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Jody Kruskal

Action Board Holes Flare Out. Why?

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I had the end off my 38 button Jefferies when I noticed something I had not seen before. Some of the holes on the inner side of the action board had wood removed to make the hole flare out to one side.

 

What’s that all about? Would this change the timbre or perhaps the volume of the tone? I think the practical effect would be to enlarge the chamber.

 

post-557-0-90938500-1443758254_thumb.jpg

 

You can see from the photo that five holes have been crudely carved wide... all to varying degrees.

 

Can anyone help me solve this mystery?

Edited by Jody Kruskal

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Hi,

 

I have a 44 button jeffries, D/G, it also has flared holes, worse than yours. The reason being that the holes are outside the chambers and have to be tapered in. They are only the middle chamber holes, not on the outside, and there is insufficient room to fit the reeds and mechanism above if they are not flared. The start of the hole being outside the chamber, the end in the chamber. The 44 note Jeffries has a thicker action board. This may be the same with your instrument.

 

David

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Jody, this was discussed in a little depth as part of this thread: http://www.concertina.net/forums/index.php?showtopic=15225&hl=%2Bnasal+%2Binboard+%2Breeds. Many Jeffries with the dealer's stamp "R. Whitten" seem to have had this done to them, so it might have been a dealer's later modification. For what it's worth, my CG Jeffries has a lot of them and to my mind it has a loud, but also a very mellow sound for a CG. How would you describe your GD?

 

Adrian

post-6143-0-42878100-1361736394_thumb.jpg

 

Edited by aybee

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I have seen this on many Jeffries but I don't think I have ever seen a Whitten stamp and I would not think it was an aftermarket conversion by a particular dealer. Someone with good connections once told me the modification was done to aid in starting a reluctant reed.

 

There is an acoustic phenomenen found in flutes in which the short column of air sitting in the finger hole has physical characteristics separate from the air in the main tube (this is not a great explanation, if Dana sees this perhaps he will explain, as he told me about it). Should this also be true in concertinas then this modification would spoil the affect and this may be the intention. It could only be to improve the volume, the tone or the response of the reed. If it was to make an alteration in one of these factors then reversing it may demonstrate the nature of the change. It could be done by filling the scalloped part of the hole with an easy moulded and easily removed filler.

Edited by Chris Ghent

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Or is it done merely to make the holes line up with the chambers better? This is a guess, but I could imagine that the physical layout requirements of the action board holes and the reed pan chambers might be different enough that the overlap between the two might be improved by scalloping.

 

I don't have the time right now, but my guess could be proven right or wrong in photoshop by taking two photos of the two sides, flipping one, using opacity to superimpose the two and see both. If the scalloped holes improved the fit to their opposite chambers, that would be obvious by this method.

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It is definitely not that. The hole is not shifted by the scallop, if anything its entry to the chamber is made bigger which would make it harder to fit into a chamber rather than easier.

 

I have seen a padhole which was on a skew angle to line up a difficult pad position with a chamber which was not perfectly below but these scallops are not like that.

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I posed this question of scallped pad holes to Geoff Crabb a while back. Geoff in his thorough and inimitable way produced a treatise on possible reasons why these pad hole modifications may have been done. Geoff also stated that it was never Crabb practice to either produce or do these modifications.

 

Perhaps Geoff will comment. My recollection is that he suggested some possible "practical" reasons to scallop the pad holes. This might involve improving air flow around the clamp of a note with restricted chamber size; clearance for clamp screws; or attempts to equalize the timbre of notes situated in the interior of the reed pan.

 

There is also the "frightening" :o possibility that someone began making these modifications imitating the practice of modifying flute holes discussed earlier. And then these modifications were imitated :wacko: :o !

 

My inquiry to Geoff was instigated by a conversation I had with Noel Hill. Noel's take was that the scalloping was largely ill advised attempts at improving response or tone and were inspired by flute modifications.

 

However, I must add that I have several Jeffries duets where the scalloped pad holes greatly out number the straight ones. I find it difficult to believe these were not the work of the Jeffries Bros. themselves. For what exact purpose I'm not really sure :blink: .

 

Greg

Edited by Greg Jowaisas

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Is the a general consensus that this is found mostly on 38+ button Jeffries anglos and duets? I don't think I've taken a 38 apart that didn't have this done to the LH thumb button hole, and it is often seems not as crudely done as those on the outer holes. I don't think I've ever seen a 31 button anglo with this, but then I've not had many of those apart...

 

Adrian

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I'm inclined to think this was the result of one of the many misconceptions people ( including me ) have had about how concertinas work acoustically. In flutes and wood winds, flaring the underside of a tone hole with a fraise is generally done as a fine adjustment of tuning or stabilization of a note. None of the things that result from this in a flute or other woodwind apply to a concertina chamber. The amount of wood scooped out in these instruments and similar ones I've seen, is much larger than the sort of thing you'd find in anything but a wind instrument with a badly placed hole. The scooped areas are in line with the chambers ( look at the outlines of the chambers on the wood) which would seem to indicate someone was trying to control the flow of air. Some are oriented toward the forward end of the reed, some toward the heel. Since most reeds are mounted as outboard as possible, this would only be over the reed clamps on some of the reeds, so I doubt if making room around them was the purpose. I heaitate to speculate, except to say someone found a problematic note, tried something, and decided it made a difference. ( hard go go back and check ) and then ran with it. There are times when a reed finds itself in an unfriendly environment, and any of a half dozen changes will alter the environment enough to be good again. They might of attributed their success to better air flow, when it was actually the increase in volume that resulted that did the trick, or a change in the impedance of the pad hole relative to the chamber. Making that sort of physical change has multiple effects. As most of us have found, such tinkering is generally not necessary. On the occasions where I have found trouble, the culprit has always been with the reed, the window, a valve, or a corner block that was starting to let go.

On the other hand, pad hole design is important. Too small a hole can strongly damp reed harmonics at higher volumes, making the reed sound choked. Hole depth ( plate thickness ) can create flow problems if excessive and sharp edges can cause the hole to act smaller at higher volume. Air flows out of a hole in a straight line for a short distance at least, and if the vibrating air columnist a pad hole reaches up to a too low pad, it flattens the note. Small pad holes need more pad lift. Air flowing into a hole comes mostly from the side, not from above, so rounded corners help keep this flow smooth. This also allows a gradual change in impedance between the restricted cavity, and the wide open room which boosts volume. (This is why brass instruments have belled ends. The old wooden krum horns with their unbelled ends were not loud instruments). Too abrupt a change actually acts like a mirror to the sound waves.

Dana

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The Mystery continues... and now, I'm even more curious. Colin, Rosalie and John Dipper... what do you have to say about this?

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Is the a general consensus that this is found mostly on 38+ button Jeffries anglos and duets? I don't think I've taken a 38 apart that didn't have this done to the LH thumb button hole, and it is often seems not as crudely done as those on the outer holes. I don't think I've ever seen a 31 button anglo with this, but then I've not had many of those apart...

 

Adrian

I've just checked a C Jeffries F/C 32 key anglo and that had a very neat scallop cut into one pad hole on the lowest F reed on the left hand side - so they did exist, probably pre-1900 even on the smallest anglos. Also seen them on a Dipper but not on a Crabb

 

Alex West

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My G/D 1920s Jeffries Brothers 32 key anglo (originally Ab/Eb) has an oval pad hole on the lowest G/D. Wondering if it was originally flared but "trued up" at some point in it's life, making it almost 3mm longer than the width.

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Like many, what may appear, simple queries, the answers can be quite complex so I offer the content of the following attachment.

 

 

 

Whilst I have tried to approach the subject logically, my opinions or thoughts expressed in the attachment may not agree with those of others.

However, I hope it may be found edifying :) , interesting :mellow: or amusing :lol:.

 

Geoffrey

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It's certainly edifying and interesting. One minor niggle - where you have "sighted" in a couple of places, I think you mean "sited".

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I've just acquired an early Rock Chidley 48 key treble - on opening, to my surprise, I saw that most of the action board pad holes have been reamed out to give the sharp edges a smoother profile.

 

(I'd post a pic if I had more storage space.)

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