As I've said in a previous post, assuming that it is possible to get 105db+ of flat, diffraction free mids and highs, I keep wondering how the bass section should look like?
At this sound pressure requirement horns seem to be the only way, only that I believe these would be very hard to set, and also, will have quite a visual impact.
Now, I know that you had the chance of listening to the RAAL system. The bass section is probably the single most effective configuration for achieving a high pressure level, huge radiation surface and a small package.
If I remember correctly he is using 5*15' woofers, in a cardioid configuration. How was the sound. Would something like this fit to your requirements?
If 105dB is not a must and 103db would fit the bill, I can imagine a system with a folded baffle using 4-5 15" woofers, one OmniTop with a very high efficiency 12" midrange (something form 18Sound maybe), and the Azura horn.
How would that be? I believe some EQ will be needed for the bass array, but then it's not like forcing a 15" driver to reach 105dB, and probably some more problems will appear at the crossover transition from a cardioid configuration to a monopole one..
At this sound pressure requirement horns seem to be the only way, only that I believe these would be very hard to set, and also, will have quite a visual impact.
Now, I know that you had the chance of listening to the RAAL system. The bass section is probably the single most effective configuration for achieving a high pressure level, huge radiation surface and a small package.
If I remember correctly he is using 5*15' woofers, in a cardioid configuration. How was the sound. Would something like this fit to your requirements?
If 105dB is not a must and 103db would fit the bill, I can imagine a system with a folded baffle using 4-5 15" woofers, one OmniTop with a very high efficiency 12" midrange (something form 18Sound maybe), and the Azura horn.
How would that be? I believe some EQ will be needed for the bass array, but then it's not like forcing a 15" driver to reach 105dB, and probably some more problems will appear at the crossover transition from a cardioid configuration to a monopole one..
That's an interesting sub... Thank you for the link.
Here is another interesting project, dipole this time. ESL 63, Unity Horn and 8 woofers / channel dipole sub
Here is another interesting project, dipole this time. ESL 63, Unity Horn and 8 woofers / channel dipole sub
Since you're concerned about bass...
Danley Sound Labs, DTS-10 " Super Spud" kit and build thread - Home Theater Systems - Electronics and Forum - HomeTheaterShack
Danley Sound Labs, DTS-10 " Super Spud" kit and build thread - Home Theater Systems - Electronics and Forum - HomeTheaterShack
It is an interesting design. Reminiscent of the old Beostatic.
The free field measurement show concern with such large format dipole woofers. Look at the measurement at 1, 3 and 5 in the pdf. You see that the form of the gradient roll off of the dipole is a function of distance from the dipole and the dipole separation.
That's a very interesting sub. There's a longer thread at AVS with Tom, Mike and Ivan from DSL all contributing. Tom really impresses me with the way he comes up with unconventional designs that 'just work.'
Danley DTS-10 "Super Spud" DIY kit - AVS Forum
I am thinking about an arrangement of woofer dipoles - one stacked behind the other - for some time now but can't wrap my head around it how summation or directivity (including the listening distance impact) would be affected.
Might be I'm wrong but it seems to me that when doing so with two 15" at a distance of say 30" there is a sonic pattern in the lower department that "feels" good.
I haven't tried to apply appropriate delay yet to make them "time aligned" for the listening position - just run some simus but failed to draw any meaningful conclusions.
Michael
In the free field, if the axial arrangement is +, -, +, -, you basically still have a dipole at low frequency. As the frequency rises you will have the peaks and nulls but the axial spacing and magnitude will be dependent on the both the dipole separation and the separation between the two dipoles. Pretty much a 6dB increase in low frequency output, but the first null will be below the null for a single dipole. Behavior with distance is qualitatively the same as a dipole at low frequency as well.
Behavior in a room is actually determined by 4 monopole sources with different polarity and positioning, as well as source and baffle size.
Thanks for your reply, John and Bill.
Interesting to hear that both +/- +/- and +/- -/+ polarity makes sense to you
On the other hand there must be something I didn't get right in my simu's
For the +/- +/- connection I get basically a dipole behaviour slightly asymmetrically changing with frequency but not much.
The +/- -/+ connection is quite a different animal.
Below a stacked dipole at a distance or roughly 3 feet 90cm connected in +/- -/+ polarity at 50Hz to 200Hz with a delay set to meet time of flight
seems to sum up as a "kind of" cardioid ??
Michael
Interesting to hear that both +/- +/- and +/- -/+ polarity makes sense to you
On the other hand there must be something I didn't get right in my simu's
For the +/- +/- connection I get basically a dipole behaviour slightly asymmetrically changing with frequency but not much.
The +/- -/+ connection is quite a different animal.
Below a stacked dipole at a distance or roughly 3 feet 90cm connected in +/- -/+ polarity at 50Hz to 200Hz with a delay set to meet time of flight
seems to sum up as a "kind of" cardioid ??
Michael
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The 2nd order gradient setup is classic, right out of Olson's paper on gradient loudspeakers. I can be thought of as 2 cardioid systems connected out of phase.
An externally hosted image should be here but it was not working when we last tested it.
Thats the thread ?
http://www.diyaudio.com/forums/multi-way/14697-second-order-gradients.html
Good read.
The description of the sonic outcome is probably what I got the good feeling from - very exciting !
I was checking - had my 15" dipoles operating out of phase - but at same level (split power by shunt C) and no "RC filter" for the back radiating wave of course...
Room for improvement, as it seems - to do a 2OG setup correctly...
Michael
http://www.diyaudio.com/forums/multi-way/14697-second-order-gradients.html
Good read.
The description of the sonic outcome is probably what I got the good feeling from - very exciting !
I was checking - had my 15" dipoles operating out of phase - but at same level (split power by shunt C) and no "RC filter" for the back radiating wave of course...
Room for improvement, as it seems - to do a 2OG setup correctly...
Michael
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On the other hand - there seems to be no big benefit compared to a pure cardioid woofer telling from the directivity pattern ?
The lack of needing any dampening material - which is something serious *for me* - is on the pro side though
I remember some have been guessing about what the CS1 double double bass is good for:
Emerald_Physics_CS1
seems to be probably a 2nd order gradient design ?
Michael
The lack of needing any dampening material - which is something serious *for me* - is on the pro side though
I remember some have been guessing about what the CS1 double double bass is good for:
Emerald_Physics_CS1
seems to be probably a 2nd order gradient design ?
Michael
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I didn't read that thread but the thing is, when it comes to room response in the modal region it is not about directionality. It is about how the sources couple to the room. Ultimately, be they dipoles, monopoles or cardioids, they are all equivalent to multiple monopole sources distributed around the room, in or out of phase, with or without delay.
More likely the front and rear are both dipole sin phase, used to increase SPL in a somewhat compact package.
Remember that when you get to a 2nd order gradient system excursion goes like (1/f)^4. So over 1 octave excursion goes up by a factor of 16.