Pianos normally have 88 keys, ranging from A0 to C8. One of Bösendorfer's pianos go down to F below the low A. The other model goes down to C. How did this happen?

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    Personally, I'd ask the opposite question - why did everybody else stop at 88? I mean, I very rarely see any music which uses the top or bottom octave on a standard 88, but that's no reason to not give people the option. Also, if you're looking at any music, say, before mid-Beethoven, they only had a 5-octave range anyhow, so composers faced the same limitations as players. Who knows what they would've written had they the range to do so? You can even see in some early Beethoven where he was struggling to fit certain motifs within the range of the smaller pianos that existed at the time. Mar 20, 2019 at 15:10
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    @DarrelHoffman - I've seen the bottom octave of the piano used often enough in classical music. In several of those cases, I've even seen those notes notated with ledger lines but no ottava lines.
    – Dekkadeci
    Mar 20, 2019 at 15:31
  • For example, Tchaikovsky's Piano Concerto No. 1 requires both A0 AND C8 to be played on the piano!
    – user53472
    Mar 25, 2019 at 12:04
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    I'd suggest they stopped at 88 for a couple of possible reasons. A0 = 27HZ in equal temperament with a baseline of 440 on A4. At a lower pitch range, say, A4=432, if my calculation is correct, A0 is 22.375 HZ. The average range of human hearing is about 20 HZ to 20KHZ ... so A0 is about as low as the human ear could differentiate pitch on the piano in the 1700-1800's. There was just not much point in try to go any lower at the time. The historical gradual upwards shift of the reference tonal center and Bösendorfer's competitive spirit might explain why they make a 92/97 key model. Mar 25, 2019 at 16:17

3 Answers 3


These extended Bösendorfer ranges go back to Busoni's day. He wanted to match the range of pipe organs, as he was making transcriptions of J. S. Bach's organ works at the time.

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    @CarlWitthoft It only makes sense that they continue to make them because people buy them.
    – Mohair
    Mar 20, 2019 at 15:30
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    And then somebody built an organ with a 64' stop...
    – Hobbes
    Mar 20, 2019 at 17:48

replete's answer is correct that the original reason was to have a bigger range, as needed for some organ music. However, I don't think that's the reason those Imperial models are so sought-for over all these years – actually playing the lowest notest is scarcely musically useful.

The reason why people want Bösendorfer Imperial is that they sound awesome, even when the low strings aren't played. This probably has two main reasons:

  • The big sound frame is better at transmitting all frequencies, in particular those on the low end of the regular range. These strings aren't already at the very limit of what the resonator can do, like they are on many other pianos, but still in the range of what it can comfortably do, so thundering octaves actually thunder and don't just “clank”.
  • The low strings give a denser sympathetic-resonance spectrum, when the pedal is pushed. As a result, a Bösendorfer has a richer sound even in high, soft, legato passages.
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    Plus to a pianist, a Bosendorfer is like a 2-ton pickup to a Texan :-) Mar 20, 2019 at 15:00

Yep. There's of course another reason than cannot be underestimated: bling.

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    Hey, I live in Bösendorfer's home town. You can't tell me that they don't sell their image. Mar 20, 2019 at 11:43
  • I don't doubt that they promote their own image, but on the other hand, have you ever tried playing one?
    – David K
    Mar 22, 2019 at 3:47
  • @DavidK - can't say I have. I'm sure they sound great. But honestly- how often do we need these notes? Mar 22, 2019 at 9:46
  • I believe the one I tried had just the usual 88 notes. But they all sounded great from one end of the keyboard to the other. That makes an astoundingly good-sounding piano. Also an astoundingly high price.
    – David K
    Mar 22, 2019 at 12:27
  • Oh, I thought you meant one with extended bass. I've played the normal 88 keyed ones. Yes, they are very nice modern pianos, and beautifully made too. Mar 22, 2019 at 15:12

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