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Old 14th February 2010, 12:22 AM   #11
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by max axe View Post
Yes, breaking it down into pieces.....
But maybe bjornos design, or something just a bit larger, that I could build as a case for the instrument and its horn...
Hi Max,GM_all

A new HR simulation of the 'portable sub' now not so portable but maybe can be curled up to a 'case' ( detachable sections)?

b
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Old 14th February 2010, 10:19 AM   #12
max axe is offline max axe  United States
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Thank you for the work and the insight. GM, thank you for jumping in.

Please note that I am not versed in speaker terminology. I might use a few abbreviations, but I dont know any of these you guys are using, sorry.

GM, to your point that it is not surprising that horns are loud, lets say then that it should be possible to achieve the same freq range and SPL with a speaker the volume of a trombone fed with the same power output as a person. Something I dont know about acoustics precludes this dream.

Just quickly lets look at the lung power. Sherwood says in Human Physiology that the energy used in respiration during heavy exercise is 5% of total. I remember that a trained athlete can produce sustained 1/4 hp. Is this right?; 1/4 hp = 186 watts times 5% = 9.3 watts. A trumpet puts out up to 10 watts acoustic power at 130 db. let me search....Ok I looked up calories burned playing a trumpet and they give 500 calories per hour which if Im correct is 0.6 watts. Of course that is normal levels, so high levels could be easily 10 times, say 6 watts, but of course it must be over ten if the horn is emitting 10, and what should the efficiency really be? very low in real terms, as an acoustic transducer, but It seems very high indeed by ballpark methods. Anyway I want to produce 130 spl at 80 hz with a trombone cubic volume at 10 watts.....ok, ok just down to 200 Hz, I will make it easy on the Gods.

But I take your valuable words to heart and I will give up the rear loaded concept. Its shaping up that I will use bjornos design for a bass free standing unit covering 40 to 200 Hz. I will hand hold, probably resting on shoulder an 8 inch mouth horn. Now I have an octave hole. Hmmm. I should have called the thread "can any small system with the approximate volume of a trombone reach 200 Hz with high efficiency?"

thank you

Max
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Old 14th February 2010, 10:54 AM   #13
max axe is offline max axe  United States
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bjorno and readers

bjorno thank you for the latest. I will have to dig into this to understand the geometry of the four drivers on the horn throat. Looks like small entrance holes, and dare I imagine, without know what Im talking about, a time alignment problem with the tweeter you have blocked off with grey? Does someone have a link to this kind of design? I would have to make it aesthetic somehow for the purpose.

I have managed to download hornresp. I consider this a major acheivement. (I mean finding and downloading; of course the program must be genius) Now I guess I will have to learn about speaker and horn design. I was sort of hoping to skip those years of this project. But if anyone wants to jump in, I am wondering before digging in, how bad the effect of non ideal horn shapes i.e. salvaged trombone bell would be on the response. Remember that I dont really think I am after audiophile idealism, although clearly better than a megaphone! But I am starting to read here and there, and Im afraid I will end up building some wood monstrosity and everyone will laugh me off the stage. Bare in mind there's lots of people out there watching. Tractrix? exponential? conical? ....maybe if I wait long enough, someone will just tell me what to do.

I suppose I could always mount something for looks only, since that was part of the goal, (see rough visualizations) and place the entire monitor on the floor, but then I would have to be in psychiatric care. In practical terms, If the two Horns I have (one the megaphone) cant be salvaged for the bell, and if a trombone flare is just so horrible (always will be to an audiophile), then I would have to lathe the shape and lay up fiberglass, although I may die before finishing. I think a four sided horn is out for visual reasons. I could maybe go six or more sides, building like a wood strip canoe over a core of some kind. It could be sort of charming in a backwoods sort of way...
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Old 14th February 2010, 12:26 PM   #14
mightym is offline mightym  United States
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If I understand this thread correctly, Max Axe is attempting to make a synthesizer which mimics woodwind sounds, "be" the audio source. At least in appearance.

My impression is that this is to be used for "live" performances.

Why not consider mounting a peerless driver that you already have, which will produce nearly the entire audio spectrum ( especially in the nearfield ). Then reinforce with a small portable pa?

If the post with the musical instruments showed the "Horn", I see no reason why a small battery powered chip amp couldn't be attached to the end of the instrument, with a speaker in a simulated bell attached to the end to LOOK like a horn. Then simply attach a mic. as any live trumped performer might use to the instrument.

This seem to me like a solution not requiring the reinvention of the wheel, and gives the impression of an instrument. The psychoacoustics of a live performance instrument are satisfied. The people front and center will hear both an instrument, and PA reinforcement, and in a small enough venue, the PA may not even be necessary.

If this isn't working toward a solution, feel free to ignore...

Just my thoughts,
John
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Old 14th February 2010, 01:04 PM   #15
max axe is offline max axe  United States
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John

I think you're getting the point. But in fact I do play in a mind wrenchingly loud maelstrom which I must overcome. I normally play the flute with a couple of flamenco guitarists, electric bass and drum kit. Even with close floor monitors, its maddening to try to hear what youre doing. You constantly think your instrument is broken or something terrible has gone wrong. Imagine trying to give a speech or sing a song in front of 200 people and finding you cant use consonants. But your point is valid in a number of ways though. The idea of audiophile reproduction is not so much an issue because the instrument in question is playing as a monophonic voice. A change in timbral characteristics from speaker coloration is like playing a violin made from different manufacturer. In fact SOME fixed resonances might create a more realistic sounding instrument, because the samples that the synth plays are probably every third note up the scale and who knows how they processed them.

Hmmm, I didnt have to go far to read about the Unity Horn. I spoke too soon of course, sorry. "Unmatched voice intelligibility and precise music reproduction due to the time-aligned phase coherent design"

Man, the degree to which you brains get into this stuff! I dont really know if I have it in me to get up to speed on the science within this lifetime.

When I hear statements like "the subtle airy presentation of the fifth octave" I realize that we are in different worlds as far as goals go. Im just trying to survive sonic hell.
Ive recorded in some of the best studios in Arizona, and I guarantee that while engineering these, there is an effort made, but its nothing like what the audiophile gets into. And then there is all of the compression and effects applied....

Then stage performance is a completely different world than studio recording and you are cast into a roaring, reverberating, clipped, feedback plagued nightmare of audio overload. Its mainly this world that Im trying to create a solo voice instrument loud enough to be heard so I can just figure out what Im doing, whos playing what.

thank you

max
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Old 14th February 2010, 01:20 PM   #16
max axe is offline max axe  United States
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I just wanted to be clear that I am usually close to electricity. I have to have a midi instrument line out from the instrument. This goes to a synth module standing close by. From that module, a line goes to the main PA and another line would go to a small amp sitting on the module which would have a speaker cord that would run back up to my instrument. Not ideal, but workable. I have my doubts about a battery operated amp on the instrument because of the extra weight size and complexities.

I rather like the idea of bjornos bass tube and the horn loaded concept for the power of it. But Im stuck on not going more than about 8 inches in diameter, and the horns in question seem to be twice that, although I havent checked bjornos last analysis for dimensions. Im not too keen on getting deep into crossover design either, and I would be willing to compromise sonics to some degree to simplify that part of the project.

Thanks,

Max
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Old 14th February 2010, 01:36 PM   #17
mightym is offline mightym  United States
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Quote:
Originally Posted by max axe View Post
I think you're getting the point. But in fact I do play in a mind wrenchingly loud maelstrom which I must overcome. I normally play the flute with a couple of flamenco guitarists, electric bass and drum kit. Even with close floor monitors, its maddening to try to hear what youre doing. You constantly think your instrument is broken or something terrible has gone wrong. Imagine trying to give a speech or sing a song in front of 200 people and finding you cant use consonants. But your point is valid in a number of ways though. The idea of audiophile reproduction is not so much an issue because the instrument in question is playing as a monophonic voice. A change in timbral characteristics from speaker coloration is like playing a violin made from different manufacturer. In fact SOME fixed resonances might create a more realistic sounding instrument, because the samples that the synth plays are probably every third note up the scale and who knows how they processed them.

Then stage performance is a completely different world than studio recording and you are cast into a roaring, reverberating, clipped, feedback plagued nightmare of audio overload. Its mainly this world that Im trying to create a solo voice instrument loud enough to be heard so I can just figure out what Im doing, whos playing what.
Max,
In my youth I spent a lot of time performing on stages too. I was just a singer in the band, so I can relate to your dilemma.

A couple of comments/questions regarding the quote above.

"I normally play the flute with a couple of flamenco guitarists, electric bass and drum kit."

How is your flute mic'd? is it attached to the instrument? Floor standing?

Your synth could be mic'd the same way ( as I outlined it in my prev. post ).

As to the Cacaphony on the stage, I never had the benefit of using the " in ear " monitors that are so popular on live TV shows today, so I have no experience with them. They seem like an ideal situation for the musician, the plugs physically block extraneous noises and protect your hearing, while allowing you to monitor the performance. I have no idea what a setup like that costs, but would seem like part of the solution.

The solution I outlined previously, I thought, was rather elegant. It's compact, easy to transport, etc....You posted again while I was typing, I didn't realize that the instrument had to be hooked up to the other synth module, too bad that kinda blows my solution, unless you wanted to work in extra complexity with a couple of wireless connections....

Oh well,
John
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Old 14th February 2010, 01:56 PM   #18
max axe is offline max axe  United States
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John

Yes finances are a bit of an object, and the wireless things can cost quite a bit, and there are all the little extra things to set up and keep track of. You can go wireless with the midi instrument as well, but again I didnt want to spend the money just now when I dont mind so much a wire hanging off of me. The worst is when you step on the wire and it rips the instrument out of your hands on to the floor.

But I like the idea of a full-range stuck right in the mouth of a bell, it is something I am considering. And this would work ok with a speaker cord coming from an amp. But Im starting to get attached to the idea of true horn level SPL or nearly, and not worrying about blowing up my little speaker. But if anybody has a suggestion for a 5 or 6 inch full range that would work well with a trombone shaped labyrinth Im all ears.

I use a floor standing mic stand. yes, I could play the midi instrument with small full range directly into the mic. But there is already a line coming from the synth engine to the main PA, so I could go either way.

Now if this system that bjorno is coming up with could sound as good as I imagine, I could see making a pair and using it as a stand alone PA in its own right. It would look very cool to have those horns. Certainly for now there is the problem of the octave + between 200 and 550 Hz. ......an 8 inch horn that goes to 200 Hz....."impossible" said the engineer to the trombone player.

GO BJORNO!

Thanks
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Old 14th February 2010, 02:31 PM   #19
GM is offline GM  United States
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Quote:
Originally Posted by max axe View Post
GM, thank you for jumping in.
You're welcome!

Hmm, don't have the time/inclination to do the research, but it sounds like you're comparing apples to oranges for what's required. The point I was trying to get across is a human's ability to create an impressive amount of sustained back pressure, far more than can be realized with a relatively small electrically actuated moving coil compression driver and why relatively small high SPL horns such as used on trucks or sirens are driven by air compressors, so what's needed is a way to use this type of system to reproduce the desired BW, but even then I'm thinking it's going to require a relatively large, expensive two stage compressor to play low into a musical instrument sized throat.

Anyway, what you're trying to accomplish doesn't make sense to me as I understand it. I mean you can't hear an electric guitar when you're playing it except through its speaker system, so seems to me that housing your synth in a mock horn and placing a pair of line arrays slightly behind you to both be able to hear it as well as make sound appear as coming from you seems the way to go.

Then it's just a matter of how many simple speaker modules is required to get the desired SPL at 'X' distance, so take a gander at prosound line array system tech papers to learn the basics and just buy what's required if you need enough acoustic power to play in large venues or DIY with cheap woofers and piezo tweeter horns for < ~250 seats otherwise.

GM
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Last edited by GM; 14th February 2010 at 02:33 PM.
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Old 14th February 2010, 08:41 PM   #20
max axe is offline max axe  United States
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I think a line array could be a good solution. Whats missing are two things; the personal feedback of having the actual instrument in your hands be alive and produce sound and the visual impact of having a horn except if you put a fake one on as you indicate. That second requirement is bigger than one might think, and you can get an idea by looking at the instrument with and without the horn in previous post.

Of course you are right that you can hardly hear an electric guitar. In fact the guitarists and bass player use a personal monitor for that reason. The line array would work well, but the onboard system would be better if it can be designed, just like it would feel better to have your voice issue from your mouth instead of your toes when you talked. But I cant bring myself to put a fake horn on the instrument. People always ask, and how many times I would have to say its fake...

But there is still the question of the trombone horn cut off frequency being more than two octaves above its low notes. I guess most of the energy is in the harmonics, which probably explains it. I should have said its unfortunate, not amazing that you cant make a speaker with trombone dimensions to reproduce a trombone sound.

Everyone thought the induced drag due to span loading on a glider was an inviolable law and that elliptical lift distribution was the best obtainable, but then they put bird feathers on the tips and found they could cut the wing span in half. I wish there was some similar magic for horn size....its a possible question, can you make a more gradual low freq roll off perhaps by compromising horn dimensions.

thank you

max

Last edited by max axe; 14th February 2010 at 08:59 PM.
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