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 Post subject: PRESSURE
PostPosted: Sun Jun 14, 2020 4:37 pm 
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I hear this term, "back pressure" a lot in regard to whistles. What is it and how does affect a whistle's tone of playability? Is it desirable?

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 Post subject: Re: PRESSURE
PostPosted: Sun Jun 14, 2020 8:46 pm 
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Michael,

I would say, back pressure is analogous to drinking through a straw. Drinking through a a large diameter straw allows the drink to flow with ease. When you draw with force, more liquid easily flows, unrestricted. This would be like unto a whistle with low back pressure[/i]--air is able to flow freely through the whistle whether you blow with lots of force or little force.

Drinking through a small diameter straw limits the flow of the drink. When you try to increase the flow, you feel the pressure build in your mouth because the straw is too small to allow the flow you desire. This is like unto a whistle with [i]higher back pressure
. You may blow with great force, but, the whistle design restricts the flow of air. The harder you blow, the more you feel an increase in resistance to the pressure you are applying as the whistle limits the flow.

I wouldn't say back pressure is good or bad. I think it is about preference. I think most players (generally) fall in the middle--average back pressure works well for them. Others may prefer higher or lower.

It seems that back pressure whistle design can have some affect the tone of the whistle, and also affect your breathing--that is with little or no back pressure, you may expend all the air in your lungs quickly, before you get through a musical phrase. A whistle with lots of back pressure may allow you to get through a phrase in one breath, however, your body may desire a breath (oxygen) before you expend all the air in your lungs through the whistle; the opposite problem.


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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 2:34 am 
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That's pretty much how I see it too.

Although I'd just say with more back pressure it was harder to blow.

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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 10:04 am 
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I had never heard of "backpressure" regarding whistles until I joined this site. I had heard it referred to previously, with wind instruments, as "acoustic impedance".

Most of my experience has been on Highland bagpipes and flute. On both instruments there's a ratio between how much effort you put in and how much tone comes out.

Some instruments seem recalcitrant (brass players call it "stuffy") where it's like you have to force the tone through the thing, and the amount of effort you put in doesn't seem to be adequately rewarded.

Other instruments feel "freeblowing" and responsive, where with little effort you get a big resonant tone.

On bagpipes and flutes it's a good/bad thing: stuffy is bad, freeblowing is good.

I've come to realise that with whistles it's not that simple, especially with Low Whistles. Because with Low Whistles the more resistance/impedance/backpressure you have the more air-efficient the whistle is. Yes it takes a greater force of air, but less volume of air.

You pick up a Low Whistle that's very freeblowing and it's wonderful! Until you're playing a slow air with long High B's and you can't sustain a High B long enough because the air is rushing unimpeded through the instrument.

It also impacts the ease or responsiveness of the high notes, which will be stiffer with higher impedance and easier with lower impedance. (At least that's been my experience.)

What's nice is that some makers, like Colin Goldie, use a variety of windway heights giving a variety of impedance levels. You can play the various sorts and see what you prefer. Each Goldie is engraved with the specific windway height.

(Now if only whistles had adjustable ramps, with a little knob you could twist to dial in the exact windway height you want.)

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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 12:16 pm 
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pancelticpiper wrote:

(Now if only whistles had adjustable ramps, with a little knob you could twist to dial in the exact windway height you want.)


Are you thinking of something similar to Mollenhauer’s Evo Helder, specifically pic number 14 here: https://www.mollenhauer.com/en/catalog/ ... ood-detail

Last pic here: https://www.mollenhauer.com/en/catalog/ ... il#content


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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 1:27 pm 
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pancelticpiper wrote:
I had never heard of "backpressure" regarding whistles until I joined this site. I had heard it referred to previously, with wind instruments, as "acoustic impedance".

What's nice is that some makers, like Colin Goldie, use a variety of windway heights giving a variety of impedance levels. You can play the various sorts and see what you prefer. Each Goldie is engraved with the specific windway height.

(Now if only whistles had adjustable ramps, with a little knob you could twist to dial in the exact windway height you want.)


Wow, that's a great idea; the adjustable windway. Maybe an adjustable window too. Even a 2-position lever for the windway would in some cases really help solve problems or give playing and tone options.

I know two whistles I'd like adjustments on: a Clarke original and a Tony Dixon DX006, for different reasons. The Clarke has such a large windway that NASA used a smaller version of it to design rockets in the Apollo launch engines. It needs to be reduced by about 30%, just eyeballing it. I have lots of lung capacity, but why waste it? The Tony Dixon DX006 is an excellent whistle with superior tone I have no complaints about. The whistle works fine as is, but after playing it a while I was wondering if a slightly larger windway would have given it tonal options. The mind wanders.


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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 1:53 pm 
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RoberTunes wrote:
The Clarke has such a large windway...it needs to be reduced by about 30%...


That's the advantage of Clarkes! You can reduce the windway as much as you would like. And you can make the shape of the blade, and the blade's position vis-à-vis the end of the windway, any way you choose.

Back around 1980 my first teacher/mentor had an amazing Clarke. He had spent much time working on the windway and the blade.

It was his main whistle when he was living in Ireland, rucksacking the country over, hanging out with the Keenans, Micho Russel, and others. Everybody like his Clarke.

He generously loaned me that Clarke for a week, and I spent many hours trying to get my Clarke to sound just like his. I got very, very close! I think my Clarke is around 95% the whistle his is. There was a certain magic 5% I just couldn't create.

I still have my Clarke, I could photograph it. Whether or not you use mine as a guide, you can make your Clarke into an extremely good whistle, one that will blow away all those expensive wood and silver boutique whistles.

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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 1:58 pm 
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bwat wrote:

Are you thinking of something similar to Mollenhauer’s Evo Helder?


That's really cool. I can't tell how it works.

For sure recorders and whistles have similar tone-producing mechanisms.

I would think you would have to be able to independently move the floor and the ceiling of the windway, which would allow you to adjust not only the windway height, but the opening's position vis-à-vis the blade. That would be superb.

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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 4:30 pm 
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pancelticpiper wrote:
I had never heard of "backpressure" regarding whistles until I joined this site. I had heard it referred to previously, with wind instruments, as "acoustic impedance".
For the record, acoustic impedance, by any definition I know, has nothing to do with backpressure, or resistance to blowing. Acoustic impedance relates to the back-and-forth vibration of air molecules in the acoustic signal, not the bulk flow of air through an instrument.


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 Post subject: Re: PRESSURE
PostPosted: Mon Jun 15, 2020 10:09 pm 
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RoberTunes wrote:
pancelticpiper wrote:

(Now if only whistles had adjustable ramps, with a little knob you could twist to dial in the exact windway height you want.)


Wow, that's a great idea; the adjustable windway. Maybe an adjustable window too. Even a 2-position lever for the windway would in some cases really help solve problems or give playing and tone options.


A flute has an adjustable aperture. With practice the mouth has all the necessary and desirable adjustments.
If a ramp was adjustable how would that change windway hight? Unless it was a compound adjustment.

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 Post subject: Re: PRESSURE
PostPosted: Tue Jun 16, 2020 1:35 am 
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pancelticpiper wrote:
bwat wrote:

Are you thinking of something similar to Mollenhauer’s Evo Helder?


That's really cool. I can't tell how it works.

For sure recorders and whistles have similar tone-producing mechanisms.

I would think you would have to be able to independently move the floor and the ceiling of the windway, which would allow you to adjust not only the windway height, but the opening's position vis-à-vis the blade. That would be superb.


It's described here but it's auf Deutsch: https://youtu.be/fFgKqsIrWBg?t=1030
Can't say I understand it all (I did German in school so I get a fair amount and can guess a lot from context and the change in sound when she demonstrates) but there's worse ways to waste time on the youtube than watching this.


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 Post subject: Re: PRESSURE
PostPosted: Tue Jun 16, 2020 7:01 am 
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bwat wrote:
It's described here but it's auf Deutsch: https://youtu.be/fFgKqsIrWBg?t=1030


That is interesting. Thank you for the link.

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 Post subject: Re: PRESSURE
PostPosted: Tue Jun 16, 2020 7:17 am 
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bwat wrote:

It's described here but it's auf Deutsch: https://youtu.be/fFgKqsIrWBg?t=1030


Hard to tell exactly from the diagram, but it looks like the floor of the windway moves up and down but the ceiling remains constant?

What I would like is the floor and ceiling independently adjustable, which means that you could keep the windway at the same height but change it's relationship with the blade.

Better yet if the floor and ceiling are each independently adjustable front and back so that you can introduce a taper to the windway.

Even if whistles like that weren't sold to the consumer they would be great tools for the maker. It's the sort of thing Boehm would have done! In an offhand way he mentions that to discover the ideal hole locations he made a flute with moveable holes. What an amazing thing! But to him it was a mere tool to help him in the design process.

Or a maker could let a customer try the adjustable whistle, experimenting with various parameters, to find out the player's preferences.

I think that most players, if they had an adjustable whistle, would just leave it the same once they got it dialed in.

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 Post subject: Re: PRESSURE
PostPosted: Tue Jun 16, 2020 12:39 pm 
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pancelticpiper wrote:
Hard to tell exactly from the diagram, but it looks like the floor of the windway moves up and down but the ceiling remains constant?

What I would like is the floor and ceiling independently adjustable, which means that you could keep the windway at the same height but change it's relationship with the blade.

Better yet if the floor and ceiling are each independently adjustable front and back so that you can introduce a taper to the windway.
The second of bwat's links shows just such a device.
bwat wrote:

From the looks of this, you can adjust the height of the windway ceiling and windway floor independently, then use your lower lip to adjust the angle of the floor. The mind boggles.

Image


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 Post subject: Re: PRESSURE
PostPosted: Tue Jun 16, 2020 2:32 pm 
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Having dealt with organ pipes for 40 years and voiced on pressures from below 2" (water column) to at least 10", I'd find that very interesting. By not being about to adjust the cut-up or 'blade' the whistle with this configuration isn't likely get any louder, but more efficient which I suppose is the point. 'Back pressure' is a odd term to me, too.

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