Disklavier

Mike,

Some thoughts from my side: Even if you forget Midi, and just look at 
the basic recording/reproduction capabilities of the disklavier, there 
are limitations due to the mechanical and electrical design. If you are 
a critical listener and especially with classical music, you wiill know 
that on order to play an accent in a chord, you basically play arpeggio, 
in order to place the accent on the note where you want it to be. Now 
your fingers/ears are faster then the "resolution" of the Disklavier. 
This results in the reproduction of an arpegio that might be 5 ms into 
15 ms, as this is the fastest "resolution" of the Disklavier. ( do not 
take these figures as absolutes, they are just to illustrate the point).

Can you hear the difference?  Some people can,  my pianoteacher could, 
sometimes it just "hears" different. In pieces like Songs Without Word 
from Mendelssohn, where the accents  are extremely important, you might 
be hearing this easier then in Rags from Joplin.

I did some subjective tests taking a purchased recording that I play on 
my old MX100B to a new PRO model, and I found it noticable better, but 
then, it could also be that the Pro model was newer and better 
regulated. I have not been able to confirm from Yamaha, that the minimum 
"resolution" as I call it in laymans terms, has increased between the 
older and the Pro models.

Greetings from Curacao,  

Winfried.

Robert Welcyng wrote:

>Mike, I do not have the definitive answer to your question, but I have 
>some thoughts.
>
>It's pretty difficult to make measurements that would answer your 
>question.  Here's why:  Suppose you wrote MIDI files with two, three, . 
>. . up to 16 simultaneous notes, put them on a diskette, and played 
>them.  With a DAT recorder, you could audio-record the result and 
>examine the resulting audio waveforms using software like Sound Forge or 
>Cool Edit.  When you looked at the summed waveforms of all the notes, 
>however, you would see a scramble of the initial transients of all the 
>notes piled upon one other.  You would not be able to distinguish any 
>particular note lagging another unless the timing error were really 
>gross.  Playing through and recording just 15 files would not be 
>sufficient.  You would also need to vary the velocities of the notes in 
>the range of, say, 20 through 100, and, in addition, you should vary the 
>Disklavier volume control setting in steps from, say, 0 to say -9.  All 
>of this would be a lot of work and wouldn't yield the answer to your 
>question.
>
>The approach to take is not to try to determine how many milliseconds 
>the timing errors are, but to listen for a problem (and no fair watching 
>the keys).  Can you detect any timing differences aurally?  As you've 
>indicated, you haven't discerned a problem.  I can't say that I have 
>either, at least not with PianoSoft diskettes.
>
>Here's what I have to offer:  One of the experiments that I have done 
>with the Disklavier was to determine the timing accuracy of my Mark II 
>from recording to diskette through reproduction.  I played a series of 
>random legato notes about one second apart at various random velocities. 
>  While playing those notes, I recorded, simultaneously,
>
>1) E-SEQ to a Disklavier diskette
>
>and
>
>2) to a DAT with microphones connected.
>
>Using Sound Forge, I determined to within a millisecond the time 
>differences between the starts of the notes that I played.  (With the 
>notes separated by about a second, it was easy to read the time where 
>each started.)  I then played the Disklavier diskette (Volume = 0), 
>recorded the audio again with the DAT, and compared the note initiation 
>time differences as reproduced with that as originally played.  Here's 
>what I found:
>
>1) At note velocities between 80 and 100, 90% of the timing errors were 
>within plus or minus 5 milliseconds.
>
>2) At note velocities between 20 and 40, 90% of the timing errors were 
>within plus or minus 15 milliseconds.
>
>Those results don't apply directly to your question, but suppose the 
>timing errors within a chord did run 5 to 15 milliseconds.  Would it be 
>possible to hear unwanted arpeggiation?  Here's my opinion based on a 
>short experiment using Sound Forge:  As one approaches 10 milliseconds 
>time difference between two notes that are supposed to be played 
>simultaneously, the playing does begin to sound a little sloppy. 
>(Anyone is free to disagree with me.)
>
>Based on the foregoing, I would expect that if you are experiencing 
>arpeggiation of chords, you may be able to improve things by raising the 
>velocity of the notes in the chord or by operating the Disklavier at a 
>higher volume setting.
>
>In summary, there are timing errors introduced by:
>
>1) the pianist (as Mike pointed out)
>
>2) the Disklavier recording process
>
>3) the Disklavier reproduction process
>
>In the design of the Disklavier, there are surely many engineering 
>compromises.  For example, the keyboard and hammer motions are serially 
>sampled; even at very high speed, timing errors, however small, must 
>occur.  The important issue is: Overall, does the Disklavier, despite 
>its engineering compromises, perform to your satisfaction?  Any 
>detractor can rant about the engineering compromises inherent to the 
>Disklavier and to the MIDI protocol, but do those compromises 
>significantly--even noticeably--impair performance as you hear it?  And, 
>could you afford a better alternative if there were one?
>
> >(and what
> > speed is the Disklavier's MIDI-in interface capable of?)
>
>+++ All MIDI interfaces transmit and receive at 31,250 baud.  That's in 
>the MIDI specification.
>
> > 3.  Does the Disklavier buffer the MIDI playback signal so that the
> > output to the solenoids is parallel when it needs to be?
>
>+++ The Disklavier does buffer playback for about 0.5 seconds.  I don't 
>know how closely in time two or more solenoids can be driven.  What does 
>it matter to the listener if a timing error is present but is too small 
>to be aurally detected?
>
> > 4.  Does conversion of MIDI files to ESEQ format eliminate the
> > problem?
>
>+++ I've never been able to detect any difference in performance (as 
>recorded on DAT and observed with Sound Forge) between a MIDI file and 
>its corresponding E-SEQ file.
>
>Be aware, however, that in playing the same E-SEQ file (or MIDI, for 
>that matter) twice in a row (on my Mark II anyway), you will find 
>differences in note timing betwen the two successive playings.  The 
>errors are on the order of 5 milliseconds for note velocities of 40 to 
>100, and up to 15 milliseconds at note velocities of about 20.  I can 
>measure those errors using Sound Forge, but I could never hope to detect 
>them by ear.
>
> > 5.  Relative to this problem, does it matter whether the MIDI output
> > is from an I/O device within the Disklavier control unit, vs. a
> > signal from an external PC?
>
>+++ It depends.  An old PC I once had (running Windows 3.1) would 
>lug-down, with Cakewalk used as a sequencer, if I started using Windows 
>Explorer (or whatever it was then).  Now, with the commonly used 
>machines and OS's, and with reasonable care, I wouldn't expect a problem.
>