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Velum Under Fretwork - Replace Or Renew ?


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#19 Don Taylor

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Posted 14 May 2017 - 03:09 PM

Don, I see no reason to suggest that the effect of breathable woven fabric baffles would be ' purely cosmetic '. That is certainly not my experience. Rod.

Fair enough. I must make myself some baffles like this and hear what effect they have.

I, perhaps mistakenly, assumed that a thin cotton or silk cloth baffle would have little effect.

What effects do you hear?

#20 JimLucas

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Posted 14 May 2017 - 04:28 PM

I, perhaps mistakenly, assumed that a thin cotton or silk cloth baffle would have little effect.

What effects do you hear?


While I don't expect there would be a great effectt on the sound, I believe the fabric (I hesitate to call it "a baffle") would help keep foreign objects -- even some dust -- out of the interior of the instrument.

 

I've also seen concertinas where there was a kind of gauze glued inside the fretwork, apparently for this purpose.  Unlike the less permeable fabrics and leathers, the gauze doesn't need spacers to offset it from the fretwork, since the openness of its mesh doesn't significantly impede airflow.



#21 Chris Ghent

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Posted 14 May 2017 - 07:32 PM

If you want an idea of the ability of a fabric to block sound pressure of higher frequencies you can experiment easily by placing the fabric over your ears. This is not an invitation to walk around with your underpants over your head though if you are in the habit feel free to continue.

My experience of the effect of thin fabrics is easily expressed using that fine scientific phrase, bugger all. They will, however, as Jim has pointed out, lead to less wear of the slots in the end bolts.

The thicker the filter, the lower in pitch the sounds it will block or attenuate. I think I heard somewhere it take 6 metres of something solid to block the lowest sounds from a jumbo jet. Or any vacuum no matter how thin. Hard to wear those on your head.

#22 Jody Kruskal

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Posted 15 May 2017 - 02:06 AM

Hmm. Vacuum hat. Could be good for foreign sleeping arrangements in outer space.

 

My Jefferies Anglos are loud. In sessions, I've often wished I could simply turn them down. Instead, I play quietly. Should I consider installing baffles?

 

Don, you suggest  "PVA foam sheet (as used in crafting) works quite well in lowering volume without greatly affecting tone."

 

Is that what Frank Edgley uses? I think so. How thick? I seem to remember seeing it at about 3 mm.


Edited by Jody Kruskal, 15 May 2017 - 02:14 AM.


#23 wayman

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Posted 15 May 2017 - 03:19 AM

To speak to the properties of fabric 'baffles', the Morse Geordies and Beaumonts have what the Button Box calls 'grill cloth' because the material used has no effect on the sound whatsoever -- it doesn't 'baffle', it only (1) keeps dust, etc, out of the instrument, and (2) looks nice, if that's your preferred aesthetic. (Some folks prefer having nothing there, because the visible brass levers and the leather pads move gives the instrument a steampunk aesthetic and is desirable to them. I suspect if one asked nicely and paid a little more, one could get grill cloth on other Morse models, though I don't recall this being requested by anyone 2010-2016 and it may never have been requested.)

 

The Button Box's grill cloth is acoustically-transparent speaker cloth (such as you'd find on stereo speakers) -- specifically engineered to not affect the sound in volume or tone. As there's no need to keep it spaced away from the inside of the ends, it is glued directly to the ends with PVA. So they're removable, if there's ever a desire (by a second owner, say), with a little effort.


Edited by wayman, 15 May 2017 - 03:20 AM.


#24 Don Taylor

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Posted 15 May 2017 - 03:11 PM

Don, you suggest  "PVA foam sheet (as used in crafting) works quite well in lowering volume without greatly affecting tone."
 
Is that what Frank Edgley uses? I think so. How thick? I seem to remember seeing it at about 3 mm.

Jody:

The only Edgeley I have used is that Ab/Eb that you had the loan of last year. Don't ask, but that concertina likes to get about. It had very thin leather baffles which I don't think we're meant for sound reduction.

The EVA foam that I used was two thicknesses: a full size piece of 3mm and then another half size 2mm piece over bottom where the bass reeds are on my Peacock. I would have tried thicker but there is not much room between the action and the inside of the concertina's end.

Last night it occurred to me that an easier way to test various materials for use as baffles would be to use a speaker playing some concertina music rather than swapping the baffles in and out of the concertina. It is quite difficult to quickly judge how much a particular baffle works because it takes too long to swap them back and forth. It is really subjective. I find I have to play with a baffle in place for a few tunes before I can say to myself that I like/dislike the result. My first set of baffles were made of leather and they certainly reduced the sound level noticeably, but after a while I came to dislike the rather muffled tone that resulted.

We are not talking volume control type level reduction here, I just wanted to stop the low accordion reeds sounding so dominant.

BTW. I originally bought the EVA foam sheets to make 'head gaskets' for the ends of a Crabb that was warped and leaked air around, well, everywhere. Then I read somewhere that EVA foam is 'acoustically neutral' and that the commonly available ear plugs, the soft squishy ones, are made of EVA foam. It is 'cheap as chips' on eBay and very easy to work with.

Don.

#25 Jody Kruskal

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Posted 15 May 2017 - 10:01 PM

Hi Don,

 

I might give this 3mm foam a try.

Did you cut it with a hole in the center to match your action board?

Did you worry that you would make it such a tight fit that you would prevent air from passing at all? Did you cut little holes to let the air pass?

Did you glue it to the inside of your grill?

How would you say it affected your timbre, volume, and playability?

What color did you use?

 

There is a quality of my timbre that folks call shrill and can annoy, so I guess that I'm hoping it will cut down on the treble side of things as well as volume. Do you think I'll be disappointed or pleased?

 

Photos?


Edited by Jody Kruskal, 15 May 2017 - 10:15 PM.


#26 wayman

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Posted 16 May 2017 - 03:58 AM

The EVA foam that I used was two thicknesses: a full size piece of 3mm and then another half size 2mm piece over bottom where the bass reeds are on my Peacock. I would have tried thicker but there is not much room between the action and the inside of the concertina's end.


Last night it occurred to me that an easier way to test various materials for use as baffles would be to use a speaker playing some concertina music rather than swapping the baffles in and out of the concertina. It is quite difficult to quickly judge how much a particular baffle works because it takes too long to swap them back and forth. It is really subjective. I find I have to play with a baffle in place for a few tunes before I can say to myself that I like/dislike the result. My first set of baffles were made of leather and they certainly reduced the sound level noticeably, but after a while I came to dislike the rather muffled tone that resulted.

 

 

This using the speaker trick is brilliant! Did you build some sort of jig (or just use dots of the same spacing material, whatever that is) to space the foam the same distance off the speaker cloth/surface as it would be spaced from the inside of the fretwork? Did you do anything to take into account sound that might travel around the edges of the baffle (ie, go to the trouble of making end frames) and find that this makes much difference? (I'm curious, given that a few concertinas such as the Scard for the Manly Morris Men now for sale have fretwork openings in the end frames (and I have no idea how they sound), and on the melodeons I've seen with this -- notably, Owen Woods's Bergflødt -- this makes a huge difference in sound volume and tone.)

 

How effectively did you find that dampening part of the area (over the low note area) with more thickness worked? 

 

There can be so little clearance between the levers (when pads are up) and the inside of the fretwork! On the Beaumont particularly, this is something the maker must really pay attention to, to avoid a few extremely long levers clacking against the fretwork before the button is fully depressed. And, when it's working perfectly, you probably wouldn't have 2mm for foam! 


Edited by wayman, 16 May 2017 - 04:23 AM.


#27 wayman

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Posted 16 May 2017 - 03:59 AM

 

What color did you use?

 

 

You get right to the heart of the matter!!!  B)



#28 Don Taylor

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Posted 16 May 2017 - 08:36 PM

Hi Don,
 
I might give this 3mm foam a try.
Did you cut it with a hole in the center to match your action board?


I used a leather baffle that I made before as my template. Here is how I made the leather baffle:
http://www.concertin...showtopic=17355
I used a hollow punch to make individual holes in the baffle for each button.
 

Did you worry that you would make it such a tight fit that you would prevent air from passing at all? Did you cut little holes to let the air pass?

I found that the result was pretty air-tight so I added a small (about 3/16" dia) vent hole near the top of the leather baffle. This was enough to free up the bellows ability to get air.
 

Did you glue it to the inside of your grill?

No I used some small strips of sticky backed velcro. This has two effects (1) it raises the baffle off the end, and (2) made the baffle removable.

 

How would you say it affected your timbre, volume, and playability?

 The leather version cut down the volume quite a lot but it also made the tone a bit muffled.  After using it for a few weeks I decided that I did not like it.
 
The EVA foam only seems to reduce the volume, I don't notice a difference in tone.  It does not quieten the concertina as much as the leather baffle did, but I am happy with it.  I just wanted to quieten the left hand side lower reeds on an accordion reeded duet and not the whole concertina.
 

What color did you use?

 Black!  But you can get all sorts of colours.

 

There is a quality of my timbre that folks call shrill and can annoy, so I guess that I'm hoping it will cut down on the treble side of things as well as volume. Do you think I'll be disappointed or pleased?

If your recordings are anything to go by then you should ignore those naysayers. The tone on your Jeffries is just right for the music you play.

I think that you will be able to reduce the volume a little but keep the tone as it is.

But you could just buy some foam and experiment with it held against a speaker while it is playing one of your CDs. This might give you an idea on what it can do for you.

Whatever you do make it reversible.
 

Photos?

I will add some in the next day or two.

Don.



#29 Don Taylor

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Posted 16 May 2017 - 08:40 PM

This using the speaker trick is brilliant! Did you build some sort of jig ...


I have not actually tried this trick. It just occurred to in the middle of a sleepless night that it might be a lot easier than making different baffles to try.




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