John Pearse string guages

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Re: John Pearse string guages

Postby kwl » Wed Feb 15, 2017 2:42 pm

Thanks for the update, Don.

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Re: John Pearse string guages

Postby rtroughear » Thu Feb 16, 2017 9:27 am

Don
I mostly make 6-string dulcimers and always use a wound pair of 0.022/0.024 for the bass string. The resulting sound seems to have an extra dimension to it that I like. I loosely explain it by suggesting that the harmonic series for the two strings will be slightly different, and leave it at that. But like anything to do with musical strings, the more you look, the more worms get out of the can.

There is a difference in string tension between the two different gauges. Using my Universal String Tension Calculator, the 0.024 is 19.7lb (27.5" VSL @ D147Hz) and the 0.022 is 16.6lb. A 15% tension reduction. For the 0.010/0.009 strings the tensions are 14.9lb and 12lb; a 20% tension reduction in the thinner string. I don't know what this might mean in itself, but one of the consequences will be that a finger fretting the two strings will probably stretch one of them more than the other, changing the pitch differentially, and possibly making an audible difference relative to two same-gauge strings. That's assuming they start at the same pitch.

BUT: Piano tuners routinely tune "unison" strings slightly differently. Not so that they will produce beats, but because it changes the nature of the initial sound attack when the string is struck.
StringMistuning.jpg
StringMistuning.jpg (45.98 KiB) Viewed 160 times
This is a picture of the amplitude spectrum of a dual string at different levels of mistuning. 0.64Hz would be considered a large mistune resulting in beats. But at the smaller tuning differences there are no beats, but a stronger initial sound attack. (Track down the work of Gabriel Weinreich if you want to follow this up more).

Has this got anything to do with Pearse 10/9 strings? Maybe - maybe not. The two different gauge strings will have slightly different effective vibrating string lengths due to their different stifffnesses. So even if they are individually tuned accurately to the same note, when they are struck together and fretted the two will have slightly different fundamental frequencies as you go up the fretboard, and will exhibit the behaviour in the picture above. It might even lead to pitch differences large enough to exhibit beats. This phenomenon of beating is utilised in Finnish Kanteles, where each single string has two effective vibrating lengths, depending on whether the sting is vibrating vertically or horizontally. Here is an exerpt from the Masters Thesis of Henna Tahvanainen in Finland.
Kantele_String Vibrations.jpg
On a dulcimer, this effect will be cancelled out to some extent if the bridge is slanted for compensation, and the thinner string (longer effective VSL) is closest to the player.

I don't claim that the above is the explanation for Pearse's string choice, but there are some reasons to think that unison strings of different gauges might alter the tone relative to a same-gauge pair.

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Re: John Pearse string guages

Postby Don O. » Thu Feb 16, 2017 9:59 am

Wow! Thanks for all that, Richard. Lots to chew on there.

If I had to guess, though, and that's all I have, I think it strains credulity that that much scientific thought went into the design of these strings. The late John Pearse was a musician, not a scientist. Ditto for his ex-wife, who is still involved with the company and was a professional dulcimer player. So she surely had input into that set. Perhaps it's something she experimented with, or perhaps she stumbled on it by accident, or perhaps it's something another dulcimer player suggested that she try. In any case, however it happened, she probably liked how it sounded and that was that. All of that is sheer speculation of course, but being a musician, I know how I think about such things. Bottom line, how does it sound? If it sounds good, it is good. I don't dwell on the science. But in this case I was curious, and your explanation may well be the correct one. I just find it hard to believe that much forethought was put into the design.

I do think it is interesting that you use a mismatched bass course. This is the first I've heard of a maker using a mismatched course in a purposeful way.

Maybe the reason that John Pearse did not answer my query is that, the truth be told, they just don't know the answer? Maybe John said that's what he wanted, and that was that?

I don't want to change strings on any instruments I have right now, they aren't needed. But I am picking up a recent used purchase soon, and I usually put on fresh strings as a standard procedure. So I will use a set of these and report back my impressions.
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Re: John Pearse string guages

Postby rtroughear » Fri Feb 17, 2017 6:12 am

Don, I'd also be surprised if the different gauges on Pearse strings was because of some analysis pointing them to it. I only use two different bass strings myself because it sounds better to me - that's what counts. The reasons behind the sound change can be left to places like this to chew over for idle consideration- or not worried about at all....

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Re: John Pearse string guages

Postby Don O. » Sat Feb 18, 2017 5:52 am

Well, I picked up the dulcimer and put on the John Pearce set. I am impressed. They sound great! The bronze wound bass string sounds much better to my ears than the nickel wound one I was using before, and the .012 middle string and .009/.010 melody stings have low tension, making for very easy playing. I play mostly DAD chord melody style, and these seem particularly suited to that. I think this will be my go to set from now on.

As far as the mismatched melody strings are concerned, I could mot detect any particular specific effect on the sound. And I don't really feel or notice it while playing. So I still don't discern the reason for the mismatch, but it does sound great so I suppose I should just go with it and not overthink it.
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