Why not the piano as a reference for bass

I have always used well recorded piano compositions as an analytical tool for determining system. I will attempt to explain how I use piano recordings as an analytical tool.  Rather than concertos and symphonies, it is best sonatas.  I have some sonatas that, rather than solo piano, add a violin.   That is in my opinion the best analytical tool.  So how and why? …

Crossover and Driver Integration:  The piano, as others stated, is a singular instrument covering a broad frequency range.   Problems with speaker driver integration and crossover design, or issues with ragged frequency response of electronics become easily evident by using well recorded piano recordings.  As an example, in my past, I had hybrid Apogees.  The lower piano registers were slow and smeared compared to the wonderful midrange and highs.  
 

Dynamics:  While not the best test for percussive crescendos or rock dynamics, the piano by definition as a percussion instrument, is one of the best instruments to use for analyzing system dynamics, especially microdynamics.  While I agree in part with @audiokinesis that the fundamental and first overtones do not have the same impact as other instruments, well recorded closed miked piano will have strikingly vivid first wave percussive impact.  The real value is in analyzing the microdynamics of secondary harmonics and how ppp notes are developed in a composition.  
 

Detail Retrieval:   Well recorded piano is an excellent test for detail retrieval including, harmonic decay, the sound of the hammers vs the strings vs sound board, as well as how the notes decay into the venue.  Piano recordings can easily discern engineering techniques such as close miking vs far miking.  A well designed audiophile system should be able to discern these attributes of well recorded piano.  Here, combined with my discussion on dynamics, is where the piano is excellent for bass analysis.  Analyze bass note first wave (fundamental impact). Is it sharp and striking.  Analyze how it decays and the sound of all the secondary harmonics.  Determine if you can discern the hammer strike from the string sound and sound board.  This is an excellent test for comparing equipment.    
 

Imaging:  Closed miked piano recordings will be able to develop an image that shows the position of the mike relative to the keyboard.  Image palpability will be evident.  
 

In conclusion, piano recordings are an excellent analytical tool in general, and for bass as well.  Yes, you will need to use other records of other instruments to analyze bass impact, but these others are not as good for bass detail and especially for bass integration.  
 

Apologies for my usual pontifications and typos in advance.  

@richardbrand 

Have you witnessed the 64 foot pipe? I've always wondered what the experience would be like. You probably never hear/feel that pipe by itself so maybe hard to describe. I'm sure you do feel it but it's hard to imagine hearing nothing at the same time. Am I making any sense? Just curious about this and have started conversations before about what we can hear/feel below 20hz. I have read that in some instances, some people are able to hear down to 12hz. I heard 17hz on my system with a test record, rather subtle but there. Nothing below that and nothing felt, probably just exceeded system capabilities. Played louder, I might have heard something, hard to say. Anyway, fun stuff. 

Thanks All!  I could not be more pleased with the results of this thread.  Great facts, expressed practical experience combined with differing informed opinions.  Throw in the consistent civility to top it off.  I look forward to reading  posts as more seem to keep coming. 

@billpete 

Have you witnessed the 64 foot pipe?

Alas no!  I am slightly friendly with several organists in Sydney but none has hinted when that 64 foot monster might be exercised.

Mostly I hear church and cathedral organs, and the refurbished beast in the Sydney Opera House.  Olivier Latry, the organist from Notre Dame in Paris, featured in Saint-Saens Organ Symphony and Poulenc's Concerto for Organ, Strings and Timpani - one of my personal favourites.  The next day we went to his organ masterclass at the Opera House.  It is amazing how each student had a USB stick with their personal settings for the organ configuration.  I'd like to build a relational database representing that organ and its multiplicity of parts.

I have heard a piano recital given on a Sturt and Sons concert grand piano, but not the full 108-key model.  The Australian Broadcasting Corporation released video and CDs of Beethoven's Piano Concertos played on a Stuart piano.

@audiokinesis 

I’m saying that the lowest fundamentals (and sometimes the corresponding first overtones) of the lowest notes of a non-Bosendorfer grand piano contain so little energy that they do not merit being reproduced in a live music setting. 

I want to try to nip this idea off, here and now!

Just try this little experiment.  Find yourself a mechanical (not electronic) piano and play the lowest key.  You will hear the fundamental note, plus overtones.  To discover what the first overtone sounds like, move up one octave and play that key.  If the two notes sound as if they are the same frequency, then you cannot hear the lowest fundamental.  But my experience on a Kawai upright piano is exactly the opposite, the lowest note is clearly an octave lower and is clearly audible.  Just in case somebody suggests that the fundamental one octave up is also inaudible, hop another octave up and repeat.  They cannot all be inaudible!

Why an octave? An octave is just double the frequency and in Western music there are eight white piano keys spanning an octave (which is why the Latin for eight features in its name).  There are seven white keys and five black keys before each octave pattern repeats - 12 notes in all.  When Pete Townshend said he chose his double bass for the session, he doubled his pay by doubling this on an electric bass guitar 12 notes higher.  Had me a bit confused but he was just playing one octave up, something very common in orchestral pieces where cellos double the basses, the picolo doubles the flute and so on.

The physics of the fundamental vibration of a string are well known.  The vibration frequency depends on the length of the string, the mass of the string and the tension in it.  The fundamental frequency is where the entire string between its fixed ends moves in the same direction.  But there is another mode, where the middle of the string remains stationary, and the two halves move in opposite directions.  This is the first harmonic, and it is an octave up from the fundamental.

And there are even more vibration modes, where there are four, five, six and so on stationary points in the string.  By and large these modes do not sound pleasing.

One more thing.  A string can also vibrate along its length, and that vibration can be picked up.  Usually the sound is horrible, like a violinist’s finger sliding on the string.  When bowing, it is important that the bow remains at right angles to the string to avoid longitudinal resonances.  It is said that violinists take about five years to learn how to use the left hand to get the right notes.  The next five years is learning how to bow properly.

So can piano be a useful guide to loudspeaker bass reproduction?  Absolutely.  I will take four speakers I am familiar with as examples.  The first is the market-leading bookshelf speaker from KEF – the LS50.  Its bass output has a 3-db roll-off at 79-Hz, which is well over an octave above the 31.5-Hz fundamental of a standard piano’s lowest note.  You won’t get much of its first harmonic either!

Staying with KEF but spending maybe eight times as much, we get the slightly bigger bookshelf KEF Reference 1.  Its 3-db bass rolloff is at 45-Hz so you will not get much of the fundamental but the first harmonic should be all there.

My third speaker is a full-range electrostatic from Quad – the ESL-2905. I cannot find its 3db rolloff but it is flat to 45-Hz and 6db down at 31-Hz.  No real need for a subwoofer here.

Finally to a subwoofer – the 18” servo controlled Velodyne DD-18.  This has a 3db rolloff at 14.1-Hz, more than an octave below that fundamental.  Good for a Bosendorfer or Stuart concert grand.

The Velodyne fleshes out the Reference 1 beautifully, and takes a bit of the bass load off the Quad, which otherwise has little need of a sub.