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Reed Voicing


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In http://www.thesession.org/discussions/display.php/3474, Bob Tedrow commented

Re: tuning a box

 

Thanks for the invitation to comment, Jack [Gilder].

 

I did a little offhand calculation here, I believe I have tuned over 4,800 reeds in the last ten years. This includes all the reeds in the 80+ concertinas I have built and a bunch of others I have worked on over the years. Hmm. maybe that is a low estimate.

 

I think it does give me the authority to speak on this one subject at least.

 

I don't believe I can separate tuning from voicing and profiling reeds because they are related.

 

Generally, neat calm filing on the lower end of the reed will lower the pitch and filing from the tip area will raise the pitch...  [snip]

Since that discussion quickly got off track, I wonder if Bob (and others) would expound on the concept of Voicing concertina reeds?

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I think all persons who have tuned reeds would agree with the following:

 

 

Steel reeds of any given dimensions can be profiled to speak with a range of more than one frequency. (edited... well not more than one frequency at a time, of course)

 

The timbre of reeds is altered by changing their profile.

 

The timbre of reeds profiled at the extremes of their individual range is generally unsatisfactory.

 

 

The speed of a reed (how fast it starts) can be altered by changing its profile, and it's set.

 

 

These adjustments must be done by hand and ear.

 

There exists no formula to balance these properties.

Edited by Bob Tedrow
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I fully concur, but confess to the use of a good quality meter.

 

Its worth while adding that when filing the reed near the root, or in the belly area - to flatten its pitch, its important to file evenly so as to keep the section rectangular, i.e. not sending it trapezoidal.

 

Also to stress the use of appropriate tools and techniqyes, so as not to leave steps, deep scratches or grooves that will form stress raisers and reduce the fatigue life of the reed tongue.

 

Dave

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  • 11 months later...
The timbre of reeds is altered by changing their profile.

:) In what way?

Bob also said:

These adjustments must be done by hand and ear.

There exists no formula to balance these properties.

There is no "cookbook" answer.

 

The closest I've come in my own limited experience is that if you don't want to alter the timbre when retuning, you must retain as closely as possible the original contour -- the variation in thickness along the length -- of each individual reed. (I don't know in detail what the effect would be of varying the thickness across the width, but the only examples I've seen of that have not been original, and sounded disastrous. I avoid it.) And the contour of the set -- varying the height of the reed above (or below) the top of the frame -- is also important. It's more important for response than for timbre, but it is very important.

 

Unfortunately, I find that altering the set -- usually by simply flattening out any variation -- is a form of "damage" commonly inflicted by inexpert tuning. A warning to anyone who wants to try their own tuning: The fact that you're changing the pitch does not mean that that's the only thing you're changing. And if pitch is the only thing you're paying attention to, the result is almost certain to be poorer than it could have been. (That's a gentle way of saying you could turn a treasure into junk.)

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The closest I've come in my own limited experience is that if you don't want to alter the timbre when retuning, you must retain as closely as possible the original contour -- the variation in thickness along the length -- of each individual reed. 

 

Thank's Jim, but the timbre has already been altered. Could it be that an accordion tuner, with limited experience of concertinas, have got it wrong?

 

You say "by ear" but does this mean you just hack away until it sounds ok or is there a more systematic approach? I take your point about the thickness of the reed along its length being important, but in what way? As I understand it by thinning the reed at the base you lower the pitch. So if you thin the reed along its full length, do you just alter the timbre and leave the pitch intact? If so, in which way will it alter the timbre?

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Could it be that an accordion tuner, with limited experience of concertinas, have got it wrong?

Seems very possible. There are significant differences in construction between accordions and English-made concertinas, and these can affect which variables are important. When I was hanging out on rec.music.makers.squeezebox, I noticed that the accordion folks not only seemed to use significantly different techniques for some tasks (for tuning, in particular), but they also had different concerns. E.g., replacing broken reeds seemed a commonplace, even on the best accordions a few decades old, while it seems quite rare on even the cheapest 100-year-old concertinas with steel reeds.

 

You say "by ear"...

Actually, it was Bob who said that, but I didn't disagree. ;)

 

Learning to shape reeds is like learning to throw a ball. You don't compute which muscle fibres to contract, and while some qualitative advice can help, there is no formula. Except that it's like learning to throw a ball if you had to use a new ball for each toss, and you had to make your own balls.

 

...but does this mean you just hack away until it sounds ok or is there a more systematic approach?

I believe the "systematic approach" taken by most professionals is to take their time. There are different ways to do this, all important. One is to build up experience -- usually over years -- with instruments that have been tuned and voiced by others, and build up a correlation between the contours you see and the results you hear. Another is to practice on instruments that are already in a shape that needs improving (so that any mistakes will not have traumatic consequences), making small incremental changes and becoming familiar with the changes in sound that result from your actions. Another would be to make a series of your own reeds, with different profiles, and see what each sounds like. Note also that the contour interacts with the set, the chamber size, the reed size, the reed's pitch, the material of the ends, and probably more, so you'd need to learn to correlate results with variation in all those parameters.

 

I take your point about the thickness of the reed along its length being important, but in what way?

You seem to be asking for a formula, or what I call a "cookbook" answer, after I've already told you there is none. I'll elaborate. I don't have one, and I've never heard anyone else claim that they did... quite the contrary. I think it might be possible to develop one, but with all the parameters that one could vary, I think one would need to produce and test a thousand or more experimental reed-profile-chamber combinations to get a statistically relevant sampling. Frankly, that's a project I'd love to undertake, but my current situation is such that someone else would have to fund it. Wanna volunteer the money? :)

 

As I understand it by thinning the reed at the base you lower the pitch.  So if you thin the reed along its full length, do you just alter the timbre and leave the pitch intact?

Probably not. First of all, if you assume "constant" thinning along the entire length, would you mean a constant thickness removed, or a constant fraction of the thickness? Those would have to have different effects, so at least one would change the pitch, and I suspect that both would, though I don't know in which direction.

 

Note that the reed flexes along most or all of its length, so one can get the same change in pitch by thinning either narrow or comparatively broader segments of the length, and many quite different contours can give the same pitch, but different timbres. E.g., thinning the free end will tune a reed sharper and thinning the fixed end will tune it flatter, so if you do both in some appropriate combination you can return the reed to its original pitch, but with both ends comparatively thinner with respect to the middle, as well as thinner in absolute terms. Similarly, some distribution of thinning in the middle of the length could leave the pitch unchanged, while changing the contour ratio (and the timbre?) in the other direction. But the reed is a continuous length, so the potential variation is infinite, and though the number of differences the ear can distinguish is finite, it's huge.

 

If so, in which way will it alter the timbre?

I don't know. (Can you even limit the "measurement" of timbre to a one-dimensional scale?) My efforts so far have almost exclusively been to avoid changing the timbre when I work on reeds. So my procedure has been to note the reeds contour, and alter it as little as posible. This means, among other things, that any filing is distributed along the length (not the entire length), so that no new localized depression is added to the contour.

Edited by JimLucas
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I don't know. 

 

OK. But with all the apparently complicated discussion on voicing, tuning and timbre that has appeared on this site and the vast experience these people appear to have I shall be very surprised if someone doesn't have the answer to this simple question.

 

Anyone?

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Also to stress the use of appropriate tools and techniqyes, so as not to leave steps, deep scratches or grooves that will form stress raisers and reduce the fatigue life of the reed tongue.

 

Dave

 

A case in point, I've recently been asked to do some work on a nice metal ended Lachenal. The reeds have a quality sound and responsivness. Sadly they have been carelessly filed, and several have deep gouges filed across the reed. Two reeds have already broken, and close inspection shows that at least one has failed along one of these file marks.

 

Is there any point trying to reprofile the other marked, but so far unbroken reeds?

 

Theo

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...with all the apparently complicated discussion on voicing, tuning and timbre that has appeared on this site and the vast experience these people appear to have I shall be very surprised if someone doesn't have the answer to this simple question.

Well, since you seem to disbelieve what has already been said by myself and others -- including Bob Tedrow, one of those with "vast" experience, -- I guess you would be surprised. Except that to be surprised, you will have to believe what you're told.

 

Other things that may surprise you:

... "Simple" questions don't necessarily have simple answers.

... Your question is not simple.

... Bob Tedrow has already answered your question:

These adjustments must be done by hand and ear.

There exists no formula to balance these properties.

I will not repeat it, again. :angry:

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... things that may surprise you:

... "Simple" questions don't necessarily have simple answers.

... Your question is not simple.

... Bob Tedrow has already answered your question:

 

These adjustments must be done by hand and ear.

 

There exists no formula to balance these properties.

As a repairer for the past 35 years, I couldn't agree more with what Bob and Jim have already said.

 

There is no simple "cookbook" formula. The only way to get it right, for a given note on a given instrument, is to listen carefully to the reed, both on the tuning bellows and in the instrument, and gently adjust it until you are satisfied with the timbre and response. Experience is the key.

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... Two reeds have already broken, and close inspection shows that at least one has failed along one of these file marks.

 

Is there any point trying to reprofile the other marked, but so far unbroken reeds?

Theo,

 

FWIW, I would usually try to erradicate, or at least reduce such damage by reprofiling, feeling that otherwise I am leaving a "stress point" in the reed, but it may be that some are already too badly weakened and (ideally) need replacement.

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I've been following this discussion with great interest, because it seems close to addressing some questions I've had about my own concertina.

 

I've owned my Lachenal crane for a few months now, and I've noticed the reeds within about half an octave of middle C, going either way, have a particular richness or "snap" to them which is very pleasing to my ear and seems to cut through the other instruments in our sessions in a way the higher notes do not. I have always assumed this was tied to the set or profile of the reeds and could be addressed on that distant day when I finally have the money saved to send the instrument out for inspection, tuning, and general adjustment.

 

After reading this thread (and its sister), I wonder if this is more likely just the nature of the concertina (my concertina, anyway)? Since this is the first I have owned or even played for more than a few seconds I've really nothing to compare it to. Before playing the concertina, I would have thought the higher notes would have had more cutting power than the middle ones. Is this just one of those idiosyncracies of the concertina? Or is it something which can/should be addressed?

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Is this just one of those idiosyncracies of the concertina?  Or is it something which can/should be addressed?

From what you have said, I would infer that you think the instrument could benefit from some servicing, in which case you cannot really judge its potential until such time as that is being done, but it could simply be "just one of those idiosyncracies of the concertina". :huh:

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