Call for scaling spreadsheets

[Jason Kanter]

Frank - do you shoot for equal tension per string, or equal tension per 
unison?

----- Original Message ----- 
From: "Frank Emerson" <pianoguru at earthlink.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Saturday, September 30, 2006 12:05 AM
Subject: Re: Call for scaling spreadsheets


> Joe and Ron,
>
> I have been following this thread for some time.  As a designer of scales
> for new pianos, I could offer a VERY lengthy discourse on this subject.  I
> do not have time to get into this, and on that scale.  Ron, your
> contribution seems to me to be the most practical and applicable to the
> immediate situation.  When one is designing a new piano, with a full 
> palate
> of variables at his disposal, many things must be taken into 
> consideration.
> On the other hand, when you have the bass strings, and every other 
> variable
> is "nailed down," all that you have to determine is the number of strings
> to replace with each wire gage.  Without control of any other variable,
> such as speaking length, hitch pin placement, bridge configuration, bridge
> pin configuration, bridge design, soundboard design, rib placement and
> design, etc., all you have to determine is the wire gage to use for each
> note.
>
> Forget about inharmonicity, loudness factor, stiffness, characteristic
> impedance, longitudinal mode partials, etc, etc.  All of these are valid
> considerations if you are designing a new scale, but all are irrelevant,
> and beyond your control, if all you need to know is what gages of wire to
> use for each note in the plain wire sections.  I have a multi-page
> spreadsheet for such calculations, but it is an ever evolving thing.  Each
> time I use it, I add new calculations.  It would be useless to anyone who
> is not familiar with its evolutionary development.
>
> Count the hitch pins in each plain wire section.  This will tell you a lot
> about the original design intent. If there are three hitch pins for every
> two unisons, this simplifies things.  If there are more hitch pins than
> this ratio, you have to determine how many strings have to be tied off and
> how the side bearing would be influenced.
>
> All you need, in terms of a spreadsheet, is a simple calculation of the
> tension for each note and a graph to display the tension from note to 
> note.
> A reasonable target tension is 160psi.  Ideally you want to minimize the
> range of fluctuation either side of this target.  Each time you increase
> the diameter of the wire, you will see a peak in the graph.  This will
> guide you in determining when and where to change the wire gage.  You must
> always have an even number of notes per wire gage, unless you have enough
> hitch pins to allow tied-off strings to account for this.  The goal is to
> keep the fluctuation in tension within as narrow a range as possible.  In
> smaller pianos, it is expected and acceptable to allow a slight upward
> curve in the tension in the highest few notes of the treble.Get the 
> tension
> right in this range, and trust that the original design takes all of the
> other considerations into account
>
> Frank Emerson
> pianoguru at earthlink.net
>
>
>> [Original Message]
>> From: Ron Nossaman <rnossaman at cox.net>
>> To: Pianotech List <pianotech at ptg.org>
>> Date: 9/29/2006 3:37:59 PM
>> Subject: Re: Call for scaling spreadsheets
>>
>>
>> > I guess my question that started this great discussion was really can
> one
>> > start with a given ( the bass strings ) and produce a scale that will
>> > compliment them.
>> > Joe Goss RPT
>>
>> Sure one can, but it won't be all that complimentary because
>> that's backward. Without moving bridges and changing speaking
>> lengths, about all you can do with plain wire is determine
>> tension ranges with wire gage. Inharmonicity will be what you
>> get. By far the most control and improvement in rescaling
>> happens in the bass, which in this case is already nailed down
>> to whatever the existing bass strings give you.
>> Ron N
>>
>
>