What BassAwdyO posted could be tweaked with a digital delay unit added to the amplifier for the rear driver and then used like the Meyer Sound subwoofer. There is nothing really all that special about this: A short delay (just enough to shift the phase of the signal) can cause an output null at the very rear of the subwoofer only, creating a cardioid radiation pattern. This seems to be the latest thing in professional audio subwoofers, where powerful output can be generated outdoors or in large spaces without spilling tons of LF energy onto the stage. This wouldn't be so important in a small listening room, but outside it apparently makes quite a lot of difference in the possible system configurations for live audio. The rear driver even provides a good deal of extra output in the forward direction, though not quite so much as an extra front-firing driver on a monopole subwoofer.
well it looks like this has already been done... and it works
I hate it when I think of something only to find that it has already been done, but it happens to all of us. Quite often for me. But I do enjoy seeing that the idea does work.
You know I started a thread before about this. It was called Quasi-dipoles.
This is the subwoofer forum right?
What benifits does an open baffle design have in the subwoofer range EXCEPT dipole radiation?
I would think that two sealed boxes radiating as a dipole would give you less distortion than a single driver dipole, but maybe I'm wrong here. Isnt the airspring of a sealed box much more linear than the suspension of a speaker? Thats what I've heard before...
If that is true, I would see that as an advantage.
One thing I see as an advantage to the boxed designs is the fact that you have alot more overexcursion protection. Ask yourself how much power does a dipole take to reach maxiumum excursion at 20hz and how much a sealed box takes.... then look at what happens when you drive them past that point
Like I said before, I started a thread a long time ago called Quasi-dioples... if anyone wants to continue this discusssion we can do it there. This thread is about ripoles... I dont want to threadjack anymore!
I hate it when I think of something only to find that it has already been done, but it happens to all of us. Quite often for me. But I do enjoy seeing that the idea does work.
You know I started a thread before about this. It was called Quasi-dipoles.
This is the subwoofer forum right?
What benifits does an open baffle design have in the subwoofer range EXCEPT dipole radiation?
I would think that two sealed boxes radiating as a dipole would give you less distortion than a single driver dipole, but maybe I'm wrong here. Isnt the airspring of a sealed box much more linear than the suspension of a speaker? Thats what I've heard before...
If that is true, I would see that as an advantage.
One thing I see as an advantage to the boxed designs is the fact that you have alot more overexcursion protection. Ask yourself how much power does a dipole take to reach maxiumum excursion at 20hz and how much a sealed box takes.... then look at what happens when you drive them past that point
Like I said before, I started a thread a long time ago called Quasi-dioples... if anyone wants to continue this discusssion we can do it there. This thread is about ripoles... I dont want to threadjack anymore!
and BTW I HATE it when people say that the front and rear radiate 180degrees out of phase. When people say that it makes it sound like a comb filter or something. They're of reverse polarity. While it is true that they radiate 180degrees out of phase AT ALL FREQUENCYS. Just saying they radiate at 180degrees out of phase doesnt cut it for me.
I think I'm going to start hating it when people call subs monopoles too. A monopole sub would be VERY VERY VERY VERY VERY VERY VERY big.
I think I'm going to start hating it when people call subs monopoles too. A monopole sub would be VERY VERY VERY VERY VERY VERY VERY big.
BassAwdyO said:
planet10 said:
Or a situation where the listening room is the inside of the box* -- i guess that is withing the definition of VERY BIG.
*(ie mounted in the wall with the box in the next room)
dave
Well the two of you better get used to it.
Just how else would you discribe something when the polarity is reversed?! What is the signal when reversed?!
Gues what.... It's called 180 DEGREES OUT OF PHASE! Too bad if it doesn't "cut it" for you. It works perfectly fine for everyone else in the world.
And one more thing that you're ******* me off about is this monopole BS.
People DO NOT refer to traditional subwoofers as monopoles because of their radiation pattern. They are referred to as MONOPOLES because the sound radiates ONLY FROM ONE SIDE OF THE ENCLOSURE!
It's radiation pattern under a certain freq is referred to as omnipolar.
Get over it or drop the subject!
Hi,
of course The principle design is not bound to any driver size. A 18" simply needs larger casings, but the physics behind that stay the same.
Since a dipole doesn´t couple very efficiently to the air and a lot of air volume needs to be moved in the lowest bass region, large membrane areas are one of the prime requirements of a dipole, the more so the higher the dynamics requirement and the room size are.
jauu
Calvin
of course
The principle design is not bound to any driver size. A 18" simply needs larger casings, but the physics behind that stay the same.Since a dipole doesn´t couple very efficiently to the air and a lot of air volume needs to be moved in the lowest bass region, large membrane areas are one of the prime requirements of a dipole, the more so the higher the dynamics requirement and the room size are.
jauu
Calvin
Hi,
of course
Since a dipole doesn´t couple very efficiently to the air and a lot of air volume needs to be moved in the lowest bass region, large membrane areas are one of the prime requirements of a dipole, the more so the higher the dynamics requirement and the room size are.
jauu
Calvin
Thanks Calvin!
A couple of questions before I start looking for the drivers.
A high Xmax, I'd guess?
A high Qms...
Then, why do I always see the magnets protruding the sides?
Do these chambers need to be as narrow as possible?
Is the ratio side chamber / middle chamber roughly 0.5 to 1?
I've looked around on the web but there are no quick easy to understand answers..
Thanks
Gerrit
Bastanis!
Bastanis have done something like that with their MANDALA bass module. I haven't heard them, but they look like they sound great.
Bastanis | Bausätze Mandala (scroll to the bottom to see the Mandala)
cheers,
-Tal
Bastanis have done something like that with their MANDALA bass module. I haven't heard them, but they look like they sound great.
Bastanis | Bausätze Mandala (scroll to the bottom to see the Mandala)
cheers,
-Tal
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