Rescaling question

[jamesp]

Hi all

After Barrie's last comments that Rogers pianos weren't very well scaled I've had a good look into this. I've measured all the relevant parameters and popped them into a spreadsheet:

http://www.jamespyke.plus.com/index_fil ... caling.xls

I haven't yet destrung it so I could only measure the string diameters with a vernier caliper; this isn't as accurate as my micrometer so there is likely to be a small error in these measurements but it's the best I can do for now.

I've plotted the various parameters in charts in the spreadsheet and was wondering if some of you folks would be prepared to take a look and comment on the need for rescaling and the areas that could be improved.

The breaks are at note #s 49-50 and 67-68. Interestingly 49-50 doesn't show up as a step on the inharmonicity curve but 67-68 does, as do one or two other points where a string size change occurs. These quirks are very near the top end so I have no idea how much of an improvement changing the scaling here would bring?

Many thanks indeed.

James

[Barrie Heaton]

its not to bad but a small error on the string diameters and length make a big differences have a word with Jhon Delacour’ he loves rescaling and will do you a nice set of bass strings to match

Barrie,

[PianoGuy]

The breaks may not show up in your table because tonal aberrations may be due to the physical break itself, and the cutaway bridge (if applicable) not the scaling. You do need to be accurate on measurements too.

I'm not particularly expert on string tensions except for basic theory, so I'd suggest speaking to someone like Barney Unwin who often calculates better scaling for rebuilt pianos, but I reckon you could go for a slightly higher tension scale, keeping under 65% of breaking stress (essential where there is an eye rather than a return string) and trying to even out the tension throughout.

Replacing the string material with Roslau rather than the awful Scottish stuff it was originally strung with alone may help.

[jamesp]

Thanks guys. I've spoken to John Delacour today who was very helpful and a sample of my bass strings are on their way to him now.

Cheers

James