Bass strings changing scale

[John Delacour]

At 5:03 PM -0600 12/1/01, Ron Nossaman wrote:
>  >Can you explain, preferably with some numbers, what you mean by
>>"impedance across
>>the transition", how you measure it.
>>
>>JD
>
>I'm using a modified version of something supplied by Harold Conklin. which
>he describes thus:
>
>One expression for Zg is: Zg
>= (number of strings per note) x
>(tension x mass per unit length)^0.5.
>So we can increase Zg by increasing
>the tension, core size, wrap size,
>number of strings per note, any or all.

So when you say you "blend impedance over the transition" going from 
treble to bass, what do you want this impedance curve to do at the 
transition to the singles?

By the look of it you will get Zg rising steadily as you proceed down 
through the bichords from say 7 to 11 for argument's sake, and then 
what?  Will you go for 11+ on the top single and continue the curve? 
If so, then it seems you require an even bigger jump than you said a 
while ago, a jump far bigger than I've seen on any piano.

Suppose we take the break on an easy piano like the Bechstein Model B 
at 13/14 with lengths 1275/1254 with A1 at 1481 and top bichord A25 
at 1000 -- I append all the lengths and original pattern measurements 
to give you some idea of the scale -- How would you treat this? 
Originally it is strung without any double-covered strings and the 
bottom few notes are not good.  The result of double-covering the 
first six or seven strings and increasing the tension is a distinct 
improvement and several customers ask me to do this, but that's just 
a detail.

I'd be interested to see how you'd scale this piano, bearing in mind 
that a 0.40mm cover on a #17 core gives a good break.  I'll then have 
a far better idea of what we're talking about.

JD




148.1	25.0	5.17
146.6
145.0
143.5
141.9
140.2
138.5
136.7
135.0
133.1
131.3
129.4
127.5	23.0	3.42
125.4	22.0	2.94
123.4
121.3
119.2
116.9
114.6
112.3
110.0
107.5
105.0
102.5
100.0	17.0	1.90