Reply #2 on: May 25, 2016, 01:21:16 AM »
In the case of organs, what you hear on the low end of the 32s, and (rarely) 64s is not the fundamental, but the overtones -- which is why the "resultant" stop is found: it is actually not one pipe sounding, but two: one at the octave above the supposed pitch, and one at the octave and a fifth.  Which are the first two overtones.  (for a 32 foot resultant, it would be a 16 and a 10 2/3)  I've never found it very convincing, but it beats trying to put a 32 foot principal into a small building, and it's better than nothing.

However, if you have the real pipes, then you actually will feel the fundamental.  You don't hear it as such, but you surely do feel it.  This is, of course, where high -- never mind low or mp3 -- fidelity reproduction (or for that matter electronic instruments) of major organs is usually unsatisfactory; the equipment simply can't reproduce those frequencies, even if they are on the recording or in the sound description file for the electronic instrument -- which they usually aren't.

The only way to experience it is to go to a place where there is a pipe organ with these stops available and feel it.
Ian

Offline chrisbutch

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Re: Lowest Bass Notes on a Bosendorfer Imperial 290
«Reply #3 on: May 25, 2016, 07:59:34 PM »
I seem to remember that the main justification used by Bosendorfer in adding these extra strings was not so much the expectation that they would often be played (although the keys are present), but their value as sympathetic strings adding  richness to the piano's general sonority when undamped.

More recently Stuart and now, I see, Paulello have launched 102-note pianos, presumably partly with the same intention (although they extend up as well as down).

Ian Sinclair - your mention of 'resultant' 32's brought back memories of a Compton extension organ I used to play with just such a device. Actually it was quite convincing, at least in its setting (a school hall).

Offline pantonality

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Re: Lowest Bass Notes on a Bosendorfer Imperial 290
«Reply #4 on: May 27, 2016, 03:04:12 PM »
One other reason for the extras notes on the Bosie 290 is that their presence pushes the normal lowest note (low A) farther into the sound board where it can be more easily excited and produce more fundamental. Think about it, it's harder to move a speaker's cone by pushing on the surround than from the center which is why the the voice coil is where it is (in the center).

Offline octave_revolutionary

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Re: Lowest Bass Notes on a Bosendorfer Imperial 290
«Reply #5 on: May 29, 2016, 03:49:04 PM »
Thanks, guys, that's pretty much what I thought about feeling as opposed to hearing the note. The ear does not interpret the notes at those frequencies as a pitch, but the body feels it, and any perceived timbre is simply due to the overtones produced.

I still wonder about the following, though: I really like the sound of  good Bosie; but how is it, that in spite of all this, does a Bösendorfer fail to match a Steinway or a Kawai in terms of power? I can't think of a better way to put it that the basses of a Bosie sound kind of like like "burnt toast", as opposed to the hearty 8-grain loaf of a Steinway. Is it more the type of wood that is used, or rather the old-style  4-piece rim, or the soundboard that contributes to this factor? and why haven't they done anything to improve on this, after over 180 years in existence as a firm??!