Mechanical Music Digest  Archives
You Are Not Logged In Login/Get New Account
Please Log In. Accounts are free!
Logged In users are granted additional features including a more current version of the Archives and a simplified process for submitting articles.
Home Archives Calendar Gallery Store Links Info

Announcement: End-of-Year Fundraising Drive In Progress

Our End-Of-Year Fundraising drive is in progress. If you haven't contributed to the operation of the MMD in the last 12 months, this would be a great time to contribute. There's a PayPal link at the bottom of each page on the website.

If you aren't sure when you last contributed, please send me a note using the contact form at the bottom of this page and I'll look you up in my records.

Thank you for your generous support!
Jody

P.S. While your support is needed and appreciated, you do not need to contribute to be a subscriber. If you have subscribed and aren't receiving your Digest, please use the contact form at the bottom of the page and let me know. Thanks!

MMD > Archives > November 1998 > 1998.11.03 > 16Prev  Next


Rachmaninoff CD - Mechanics versus Mathematics
By Julian Dyer

Regarding the injured sensibilities that Wayne Stahnke's 'tinkering'
with the Ampico rolls for the CD has produced, perhaps it should be
noted that a rigorous mathematical model of something can be 100%
accurate.

Forget the 'improved' _mechanical_ devices from the 1960s onwards,
because these produced bastardised performances, their analogue
representations inevitably having performance traits at variance with
the way the rolls were coded.  (The mechanical equivalent of two wrongs
not making a right.)

A computerised mathematical model theoretically can provide a 100%
accurate representation of the way a mechanism works, although the
minutest details of the system must be right, which can be hard to
achieve rigorously (i.e. by mathematical equations).  In practice,
the rigorous approach inevitably has a degree of heuristic (rule-based)
modelling as well, which is much more open to individual judgement.
The beauty of all this is that if some particular aspect isn't right,
you just add another subroutine to correct it!

If it's all a bit theoretical, consider the LP and the CD.  An LP
is an analogue model of a sound, with a wiggly groove representing the
waveform.  A needle slops its way along the track to read it, picking
up all sorts of mechanical distortions along the way, vibrations as the
mechanism resonates, rumbles from the turntable bearings, that sort of
thing.  A CD is just a string of numbers, representing measurements of
the position of the waveform 44 thousand times a second.  The sound you
hear from the CD player is from a mathematical model of what a series
of such numbers should sound like - it is not the original sound
itself.

In general, it is now agreed that the distortions and inaccuracies of
the CD are less unpleasant than those of the LP, although it took some
refinement to get that far.  It's the same sort of thing between using
a mechanical device and a mathematical model to play a roll - although
of course the roll itself is digital to start with, LP vs. CD just being
an illustration that may have some real-life meaning!  The difference
is that a (digital) roll is edited to suit the original playback
mechanism, while an (analogue) LP cannot be edited this way.

What all this really means is I can't see anything wrong with the
approach Wayne's taken.  It works because he has put enough, correct,
detail into the model.

Julian Dyer

 [ Early in the development of the IMI Cassette Converter in the 1970s,
 [ Wayne asked the 'best ears in town' to evaluate the performance of
 [ his device (electric magnet valves) in comparison with a roll-playing
 [ reproducing piano.  He learned a lot: the 'best ears' were the
 [ old-time piano techs and player piano techs of Los Angeles, who
 [ worked at, or frequented, Dick Carty's piano shop.  They all loved
 [ and thoroughly knew the classical pieces being played, and they
 [ taught Wayne the subtleties.  You could say that Wayne's mathematical
 [ studies were ultimately confirmed independently by 'the best ears
 [ in town.'  -- Robbie


(Message sent Tue 3 Nov 1998, 14:43:47 GMT, from time zone GMT.)

Key Words in Subject:  CD, Mathematics, Mechanics, Rachmaninoff, versus

Home    Archives    Calendar    Gallery    Store    Links    Info   


Enter text below to search the MMD Website with Google
Loading



CONTACT FORM: Click HERE to write to the editor, or to post a message about Mechanical Musical Instruments to the MMD

Unless otherwise noted, all opinions are those of the individual authors and may not represent those of the editors. Compilation copyright 1995-2017 by Jody Kravitz.

Please read our Republication Policy before copying information from or creating links to this web site.

Click HERE to contact the webmaster regarding problems with the website.

Please support publication of the MMD by donating online

Pay via PayPal

No PayPal account required

                                     
Translate This Page

. .