Would mathcad then "swallow" a pipe as a conical section without any expansion (i.e mouthdiameter/throatdiameter =1)?
Regards
Chalres
DJK:
my two cents...
"The first and second openings are spaced apart a predetermined distance close enough together so as to avoid decreased low frequency performance and far enough apart to prevent deep notches in the system frequency response at higher frequencies. "
I use a spacing of 1/4 the total tube length -- as does the Bose Acoustic Wave Music System
"Preferably, the pressure wave transmission line means comprises a tube and said vibratile means comprises a diaphragm with the cross sectional area of said tube less than that of said diaphragm."
"the ratio of tube to cone areas (ATCR) typically controls the size of the system response peaks at the frequencies where the tube length is an odd multiple of a quarter wavelength for a single tube. For some typical speakers and an ATCR of 1 these peaks are relatively large. For ATCR of 0.5, the system response is relatively smooth"
The area of the tube should be 1/2 the area of the driver's cone (within the rubber suround)
"The free air resonant frequency of the loudspeaker driver may be chosen to be that at which the length of the longer of the tubes is a half wavelength and thereby lessen response irregularities that might be produced by resonances between reactive components of the loudspeaker driver and the tube."
The Fs of the driver should be 1/2W of the longest tube for tighter more articulate bass.
"Preferably, the loudspeaker driver is overdamped to avoid undesired resonances between the loudspeaker and the tube."
A Qts of 0.3~0.4 rather than an infinite baffle Qts of 0.5~1.0
Agreed
"It may be desirable to use equalization circuitry to insert a notch in the system response at a frequency below that for which the tube length is a quarter wavelength."
The Acoustic Wave Music System uses a small(er) tube and bass boost with a subsonic filter -- lots of bass for a small box. Why not?
my two cents...
"The first and second openings are spaced apart a predetermined distance close enough together so as to avoid decreased low frequency performance and far enough apart to prevent deep notches in the system frequency response at higher frequencies. "
I use a spacing of 1/4 the total tube length -- as does the Bose Acoustic Wave Music System
"Preferably, the pressure wave transmission line means comprises a tube and said vibratile means comprises a diaphragm with the cross sectional area of said tube less than that of said diaphragm."
"the ratio of tube to cone areas (ATCR) typically controls the size of the system response peaks at the frequencies where the tube length is an odd multiple of a quarter wavelength for a single tube. For some typical speakers and an ATCR of 1 these peaks are relatively large. For ATCR of 0.5, the system response is relatively smooth"
The area of the tube should be 1/2 the area of the driver's cone (within the rubber suround)
"The free air resonant frequency of the loudspeaker driver may be chosen to be that at which the length of the longer of the tubes is a half wavelength and thereby lessen response irregularities that might be produced by resonances between reactive components of the loudspeaker driver and the tube."
The Fs of the driver should be 1/2W of the longest tube for tighter more articulate bass.
"Preferably, the loudspeaker driver is overdamped to avoid undesired resonances between the loudspeaker and the tube."
A Qts of 0.3~0.4 rather than an infinite baffle Qts of 0.5~1.0
Agreed
"It may be desirable to use equalization circuitry to insert a notch in the system response at a frequency below that for which the tube length is a quarter wavelength."
The Acoustic Wave Music System uses a small(er) tube and bass boost with a subsonic filter -- lots of bass for a small box. Why not?
" "It may be desirable to use equalization circuitry to insert a notch in the system response at a frequency below that for which the tube length is a quarter wavelength."
The Acoustic Wave Music System uses a small(er) tube and bass boost with a subsonic filter -- lots of bass for a small box. Why not?"
So, maybe we could just forget the Tuning-According-to-Fs thing and tune it to the target F3...? Provided it is higher than dictated by the TAFs, as mentioned.....
The Acoustic Wave Music System uses a small(er) tube and bass boost with a subsonic filter -- lots of bass for a small box. Why not?"
So, maybe we could just forget the Tuning-According-to-Fs thing and tune it to the target F3...? Provided it is higher than dictated by the TAFs, as mentioned.....
By the way,
Have you ever used/heard an EAS utilizing a "Linkwitz Transform" or some similar circuitry? How does your Cannon compare in accuracy? I'm anticipating a fair amount of delay from a 22ft. tube.
What gives?
Have you ever used/heard an EAS utilizing a "Linkwitz Transform" or some similar circuitry? How does your Cannon compare in accuracy? I'm anticipating a fair amount of delay from a 22ft. tube.
What gives?
qi said:
I saw a brouchure for a new "Accoustimass" (model 10?) with a picture of the guts. It appeared to be a standard transmission line with two drivers offset by about 1/3. The mouth had a flared port, which I assume doesn't do much. I didn't listen to it, but I imagine it probably works okay. Of course, they were charging a grand for the thing - probably two or three times what other companies would charge for something equivalent.
fortyquid:
I have a 15' delay dialed in to the sub setting on my Denon home theatre receiver. It seems to "align" the sub with the five surround units.
With a 22' long tube you have a 1/4W tuning of 13HZ which means you would use a driver with an Fs of 26HZ.
I have a 15' delay dialed in to the sub setting on my Denon home theatre receiver. It seems to "align" the sub with the five surround units.
With a 22' long tube you have a 1/4W tuning of 13HZ which means you would use a driver with an Fs of 26HZ.
Davy Jones:
I believe the Bose Acoustimas 10 is a 6th order bandpass system consisting of dual ported chambers -- very muddy IMO.
In contrast, the Bose Cannon consists of a dual transmission line (using the same driver).
The short tube is 25% of the total length. The long tube is 75% of the total length. The long tube is tuned to 1/2W of the driver's Fs.
For example, (according to the Bose patent) you can tune a cannon to 20Hz using a driver with an Fs 0f 40HZ.
My cannon is tuned to 19HZ (15') using a driver with an Fs of 28Hz. It seems to work really well.
IMO Bose retail products are VERY EXPENSIVE for what you get.
I believe the Bose Acoustimas 10 is a 6th order bandpass system consisting of dual ported chambers -- very muddy IMO.
In contrast, the Bose Cannon consists of a dual transmission line (using the same driver).
The short tube is 25% of the total length. The long tube is 75% of the total length. The long tube is tuned to 1/2W of the driver's Fs.
For example, (according to the Bose patent) you can tune a cannon to 20Hz using a driver with an Fs 0f 40HZ.
My cannon is tuned to 19HZ (15') using a driver with an Fs of 28Hz. It seems to work really well.
IMO Bose retail products are VERY EXPENSIVE for what you get.
qi said:
The new one is a garden variety transmission line with offset drivers. Reckon they've been playing with Martin King's software? Go here:
http://www.bose.com/controller;jses...m10_surround_index&pageName=/cgi-bin/htsearch
... then click on "powered Acoustimass module" to see a cutaway picture.
Mind you, I'm certainly not advising anyone to buy one. But it should sound a heck of a lot better than previous Bose stuff.
For about the same fraction of the cost of the new Bose acoustimass enclosures you could snag a Shiva and plate amp with FAR superior sound. For those who want easy to connect and have seemingly loud bass, buy the Bose. If you want REAL bass for about the same price as an acoustimass enclosure...look for an Adire driver and a plate-amp that fits your budget.
My friend's acoustimass sounds "raw" (could be resonance) to me and gives away its Equalization-type sound. Not a bad machine, until you listen attentively which is all I do. Cheap particle boards too, yucky plastic that doesn't sit flush. I won't bash any driver materials or driver choices as that is some compromise that Bose felt necessary, but for the money they charge fit&finish should come before their customer service; as they wouldn't need it with better built loudspeakers.
Anyway, time to play with MJK's sheets as I've finally figured out how to use it...n_open and n_closed...I get it!
My friend's acoustimass sounds "raw" (could be resonance) to me and gives away its Equalization-type sound. Not a bad machine, until you listen attentively which is all I do. Cheap particle boards too, yucky plastic that doesn't sit flush. I won't bash any driver materials or driver choices as that is some compromise that Bose felt necessary, but for the money they charge fit&finish should come before their customer service; as they wouldn't need it with better built loudspeakers.
Anyway, time to play with MJK's sheets as I've finally figured out how to use it...n_open and n_closed...I get it!
Davey Jones:
I see what you are talking about (finally)😀
It looks like a transmission line with a pre-chamber (ala Daline or even Voight 1/4 wave pipish -- see Planet10's page).
I believe the Bose 610 also uses this design (but not down-firing).
"Mind you, I'm certainly not advising anyone to buy one. But it should sound a heck of a lot better than previous Bose stuff."
Agreed -- much better than the 6th order bandpass IMO.
I still believe the Bose Cannon is the best bang for the buck -- and easy to DIY.
Cheerio!
I see what you are talking about (finally)😀
It looks like a transmission line with a pre-chamber (ala Daline or even Voight 1/4 wave pipish -- see Planet10's page).
I believe the Bose 610 also uses this design (but not down-firing).
"Mind you, I'm certainly not advising anyone to buy one. But it should sound a heck of a lot better than previous Bose stuff."
Agreed -- much better than the 6th order bandpass IMO.
I still believe the Bose Cannon is the best bang for the buck -- and easy to DIY.
Cheerio!
"I have a 15' delay dialed in to the sub setting on my Denon home theatre receiver. It seems to "align" the sub with the five surround units."
Way cool!, if your reciever can do it.
But the problem isn't so much delay as group delay. I would expect any enclosure utilizing both waves of the driver to exhibit a nasty, quasi-6OB (Paris skyline) group delay, giving, if I am not mistaken, the kind of indistinct rumbling one hears from the Wal-Mart subs we've heard discussed. All right for movies I suppose, due to the lack of real experiencial reference (not having ever heard the sound of a tanker truck exploding, it would be difficult to determine whether or not the sound emminating from that box was in any way similar to the sound of said explosion), but I am intimately familiar with the sound of a bass drum, at least, from playing right accross the stage from one, or of a 'cello, being that it is my major area of performance. I am wondering not "does it sound good?" but "does it sound real?". I am always looking for a way to attain that sound like breathing wood (if you will excuse the rather Elliotic discription) and not pay an arm and a leg for it, as per the infinate baffle approach.
So, if I may be so bold as to reiterate, to what do you compare the sound of your cannon? Have you ever heard an EAS or other sealed sub that you could compare it with? Sorry to ask; they're rare, I know. But I'm trying to find an aural/cognative referrence for your discription.
"With a 22' long tube you have a 1/4W tuning of 13HZ which means you would use a driver with an Fs of 26HZ."
Yup, 25Hz, actually....
Way cool!, if your reciever can do it.
But the problem isn't so much delay as group delay. I would expect any enclosure utilizing both waves of the driver to exhibit a nasty, quasi-6OB (Paris skyline) group delay, giving, if I am not mistaken, the kind of indistinct rumbling one hears from the Wal-Mart subs we've heard discussed. All right for movies I suppose, due to the lack of real experiencial reference (not having ever heard the sound of a tanker truck exploding, it would be difficult to determine whether or not the sound emminating from that box was in any way similar to the sound of said explosion), but I am intimately familiar with the sound of a bass drum, at least, from playing right accross the stage from one, or of a 'cello, being that it is my major area of performance. I am wondering not "does it sound good?" but "does it sound real?". I am always looking for a way to attain that sound like breathing wood (if you will excuse the rather Elliotic discription) and not pay an arm and a leg for it, as per the infinate baffle approach.
So, if I may be so bold as to reiterate, to what do you compare the sound of your cannon? Have you ever heard an EAS or other sealed sub that you could compare it with? Sorry to ask; they're rare, I know. But I'm trying to find an aural/cognative referrence for your discription.
"With a 22' long tube you have a 1/4W tuning of 13HZ which means you would use a driver with an Fs of 26HZ."
Yup, 25Hz, actually....
"So, now that the patent has expired, who's going to do a write-up on Wave Cannon theory?"
Simple, its based on RF theory, the half square antenna.
Simple, its based on RF theory, the half square antenna.
"Simple, its based on RF theory, the half square antenna."
For those of us too dumb to know what the hell you're talking about, could you elaborate?
;-)
For those of us too dumb to know what the hell you're talking about, could you elaborate?
;-)
fortyquid:
"So, if I may be so bold as to reiterate, to what do you compare the sound of your cannon? Have you ever heard an EAS or other sealed sub that you could compare it with? Sorry to ask; they're rare, I know. But I'm trying to find an aural/cognitive reference for your description."
I would say sealed subs are generally more accurate but require lots more amplification. Also I personally know diddily about electronics and equalization circuitry so that route would be a steep one for me.
I heard what you speak of at the Towson Cinema in Maryland (theatre #6?) and it was AWESOME bass - very tight and deep.
The musical score of PIRATES OF THE CARIBEAN was reproduced beautifully with lots of deep clean bass,
If I were you I would go that route and KEEP US POSTED 😀
Hey! Let's do it all...
"So, if I may be so bold as to reiterate, to what do you compare the sound of your cannon? Have you ever heard an EAS or other sealed sub that you could compare it with? Sorry to ask; they're rare, I know. But I'm trying to find an aural/cognitive reference for your description."
I would say sealed subs are generally more accurate but require lots more amplification. Also I personally know diddily about electronics and equalization circuitry so that route would be a steep one for me.
I heard what you speak of at the Towson Cinema in Maryland (theatre #6?) and it was AWESOME bass - very tight and deep.
The musical score of PIRATES OF THE CARIBEAN was reproduced beautifully with lots of deep clean bass,
If I were you I would go that route and KEEP US POSTED 😀
Hey! Let's do it all...
BAM:
"So, now that the patent has expired, who's going to do a write-up on Wave Cannon theory?"
This entire thread in PDF format might be a good start?
"So, now that the patent has expired, who's going to do a write-up on Wave Cannon theory?"
This entire thread in PDF format might be a good start?
What is an EAS subwoofer? Electronically Assisted Sealed?
I could probably write a web page for the Double Waveguide-Transmission Subwoofer. (I'm trying to think of a new term to coin that will sound unique.)
I have a 4" driver that I am going to use to design an experimental dual-waveguide subwoofer.
I could probably write a web page for the Double Waveguide-Transmission Subwoofer. (I'm trying to think of a new term to coin that will sound unique.)
I have a 4" driver that I am going to use to design an experimental dual-waveguide subwoofer.
BAM:
"What is an EAS subwoofer? Electronically Assisted Sealed?"
(google: "EAS subwoofer")...
http://sound.westhost.com/project48.htm
"What is an EAS subwoofer? Electronically Assisted Sealed?"
(google: "EAS subwoofer")...
http://sound.westhost.com/project48.htm
For the name: The second tube is used to provide a phase shift at the larger tube's 1/2WL Freqeuncy to combine both phase shifts to 'double' the sound emanating from the cannon. "ground shifter"( ?)
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