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Author Topic: The 21st Century Box  (Read 34852 times)

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IanD

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Re: The 21st Century Box
« Reply #80 on: October 02, 2011, 10:07:41 PM »

And as soon as you do something like the Schweizeorgeli you've gone away from the whole flat-mounted reeds concept...

I'm not so sure. All of the reeds are flat mounted in the Orgeli, in that the pallet lies in the same direction as the reed... rather than perpendicular as in a block.

I meant the idea of flat-mounted reeds right next to the "outside world" with the minimum of obstacles in the way.
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Owen Woods

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Re: The 21st Century Box
« Reply #81 on: October 02, 2011, 11:15:30 PM »

But what obstacles are in the way? The levers I suppose, but they are just bits of metal, I can't imagine that they are hugely important in the sound given. The inside of the reedbox perhaps, although this may focus the sound in a pleasing way.
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Chris Ryall

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Re: The 21st Century Box
« Reply #82 on: October 03, 2011, 08:06:46 AM »


I'd always thought of reeds as an 'inside' thing - but there really is no reason other than protection. I think the old problem of beard bits/upset reeds would be rather more prevalent, but there's no  fundamental engineering issue. interesting.  :|glug
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oggiesnr

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Re: The 21st Century Box
« Reply #83 on: October 03, 2011, 09:26:30 AM »

So going back to very basics, does it have to be "melodeon" shaped?

The distinguishinf feature of a melodeon is it's push/pull diatonic right hand and it's bass end.  Could these be handled better in a different physical structure?

This is Harry Geuns' hybrid bandoneon design with the buttons on the leading edge so to speak. http://www.bandoneon-maker.com/harrygeuns.htm (sorry but his website doesn't seem to let me quote the exact page, follow the link to "Hybrids" on the navigation bar)  It's unisonoric (and I don't really consider it a bandoneon  (:)) but it is a different approach.

I have also seen bandoneon shaped "concertinas" with chords on the bass end.

How wedded are we to the melodeon "look"?

Steve
« Last Edit: October 03, 2011, 09:29:11 AM by oggiesnr »
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Re: The 21st Century Box
« Reply #84 on: October 03, 2011, 09:45:49 AM »

So going back to very basics, does it have to be "melodeon" shaped?

The distinguishinf feature of a melodeon is it's push/pull diatonic right hand and it's bass end.  Could these be handled better in a different physical structure?

This is Harry Geuns' hybrid bandoneon design with the buttons on the leading edge so to speak. http://www.bandoneon-maker.com/harrygeuns.htm (sorry but his website doesn't seem to let me quote the exact page, follow the link to "Hybrids" on the navigation bar)  It's unisonoric (and I don't really consider it a bandoneon  (:)) but it is a different approach.

I have also seen bandoneon shaped "concertinas" with chords on the bass end.

How wedded are we to the melodeon "look"?

Steve

Or a Franglo

http://www.concertina.info/tina.faq/images/dipp.htm
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IanD

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Re: The 21st Century Box
« Reply #85 on: October 03, 2011, 03:54:56 PM »

But what obstacles are in the way? The levers I suppose, but they are just bits of metal, I can't imagine that they are hugely important in the sound given. The inside of the reedbox perhaps, although this may focus the sound in a pleasing way.

Anthing beween the reed and the "outside world" will affect the sound, and this may or may not be in a "pleasing" way -- I doubt that much research has been done into this (except by building boxes "the way they're built") so the good/bad result is probably random, and usually in a case like this the odds are greatly in favour of messing things up rather than improving them. I know cassotto chambers deliberately add such cavities to "improve" the sound, but I didn't like the resulting dullness (or you could call it richness...) on the ones I've heard.

All I know is that the boxes I like the sound of best tend to have the least obstructions between the reeds and the ear (big pallet holes, this pallet board, open grille). Of course it's possible that like super-heavily-hopped American IPAs more is not always better and the flat-mounted reeds idea I've been suggesting will indeed sound too bright, but there's only one way to find out...

Ian
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Steve C.

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Re: The 21st Century Box
« Reply #86 on: October 03, 2011, 06:45:12 PM »

Must have a foot bass.  Must have a foot bass.  Must have a foot bass. >:E
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Stiamh

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Re: The 21st Century Box
« Reply #87 on: October 03, 2011, 08:00:48 PM »

All I know is that the boxes I like the sound of best tend to have the least obstructions between the reeds and the ear (big pallet holes, this pallet board, open grille). Of course it's possible that like super-heavily-hopped American IPAs more is not always better and the flat-mounted reeds idea I've been suggesting will indeed sound too bright, but there's only one way to find out...

Ah, I think I know the answer to that one... get yourself a very large development budget?  >:E

IanD

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Re: The 21st Century Box
« Reply #88 on: October 03, 2011, 09:45:33 PM »

All I know is that the boxes I like the sound of best tend to have the least obstructions between the reeds and the ear (big pallet holes, this pallet board, open grille). Of course it's possible that like super-heavily-hopped American IPAs more is not always better and the flat-mounted reeds idea I've been suggesting will indeed sound too bright, but there's only one way to find out...

Ah, I think I know the answer to that one... get yourself a very large development budget?  >:E



Maybe some kind person will step up to the bar, so to speak... ;-)

Ian

P.S. "Large" needs to be taken in context -- development budget for one of our chips is >10M...
« Last Edit: October 04, 2011, 12:54:44 PM by IanD »
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Owen Woods

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Re: The 21st Century Box
« Reply #89 on: October 04, 2011, 01:31:31 AM »

But what obstacles are in the way? The levers I suppose, but they are just bits of metal, I can't imagine that they are hugely important in the sound given. The inside of the reedbox perhaps, although this may focus the sound in a pleasing way.

Anthing beween the reed and the "outside world" will affect the sound, and this may or may not be in a "pleasing" way -- I doubt that much research has been done into this (except by building boxes "the way they're built") so the good/bad result is probably random, and usually in a case like this the odds are greatly in favour of messing things up rather than improving them. I know cassotto chambers deliberately add such cavities to "improve" the sound, but I didn't like the resulting dullness (or you could call it richness...) on the ones I've heard.

All I know is that the boxes I like the sound of best tend to have the least obstructions between the reeds and the ear (big pallet holes, this pallet board, open grille). Of course it's possible that like super-heavily-hopped American IPAs more is not always better and the flat-mounted reeds idea I've been suggesting will indeed sound too bright, but there's only one way to find out...

Ian

I agree about cassotto chambers... but they are a right angle in the air flow inside the block. With such a large cavity I'd be surprised if the cassotto effect was noticeable.

I think that someone should have a go at your idea of a box. Easiest way would be to get a 1140 one row 2 voice, rip out the soundboard and replace with a CNC drilled one. Job done. Do lots of recordings before and after, try analysing the spectrum as well. No need to change the mechanism, the blocks are already in the right orientation so it would just be a case of copying it in aluminium and sticking it in. A 1140 could set you back £100 for one in good nick or much less for one which is a bit beat up. Getting the board milled would cost you... more.
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Re: The 21st Century Box
« Reply #90 on: October 04, 2011, 07:59:56 AM »

Jeez, Ukebert - quite a lot of work and you'd have to be handy too.  Also those spectral analysers aren't hanging about loose. I think you're describing less an amateur hobbyist's evening diversion, more a systematic technical project that would be more suitable for a final year engineer.  :|glug
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IanD

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Re: The 21st Century Box
« Reply #91 on: October 04, 2011, 11:45:43 AM »

Jeez, Ukebert - quite a lot of work and you'd have to be handy too.  Also those spectral analysers aren't hanging about loose. I think you're describing less an amateur hobbyist's evening diversion, more a systematic technical project that would be more suitable for a final year engineer.  :|glug

You don't need an expensive benchtop spectrum analyser, a decent mic and a PC soundcard with analysis software will do the same thing for much less. Getting the CNC milling done is easy (it just costs money) but software to do the design may be rather expensive, it's not the kind of thing aimed at the hobbyist market -- a complete suite of custom chip design software like we use costs more than a million dollars per head...

But I agree that yet again we're talking about a proper engineering investigation...

Ian
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oggiesnr

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Re: The 21st Century Box
« Reply #92 on: October 04, 2011, 12:13:20 PM »

A 50-100 watt laser cutter with the design processed through CorelDraw should do the job, albeit slowly.  Using that technology I'd be tempted to use perspex rather than aluminium (cuts easier with a lower power laser).  Again for the same reason possible MDF rather than plywood although there can be issues round cutting some grade of MDF that way.

Steve
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IanD

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Re: The 21st Century Box
« Reply #93 on: October 04, 2011, 12:47:27 PM »

A 50-100 watt laser cutter with the design processed through CorelDraw should do the job, albeit slowly.  Using that technology I'd be tempted to use perspex rather than aluminium (cuts easier with a lower power laser).  Again for the same reason possible MDF rather than plywood although there can be issues round cutting some grade of MDF that way.

Steve

I think you need a proper CNC depth miller to machine out the reed chambers, especially given the slope on the chamber floor.

Ian
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Owen Woods

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Re: The 21st Century Box
« Reply #94 on: October 04, 2011, 07:03:59 PM »

Jeez, Ukebert - quite a lot of work and you'd have to be handy too.  Also those spectral analysers aren't hanging about loose. I think you're describing less an amateur hobbyist's evening diversion, more a systematic technical project that would be more suitable for a final year engineer.  :|glug

Well I did suggest it! Spectral analysers you can buy software for, but it would be a nightmare to get repeatable results - if you were doing it properly you'd have to have something which maintains a constant pressure in the bellows. I reckon that you could get a very vague impression of the effect by simple measurements though, blind tests and so on. Would be vague.

Well I have a copy of solidworks, that's all you would need. It's a moderately expensive piece of software I believe (I got it free by careful persuasion) but it would do the job. Then just hire someone to do the work. I'd describe that as trivial though, as all you need is money!
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IanD

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Re: The 21st Century Box
« Reply #95 on: October 05, 2011, 12:13:31 PM »

Jeez, Ukebert - quite a lot of work and you'd have to be handy too.  Also those spectral analysers aren't hanging about loose. I think you're describing less an amateur hobbyist's evening diversion, more a systematic technical project that would be more suitable for a final year engineer.  :|glug

Well I did suggest it! Spectral analysers you can buy software for, but it would be a nightmare to get repeatable results - if you were doing it properly you'd have to have something which maintains a constant pressure in the bellows. I reckon that you could get a very vague impression of the effect by simple measurements though, blind tests and so on. Would be vague.

Well I have a copy of solidworks, that's all you would need. It's a moderately expensive piece of software I believe (I got it free by careful persuasion) but it would do the job. Then just hire someone to do the work. I'd describe that as trivial though, as all you need is money!

You might need an acoustic laboratory with calibrated microphones to to accurate absolute measurements, but you can do accurate comparative ones with a reasonable mic and a PC audio input -- I should know, I've spent a lot of time playing with speakers at the bottom of the garden and it's easy to reliably measure differences well below 1dB which would be completely inaudible.

Given that measurements can undoubtedly detect differences we can't hear (0.01% amplifier distortion vs 0.001%, anyone?) small changes in the response will undoubtedly happen, either due to small construction or material differences, but a small move in a narrow resonant peak or dip is unlikely to be audible (see the paper just posted in the soundboards thread). So unless the measured changes are so big that it's obvious that they'll be easily audible (which I suspect they will be with the milled reed-pan idea, otherwise I wouldn't be suggesting it) you still need listening tests to detect whether people can actually hear the difference.

Also since long-term audio memory is unreliable you have to hear the things you're comparing in quick succession, so 2 boxes would be needed which are identical apart from the change under investigation.

Incidentally it looks like somebody has stepped up to the bar and plans to build a box using my ideas, but prefers to remain anonymous for commercial reasons.

Ian

P.S. No fishing, I'm just not going to take the bait ;-)
« Last Edit: October 05, 2011, 12:22:44 PM by IanD »
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IanD

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Re: The 21st Century Box
« Reply #96 on: October 05, 2011, 06:32:15 PM »

This might have been posted before, but here are some sources of information about free-reed acoustics:

http://physicstoday.org/resource/1/phtoad/v64/i3/p44_s1?bypassSSO=1 -- most recent, PDF has more detail
http://www.public.coe.edu/~jcotting/acoustics.html -- earlier detailed papers
http://www.concertina.org/pica/pica_2005_2/html/reed_cavity_design_resonance.htm -- by Tom Tonon

Most concentrate on the reed itself, Tom Tonon's paper delves into reed chamber resonances and their (mostly bad!) effects.

There's nothing I can find *anywhere* about pallet board and body materials :-)
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Andy in Vermont

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Re: The 21st Century Box
« Reply #97 on: October 05, 2011, 06:57:51 PM »

There's nothing I can find *anywhere* about pallet board and body materials :-)

Ian, years ago (2004 or before), Wim Wakker did a presentation at a concertina conference in NY City on free reed acoustics, and while he did focus largely on the reed and reed shoe, he also discussed the body materials and grille -- I'm not certain if this paper, or some version of it, is published somewhere, but you might be able to find it, and I believe you will find it interesting.  In that context, he made some comments comparing the kind of harmonics that were desired for accordions versus concertinas, but I don't recall whether it was really part of the paper, or just an extended response to someone's question after the paper.
-Andy

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Re: The 21st Century Box
« Reply #98 on: October 05, 2011, 07:18:39 PM »

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IanD

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Re: The 21st Century Box
« Reply #99 on: October 06, 2011, 11:46:24 AM »

http://www.concertinaconnection.com/concertina%20reeds.htm

That sounds like it...

Thanks, another interesting paper.

There's a bit at the end that says:

          The type of wood used for the ends plays only a small role it the sound quality of a concertina. The
          sound produced by the vibration of the ends is nihil compared to the sound reflection they cause. There
          is a difference between instruments with hard and soft wooden ends, but again, it is the absorbing effect
          that causes the difference, not the vibrating of the ends.

which I think agrees with what I've been saying.

Looking more deeply into the effect of body resonances in boxes, I think that saying that the pallet board and/or body should resonate because that's what stringed instruments do is missing the point -- stringed instruments have had years of extensive research (or trial and error) to find parameters for material/thickness/shape which make the instrument sound good, and if you get these wrong you can get truly horrible-sounding instruments with wolf notes and dead zones -- even small changes like moving a brace or a bass bar can radically alter the sound. But stringed instruments by their nature rely on resonant structures to radiate the sound, they don't have any choice.

Also instruments which rely on resonant structures or cavities or air columns need a huge size range to cover the frequency range of a small free-reed instrument -- think of double bass to violin, or bass to sopranino sax, or pipe length in organs -- to get the resonant frequencies to match the instrument range and enhance the sound. The sound generation mechanism in free-reed instruments is much more scale-invariant so a given size body covers a very wide range of frequencies, and this makes it almost impossible to come up with any structure where resonant sound enhancement can possibly work over anything like the entire range of the box, it's basically much too small and stiff and covers too wide a frequency range.

So any resonances are likely to occur at quite high midrange frequencies and be uneven across different notes. Funnily enough, this is precisely what stringed instrument makers try very hard to avoid because it gives an uneven, peaky, harsh sound, so I can't see why anyone could think this is a good idea for boxes. The idea that you can just aim to build a box which happens to sound good due to resonances by chance is crazy, odds are probably at least 10-to-1 in favour of it sounding worse, not better -- and if one did happen to sound good, changing anything (wood, thickness, material, size, reed blocks...) would be likely to tip it off the "good" peak again.

The other risk is that sharp resonances tend to absorb energy, which leads to "wolf notes" in violins (which won't play stably) and problems with reeds starting our sounding in free-reed instruments (see Tom Tonon's paper). At lower frequencies where you might feel the body vibrate a different problem occurs (the structure becomes acoustically transparent), because you have uncontrolled radiation from the body which will also vary across notes -- whether this is loud enough compared to the normal sound from the reed is a moot point, but again this can hardly be a good thing.

One example that I know of for sure is that the sound holes in the bass end cover form a Helmholtz resonator with the volume of the air inside the bass end, and this acts as a lowpass filter (which you do want to remove the treble spectrum and stop it obscuring the right hand) but with a peak around cutoff -- this can lead to an unpleasant "honky" sound from the bass end. My Oakwood suffers from this to some extent, so I measured the spectrum and found such a peak which goes away if you take the bass cover off (but then there's too much treble). The frequency corresponds with the resonance calculated from the hole sizes and internal volume (I used reflex port calculations from speaker design which include the end effect for holes in thin panels).

My Dony 3-row has smaller cover hole area and more internal volume, a lower resonant frequency and a less nasal sound (but is also more muffled) -- since the reed blocks in the Model 4 were based on the ones in my 3-row I know this isn't causing the difference.

But I doubt whether many box makers are aware of what's going on, at best they probably drill more holes until they got the sound they wanted -- maybe Oakwood did this and picked a relatively large hole area to get a brighter louder bass end sound to match the bright treble end, but at the cost of a not-so-pleasant honky sound.

I have an idea (based on many years of speaker design experience) on how to fix this problem, but this time I'm not going to tell everyone since it looks like my "ideal" box may actually get built ;-)

Cheers

Ian
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