Jump to content


Photo

Reed Vent Widths


  • Please log in to reply
31 replies to this topic

#1 alex_holden

alex_holden

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 576 posts
  • Gender:Male
  • Location:Lancashire

Posted 12 April 2017 - 02:25 AM

Why do low reeds have wider vents than high ones? What would happen if one were to make a set of reeds that were all the same width?

Related question: if one were to proportionally scale all the reeds wider or narrower (not changing the lengths or profiling), what effects would that have on the instrument?

#2 David Hornett

David Hornett

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 184 posts
  • Gender:Male
  • Location:Hobart

Posted 12 April 2017 - 02:52 AM

I don't know the answer, but I do make all my reeds 10% wider than the corresponding Lachenal pitch 'cause I thought it may alter the volume, but there seems little difference, I guess it would be hard to hear 10% and even harder to attribute it just to the reed width. Possibly width increases the pressure required of sound the reed, it would certainly add to air usage, but again at 10% it is hard to notice anything.

 

As far as I understand, it is not width but length and profiling, including end weights on bass reeds, that alters pitch.

 

I have got some rather wide reed shoes I could send you if you would like to file them out and experiment, they can take a lot of widening, I overdid the design and then had a few thousand laser cut before making a concertina .. Hmmm ... live and learn. I use them in my instruments, but have some to spare.

 

David



#3 Geoff Wooff

Geoff Wooff

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 2097 posts
  • Gender:Male
  • Location:France

Posted 12 April 2017 - 04:23 AM

One of the old makers  ( was it George  Jones ?)  who marketed a  "Broad Steel  Reed"  Anglo.  These models had significantly wider reeds  than  other makes. The  tone was very nice but     these instruments were not quick  to speak.  Perhaps  they just needed a bit more  pressure ?  I have had several of these  through my hands over the years and they  all  display this  less than rapid  attack    but very nice tone quality.



#4 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 12 April 2017 - 04:57 AM

"As far as I understand, it is not width but length and profiling, including end weights on bass reeds, that alters pitch." Yes thats the case.

 "it would certainly add to air usage, but again at 10% it is hard to notice anything." agree

"I thought it may alter the volume" of cores but the Volume we hear is in logarithmic relationship. By Dubbing the width Amplitude is also doubled but we hear not much change in Volume because + 6dB is 1,52 of the actual heard increase loudness. Easier is it to imagine to double or divide the distance to the instrument by lessening would equal to double or divide the width by two of a reed. The hole thing is much more complicated in reality. Depending on pitch all vary a bit and also depending on the staring Volume. So one would notice an increase of volume but not as much as one would expect. An other effect my more be getting a problem on high pitched reeds if the relation on length to width is modified. The reed also produces sound in its cross section (torsion vibrations) normally not taken in account but such high pitched reeds with increased width may produce unwanted modes and therefore irritating overtone structures. Bud please do some tests would be interesting to see and hear the result.

Best regards Joahnn Pascher


Edited by Johann, 12 April 2017 - 05:14 AM.


#5 David Hornett

David Hornett

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 184 posts
  • Gender:Male
  • Location:Hobart

Posted 12 April 2017 - 05:17 AM

The Jones 'broad steel reeds' are parallel reeds, at least the Jones I have is, and yes it is a little slow to speak, and very mellow with a bit of a woody echo. My reeds are also wide and parallel, but they don't have the same tone as the Jones, and i like to think that my latest instrument is just a little quicker.

 

I once put a (tapered) Lachenal reed in the Jones  (C5), the shoe had to be packed, (the reed tongue had broken and I had at that stage not got around to making a new one). However the Lachenal  reed played more like a Jones than a Lachenal, so we may have a lot of other factors at work too, for instance my Jones reed chambers are not tapered to the instrument's centre like the Lachenal, and they are also a little deeper, whether this makes a difference or not I have no idea.

 

Thank you Joahnn, I found your comments about amplitude and volume interesting.

 

David 



#6 alex_holden

alex_holden

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 576 posts
  • Gender:Male
  • Location:Lancashire

Posted 12 April 2017 - 06:25 AM

I have got some rather wide reed shoes I could send you if you would like to file them out and experiment, they can take a lot of widening, I overdid the design and then had a few thousand laser cut before making a concertina .. Hmmm ... live and learn. I use them in my instruments, but have some to spare.


Thanks for the offer, David. I have a small CNC milling machine and have made a handful of prototype reed frames on it so far. I'm currently designing the full set of reeds for my first instrument in CAD, and got to wondering how/why the original makers chose the widths they did. There must be some sort of compromise factors involved.

Incidentally the Lachenal reeds I'm working from are slightly tapered, with the taper varying without much apparent logic between about 0.75 and 1.5 degrees. I decided to rationalise on a 1 degree taper for all of mine. I'm also using a different length and tip width for every pitch (it wasn't much more work, and I figure it should make the profiling simpler).

#7 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 12 April 2017 - 07:58 AM

"with the taper varying without much apparent logic between about 0.75 and 1.5 degrees" this tapering is it on the reed tongue?

I am from Austria i i only have experience with accordion reeds. 



#8 alex_holden

alex_holden

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 576 posts
  • Gender:Male
  • Location:Lancashire

Posted 12 April 2017 - 08:14 AM

"with the taper varying without much apparent logic between about 0.75 and 1.5 degrees" this tapering is it on the reed tongue?
I am from Austria i i only have experience with accordion reeds.


Yes. Looking down on the reed from above, the free end is slightly narrower than the clamped end. I think this aids with fitting it accurately, because if you make the reed too long and initially slightly too narrow but with the correct taper angle, you can keep filing metal off the tip and moving the reed forwards a bit at a time until the side clearance is just right.

#9 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 12 April 2017 - 09:16 AM

"I think this aids with fitting it accurately, because if you make the reed too long and initially slightly too narrow but with the correct taper angle, you can keep filing metal off the tip and moving the reed forwards a bit at a time until the side clearance is just right."

Yes this is the main reason way this is done. But there are other reasons for this as well. The old DIX mensur for accordions had both tapered and parallel reeds on the same set parallel for the lower pitched reeds.I also know old accordion reeds that had different amount of tapering and width. Also remember of having seen old reeds with the tapering the other way round. The timbre of the reed is effected. But it is nearly in possible to describe in witch way.  So if you want to copy the old sound keep as close to the original dimensions as possible. But keep in mind that the final result always will be slightly different. And as mentioned before here there are other aspects that contribute to the sound as well not only the reed itself. I find it very exiting that you do make the reeds your self on the small CNC. I have a self built CNC too. but i use it manly for wood and Aluminium. Would you share the drawings? i am thinking of making one day my own Concertina as well and i don't want to use Accordion reeds. Best regards, Johann   

  

 

 



#10 Mike Pierceall

Mike Pierceall

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 451 posts
  • Gender:Male
  • Location:Southern California U.S.A.

Posted 12 April 2017 - 11:58 AM

Why do low reeds have wider vents than high ones? What would happen if one were to make a set of reeds that were all the same width?

Related question: if one were to proportionally scale all the reeds wider or narrower (not changing the lengths or profiling), what effects would that have on the instrument?

This is a 32' reed from one of my harmonium restorations.  It speaks as quickly as the smallest reed in the organ.  Large reeds need to be sturdy due to the force required to lift them.  I once restored an organ where 7 of the sub-bass reeds were broken off at the heel and the tongues had been sucked into the air reservoir.

Attached Thumbnails

  • IMG_2017.JPG


#11 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 12 April 2017 - 02:13 PM

This may be different in reed organs, but i do a lot with very low reed and big size of reeds in styran type diatonic accordions. It also depends a lot of the size oft the reedchamber.

But for sub contra basses it is very difficult to get them speek as fast as mid range reeds.  And it is not a question of the width. Best regards, Johann



#12 David Hornett

David Hornett

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 184 posts
  • Gender:Male
  • Location:Hobart

Posted 12 April 2017 - 05:00 PM

Johann, I play diatonic accordion, but what is a 'styran type diatonic accordion'? Is it an Austrian Diatonic with the very deep oompah type bass?

 

​I too find that the low bass concertina reeds are slower to speak (from about C3 down) but I figure it is my lack of skill at making them rather than some intrinsic characteristic of the reed.

 

David



#13 alex_holden

alex_holden

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 576 posts
  • Gender:Male
  • Location:Lancashire

Posted 13 April 2017 - 01:03 AM

This is a 32' reed from one of my harmonium restorations.  It speaks as quickly as the smallest reed in the organ.  Large reeds need to be sturdy due to the force required to lift them.  I once restored an organ where 7 of the sub-bass reeds were broken off at the heel and the tongues had been sucked into the air reservoir.


Although much bigger, the proportions don't seem very different from concertina reeds. Imagine if a reed this long was as narrow as the highest reeds in a concertina: intuitively I would expect it to perform poorly if at all, but I'm not sure that I understand the reasons why. Do lower reeds need a greater vent area (and consequently consume more air) because we need to make larger 'packets' of air to produce low frequency sounds?

#14 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 13 April 2017 - 04:54 AM

Johann, I play diatonic accordion, but what is a 'styran type diatonic accordion'? Is it an Austrian Diatonic with the very deep oompah type bass?

 

David

Hi David, Yes it is.  I go down to sub contra Ab 0 = 25,9 Hz Usual the basses are not as deep on this Instruments.  


Edited by Johann, 13 April 2017 - 04:55 AM.


#15 Chris Ghent

Chris Ghent

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 1053 posts
  • Gender:Male
  • Location:Blue Mountains NSW

Posted 13 April 2017 - 09:26 AM

I measured acouple of Jeffries sets about ten years ago and the taper in the reeds was consistent, not consistent as in a particular angle, but in that each reed vent, no matter the pitch, was 4thou (.1mm) narrower at the tip than the root. Consequently the taper angle increased as the pitch went up.

#16 alex_holden

alex_holden

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 576 posts
  • Gender:Male
  • Location:Lancashire

Posted 13 April 2017 - 01:31 PM

I measured acouple of Jeffries sets about ten years ago and the taper in the reeds was consistent, not consistent as in a particular angle, but in that each reed vent, no matter the pitch, was 4thou (.1mm) narrower at the tip than the root. Consequently the taper angle increased as the pitch went up.


Thanks, these Lachenals are definitely not that consistent. Perhaps they used an assortment of die sets that were made or repaired at different times. Using the same angle for them all will make it easier for me to cut the tongues because I won't have to keep adjusting the angle of the shear tool for each size.

#17 d.elliott

d.elliott

    Heavyweight Boxer

  • Members
  • PipPipPipPipPip
  • 1204 posts
  • Gender:Male
  • Location:Sheffield, South Yorkshire, England

Posted 13 April 2017 - 02:31 PM

For what it's worth, I was told that the taper on reeds from clamp to tip, is to make fitting quicker and easier, and when I have had to re-tongue a reed then I have always blessed the chap who thought of the idea, parallel reads are much harder to fit.

 

Johann Comments: "As far as I understand, it is not width but length and profiling, including end weights on bass reeds, that alters pitch." Yes thats the case.

 "it would certainly add to air usage, but again at 10% it is hard to notice anything." agree

 

Actually its the flexural rigidity in the bendy length of the reed balanced against the mass at the  swung end, the tip.  Recently I had to advise on a concertina, a new build' that was superb in all respects, except it played like a 'plum pudding'. The reeds were all the right things but the tongues were too thick in the bending area making the reeds to stiff to deflect and spring with the necessary amplitudes and response under normal playing pressures, The solution was to take the instrument flat by a full tone to thin the reeds, then bring the reeds back to pitch. If I am re-tonguing a reed I spend a lot of effort determining the reed target thickness as well as the fit to the reed frame.

 

Dave



#18 Johann

Johann

    Chatty concertinist

  • Members
  • PipPipPipPip
  • 104 posts
  • Location:Upper Austria

Posted 14 April 2017 - 11:26 AM

 

 

Actually its the flexural rigidity in the bendy length of the reed balanced against the mass at the  swung end, the tip.  Recently I had to advise on a concertina, a new build' that was superb in all respects, except it played like a 'plum pudding'. The reeds were all the right things but the tongues were too thick in the bending area making the reeds to stiff to deflect and spring with the necessary amplitudes and response under normal playing pressures, The solution was to take the instrument flat by a full tone to thin the reeds, then bring the reeds back to pitch. If I am re-tonguing a reed I spend a lot of effort determining the reed target thickness as well as the fit to the reed frame.

 

Dave

Hi Deve i take this as the normal condition that "flexural rigidity in the bendy length of the reed balanced against the mass at the" is in optimal state.  sure this may not always be the case and one has to optimist as you explain. Of cores it can be the other way round as well. If if the reed is already to flexible one cant do anything as replacing.  If you compare reeds withe the same  flexural rigidity and mass then one can compare volume in relation to widths. There is also a bit of possible variation depending on the type of musician, especial in accordions newer reeds tend to be stiffer as older reeds in rather old accordions. And the exact opposite can be noticed stiffer reeds can produce more Volume in accordions but the want be as fast in talk reaction and want speak as as easy with low pressure. So in the end it is not so easy to answer whats best it also depends on the instrument and the plying style of the musician. So i understand that you as i can do a lot to reeds to make them suitable to the accordion and the musician. Talking abut how width contributes to volume is an totally different thing. Sure the type of profiling also my contribute to more or less volume but in the ed we don't have a lot of choice in variation the profile at a given length and pitch. Best regards Johann






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users