What kind of effect would this dipole mounting have?

[Mazeroth]

Any idea what type of response this type of dipole mounting would have? The woofers would be wired out of phase so they don't cancel each other out. There would also be more bracing to stiffen the frame. I just wanted to make this up quickly.

I apologize for the cheesy pic!

Thanks!

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[joecarrow]

Nice render- it's clear what you mean.

I don't think that it would be beneficial, honestly. I believe that the radiation pattern would have lobes all over the place; if you added some delay to the rear woofers you might be able to pull off some sort of cardioid response- but really, I don't think it's the way to go.

What about mounting them more like the woofers in the Phoenix? http://linkwitzlab.com/woofer.htm

[AJINFLA]

You would either have a compound dipole or a quadrupole, depending upon polarity wiring.

cheers,

AJ

[Mazeroth]

Thanks, AJ! I can't believe I didn't see that on SL's site:

B1 - "Compound dipole" woofer model
Completely open driver arrangements have been used by Celestion and Legacy Audio. A simple model to describe this case would be given by two drivers mounted on their own small baffles of effective radius d1 and separated by 2d2 from each other.

The model predicts that the SPL at very low frequencies is merely the sum of two dipoles with spacing D = d1. The separation 2d2 between them has no influence on the total output as long as it is small compared to the wavelength of radiation. I see no compounding effect other than summing two dipoles, but the two baffles might as well be placed next to each other. A single driver in an H-frame would have the same output if the distance D between the openings is 2d1. Even order non-linear distortion can be reduced by reversing one of the drivers in the compound configuration so that the two magnets face each other. The whole arrangement does not strike me as a very effective use of a second driver and cabinet space compared to an H or W frame. I have no data how high in frequency the "compound woofer" can be used, but its radiation pattern will become more lobing than that of the two point source woofer.

[AJINFLA]

I discussed the quadrupole arrange w/ SL and he agreed there was really no advantage to it. An example is shown here:

https://www.htguide.com/forum/showpost.php?p=294338&postcount=11

I spoke to the designer Clayton Shaw also. Looks like he may have had a change in direction, seeing that the quadrupole is dreadfully inefficient at LF.



Can't blame him for going with dipoles w/ waveguides, now can I ? :W

cheers,

AJ

[Mazeroth]

I guess I'll just have to move on to plan B:

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:B

[Mazeroth]

This 3D stuff is pretty fun!

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Now THAT'S what I'm talking about! :T

[joecarrow]

You're getting somewhere, but I think that the Phoenix woofer configuration will give you a big advantage in force cancellation, preventing the baffle from being shaken by the woofers. On a positive note, your configuration will prevent cavity resonance and allow a somewhat higher crossover point.

On a side note- what program are you using?

[cjd]

Pshh. Straight baffle mounting for dipole is the way to go.

You need wider baffles on the woofer lines. :P

[Mazeroth]

On a side note- what program are you using?

I'm using a copy of 3D Studio Max. My brother used to do graphical work on a PC, professionally, but about five years ago he switched over to the Mac. That was good for me, because I picked up his copy of 3D Studio Max for next to nothing. The newest version (9) goes for $3500 right now! I've only played around with it a few times and haven't even begun to tap its potential, nor will I ever. I just got it to mess around with.

Also, those subs are 12" mounted on a 15.5" wide baffle that's 76" tall. The mains are dual 7" drivers with a 4" (27-28mm) tweeter flange mouted on a 12.5" wide baffle that's 42" tall, if you care

Pshh. Straight baffle mounting for dipole is the way to go.

You need wider baffles on the woofer lines.

Yep, I agree with you on that. However, I'm not quite sure how to build a line array dipole subwoofer that's sturdy enough without exhibiting too many characteristics of an H-baffle. Any ideas? Also, has anyone else built a line array dipole sub before? I'd love to check one out!

[ThomasW]

Open baffle subs require a TON of drivers. When I was remodeling the house and the family room IB was off-line, I whipped up the Arvo Ultra design. With 8-12"s, it still lacked the lowest octave output of 4-12"s mounted in the IB

[joecarrow]

Yep, I agree with you on that. However, I'm not quite sure how to build a line array dipole subwoofer that's sturdy enough without exhibiting too many characteristics of an H-baffle. Any ideas? Also, has anyone else built a line array dipole sub before? I'd love to check one out!

I'd imagine that if you bolted some unistrut to a plywood face, it would be strong enough.

http://www.unistrut.com/

[Mazeroth]

Open baffle subs require a TON of drivers. When I was remodeling the house and the family room IB was off-line, I whipped up the Arvo Ultra design. With 8-12"s, it still lacked the lowest octave output of 4-12"s mounted in the IB

Thomas, do you remember the effective path difference you used with that Arvo Ultra setup? I'm wondering if upping the baffle width to 20-22" would do the trick, on a flat baffle with very small "wings" on the side to help stiffen the baffle?

Also, tell me what you guys think of this prototype: :B

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[wkhanna]

LOL!! ROTF!!!
It’s about time we build a shrine to our Master!

Great work Mazeroth!