[pianotech] ETD stretch vs pure (octaves)

PAULREVENKOJONES at aol.com PAULREVENKOJONES at aol.com
Fri Nov 13 21:02:31 MST 2009


I wasn't talking to you unless you are nature.dude. 
 
 
In a message dated 11/13/2009 9:59:12 P.M. Central Standard Time,  
dahechler at att.net writes:

PAULREVENKOJONES at aol.com wrote:
>  
>   
> In a message dated 11/13/2009 9:05:24 P.M. Central Standard  Time,
> nature.dude at yahoo.com writes:
>
>      I've seen several piano tuning software with pre-determined
>   stretches (ex. Grand Piano 6 to 7 ft, Vertical Piano 39 to  51
>     inches, etc).  It seems as if  the  middle 4 octaves or so are
>     tuned with pure octaves  while the higher and lower octaves include
>     the  stretch.  I've never tuned using pre-defined tunings. Has
>   anyone here?  I wonder what kind of results people get  using
>     software with pre-determined stretches.   Anyone wish to comment? 
>
> I shouldn't but...
>   
> There is still vast confusion in the use of the phrases "pure  octave"
> and stretch. All properly tuned octaves are slightly wider at  some
> coincident partial, so stretched. You choose the coincident  partial
> set of your liking.
>  
> I am not familiar  enough with machines to speak to how they treat
> octaves in the  midrange, but it is evident and calculable that as you
> go deeper into  the bass and higher into the treble, the octaves
> stretch more. There  is no such thing as a "pure" octave; there will
> always be some  coincident partial set beating.
>  
> P
Yes, you shouldn't  have - you are going way out of the context of what I
was trying to say -  you are back into partials, beats, etc.

To me, a pure octave is when  you play C4 and C5 together, and hear no
beats or wave-y-ness.

Just  like tuning unisons of a tri-string and they are in tune when you
hear no  beats or waves, except they are an octave apart.

If C4 is in tune and  you hear beats, that means C5 is sharp or flat.

-- 
Duaine  Hechler
Piano, Player Piano, Pump Organ
Tuning, Servicing &  Rebuilding
Reed Organ Society Member
Florissant, MO 63034
(314)  838-5587
dahechler at att.net
www.hechlerpianoandorgan.com
--
Home  & Business user of Linux - 10  years



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