Dear members,
I’ve a Grimaldi to restring made by Ducornet in 1993. It’s clear that from a certain point in the treble it’s impossible to continue stringing in yellow brass as the speaking legnths are too long. Even an increase in pitch of a fraction of a semitone would already break the string.
I’m wondering: is that a design of Ducornet or does the original Grimaldi indeed have these speaking lengths which mean that one has to switch to iron?
Regards,
Chris.
Dear Chris
That’s sounds extraordinary to me. What wire are you using for the restring? What pitch are you tuning at? Could you please make spot measurements of the speaking lengths of the Cs and F#s from middle c’ up?
Regards
CB
CAREY BEEBE HARPSICHORDS AUSTRALIA
G l o b a l H a r p s i c h o r d T e c h n o l o g y
Factory 35/17 Lorraine Street | Peakhurst NSW 2210
T +61 2 9534 2002 | M +61 408 239 267
cb@hpschd.nu | https://hpschd.nu
Twitter & Youtube: hpschdNU
I assisted two people making a Grimaldi with no modifications at all and scaling with a precision in millimeters, both happily stringed in brass at 415. I should have their scalings for the C’s and F’s in my PC. Would this help you?
Or, I have both the Nuremberg AND Paris Grimaldis drawings to check, just let me know if this can be of help.
The Paris G. was transformed in a fortepiano during its life, don’t know whether the bridge or nut was relocated.
Hi,
Currently the instrument is strung with Rose wire but as the majority of strings are getting quite old, the owner wants me to restring the whole instrument. The pitch is a1 = 415 Hz. Switching to 392 Hz would help but this is not an option. See below for the sounding lengths in millimeter… The instrument itself is well made and has an agreeable action.
The owner complains that he already spent a small fortune on replacing strings in the treble.
I could switch to e.g. Stolberg messing or use this wire for the complete instrument. This would give me a margin of 3 semitones in the treble. However the owner insists that P-wire is used. I’ve already discussed this with Mr. Birkett and he came to the same conclusion: it’s pretty dangerous to use historic messing after a certain point in the treble due to the long scaling.
Here are the details:
[See in Chris’ next post below]
Regards,
Chris.
Dear Chris,
Why don’t you contact Marc Ducornet directly, I’m sure he would be happy to help. He responds to email pretty quickly.
Best,
Matthew
New attempt in order to get a better format:
Nr Note Hz Length
1 FF 41 0
2 FF# 44 0
3 GG 46 1.895
4 GG# 49 1.893
5 AA 52 1.889
6 BBb 55 1.885
7 BB 58 1.883
8 C 62 1.878
9 C# 65 1.828
10 D 69 1.742
11 Eb 73 1.655
12 E 78 1.577
13 F 82 1.499
14 F# 87 1.427
15 G 92 1.355
16 G# 98 1.287
17 A 104 1.220
18 Bb 110 1.160
19 B 116 1.104
20 c 123 1.052
21 c# 131 1.000
22 d 138 947
23 eb 147 900
24 e 155 853
25 f 165 808
26 f# 174 766
27 g 185 725
28 g# 196 685
29 a 208 648
30 bb 220 613
31 b 233 580
32 c1 247 549
33 c1# 261 519
34 d1 277 492
35 e1b 293 464
36 e1 311 440
37 f1 329 416
38 f1# 349 394
39 g1 370 373
40 g1# 392 354
41 **a1 ** **415 ** 335
42 b1b 440 318
43 b1 466 302
44 c2 494 287
45 c2# 523 271
46 d2 554 258
47 e2b 587 244
48 e2 622 232
49 f2 659 219
50 f2# 698 208
51 g2 739 196
52 g2# 783 184
53 a2 830 174
54 b2b 879 164
55 b2 932 154
56 c3 987 144
57 c3# 1.046 134
58 d3 1.108 125
59 e3b 1.174 115
Hi Chris,
Discourse supports Markdown syntax, so you can easily make tables. I suggest you have a read of the syntax and let’s all use that for stringing lists, which commonly come up.
You can learn Markdown in ten minutes. I have mentioned this is the Site Usage posts which I urge everybody to read.
Here’s the syntax from the developer of Markdown. It is becoming a universal standard for basic markup on the web.
Dear Chris
Thanks for the string lengths. A quick comparison with my 1990 hire Grimaldi shows your 1993 lengths are slightly but not significantly longer. (Perhaps that is one of the Grimaldis which Marc did with a cranked rather than almost straight nut?)
When I plumb the numbers into the computer, I can’t see any reason why the treble can’t be successfully strung with brass @ A415: The tension is within normal safety limits.
The fine sizes of brass are very tricky to handle, and I’d suggest the problem of too-frequent breakage reported to you by the owner could lie with either a poor batch of replacement wire and/or poor string replacement technique.
Regards
CB
Thanks Carey,
If my calculations are correct, then using Rose yellow brass for f2# I obtain a value of 0,87 semitones marge from the breaking point using a diameter of 0,19 mm.
What value do you obtain for this note?
Regards,
Chris.
HI Carey and Chris, could you post your values for the material properties of brass that you are using (density, ultimate tensile strength) etc and I can verify with my maths as well. Otherwise its just comparative guesswork as to your calculations. [Speaking from my background in mathematics, six students will present six different answers.] 
Hello Andrew,
I’ve calculated using Malcolm Rose yellow brass (this data is also available on his web site):
Density (kg/m³): 8536
Maximum tension in kg/m³ for yellow brass 0,19 mm = 2,30 kg/m³
Speaking length of the f2# = 208 mm, frequency = 698 Hz
If my calculations are correct, then f2# gets a load of 2,08 kg/m³ which translates to 0,871358459 semitones from the breaking point.
Looking forward to see your results.
Regards,
Chris.
Chris wrote: 0,871358459 semitones from the breaking point.
This is not good, Chris, sorry to say! 
It can be shown that French Baroque makers strung up to about 80% of breaking point.
Another old folklore I have often heard is that iron should not exceed 1 full semitone below breaking point, while brass should be not higher than 2 semitones below breaking point.
Now you are reporting not 2, not 1, but a paltry 0.87 semitones.
This is way too risky, and any of the factors already mentioned by Carey (such as slight kinks while making the eye, or less than stellar material, or tuning to a pitch minimally higher than expected) will break the string, so I am not surprised by what you have told us.
I still do not understand what is the real problem.
We agree that all-brass sounds better for Italians.
And if we know that the difference between iron and brass is very audible in the bass, it is certainly not so in the treble.
We also know that, in any harpsichord with a carefully calculated stringing, the passage between brass and iron can be so subtle that it resists blind tests.
I know what I would do in such a situation: I would forget the “all brass” tenet and just use iron for these strings!
Then you send us a recording, and challenge us or better bet against those who say they can guess the changeover: I tell’ya, you will win all those bets!
Best
CDV
Dear Chris
Yes, your calculations appear correct. But sometimes we need to turn our computers off and refer back to the musical instrument itself.
Malcolm’s tension recommendations are maximum practical tensions, with a safety margin already built in. Your c’’ speaking length of 287mm is well below than Malcolm’s maximum scaling of 300mm @ A415 for his yellow brass. I expect the 1993 Grimaldi in question would have given reliable service for years with its original stringing from Atelier Marc Ducornet. You shouldn’t be contemplating using anything smaller than 0.23mm for f#’’ and most of the treble: My two Grimaldis never break strings.
And when there are participants on this list & others who extol the tonal virtues of wire from particular suppliers over all others, I’m amazed at Claudio’s assertion that we can’t hear the difference between iron and brass in the treble of a brass-scaled Italian!
Regards
CB
Dear Carey, my reply shows the great respect I have for your expertise.
I expect the same respect for mine, which is not minimal about harpsichord stringing.
You should not be “amazed at Claudio’s assertion that we can’t hear the difference between iron and brass in the treble of a brass-scaled Italian”, simply because I did not say, and I do not believe that.
I could hardly believe something that goes counter the subtleties in alloys I have described in webpages of mine about stringing.
What I said in my reply to Chris is that it would be very difficult to spot the changeover.
Therefore, when Chris’s calculated value shows to be too close to breaking point for comfort (and you are not showing this value to be wrong), I still believe that a reasonable solution is to shift over to iron for the treble, because the changeover will not be noticeable.
Of course the tone of the treble will be different, and the difference will be more apparent the further high we play, we all know that.
Needless to say, Chris is free to ignore my suggestion, follow your advice and try to find another solution, of course.
You show a c" at 287mm. The Nurnberg Grimaldi (someone already pointed out that the fortepianification of the Paris instrument complicates matters, since strings were moved to closse pairs… The Nurnberg Grimaldi is built throughout using an inch of 28mm, with c" built upon a 10-‘inch’ c", which is 280mm. So you have an instrument not built to the (very workable, though a bit edgy at 280) actual scale of Grimaldi. So the short answer is that the scale is much longer than I would ever undertake if I wanted A415 in brass. So there you are. Maybe bad assumptions were made, maybe nobody paid very close attention to the scale, maybe mistakes were made. Who knows? But one possibility is that he (wrongly) thought stretching the scale would make the thing sound better and took the risk, and was encouraged in this by the fact that Malcolm’s ‘English brass’ is so hard drawn, way beyond what I’m told is historical practice, that he could claim that a scale, if I remember correctly, pushing even 300mm for c" and its equivalents for other notes was possible with some degree of safety. Short answer: nope. It’s A392, or shift the keyboard a semitone physically, or use some wire that you don’t like, or your’re pretty much out of luck.
The difference, as Carey suggests, in sound between an all-brass instrument and an iron-strung instrument, even with appropriate scaling for iron, is not subtle at all. A smooth transition between the two in the high bass/low tenor in a ‘bi-metal’ instrument is not really relevant here. Yes, as I said, Malcolm’s wire is frightfully over-drawn, and that may have led to the scaling decision. Strung in all brass at or around an eq scale of 280 at A415, should not, using either Instrument Workshop yellow brass or Doc Birkett’s new historical brass, offer any problems at all, though personally in my dotage I prefer to bring things closer to around 275. Finally, I don’t understand what a factor like kg/mm^3 could possibly refer-to. Stress will be expressed as kg/mm^2, and absolute tension will be expressed as ordinary kg (f).
Indeed Claudio, I fully agree with you. Basically I was wondering how other makers string their Grimaldi.
Assuming that the scaling is correct and the pitch is a1 = 415 Hz, then stringing the instrument completely in brass in quasi impossible. In a way of speaking, just a gust of wind would suffice to break a lot of strings from e2b – c3.
I don’t have the plan of the original Grimaldi so I don’t know if the scaling on this instrument is identical. If this is the case and the original instrument was strung in brass, then the Grimaldi must have sounded at a lower pitch such as 392 Hz. Here we’re in the safe zone with 2 semitones from the breaking point of the strings.
All the best,
Chris.
Near the top of this thread, Domenico wrote:
David
Out of this discussion I draw three conclusions:
1Chris’s calculations show that from that treble f up brass is too risky and actually it breaks.
2Carey observes that shifting to iron would cause (higher up in the treble) a sound openly unlike the one expected,
3Owen shows that the problem arises because Chris’s scaling is not what it should be, and that to string the whole instrument in brass requires to lower the pitch significantly.
One alternative is of course to do what historical makers did more than once: change the position of the bridge.
But I would try a simpler mitigation. It may work.
Given that brass will break, I suggest changing over to iron in the treble: in doing so I see three goals:
a) avoiding broken strings, which the iron will guarantee,
b) preventing that the changeover becomes audible.
c) minimising the difference in sound that the rest of the treble will have.
We all know that the different “historical iron” wires available in recent times have audible differences in their sound qualities (I have tried and was surprised).
I would have strings of different makers and try out them.
This is how I would perform direct comparisons:
1I would bring the pitch of the instrument (or at least tenor and treble) down by two semitones: now the sound will not be identical to the final expected one, but it will guarantee that all the instrument can be strung in brass.
2I would string in brass, say, three strings in different parts of the treble region (I mean the range where brass breaks at the desired pitch).
3I would string besides those strings other ones in two or possibly three different modern historical irons.
At this point, the iron that better matches the brass sound, even if we are two semitones below pitch, will keep that property when the instrument is brought up to the desired pitch.
Curious to know whether, other than moving the bridge or using carefully selected iron, there is a third way.
Dear Andrew, in my previous post, when I wanted to have two sequences of bullets 1. 2. 3. 1. 2. 3. , my text in edit appears to follow it, but the “published” post changes the numbers to 1. 2. 3. 4. 5. 6. Is there any specific way to prevent this? (In the meantime I have resolved the issue deleting the periods after the numbers, but the look of the paragraphs is now less than elegant). Thanks!