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Terry McGee

Air Pump For Playing With Reeds?

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Wondering if anyone has a good suggestion for an air pump for tuning and playing with reeds? I saw an earlier discussion that more-or-less concluded that an old bellows was the way to go. Probably OK for tuning, but I also want to do some experiments with reeds, and a constant-flow, hands-and-feet-free system would be preferable. Ideally quiet so as not to interfere unduly with measurements and recordings. Desirable to have suck and blow available. Don't want to spend a fortune though. Any bright ideas?

 

Good to know too what people have tried and how well they have gone. Nice to know what traps one might fall into!

 

Terry

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Terry,

 

A hands free tuning table is what you need with tuning slots that lock the shoes into position as is mine below. School desk with bellows supplied courtesy of Peter Hyde. The bellows are held in position with a strip of rubber (salvaged from a ute cover) Bellows are operated by knee action, you can then do anything your heart desires with your hands and there is more than enough air in the bellows. The bellows are weighted on the bottom with a steel plate of just enough weight to extend them at about normal playing pressure, the top seals against the bottom of the table with a hole through the table to supply air. The nature of the tuning section is a slide that takes adapters to concertina/ accordion and harmonica reeds and tuning.The table is a school examination table with the ability to adjust height to cope with short and long legs. I tried to attach the file but the photo was oversize so I have emailed it. Feel free to attach the photos if you can and put on the site.

 

David

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Air conditioning duct pump and a plenum chamber. Mine delivers 1.6" WC. Why would you want to blow? You could use both ends of the pump.

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Wow, an altar to the art of tuning! And it's certainly an interesting story! I do love the use of organ stop knobs and the ecclesiastic font!

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Air conditioning duct pump and a plenum chamber. Mine delivers 1.6" WC. Why would you want to blow? You could use both ends of the pump.

 

Why blow? Just keeping my options open! And yes, I could easily extract blow from the other end of the pump in the case of an in-duct unit.

 

Now this is the typical in-duct fan? How big a fan gave you that pressure? (In inches, RPM, watts or whatever!)

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It is like this http://au.rs-online.com/web/p/duct-fans/1844867/.

Not super cheap but it might be possible to find a secondhand one. I seem to remember there are two sorts of duct fans, the difference is in the clearance between the fan blade and the outside of the fan. I bought the one with the tighter clearance, I think it was called a radial duct fan. This was a few years ago now, maybe 10 years (that's the same in metric) and maybe the distinction doesn't exist now because the word radial is not used in the RS fan catalogue. I run it through a lighting dimmer. I don't recall ever thinking about the watts or rpm, I bought the 6", oops...

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Also called an in line duct fan. I have the six inch with a speed control that was advertised with it for that watt range. At full hilt it is way more than you need, but turned down it goes very slow. I usually tune at about 1inch WC. Quite quiet mounted on the underside of my table. Had it rigged with a U shaped tube back in the nineties when I first got it for suck and blow. Pitched the tube within a few weeks. Never used it. You want to see the reed you are working on, and for that you only need the draw side. I originally used a Magnehelic Gage to test starting pressure, but eventually switched to a hand held electronic thing I got from a place that sells test equipment to people checking A/C systems and related industries. Nice digital read out, easy to hook up to anything .

One thing I've noticed is that room resonances and the resonances of your set up can easily influence the pressure reeds start at. I have difficulties around 50cents flat to 50 cents sharp of my G'' (G5). I remember a story about a concert hall just built that had a resonance at some note and when a dinger tried to sing it, nothing would come out. I had a much bigger blower set up on a big pipe ot another room ( too loud ) but the pipe had too many resonances and caused trouble. Mostly used it to try to get the maximum pressure a person would put on a reed. In this case, smaller was better. I use the big one to blow fumes from leather dyeing out of my shop now.

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Also called an in line duct fan. I have the six inch with a speed control that was advertised with it for that watt range. At full hilt it is way more than you need, but turned down it goes very slow. I usually tune at about 1inch WC. Quite quiet mounted on the underside of my table. Had it rigged with a U shaped tube back in the nineties when I first got it for suck and blow. Pitched the tube within a few weeks. Never used it. You want to see the reed you are working on, and for that you only need the draw side. I originally used a Magnehelic Gage to test starting pressure, but eventually switched to a hand held electronic thing I got from a place that sells test equipment to people checking A/C systems and related industries. Nice digital read out, easy to hook up to anything .

 

 

A Digital Manometer presumably. I've been thinking about getting one, so I guess your endorsement will trip the indecision!

 

 

One thing I've noticed is that room resonances and the resonances of your set up can easily influence the pressure reeds start at. I have difficulties around 50cents flat to 50 cents sharp of my G'' (G5). I remember a story about a concert hall just built that had a resonance at some note and when a dinger tried to sing it, nothing would come out. I had a much bigger blower set up on a big pipe ot another room ( too loud ) but the pipe had too many resonances and caused trouble. Mostly used it to try to get the maximum pressure a person would put on a reed. In this case, smaller was better. I use the big one to blow fumes from leather dyeing out of my shop now.

 

 

 

It would be interesting to get to the bottom of that - to determine fr example whether it's a Helmholtz resonance (ie a volume-related thing) or a standing wave (length related). I wonder if this ever surfaces in concertinas, or only on the test bed?

 

I had a reminder of how cancellations can occur in rooms recently. I'd just finished building a pair of loudspeaker boxes for our family room, plonked them in place and thought to run a quick frequency response check to make sure all was well. Rather than do the right thing, which was to test one at a time, I tested them both together. Because there was a sofa taking up the middle of the room, I put the mic stand at one end of it. Ran the test, and was appalled to see a massive cancellation in the middle of the spectrum. Smelling a rat, I moved the sofa, ran out a measuring tape and put the mic equidistant from the two speakers. Cancellation promptly disappears.
Interestingly, we suffer these cancellations any time we listen to stereo, but our brains seem quite happy to disregard them. Drives measuring systems nuts.

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Also called an in line duct fan. I have the six inch with a speed control that was advertised with it for that watt range.

That's the one, I went that way on your advice, I just looked it up and it was back in 2006...

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Wondering if anyone has a good suggestion for an air pump for tuning and playing with reeds?

 

What we used for suction in university chemistry lab was a T-attachment for a water tap. Water flowing straight through the main pipe (the "top" of the T) creates negative pressure through the Bernoulli effect, sucking air in from the side arm (the "post" of the T) and entraining it.

 

There are no artifacts from the beating of blades in the airstream, but it requires an invariant pressure/flow of water to get constant suction pressure. It's also not much help for positive pressure. However, where positive pressure was used, a standard "tool" for smoothing variations in air pressure (where flow speed was not producing Bernoulli effects) was a balloon attached to a side arm. In particular, we used those uniform, high quality balloons commonly known as condoms.

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Yes, I remember the Bernoulli effect pumps from High School. Problem in Australia is water is not all that plentiful. We had an Italian exchange student a year ago, and we had to teach him to turn the tap off while he brushed his teeth! So the sound of running water would engender such a high state of nervous concern that I wouldn't be able to concentrate on the job in hand!

 

And my Digital Manometer came in today and works a treat, thanks Dana. I connected the digital manometer, the U-tube manometer and the Magnehelic gauge together and they all agree within 2%. Very reassuring.

 

Terry

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