Wave Cannon
Design this as a musical instrument. Like the pipe organs your are trying to emulate, all you need are air column(s) that resonate at specific pedal note frequencies. Here is a technology that may be applied to get the low notes you need. This will augment the subs that will still reproduce the stop and other synthesizer created harmonics.
For your mission here to be successful, an effort that is more than a trivial pursuit will be required. The probability of success to be derived by some predesign fetch, sans tuning and voicing, is extremely low.
Regards,
WHG
Design this as a musical instrument. Like the pipe organs your are trying to emulate, all you need are air column(s) that resonate at specific pedal note frequencies. Here is a technology that may be applied to get the low notes you need. This will augment the subs that will still reproduce the stop and other synthesizer created harmonics.
For your mission here to be successful, an effort that is more than a trivial pursuit will be required. The probability of success to be derived by some predesign fetch, sans tuning and voicing, is extremely low.
Regards,
WHG
Bill,
You are a bit late to the party, the OP already has a sub in place that puts out a more than the "109 dB" that the Bose cannon claims.
Art
Yes. I don't want to take the risk of catching any Cooties that would setback my recovery. 😀
BO
Thanks, Bill. I'll do some research on this subwoofer. Believe me - I've looked at a lot of commercial models in the last several months.
As you well know, 16 hertz is tough for any woofer or subwoofer. And producing it at volume is even tougher. My current bass boxes are putting out 16 hertz. But until I get all the equipment connected and running correctly, I won't know the SPL I can maintain continuously for those lowest sounds.
I don't know that any commercial subwoofer can guarantee success either. A quick glance at the sheet you included shows that Bose unit lists a bottom range of 25 hertz. That's about half the octave for the lowest pipe sounds we will have.
I've been sent plans for a horn that looks good to me. Sims indicate that this cabinet could provide 16 hertz at SPL approaching 110 dB. It's the kind of project I can carefully work on over the Winter. If my carpentry is good enough, perhaps the finished project will meet the promised potential. Very early in this thread many were advising me that this bass issue would be the biggest challenge. And they were right - as you are.
I'm actually pretty confident that our speaker array has the potential to meet most of the goals for the project. But I haven't heard ANYTHING from the digital sound engine yet to confirm or disprove their success. That will be the only litmus test that matters.
And, besides, I don't have the money right now for any more equipment. Win, lose, or draw - we're going to have to ride the first few races with the horse we have. But that doesn't mean I'm going to stop checking out the other available horses. 😉
Bach On
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Not A Sub-Woofer
Reasons for recommending this design:
A DIY longer version would be required, built from inexpensive PVC pipe and designed to resonate at pedal note frequencies.
No large scale woodworking required.
Easy to tune and voice.
Hang from the ceiling, so floor space not occupied by a large enclosure footprint.
Reasons for recommending this design:
A DIY longer version would be required, built from inexpensive PVC pipe and designed to resonate at pedal note frequencies.
No large scale woodworking required.
Easy to tune and voice.
Hang from the ceiling, so floor space not occupied by a large enclosure footprint.
Better Late than Never
The Wave Cannon design (not the specific Bose product), if tweaked DIY, to meet the pipe organ emulation mission for pedal notes, should deliver outstanding results. There is no chance that a short tapped horn will come close replicating the output of a 32 ft. organ pipe. WHG
The Wave Cannon design (not the specific Bose product), if tweaked DIY, to meet the pipe organ emulation mission for pedal notes, should deliver outstanding results. There is no chance that a short tapped horn will come close replicating the output of a 32 ft. organ pipe. WHG
All the reasons you cited have a high ratio of appeal to my situation.
As I said, I will explore it.
Thanks!
Bach On
That's why I recommended a long TH in post #6 😉.
Do you have any measurements or simulations of the Wave Cannon design for comparison?
whgeigher - I've been doing some reading of several threads on this site on the "wave cannon" design. I don't see a lot of clear evidence that it can produce the lowest sounds I need with the types of SPL needed. There is also a lot of discussion of "POTENTIAL" delays of the signals. Many in the threads I have read seem to feel this type of design may be better suited for Home Theater than music where such delays would be a major negative.
You seem to feel they are a good candidate for our situation. So...
Could you point me to some positive empirical evidence that addresses these concerns?
Thanks!
Bach On
You seem to feel they are a good candidate for our situation. So...
Could you point me to some positive empirical evidence that addresses these concerns?
Thanks!
Bach On
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While the Bose patent discloses design details, here is a Sonotube twenty footer that should come close to meeting your requirements. Getting accurate measurements at the low frequencies of interest is a non-trivial matter as well. See the frequency response chart that includes room resonances. WHG
Bass Cannon - Positron.org
n.b., The pipe organ you are emulating has delays a magnitude larger. To get a 32 ft. pipe oscillating take time.
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AWC Notes
The design rules for a musical instrument are the antithesis of those used for general purpose loudspeaker design. In the latter we suppress resonances in the former we encourage and tailor them.
You are emulating a wind instrument, the pipe organ. Here delays in establishing air column resonance are well known for the pedal notes.
Note that there are end corrections (2*Lf) to be added tube length (L) when determining waveguide resonant modes. Lf = 8/(3*pi)*(S/pi)^(1/2) where (S) is the cross sectional area of the un-flanged tube.
I know of no other way to produce acoustic thunder for well under $1,000 USD.
WHG
The design rules for a musical instrument are the antithesis of those used for general purpose loudspeaker design. In the latter we suppress resonances in the former we encourage and tailor them.
You are emulating a wind instrument, the pipe organ. Here delays in establishing air column resonance are well known for the pedal notes.
Note that there are end corrections (2*Lf) to be added tube length (L) when determining waveguide resonant modes. Lf = 8/(3*pi)*(S/pi)^(1/2) where (S) is the cross sectional area of the un-flanged tube.
I know of no other way to produce acoustic thunder for well under $1,000 USD.
WHG
The frequency response shows a peak around 60 Hz that drops around 18 dB per octave on either side, about what one would expect. Obviously the response below 40 Hz is incorrect, no way is a resonant device with a peak near 60 Hz going to put out 125+ dB at 1 Hz.
The 140+ dB at around 60 Hz is highly suspect as far as calibration.
Since the 20 footer has it's resonant peak at 60 Hz, what length do you suppose it would need to be to drop the response about two octaves to 16 Hz?
Attachments
Hi bjorno,
You beat me to it, I like the use of compound horn for the simulation. I just used Nd. Here is just a very quick Hornresp simulation, it gets to be quite big, and does not provide much of an advantage over e.g.: a T-TQWT. SPLs are a tad over Xmax @ the passband peak, and for ~ 600L v. 1200L (give or take a few...).
Regards,
You beat me to it, I like the use of compound horn for the simulation. I just used Nd. Here is just a very quick Hornresp simulation, it gets to be quite big, and does not provide much of an advantage over e.g.: a T-TQWT. SPLs are a tad over Xmax @ the passband peak, and for ~ 600L v. 1200L (give or take a few...).
Regards,
Attachments
You could probably simulate this as a compound horn in Horn resp.
But having played with concepts similar to this in the past I can tell you that fidelity to the original signal is not one of it's strong points.
In PA where loud and proud may be an attribute at times, reproducing an instrument that has a defined character like a pipe organ is not going to be very successful. A convincing reproduction of an known instrumental tone depends on clarity and fidelity to the signal input to the speaker.
A system (loudspeaker enclosure and driver) that depends upon harmonics generated at or above the input level of the fundamental is not going to be capable of accurate reproduction.
Here are some sources:
http://www.menards.com/main/buildin.../p-1398458-c-5652.htm?tid=-136182633830498796
There are others. This one was easy!
I am working on a design. But don't really see much advantages considering how large it would need to be for this driver.
But having played with concepts similar to this in the past I can tell you that fidelity to the original signal is not one of it's strong points.
In PA where loud and proud may be an attribute at times, reproducing an instrument that has a defined character like a pipe organ is not going to be very successful. A convincing reproduction of an known instrumental tone depends on clarity and fidelity to the signal input to the speaker.
A system (loudspeaker enclosure and driver) that depends upon harmonics generated at or above the input level of the fundamental is not going to be capable of accurate reproduction.
Here are some sources:
http://www.menards.com/main/buildin.../p-1398458-c-5652.htm?tid=-136182633830498796
There are others. This one was easy!
I am working on a design. But don't really see much advantages considering how large it would need to be for this driver.
Forgot to mention.
I had a great conversation with Nick at Stereo Integrity regarding the driver parameters that I measured. He told me that they never updated the original specs they published. The driver has been made by at least two different manufacturers since the original specs were published.
So no, I'm not completely crazy.
Just partially.
I had a great conversation with Nick at Stereo Integrity regarding the driver parameters that I measured. He told me that they never updated the original specs they published. The driver has been made by at least two different manufacturers since the original specs were published.
So no, I'm not completely crazy.
Just partially.
bjorno and Oliver beat me to it!
Way to go guys.
bjorno you are missing the compression chamber.
George Augspurger did a writeup on this design in SPeaker Builder back when I had hair.
I'll see if I can find it.
Way to go guys.
bjorno you are missing the compression chamber.
George Augspurger did a writeup on this design in SPeaker Builder back when I had hair.
I'll see if I can find it.
Like many things BOSE has marketed in the past and present, there is a great deal of hype. But not that much substance.
Lots of sizzle, very little steak.
Lots of sizzle, very little steak.
Hi Oliver,
Youre right, there is no advantage if comparing to any Quarter Wave Design besides the annoying misplaced dB's between 45-60 Hz one can live without as this anomaly really lowers possible SQ a lot and cannot easily be PEQ'd without leaving Time Dispersed Frequencies..
b🙂
PS:I know how to use the 'Compound-Horn' Template but You know I'm always trying to complicate if possible:😀
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