Paul Irvin's article

I wonder whether others have read Paul Irvin’s article in the latest Harposichord and Fortepiano, and if so, what they think of it. Paul is a distinguished and experienced harpsichord and clavichord maker whom I respect, but I find myself wanting to argue with almost everything he says.
The article is essentially about the way the plectrum plucks the string. Paul identifies two schools, ‘modern’ and ‘historical’ – and puts them in opposition. ‘Modern’ makers use horizontal plectra (so he says), and the jacks are closely controlled as they move up and down so that they can’t slop around sideways. ‘Historical’ makers (according to Paul) used plectra that slope slightly upwards and jacks that were either tapered in width or fitted somewhat loosely in box slides. In this ‘historical’ system, as the jack rises, the top of the jack is pulled towards the string because of the upward angle of the plectrum; then as the plectrum begins to bend, that pushes the jack back from the string, and the string is released from the weaker, distal end of the plectrum. Paul suggests that this produces a motion in the string that is more up-and-down and with less of a side-to-side component; he further alleges that this produces a warmer sound with less emphasis on the higher partials. (I hope I have not misrepresented his meaning, and I encourage other jackrailers to read the original article).
Now, first of all, not all modern makers use dead-horizontal plectra and not all old makers used sloping plectra (in my limited experience). I for one always used up-sloping plectra in the days far distant when I was making harpsichords professionally; but the purpose was to speed the plectrum past the string on the return. I used to taper the jack bodies, but the purpose was to ensure free movement and not to permit a sidways dance at the jack tops: with upper and lower guides separated by 50 mm or so the reduction in thickness of half a millimetre or so at the lower guide is not going to allow any significant sideways movement at the top. And I do not see how Paul’s alleged ‘historical’ system will in practice reduce the side-to-side component in the string’s vibration. At the very least, this needs to be demonstrated by careful scientific evaluation and measurement.
Now I wonder what thoughts others have?

Is this article publicly available? I thought this journal is subscription only? It’d be interesting to read it before commenting. Perhaps we could encourage Mr Irvin to join our forum?

Alrighty. I have a background in mathematics, and harpsichord building. There are more studies on piano strings than harpsichord strings, but they share many similarities. Very rapidly I found a lot of deep papers on piano string vibration, both theoretical models and measurements. I’d summarize far too superficially that a struck - or plucked - string will principally vibrate in the vertical plane at first, due to details of the coupling with thew bridge and soundboard, which are compliant and not rigid, and then a horizontal motion develops over time. The vector sum of the two motions produces an ellipsoidal overall motion that changes with time as the energy decays. You can visibly see harpsichords strings doing this. Here’s a picture of some modes (in piano).


My quick view is that this is what strings do in a string/compliant bridge/compliant resonant soundboard. and the time variations happen necessarily and naturally. I don’t think trying to influence this with angle of plectrum attack makes a substantive difference (and I’d like to see measurements not assertions or subjective hearing). In a nutshell I think there are vastly bigger and more important things to control in building than this idea, and which is unfortunately based on speculation about historical plectrum angles (and this is getting dangerously close to the current open topic on old quills, the existence or not thereof).

I won’t even begin to start about phase locking which demonstrably happens between two strings at the same pitch or octave, and how this influences transverse vibration modes.

When younger I wanted a complete physical theoretical model of harpsichord string vibration. Now as time has passed, I don’t think it’s important. Practice in voicing and building matters more. Ruckers made pretty good harpsichords without having to solve partial differential equations. [I am being a bit silly but I think you know what I mean.]

I will have more to say when I have thunk on this summat more!

Yes, it is a subscription magazine; it is possible to receive it digitally.

Worth getting, you think? Who is the editor?

Referring to the full index online, I see our @CDV has several articles.

Worth getting? Well, I am a subscriber. The editor is Francis Knights.

Very interesting your comment, Peter Bavington, and also yours Andrew Bernard. My own impression is that, as Peter says, scientific and thorough blind evaluations are really needed. Surely an upward-looking plectrum may feel different, but we are talking sound, and in that respect the only audible effect is the amount of displacement from strict vertical that the string has during the very moment it leaves the plectrum: I seriously doubt that 10º either way will produce an audible difference in quality or loudness of sound. But again, I might be wrong…

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In my Hubbard kit I have observed that when you fit a carefully tapered down Delrin quill, at first it is strictly horizontal, but within a few years the plectrum curves significantly upward (the tip can be more than 1/2 millimetres up!), yet you change a broken plectrum, therefore you have two nearby jacks, one with perfectly horizontal plectrum, the other with a significantly upward pointing one. I cannot hear any difference is sound quality or loudness whatsoever … but then, my left ear has lost significant high-frequency hearing, perhaps I am getting deaf of the right ear as well? :slight_smile:

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I am also a subscriber. Except for the articles by a CDV there, I find very interesting articles in this magazine.

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This can indeed happen with Delrin quills. But please note, it doesn’t always happen. In my experience tuning and fixing harpsichords for 40 years now, I would say that Delrin quills curling up is the exception, not the norm. I’ve always wondered what causes this–whether because the way that particular sheet of Delrin was made or prepared, or whether it is caused by the conditions the particular harpsichord lives in.

The Delrin plectra we made were cut from very large sheets of Delrin that were rolled up and you could see the small quills retained some tiny amount of curve. We always took cognisance of this and put the plectrum in the appropriate way up. I could imagine that after years of decades small residual extrusions stresses could reveal themselves in curving. Since Delrin is very inert I don’t think environmental causes would degrade it. But this is all very uncertain.

Agree with Dongsok. Although I’ve seen upward-curling Delrin, I far more often see the exact opposite: that quills, as they get older, curve downwards. That would make a quill that’s horizontal at the outset a non-starter: it would almost certainly hang as it aged. Of course, true bird quills may be different in that regard.

In the small number of harpsichord jacks I’ve made, I punched the plectrum mortises to have the quill tilting upwards by 5 degrees.

I agree with Andrew: the type of material that Delrin is makes it hard to have environmental effect, and anyway I have always lived in temperate climates (Argentina, Ireland and Italy).
I am surprised that others have different effects, e.g. curving downwards.
My observations relate to plectraI have installed myself, both in my instrument and in a few others, and using Delrin from different sources. They have in common that it was me who shaved and installed the plectrum, and they always after some years curve upwards. Some details that may help to explain this effect:

  • The Delrin plectrum tapers vertically, but it is mainly shaved in the horizontal dimension: if, say, I am working with 1/4mm thick Delrin, the tip will be less than 1/2mm thick (measured before the final bevel of course). See the picture here, although as a rule my plectra are a bit shorter, i.e. protruding from the tongue about 4mm for the 8’, and 3mm for the 4’.
  • Also, as suggested by Hubbard (but not necessarily the right decision?), I leave the shining part of the Delrin up, and the opaque side obviously down, and it is the latter that I shave. This may have to do with whichever way it curves. Curving upwards is good, because every 5-10 years you just shave the plectrum a bit to keep it from being too loud. If it curves down, there is nothing you can do but to replace the plectrum.

I need to say that, again, from personal experience, I think Delrin isn’t as stable as some would have you believe. I have found many harpsichords over the years with warped plastic jacks. Different makes of jacks, usually 30 or more years old. I think it is oftentimes caused by the extreme temperature fluctuations that some harpsichords in New York City apartments go through between seasons. And of course, it doesn’t help when owners insist on placing their instrument right next to radiators or huge sunward facing windows and open at all times.

Back to Paul Irvin’s article, one of my ideas was already commented by Peter Bavington: surely the “authentic” lateral jack movement plucks in a slightly different way, but the only way to know if this has any audible effect is by scientific blind tests.

As for tapered jacks, AFAIK they are typical of the French school, and surely not found in Italian instruments.

Dear All

My copy of Harpsichord & Fortepiano arrived in yesterday’s mail, and I can now comment on Paul Irvin’s article “Modern vs historical harpsichord plucking”.

The premise is good: There is indeed considerable difference in the operation between a modern harpsichord jack, and a tapered historical jack. The former action will never feel as good, no matter how skillful the voicing and regulation.

Paul quotes the lutenist Elaine Fuller, who asserts that “An important aspect of lute technique is the direction of the finger stroke: it should be more or less perpendicular to the soundboard … thus producing what in a harpsichord would be a predominantly vertical vibration direction.” I was a little surprized by this, and I queried it with the Australian lutenist Simon Martyn-Ellis who confirmed it was in fact accurate.

However, I believe this predominantly perpendicular to the soundboard motion which Paul is demanding, is undesirable for the initial excitement of a harpsichord string. @andro has shown various string vibration patterns: It wobbles around all over the place. We have all experienced an unvoiced harpsichord plectrum, which instead of bending, inflexibly lifts the string far too far vertically before the string releases late with an explosive bang.

Hence, I believe Paul is mistaken in desiring a pluck which “maximizes the vertical vibration of the string while minimizing the effects of sideways deflection with a smoothly released string.”

In supporting evidence, I’ve taken a short video of the front 8´ GG string being slowly played on my 1773 Kirckman single. The quill contacts the string, bends, and throws the tapered jack towards the back of the register. The extent of horizontal displacement of the string is clearly visible from above as the distance between the close string pair reduces.



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Could this wobbling be responsuble of the “bloom” effect? The string would start by vibrating more or less horizontally, then achieve verticality and that would be when the sound bloom. Just a thougth.
If so, I think an horizontal vibration is indeed desirable in order to get the bloom which is part and parcel of a beautiful harpsichord tone.

(However, desirable or not, I can’t visualize how can be possible for a harpsichord string to vibrate vertically from the start, as it is plucked by the side and thus laterally displaced.)

I have not been able to find a copy of Paul’s article, but I would like to suggest a scientific approach that might help to determine what happens when a string is plucked:

  1. Interesting though that experiment may be, comparing the action of a Hubbard instrument voiced in delrin with that of a Kirckman (or other 17th or 18th C instrument) voiced in quill is not helpful: there are too many changed parameters between the two.

  2. We must be careful not to construct an hypothesis from one observation of a specific instrument. Much more video data is required to have confidence in any conclusions that might be drawn.

  3. Slow motion videos are welcome tools, but we need to observe more than just a single pluck of a bass string from above. The action of plectra on mid- and upper-register strings should be recorded and observed in the three orthogonal planes.


Hi Pluckers all,
Notwithstanding any difference in motion occasionned by quill of either natural or synthetic orignin or tapered and straight jacks, : the string goes round ‘n’ round, in a circular motion, after slipping diagonally off the quill. This was beautifully démonstrated in a very high (low?) speed film shown at a symposium in Vanves. Journées de la Musique Ancienne (Paris, France, not Texas…: ). When only the awful LED lighting is on in the workshop one can even see the changing direction of the string movement if it is a slow bass.

I would love to put a link (if even there is one) , BUT: memory fails me as to whether this was in 2015 or 2016, the two years I attended. As I am also away from home another two weeks I do not have the programs to hand and cannot thus give the names of the researchers or institutes involved. ITEMM? Have they published this? Is there an internet link somewhere? I can only suggest that those who may also have been there find their programs, and somehow contact the organizers of the time, I believe it was Carine Moretton. Tell ya what, I’ll write her myself once I find the names involved, later then. But look anyway! TwM.