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sleepymonk

Push vs Pull - why?

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I don’t agree with the fundamental premise of this discussion, at least with regards to playing ITM tunes on the Anglo. I start on pull as often as push, just depends on the tune.

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4 hours ago, eskin said:

I don’t agree with the fundamental premise of this discussion, at least with regards to playing ITM tunes on the Anglo. I start on pull as often as push, just depends on the tune.

 

...and I doubt that pushing the bellows would generally be more forceful than pulling; IMO it's rather the pulling that allows for greater volume (whereas in fact pushing the bellows might favour a vigorous attack).

 

Best wishes - 🐺

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11 hours ago, wunks said:

 A concertina reed whether Anglo, English or duet is a push reed or a pull reed, never both.  Whoever invents a bi-directional single reed assembly will revolutionize the instrument.

 

 

 

I was reading the link that Howard Mitchell provided in his response, and read a bit of the reference to Wheatstone’s Letters Patent in the 1840s. Wheatstone’s fourth improvement was a tongue that would produce the same note on a push or pull, using a self-acting valve. Is this what you had in mind?

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11 hours ago, wunks said:

 Whoever invents a bi-directional single reed assembly will revolutionize the instrument.

 

 

Ha!  I invented such an animal and got a patent for it just for fun, and of course there was no revolution.  Bi-directionality is only a small part of the many issues involved in making such basic changes to an old hand-crafted technology.   I'd rather not bring up this issue again, but you relative new comers can do a search for old threads on this issue.  

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19 minutes ago, ttonon said:

but you relative new comers can do a search for old threads on this issue.  

 

yes indeed 😁

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9 hours ago, wunks said:

Yes, and the down bow expends its energy abruptly, then peters out , whereas the up bow reserves it's power and options.

 

Therein lies one of the many challenges of bowing: maintaining an equal pressure and tone from one end of the bow to the other, regardless of bow direction. Depends on the music being performed.

 

I’m trying to draw on my experience as a violinist (where possible) in phrasing and articulation on the concertina, without pushing my luck.

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2 hours ago, ttonon said:

Ha!  I invented such an animal and got a patent for it just for fun, and of course there was no revolution.  Bi-directionality is only a small part of the many issues involved in making such basic changes to an old hand-crafted technology.   I'd rather not bring up this issue again, but you relative new comers can do a search for old threads on this issue.  

 

My assumption that such an animal didn't exist was based on a side conversation in the "Tenor/Treble" thread January 2 in which skepticism was seemingly expressed as to any "successful" version of such a reed assembly.  My apologies.

Edited by wunks
clarify

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19 hours ago, ttonon said:

Hi Ted, I don't think we can look to Physics to help solve this riddle in the way you say.  From a physics point of view, the push and pull are entirely symmetric.  The reed cannot tell whether the pressure difference it experiences is either a push or pull.  Neither can the bellows.  A bellows can collapse from too much vacuum, but it can also blow outwards because of too much compression.  

I do agree that we can probably exert more force on the bellows with a push, mainly because of the way our muscles and skeleton are constructed.  I'm sure an anatomist can provide solid reasoning, but simply, the push is accomplished by some arm muscles and chest muscles, whereas the pull is accomplished by different arm muscles and back muscles.  Perhaps the main difference lies in stronger chest muscles than back muscles.  

Best regards,

Tom

www.bluesbox.biz

 

Hey Tom,

 

Well yes, I agree that the ergonomic explanation is more relevant.

 

But risking being pedantic, the push and pull are not quite symmetric from the point of view of physics.  I know that a reed set for the pressure differential in one direction will respond the same way as an identical reed set for the pressure differential in the other direction.  But the average pressure of the air that reed is surrounded by on the draw is lower than on the push, maybe by as much as 1/4 of a psi (1/60th of an atmosphere)?

 

But that wasn't my original point.   What I was trying to say was that there is a theoretical limit of one atmosphere pressure differential on the draw, as the interior of the bellows approaches perfect vacuum.   Of course the bellows would collapse much, MUCH sooner.  On the push there is no such limit, so a much higher pressure differential is theoretically possible, although you are of course correct that the bellows would blow out, again this would happen much sooner than a pressure differential of one atmosphere!  I think considering the effect of the asymmetrical limits is interesting, even though we ought never be pushing or pulling at such extremes. 

Edited by Tradewinds Ted

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9 hours ago, Wolf Molkentin said:

 

...and I doubt that pushing the bellows would generally be more forceful than pulling; IMO it's rather the pulling that allows for greater volume (whereas in fact pushing the bellows might favour a vigorous attack).

 

Best wishes - 🐺

That vigorous attack would be the reason a push might be useful on the downbeat of a bar though!

 

As for the original premise of whether the push really IS more common on the downbeat, it does indeed depend upon the tune.  But, I would suggest it is true when playing along the rows in one of the home keys of the instrument.  These downbeats are somewhat more likely to be notes found in the root chord, and therefore more available on the push.  Passing notes in the melody, which are not in the chord, are somewhat more often found off the beat.  This falls apart for Irish traditional music commonly played in D major on a C/g Anglo, because many of the notes in the root chord are NOT available on the push in the core of the instrument, so starting a bar on the draw would therefore be required rather more often.

 

Notice that I am specifying the start of a bar since that is what was mentioned in the original post, not the start of a tune which could be pick-up notes just before the first full bar.

Edited by Tradewinds Ted

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43 minutes ago, Tradewinds Ted said:

But that wasn't my original point.   What I was trying to say was that there is a theoretical limit of one atmosphere pressure differential on the draw, as the interior of the bellows approaches perfect vacuum.   Of course the bellows would collapse much, MUCH sooner.  On the push there is no such limit, so a much higher pressure differential is theoretically possible, although you are of course correct that the bellows would blow out, again this would happen much sooner than a pressure differential of one atmosphere!  I think considering the effect of the asymmetrical limits is interesting, even though we ought never be pushing or pulling at such extremes. 

 

On push, the limit is usually the pressure at which the pads start to leak, like a safety valve on a boiler. That doesn't happen on pull.

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19 hours ago, wunks said:

 A concertina reed whether Anglo, English or duet is a push reed or a pull reed, never both.

 

Yes, but the reed that sounds on push has almost the same environment as the one that sounds on pull. The difference in absolute air presure pointed out by Tradewinds Ted is very slight. The fact that one reed is inside the chamber and the other is on the other side of the sound board is more significant, but still makes only a slight difference.

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1 hour ago, Tradewinds Ted said:

But the average pressure of the air that reed is surrounded by on the draw is lower than on the push, maybe by as much as 1/4 of a psi (1/60th of an atmosphere)?

Hi Ted, yes, we can distinguish between average pressure on the reed and pressure difference across reed.  Let's stick with practical numbers.  A typical pressure difference is about 5 inches Water Column, so for that same pressure difference, the push reed experiences 5 inches WC higher average pressure than the draw reed (2.5 + 2.5 in WC).  I fail to see though how that is significant concerning the playing of the reed.  One atmosphere is about 14.7 psi absolute, or about 408 in WC, and so the average pressure difference is only 5/408 = 0.0122 parts in atmospheric pressure. 

How can that slight average pressure affect the operation of our friend the free reed?  The only way I see is through density, but still, only a 1.2% difference in density is very small.  If you're curious enough, you can try to discern such an effect of density by playing your concertina at sea level and compare the sound to playing at about 500 feet above sea level.  Keeping the temperature the same, that will correspond to about a 1.2% difference in atmospheric density.  

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Ok, so my estimate of the average pressure difference as 1/60th, or 0.017 of atmospheric pressure, though admittedly small, was nearly 1.4 times bigger than your more informed estimate of 0.0122 of atmospheric pressure.  I think I guessed pretty well then, and but more importantly I must admit you are correct that the difference is not likely to be consequential.

 

I also forgot about the eventual practical upper limit of pads lifting if the pressure inside the bellows is too high, before the bellows blow out.

 

Sorry to have side-tracked the conversation quite so much, as I do agree that ergonomic considerations are likely the real reason why most (not all) types of diatonic bellows instruments have been standardized to start the scale on the push (or blow, for harmonica.)  And that in turn MAY lead to push notes more often on the downbeat, as discussed previously.

 

 

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On 8/14/2019 at 8:15 PM, sleepymonk said:

I would love to try a "wrong" direction concertina just to satisfy my curiosity. Can't afford a custom build to find out :< Looking forward to the revolution!

 

Well, if you really want to try it, you may be able to do so for free:   What make of concertina do you have?  and how do you feel about opening it up and tinkering?

 

If yours is a traditional concertina reed instrument, you likely could swap out all the reeds (keeping them in their reed shoes) to the opposite side of the reed pan, if the reed shoes for the push and pull reed under each button are the same size, or very close.  Absolutely free to try, and completely reversible once you are done, as long as you have carefully marked where each one was originally!  For any one button, the notes on the push and pull are usually very close in pitch so the reeds/shoes are likely to be very close in size.

 

If it is a hybrid/accordion reed instrument, and the reeds are fixed in pairs to plates screwed to the reed pan, then it is likely very easy to just turn each of those plates upside down (inside out?) to reverse the reeds, and again, this is free and completely reversible.  Again, be sure to carefully mark how they were originally.  A friend of mine actually did flip the plate holding the reeds for the C#/Eb on the right hand of one of his Wheatstone system Anglo concertinas, to make it more similar to his other Jeffries system instruments, at least for playing in D.  I changed it back, when I later bought his instrument, and it only took a couple minutes to carefully swap the one plate, so swapping thirty of them could be done well inside of an hour.

 

On the other hand, if they are accordion reeds waxed in... while this is theoretically also reversible with new wax, it would be a terrible hassle, and an amateur attempt seems a catastrophe waiting to happen. I wouldn't do it!

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You'd have thought that if the bellows direction for the start made any difference, English and duet players would have cottoned on and exploited the effect. I've never heard it mentioned. Certainly, as a duet player, I can't think of a single tune that I don't start with a pull. That is simply because it seems natural - closed bellows is the starting position. There would have to be some obvious advantage to go to the trouble of opening the bellows wide before starting.

 

LJ

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51 minutes ago, Little John said:

You'd have thought that if the bellows direction for the start made any difference, English and duet players would have cottoned on and exploited the effect. I've never heard it mentioned. Certainly, as a duet player, I can't think of a single tune that I don't start with a pull. That is simply because it seems natural - closed bellows is the starting position. There would have to be some obvious advantage to go to the trouble of opening the bellows wide before starting.

 

LJ

 

To add on that: for me, as a duet player, pull is much more natural from ergonomic point of view to a point, where I can play some phrases only on a pull or heavily struggle to play them on push, so if I could I would only play on pull :D. This is because I play fast phrases/short notes using retracting finger muscles which are naturally weaker and are further inhibited with push bellows direction. Another reason is because I operate bellows with my melody hand and pull direction is stable ballance wise (you go away from pivot point) and push can become unstable with higher volume and requires more controll.

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1 hour ago, Łukasz Martynowicz said:

Another reason is because I operate bellows with my melody hand and pull direction is stable ballance wise (you go away from pivot point) and push can become unstable with higher volume and requires more controll.

 

I believe this is an issue worth discussing separately, so I opened another thread:

 

 

Edited by RAc

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9 hours ago, Tradewinds Ted said:

Ok, so my estimate of the average pressure difference as 1/60th, or 0.017 of atmospheric pressure, though admittedly small, was nearly 1.4 times bigger than your more informed estimate of 0.0122 of atmospheric pressure.  I think I guessed pretty well then, and but more importantly I must admit you are correct that the difference is not likely to be consequential.

 

I also forgot about the eventual practical upper limit of pads lifting if the pressure inside the bellows is too high, before the bellows blow out.

 

Sorry to have side-tracked the conversation quite so much, as I do agree that ergonomic considerations are likely the real reason why most (not all) types of diatonic bellows instruments have been standardized to start the scale on the push (or blow, for harmonica.)  And that in turn MAY lead to push notes more often on the downbeat, as discussed previously.

 

 

 

I don’t think the conversation got side-tracked at all. I learned a few new things.

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