Blowing machine

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david_h
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Re: Blowing machine

Post by david_h »

I think that the pumps in both hair dryers and vacuum cleaners are designed for shifting volume and don't like operating under high-pressure low-volume conditions. I was once involved in a collective DIY project that used the wrong sort of pump.

Did someone above suggest a tractor tyre inner tune with a weighted board on it?
trill
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Re: Blowing machine

Post by trill »

Terry McGee wrote: Sun Feb 05, 2023 3:37 am . . . where I would play that note in tune and see what that yielded....
That's what I had in mind: simulating a player.
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Re: Blowing machine

Post by Tunborough »

An inflated air bed or other vessel with a constant weight sounds promising, if I can find one that I can fit in (or near) the workshop.
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Terry McGee
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Re: Blowing machine

Post by Terry McGee »

david_h wrote: Sun Feb 05, 2023 7:15 am I think that the pumps in both hair dryers and vacuum cleaners are designed for shifting volume and don't like operating under high-pressure low-volume conditions. I was once involved in a collective DIY project that used the wrong sort of pump.
I'd be pretty confident about the vacuum cleaner approach as that application does require more than a wafting of air to lift the dirt. Easily tested on the domestic vacuum cleaner if it has a blow function.
Did someone above suggest a tractor tyre inner tune with a weighted board on it?
That was me I suspect. In the old days kids would rock up to the local tyre shop and beg for old inner tubes to uses as floaties in the pool. Then some ratbag invented tubeless tyres. But possibly worth asking the local tyre place if they have any old tubes surplus to requirement.

Medicine ball? You sit on it for low D, your wife sits on your lap for 2nd octave D, and throw in some kids for fine tuning. You might need the extended family for top B....
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Terry McGee
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Re: Blowing machine

Post by Terry McGee »

trill wrote: Sun Feb 05, 2023 10:22 am
Terry McGee wrote: Sun Feb 05, 2023 3:37 am . . . where I would play that note in tune and see what that yielded....
That's what I had in mind: simulating a player.
Hmmm, we'd really want to know the extremes wouldn't we? Low D in tune near the breaking point, and High B in tune? Working on the premise that many tunes go up to High B, but not many go further?

Hmmm, but then how do you deal with my Untweaked* Mellow D whose High B comes in at Bb? Pop it into the Too-Hard Basket?

*I keep the Untweaked one to be able to compare it to the Heavily Tweaked one.
trill
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Re: Blowing machine

Post by trill »

Terry McGee wrote: Sun Feb 05, 2023 5:03 pm. . . we'd really want to know the extremes wouldn't we? Low D in tune . . .
Shiva's dilemma: how do you connect the sensor to the whistle ? And tap the screen, and blow+play ?

Answer: DUCTAPE !

I remembered I had a flow sensor around from previous breath-exercise interests. Nifty bluetooth job.

My MK Kelpie used about 60 l/m for the 3rd D.

The sensor, although inexpensive + easy to hook up, appears to have a noise floor of about 10 l/m. So, I don't have any numbers for the 1st D (lowest).
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Re: Blowing machine

Post by Tunborough »

trill wrote: Mon Feb 06, 2023 12:35 am I remembered I had a flow sensor around from previous breath-exercise interests. Nifty bluetooth job.

My MK Kelpie used about 60 l/m for the 3rd D.
Do you have a make and model for this?

I was expecting flows of that magnitude in lower whistle keys. (To put it in perspective, a normal human can sustain that flow for a few seconds at most.)

[Edited when Terry pointed out the Kelpie is a low D, not a high D.]
Last edited by Tunborough on Mon Feb 06, 2023 4:48 pm, edited 1 time in total.
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Terry McGee
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Re: Blowing machine

Post by Terry McGee »

trill wrote: Mon Feb 06, 2023 12:35 am Shiva's dilemma: how do you connect the sensor to the whistle ? And tap the screen, and blow+play ?

Answer: DUCTAPE !
Yeah, that's about where I have ended up too. I guess I just have to get over it and get on with it!
I remembered I had a flow sensor around from previous breath-exercise interests. Nifty bluetooth job.

My MK Kelpie used about 60 l/m for the 3rd D.

The sensor, although inexpensive + easy to hook up, appears to have a noise floor of about 10 l/m. So, I don't have any numbers for the 1st D (lowest).
Now that's a low D whistle made by the MK people, am I right? Snazzy-looking brightly-coloured anodised aluminium device? I looked at a video showing around their workshop - it's very well appointed. I wondered if they make things in there other than whistles. Rocket launchers, brain probes, the sort of stuff that could pay for machinery like that! See at bottom of this page:

https://mkwhistles.com/pages/team
trill
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Re: Blowing machine

Post by trill »

Tunborough wrote: Mon Feb 06, 2023 1:26 pm
trill wrote: Mon Feb 06, 2023 12:35 am I remembered I had a flow sensor around from previous breath-exercise interests. Nifty bluetooth job...
Do you have a make and model for this?
Here it is, along with the Bluetooth adapter:
https://neulog.com/spirometer/
https://neulog.com/bluetooth/
Tunborough wrote: Mon Feb 06, 2023 1:26 pm
trill wrote: Mon Feb 06, 2023 12:35 am My MK Kelpie used about 60 l/m for the 3rd D.
I was expecting flows of that magnitude in lower whistle keys. (To put it in perspective, a normal human can sustain that flow for a few seconds at most.)

[Edited when Terry pointed out the Kelpie is a low D, not a high D.]

Yes, it's a low D. The 3rd D is the one at 1174.66 Hz.

Yes, only a few seconds !
trill
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Re: Blowing machine

Post by trill »

Terry McGee wrote: Mon Feb 06, 2023 4:30 pm. . . Snazzy-looking brightly-coloured anodised aluminium device? . . .
MK does make snazzy bright ones, but their "Kelpie" is their low-cost "entry/starter" version. Black matte only, non-tunable.
Terry McGee wrote: Mon Feb 06, 2023 4:30 pm. . . their workshop - it's very well appointed. . .
Indeed ! I'll bet the Hurco mill alone costs more than a house :o !
( Maybe he really *does* sell a jillion whistles worldwide ! :shock: )
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Re: Blowing machine

Post by Tunborough »

Tunborough wrote: Sat Jan 28, 2023 6:05 pm
Terry McGee wrote: Sat Jan 28, 2023 1:04 am My next quibble is what to accept as the bottom of the xxx ooo low regime.
...
ignoring the spurious ultra low response, the low regime covers a pitch range over 7 semitones and a flow rate change from 5 to 16 L/Min, whereas the 2nd regime covers less than a semitone, produced by an 18 to 30 L/Min flow.

What do we do now?
Wow. Good question. The model matches your mouth-blown experience (and mine): the lowest frequency in the first register would be around 740 Hz, just above F#5. It's fascinating that the blowing machine opens up this huge range below that.
WIDesigner predicts minimum frequencies from a model of loop gain: when the loop gain is less than 1, the note won't sound because there isn't enough energy going into the system to sustain the oscillation. I went back to the paper that prompted the model of loop gain:
  • Roman Auvray, Benoit Fabre, Pierre-Yves Lagree, "Regime change and oscillation thresholds in recorder-like instruments", J. Acoust. Soc. Am. 131 (2), February 2012.
Not for the faint of heart.

It has three main sections: a simplified model (from whence WIDesigner gets its model of loop gain), a more complete non-linear model (much more challenging, and not suited for implementation in WIDesigner), and experimental results. If you look at the graph in their Figure 7, you'll see experimental results that look a lot like Terry's, flow rates and frequencies that continue well below where the predicted loop gain drops below 1. How is it possible that oscillation continues with a loop gain less than 1? Quite likely a deficiency in the model of loop gain.

However, I also have a model for the Q factor, and that model prompts an interesting observation: like the loop gain, the Q factor also decreases as the air flow and frequency decrease, but it stays above zero well below where the predicted gain drops below 1. For Terry's G5 note, the model says the Q factor will drop to zero around 600 Hz. Terry got down lower than that, below 500 Hz, but it's interesting that we're in the same ballpark.

This is the sort of thing I would like to explore further with a blowing machine.
trill
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Re: Blowing machine

Post by trill »

Tunborough wrote: Thu Feb 09, 2023 8:42 pm. . .For Terry's G5 note, the model says the Q factor will drop to zero around 600 Hz. Terry got down lower than that, below 500 Hz. . .
If Terry was varying pressure "smoothly", I'm wondering if the pitch-meter might have been "following a modal-peak".

Also, I'm wondering if the measured pitch (so very low) is path-dependent. One way to check is to repeat it 2 ways. Specifically, return to the pressure+pitch combination 2 ways: a) smoothly+slowly, and b) abruptly. Sometimes a system can be "coaxed" into an unexpected state by a gradual shift of drive. It reminds of a Dixon A I have. For one tune, I was occasionally able to make a smooth octave-slide (going down). But, it had to be done *very* slowly.

Another way to check would be to observe the power spectra while the pressure range was varied. For example, using the Shakuhachi tuner.

I'd want to know if the whole PSD varied smoothly or if there were any sudden jumps. Specifically, peaks appearing or dropping out.
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Terry McGee
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Re: Blowing machine

Post by Terry McGee »

I got to wondering if I was just hearing and measuring the pitch of edge tones (The Banshee in the Whistle), so I've just run this experiment...

Hooked up the usual hapless Feadog Mk 1, and covered all 6 finger holes with tape.

Feeding it about 3.5L/Min, I get about 500Hz of wafty tone. B + 20 cents, where we expect D. So well below the bottom of the low regime. The volume meter on the tuner reads 0%.
Uncover the bottom hole, 503 Hz
Uncover the 2nd bottom hole, 505 Hz
Uncover the 3rd bottom hole, 506 Hz (that's still only a rise of about 20 cents over the XXX XXX fingering)
Uncover the 4th bottom hole, 506 Hz, with a faint sense of its octave. All of the above still registering 0% volume.
Uncover the 5th bottom hole, suddenly 971.5 Hz, B5-29c. And registering 95% volume!
Uncover the top hole, 1066.7 Hz, C6+32c, 82% volume.

So what do we reckon? Are we just hearing edge tones until we get to XOO OOO? Unsupported by any jet-switching. Weak, wafty, not concerned with or affected by fingering.

But when we get to the B fingering, the jet switching action suddenly leaps into life, admittedly still rather flat at B5-29c (it's still only 3.5L/Min!), but enough energy to get the volume meter quite excited.

And then when we open the top hole for a theoretical c#, the jet switching is still in play but the very low flow rate is causing it to drag. Giving us a good 80% volume reading, but 68 cents flat.

What do we think?

And is it possible that an indicator of the bottom of the low regime is the level of flow where changing the fingering DOES change the note?
trill
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Re: Blowing machine

Post by trill »

Terry McGee wrote: Fri Feb 10, 2023 12:56 am. . . What do we think? . . .
My current belief is the our beloved whistles are simply "oscillator+resonator".

Once upon a time, I removed the head of whistle + blew. I found that the pitch varied smoothly. More pressure=higher-pitch (+more volume). No "jumps". A simple variable-frequency-oscillator.

The tube (with tone-holes) is the primary (free-free) resonator. (Player anatomy, including highly-damped, variable-volume lungs would be an additional fixed-free resonant cavity).

Seems to fit the above data.
Terry McGee wrote: Fri Feb 10, 2023 12:56 amAnd is it possible that an indicator of the bottom of the low regime is the level of flow where changing the fingering DOES change the note?
That's what I'm thinking.
Last edited by trill on Fri Feb 10, 2023 6:46 am, edited 1 time in total.
trill
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Re: Blowing machine

Post by trill »

Terry McGee wrote: Fri Feb 10, 2023 12:56 am. . . so I've just run this experiment...
Sir, is there any chance you could make sound recordings of your tests ? Either WAV or MP3 ? I would be very interested.
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