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#1 tony

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Posted 03 May 2005 - 10:10 AM

<_< I have this 46 key Lachenal Maccann,which I am very pleased with. However, when I first acquired the instrument it was in old pitch and both sides were well balanced with regard to timbre. Since it has been retuned to concert pitch the upper notes on the left hand are more 'harsh' than the lower notes on the right hand, which are more 'rounded'. The sort of difference you get between brass reeds and steel reeds. All the reeds are steel and the 'baffles' are still in place. My question is: could this be a result of where the reeds have been reduced by filing or, could it be that the sound chambers are now the wrong size for the current tuning or, could there be some other underlying reason?

#2 d.elliott

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Posted 04 May 2005 - 05:08 PM

When the instrument was tuned, I would 'assume' - that dangerous word- that new valves were fitted, and the reeds were properly cleaned and their gapping re-set. All-in-all each reed will be sounding quicker, and probably louder. Loose reeds will have been bushed back into the reed pan, again affecting apparent brightness, response and volume. In my experience little effects seem more obvious to the ear on smaller reeds than on large ones. You might be having harminics problems, but It might be a case of you are now hearing the balance and tones closer to the as-new than before. I suggest you 'play in' the instrument, letting reeds settle and optimise, which also lets your ear become more accustomed to the new pitching.

Its also possible that the previous tuning was not equal temper, which will have now been changed.

but its all guesswork, talk to your repairer!

Dave

#3 tony

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Posted 05 May 2005 - 07:30 AM

I suggest you 'play in' the instrument, letting reeds settle and optimise, which also lets your ear become more accustomed to the new pitching.

<{POST_SNAPBACK}>


Thanks Dave, I will take your advice. As it happens the difference in timbre on the left of the instrument is not a problem as it adds to the character of the accompaniment it's just that I find being able to alter the timbre an interesting subject and would like to know more.

#4 tony

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Posted 06 May 2005 - 10:39 AM

When the instrument was tuned, I would 'assume' - that dangerous word- that new valves were fitted, and the reeds were properly cleaned and their gapping re-set.


Dave,

It occurs to me that all of the repeated keys on the left are harsher than the equivalent keys on the right. Could it be that the rods on the left being shorter than the rods on the right are having an effect which I had not noticed when the instrument was in 'old tune'.

I seem to remember the Crane Duet I once owned was similar.

#5 Stephen Chambers

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Posted 07 May 2005 - 02:29 AM

... Since it has been retuned to concert pitch the upper notes on the left hand are more 'harsh' than the lower notes on the right hand, which are more 'rounded'. ... My question is: could this be a result of where the reeds have been reduced by filing or, could it be that the sound chambers are now the wrong size for the current tuning or, could there be some other underlying reason?

<{POST_SNAPBACK}>

Tony,

I'm afraid the simplistic answer to your question is "Because they always do !"

It occurs to me that all of the repeated keys on the left are harsher than the equivalent keys on the right.

<{POST_SNAPBACK}>

You were probably unaware of it on the Maccann before the retuning was done, because none of the reeds were playing to their full potential, but now that they are working efficiently you have become aware of the differences in timbre that are to be found between the ends (to a greater, or lesser extent) in all Anglo and duet concertinas.

I seem to remember the Crane Duet I once owned was similar.

Exactly !

The cause is the difference in depth between the chambering for the right and left hand reed pans, which need to be shallow on the right, to make the higher reeds function well, and deep on the left, for the benefit of the low reeds.

I would suggest that what you are hearing on the left hand side is not "harshness" (which I would equate with stridency), but rather what I would describe as a "hollowness" (or lack of "focus"), because the chambering is too deep for those highest notes on that side.

#6 Stephen Chambers

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Posted 07 May 2005 - 03:04 AM

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?

<{POST_SNAPBACK}>

Tony,

I have brought this question back to where I believe it belongs. I hope that you will now realise, from my previous reply, that you are probably blaming your tuner unfairly, and that the problem is in the nature of the instrument.

Voicing the reeds differently does not offer a solution to it, and your ear will probably soon adjust to the built-in sound/balance of your instrument, which will cease to bother you.

I'm afraid that, for design reasons, the only system of concertina that can possibly have an even timbre throughout its range is the English, otherwise you just have to put up with it !

#7 Paul Groff

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Posted 07 May 2005 - 10:20 AM

Stephen,

As usual I am in basic agreement with you but have a point or two to add, that may possibly be relevant to tony's question.

On at least some of the smaller Lachenal duets the reed pans are set into the bellows frames at an angle so that on a single reedpan the higher notes have shallower chambers than the lower. At the moment I don't have one of these instruments handy that will let me check whether the chamber for "g" on the left side is very much deeper than the chamber for "g" on the right side, but I believe you!

Another issue may be that the levers for the high notes on the left side may lead to pads that are away from the player (this can lead to a brighter tone as heard by the player). The levers for these same pitches on the right side (that is, the low notes of the right side) may lead to at least some pads whose notes are partly muted by the position of the right handrail and hand.

This latter effect may be greater on the smaller vs. the larger duets. On the one hand, the smaller duets have a smaller endplate measurement that might lead to a proportionately greater muting of the "near pads." Also, I think some of the smaller Lachenal duets had handrails more like the cheaper Lachenal anglos, i.e. not the "duet style" ones that on the larger Lachenal duets often have heartshaped cutouts to let more sound come out from the "near pads."

If this is what is going on you could test for it (and possibly mitigate the effect) with a partial baffle on the left side.

Frank Edgley (and I) have often reminded this forum about this cause for differences in timbre between different notes on a concertina. I (still) tend to think that a lot of such differences (due to this cause) are more noticeable to the player, especially when practicing in a quiet room, than to a listener a few feet away. The high frequency partials that on some notes are muted by the hand, and on other notes clearly heard by the player, are very directional and easily lost a few feet away.

Paul

Edited by Paul Groff, 07 May 2005 - 10:25 AM.


#8 Stephen Chambers

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Posted 08 May 2005 - 04:23 AM

Paul,

I hadn't bothered going into all those other potential causes for differences of timbre between different notes (on the same side of the instrument) because Tony had made it clear that the difference that bothered him was in all the notes in the overlap between the two ends :

It occurs to me that all of the repeated keys on the left are harsher than the equivalent keys on the right.

<{POST_SNAPBACK}>

And also :

I seem to remember the Crane Duet I once owned was similar.

Adding to that, he had also stated that it was a 46-key Maccann, so I had assumed that with that small range it was probably an inexpensive model, on which less attention was paid to attempting to balance the tone.

By the way, only the top-of-the-range Lachenal duets (Edeophones & New Models) had the cutout rails you describe, all the rest used the Anglo-style rails and straps.

I would fully agree with you about how "a lot of such differences ... are more noticeable to the player, especially when practicing in a quiet room, than to a listener a few feet away", indeed I was strongly reminded of it last night, when a visiting friend played one of the new anglos I am working on (of which I would probably be the harshest critic) and how much better it sounded to me in her hands, a few feet away, than when I played it myself. It was especially gratifying to hear it in the session afterwards, holding its own against two Wheatstones ! :)

#9 Paul Groff

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Posted 08 May 2005 - 08:52 AM

Hi Stephen,

Sorry I wasn't clear. I meant (and thought I wrote) that some high notes on the LH side have pads that open away from the player (hence brighter in timbre), but the low notes on the RH side (which ARE those same pitches, making up the "overlap") may be more likely to have pads that open under the right hand (hence duller in timbre).

Anyway as you say there are many causes for such differences!

Thanks,

Paul

#10 tony

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Posted 09 May 2005 - 07:32 AM

I wish to thank everyone who has made a positive contribution to this, and the sister postings, on this subject. I do not intend any disrespect. :D

First a little story: Many years ago, as a young engineer with Rank Xerox, I was at one of our monthly meetings during a heated debate when one of the older engineers declared that he had over 20 years experience and therefore was better qualified in the subject. One of the younger engineers, who was well qualified, asked if that was truly 20 years experience or was it one years experience 20 times and had he continued to make the same mistakes every year for the last 20 years.

Secondly: To assume someone lacks technical ability when you know nothing about them is a mistake.

Thirdly: Anyone who states that something does not exist, such as a formulae, belongs to the Flat World Society. If they are saying they know of no such formulae then that's fine but they, at least, could leave the Forum open for someone who may know.

Fourthly: As I understand it, if one adds weight to the end the tongue of a short reed one can lower the pitch to that of a larger, un-weighted reed. The profile is different. This will clearly change the timbre. In what way?

#11 Howard Mitchell-Borts

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Posted 09 May 2005 - 08:18 AM

...

Fourthly:   As I understand it, if one adds weight to the end the tongue of a short reed one can lower the pitch to that of a larger, un-weighted reed.   The profile is different.   This will clearly change the timbre.   In what way?

<{POST_SNAPBACK}>


Tony,

I can't fully answer your question from an anaytical point of view.

If you look at work by Cottingham on free reed acoustics, he observes that a uniform reed vibrates in a near sinusoidal way along its length but that this produces a pressure waveform which contains many harmonics as a result of the air flow being "chopped" by the reed entering and exiting the frame. There is empirical data showing this but no published equation.

I can imagine that changing the profile of the reed (including the extreme case of weighting the tip) will change the bending shape of the reed (Cottingham calls this the reed profile just to confuse us) and may also change the vibration mode of the reed. I can see how one might model the vibration of the reed using Fletcher's equations and modify it for a specific reed profile using Rayleigh's equations. This however doesn't then take the final step of transforming the reed displacement into the pressure waveform which would give us the harmonic frequencies and change in timbre.

To paraphrase what you say, the problem is computable but we haven't yet written down the algorithm nor used it for specific instances.

From a point of view of experience - I've revived a baritone anglo which has a number of weighted reeds and I had to re-manufacture a couple of them - putting a weight on the end of the reed makes the fundamental louder in proportion to the upper harmonics and results in a less "reedy" tone.


Howard Mitchell

Edited by Howard Mitchell, 09 May 2005 - 08:27 AM.


#12 Stephen Chambers

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Posted 09 May 2005 - 08:49 AM

Tony,

I could try to explain to you that the steel reeds in your Lachenal would have been made individually by hand, from strips of spring steel, by an experienced craftsman with a sharp file and a good ear/eye, but no quantifiable "formula". (For that matter, you can read how Crabb's did it here on C.net.)

But you wouldn't accept it, so why bother ? :huh:

I'm afraid we're talking "old technology" here, not "Rank Xerox". :(

Now, time to go and renew my membership of "The Flat Earth Society", where's my quill pen ? :P

#13 JimLucas

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Posted 09 May 2005 - 08:50 AM

... putting a weight on the end of the reed makes the fundamental louder in proportion to the upper harmonics and results in a less "reedy" tone.

<{POST_SNAPBACK}>

Howard, is that change simply in comparison to the otherwise-unaltered unweighted reed (which would have been at a higher pitch), or in comparison to an otherwise-identical reed, unweighted, but thinned toward its base to give it the same pitch that the weighting produced?

#14 Howard Mitchell-Borts

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Posted 09 May 2005 - 09:32 AM

... putting a weight on the end of the reed makes the fundamental louder in proportion to the upper harmonics and results in a less "reedy" tone.

<{POST_SNAPBACK}>

Howard, is that change simply in comparison to the otherwise-unaltered unweighted reed (which would have been at a higher pitch), or in comparison to an otherwise-identical reed, unweighted, but thinned toward its base to give it the same pitch that the weighting produced?

<{POST_SNAPBACK}>


Jim,

It was a while ago, I'm thinking back to the process I went through.

The concertina had a couple of broken reeds, just the frame and a stub of reed left under the clamp. I had a supply of old melodeon reeds and used them as raw material.

I selected a reed with about the same thickness as the stub and shaped it to fit without changing the profile. It was too high in pitch so I thinned the reed near the root. It sounded "reedier" than other notes around it, both weighted and unweighted.

I started again with the same thickness reed and added weight at the end instead of thinning. It was nearer the sound of reeds around it.


Howard Mitchell

#15 JimLucas

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Posted 09 May 2005 - 09:48 AM

The concertina had a couple of broken reeds, just the frame and a stub of reed left under the clamp. I had a supply of old melodeon reeds and used them as raw material.

I selected a reed with about the same thickness as the stub and shaped it to fit without changing the profile. It was too high in pitch so I thinned the reed near the root. It sounded "reedier" than other notes around it, both weighted and unweighted.

I started again with the same thickness reed and added weight at the end instead of thinning. It was nearer the sound of reeds around it.

<{POST_SNAPBACK}>

So you didn't try to closely match the reed's profile to that of the reeds nearby in pitch? Would you be able to look at those reeds now and tell us how similar or different the thickness profiles on the melodeon reeds are, compared to the nearby originals?

#16 Howard Mitchell-Borts

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Posted 09 May 2005 - 10:13 AM

So you didn't try to closely match the reed's profile to that of the reeds nearby in pitch?  Would you be able to look at those reeds now and tell us how similar or different the thickness profiles on the melodeon reeds are, compared to the nearby originals?

<{POST_SNAPBACK}>


Leave it with me Jim. I'll look when I can. I have number of other irons in the fire and the dreaded "real work" keeps getting in the way. (I'm sitting listening to terrible "on hold" music at the moment waiting for an international teleconference to start)

Howard Mitchell

#17 tony

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Posted 09 May 2005 - 10:20 AM

But you wouldn't accept it, so why bother ?  :huh:



I may.

#18 tony

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Posted 09 May 2005 - 10:22 AM

I'm afraid we're talking "old technology" here, not "Rank Xerox".  :(



You may be surprised at how old Xerography is.




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