[Biagio]

OK now I understand Tacye. If one is happy with the tone, and transition from the upper register strings sure, why not?

I can say however, having once (only once!) made a metal double strung that it sounds horrible. My neighbors didn’t know whether to call the police or heave a boot over the fence at it.

I can’t figure out how to attach files here – help!!!
Grins,
Biagio

[Biagio]

Hi Mae (and Tacye),

For fibre I use diameter per thread of 0.011″, density 0.0412 lb/cubic inch, tensile strength 52,000 lb/square inch (sorry for the imperial units, it’s how my program is set up). These may vary somewhat depending on your string maker. There has been an ongoing “discussion” for over 30 years among makers over how much to assume for compression as bedding. Personally I don’t worry about the latter.

I came up with three different variations using my 2×23 as a surrogate and will send them to you off list.

WRT Tacye’s question: a thin metal core (say 0.018″) with heavy fibre bedding and nylon wrap will be only slightly stiffer than nylon core, much thinner, and with usually better acoustic and tensile characteristics. In this instance I’d probably use steel rather than bronze core but up to you. A metal wrap will of course sound – well, metallic:-)

More anon,
Biagio

[Biagio]

We’re talking expensive harps here but in some milieus we’ll take along a couple of el cheapos expressly for a “petting zoo.” We tell the parents the kids can play them (not “catch” of course). New students can be the result.

Biagio

[Biagio]

Sounds like a plan Mae, I love it when musicians really get into their instruments!

[Biagio]

Tacye, I buy my wound strings from Vermont Strings (a member of Robinson’s Harp Shop) in the US so I can’t say what they might cost elsewhere. At lengths over 40″ they cost the same, metal or fiber core.

Right now I need to get rid of some harps. This little apartment is getting crowded!

Anyone interested in a Clark Model A in excellent condition????

[Biagio]

Tacye,

Yep on the first…one cannot (or at least should not) consider each string in isolation and this is especially true for a double strung harp. If anyone has ever tuned up a double from the first stringing they will be well aware of how absolutely awful it sounds at first. Tune the string on one side and three or four adjacent ones immediately go flat or sharp!

And once the thing is holding pitch (finally!) they will notice much more sympathetic vibrations than on a single strung. So it is quite important in the design not only to consider the total stress but the relative tensions and color across the entire band.

About metal core versus fiber core in the bass….I agree that if the lengths work they would be preferable to SFN or SFB. As a matter of fact I do think fiber core silver wound would work in this case.

You have more flexibility in design with metal core, though, as steel does not stretch (much!) and is not as brittle as bronze. But artificial silk keeps stretching forever.

As a general rule we don’t want the fiber string’s initial percent of tensile strength much greater than 50-55% nor lower than 30%, and in addition they cost a lot more. Mae’s Stoney End harp is not a particularly expensive one – small range, ac/c ply soundboard, laminate box sides – so I’m not sure she would get that much richer sound from the fiber core.

On the other hand, with rather heavy fiber bedding over a thin steel or bronze core you can get an acceptable transition at lower cost. That’s what my teacher and I ended up doing on her prototype double 26. We figured “Hey, let’s save some money and see how it sounds once it has settled in.”

Pretty good as it turns out, but we’ll make some more changes on the next one, for sure:-)

Cheers,
Biagio

[Biagio]

Mae, I ought to add that I think it’s GREAT that you are doing this! You will be making this harp truly your own. Here’s one more thought….

If you will send me Gary’s string chart for the G-G version I’ll see what I can come up with for C-C that will be within tension and tone tolerances. I’ll need the vibrating lengths and diameters for the G-G version. I’ll also need to know also whether or not you would be OK with a few wound metal strings in the bass (they’d be steel fiber bronze) and whether you have access to nylon over there (for the treble and upper mid ranges).

Guess it’s too late to also mention that Dwight Blevins makes a double 23 and has a distributor in the Netherlands (De Troubadour Harpen) – just took a look though, and alas they only have his single (the Cameo 23).

Biagio

[Biagio]

Mae, I commented a bit more on the Camac Bardic thread but it occurs to me that I left out a couple of things that might also be helpful….

If you keep those zither pegs they will not work for a string diameter great that 0.045 (standard) nor for over about 0.070 even if you substitute some with enlarged holes.

Over on the Bardic thread I suggested that I personally would find a KF180 for that low C too floppy and would use SFN. Here’s what I came up with:

Steel 0.018″ 12 fibers for bedding, 0.20 nylon wrap. The relevant numbers are:

Diameter 0.81 tension 24lbs %T36.6 T/L 0.97

No problem with Z pins since the wrap and bedding should not go through the Peg hole, just the steel core.

I just looked at that one string, but of course one would have to think through the rest as well….

Biagio

[Biagio]

With respect to KF vs nylon and diameters: The problem I’d be having here is that while I can play around with compositions the length is fixed and therefore so is the percent of tensile strength for any given type (nylon, KF, gut etc.) no matter what the diameter.

1.80mm is a good size for that low C but at the LENGTH designed for a G it will sound dull, guaranteed. To give a more specific example by messing with my rental design:

The ow G is 24.75 inches; with a 0.060 nylon the relevant numbers are:

tension 26.5lbs %Tensile 21 Tension/Length 1.07

That’s as low as I’d find acceptable even in an inexpensive harp like this.

KF at 1.35mm (0.053″) costs more and does not get me a whole heck of a lot in terms of relative “floppiness”:

tension 30 lbs. %Tensile 23 Tension/Length 1.27

OK, so what happens if I drop the range 4 steps to C and find the KF diameter that will get me something acceptable? With 1.80mm (0.71″):

Tension 24.1 lbs. %T 10.2 T/L 0.97

Rubber band with that %T, I’m afraid: wound steel/fiber/nylon would be my choice. It would e skinnier too.
Biagio

[Biagio]

In reply to Mae’s questions on my comments…

First density and why the tensile strength issue:

Well, clearly Mae understands the Taylor equations so I won’t get all mathematical here (grin). When I sit down to a new string design I have three things in mind (usually): tone/color, even feel, and (ideally) no big jumps in diameter. Obviously I don’t want strings breaking but equally as important to me I don’t want some to feel and sound like bars or rubber bands.

That’s where the tensile strength comes into play: in general (NOT always) if a string is much below 30% it can sound rubber-bandy (and if too thick like a bar). So really I’m looking at four parameters in relation to the entire band: tension in lbs. or kg, %tensile strength (%T), the ratio of %T to length (a surrogate for resistance or “stiffness”), and the diameters. Tensile strength will be a factor in the last two.

Why might not the maple board sound good with gut or fluorocarbon? Becuz….it is quartersawn 1/4″ thick rock maple with the grain running vertically. I’d worry about it splitting (too much tension) or sounding dull (too thick for the gut strings). Sounds fine though with FC, which has similar physical qualities to gut (another grin).

Cheers,
Biagio

[Biagio]

Mae, I apologize for coming in late and missing some important info (and getting pretty long-winded). Maybe this will be more helpful…

Gary’s Brittany is very similar to a bunch of 2×23 double strungs that I made for a retreat (mine go up to A instead of G but no big deal). I sold a couple overseas and the folks wanted to know what they could use instead of nylon, so I worked out a chart for Savarez Alliance. Here are the diameters in mm for a 22 from G to G:

0.48
0.48
0.48
0.56
0.56
0.56
0.56
0.69
0.69
0.71
0.71
0.77
0.77
0.81
0.86
0.91
0.95
1.01
1.08
1.08
1.16
1.16
So when ordering you would ask for HPK116, HPK116R (for red) etc. From diameters 1.01 and larger they also come in two meter lengths i.e. HPK116RA would be two meters of red 1.16mm.

This is a fairly light tension harp, about 195kg total, as is the Brittany so I think you should be OK if you have Gary’s double kit. Personally I would find the treble strings too thin for my fingers so I’d use nylon there if I could; and the last two bass a bit floppy but not too bad.

It would be a good idea, still, to ask Gary about this chart.

Best of luck with your project!

Biagio

[Biagio]

Tracye, my point exactly!

I’m sometimes asked, “Could one convert a Music Maker’s Limerick to brass or bronze?” The answer is, “Yep it’s nice that way if you drop the range 3 steps.” It’s a low head which makes conversion easier.

On the subject of tension: sometimes makers and players mean different things by that term. As a designer I use “tension” to mean the actual force directed against the sound board and frame. Many players use the term to mean how stiff the strings feel, which is entirely different.

As a “for instance” my 26 string bronze wire harp is at 530 lbs; my 26 nylon at 750. But the wire strung sure feels “tenser”! It also incidentally sounds pretty good with gut, despite the solid maple soundboard.

But I dither on…..

Biagio

[Biagio]

I’ve designed a number of double strungs; I’m jumping in here let’s see if I may help. First if I’m understanding the discussion I’m assuming:

Mae is thinking of a double strung with the same string lengths as the Bardic 27, but understands that she will have to change the diameters and probably compositions as well to compensate for the doubled tension if she just uses the same as the single. One approach would be to drop the range by four steps. An additional question is how to convert Alliance KF. Analyzing the Bardic single would give her an idea of where to go from there.

My thoughts for what they’re worth:
1) Most makers consider their string designs proprietary which is pretty silly in my mind but that’s the way it is. But you can guess the lengths from the description, usually. It’s nice to have a comparison to a single, but really does not move one very far along. What Mae needs are the lengths (and a good string analysis program). There is a pretty good free Excel program here

http://www.harpkit.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=MK&Category_Code=lib_stringanalysis

2) A drop of four steps is pretty big – around 100%-125% decrease in tension. Two steps is probably sufficient.
3) In any case, you can’t usually just do that and get a harp that still sounds decent. But if you know the lengths you can usually get a pretty decent design using that as a starting point.
4) Most double strungs have an average per string tension of about 20lbs/9kg up to 25lbs/11kg. Going higher requires a pretty heavy frame, and zither pins will not be adequate for high tension strings either.
5) Doubling tension does not require doubling SB thickness; about 40% more is adequate.
6) A typical design for a 2×27 would have nylon from treble a to around middle c, several transition strings of N/N or KF and 3 to 5 bass SFN for light tension.
7) Converting from nylon to Alliance KF or vice versa: you just need the densities and tensile strengths: nylon 0.0385lb/in^3, 44,600lb/in^2; KF 0.0562lb/in^3, 60,000lb/in^2.

Hope that helps!

Biagio

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