Design a Bose-beater

[Dave Jones]

Originally posted by The Paulinator
Those speakers are actually very respectable performers. Even the little 6" powered subwoofer is pretty impressive for its size. If you can add a larger subwoofer to that system it will WAY outperform a Bose system.

Which speakers are you talking about?

[Dave Jones]

I just discovered that I accidentally modeled the wrong Aura speaker. The one that was actually suggested would seem to be just the ticket. Do they actually achieve those T/S parameters? 80Hz Fs? Yikes.

So here we go. The Bo$e satelite has been reported to be 3"X5"X6.5" OD. Using 1/4 inch material, that yields an internal volume of 67.5in^3. The Aura NS-193-8A in that volume gives a Qts of .98 and could be crossed over in the 90 to 100Hz range. Wow. That doesn't just beat the B--se, it humiliates it.

The front would have to be a little wider than 3", because it's a 3" driver, not a 2.5" like the B-se. So, a little wider it will be. We are in the right ball park. And the box can be made effectively a little larger with aperiodic venting and stuffing.

Now then, there's the sub to think about.

[johninCR]

Since she's into art, you might want to rethink small and go for exotic instead. For example a nice pair of suitable drivers on flat OB's. If she's into modern art, maybe glass baffles. If that's not her style, then stretch a canvas across the baffle and with a grill, hide the speaker in the painting. Another good one would be the Cornu spiral horns, which hang on the wall and can double as a painting too. With those horns, a sub may become unnecessary. Small and cute is one thing, but for an art studio really cool would be much better. Plus she'd be able to make them her own creation. It might even turn into a money making art project. A subwoofer that doubles as a base for a sculpture piece or a sculpture that has a sub built into it are possiblities too. Be creative, or if you can't, let her.

[Dave Jones]

I found the actual dimensions of the Bo$e AM-15 on the net. 3 1/8 X 6 3/16 X 4 1/8 for the satellites. The little Aura 8A will do okay in that.

The bass module is much larger than I expected it to be. Over 1 1/2 cubic feet internal, I would guess. That's enormous for what it accomplishes. O.D. 8 1/4 X 16 5/16 X 29 1/8.

So how about some suggestions for the bass module?

[Hezz]

Dave,

I don't know the Qt of the driver you are thinking about but if it is in the highrange you can get very spectacular results from a dual chamber aperiodic cabinet. It is possible to get near critical damping from a modest size cabinet with a speaker in the .4 - .5 range.

Instead of the aperiodic vent loaded to the outside of the cabinet it is loaded between the primary small cabinet and the second which is between 1/3 to 1/2 the speakers VAS.

You then will get the slower low frequency roll off of a sealed cabinet which would probably be useful for such a small driver.

Hezz

[Dave Jones]

Originally posted by Hezz
Dave,

I don't know the Qt of the driver you are thinking about but if it is in the highrange you can get very spectacular results from a dual chamber aperiodic cabinet. It is possible to get near critical damping from a modest size cabinet with a speaker in the .4 - .5 range.

Tell me more. The manufacturers specs are Qts .67, Vas 1.3L, Fs 80Hz.

Instead of the aperiodic vent loaded to the outside of the cabinet it is loaded between the primary small cabinet and the second which is between 1/3 to 1/2 the speakers VAS.

You then will get the slower low frequency roll off of a sealed cabinet which would probably be useful for such a small driver.

Hezz

I am no longer a "critical damping" believer. The Qtc will be around 1.0 in a small sealed box. There's a 1 dB peak. Big deal. People rave about old Rogers speakers that have a Q of 1.2 or so. Hey, I won't have a huge suckout at 200 Hz!

[kelticwizard]

Originally posted by Dave Jones
So here we go. The Bo$e satelite has been reported to be 3"X5"X6.5" OD. Using 1/4 inch material, that yields an internal volume of 67.5in^3.

I would not suggest 1/4" building material. Even for a small box, that is too thin. I was going to suggest 3/8" building material at least. Maybe 1/2".

As for the 3" by 5" by 6.5"-I did not realize we got to use the volume of two of those cubes. I believe that if we can do that, we can come up with something even better.

Where do you want to cross over to the subwoofer? The normal crossover is generally between 70 to 140 Hz. I wuld suggest the higher crossover, which is still a half octave below's Bose's 200 Hz, since it allows you to make a smaller satellite and cuts way down on intermoduation distortion.

[Dave Jones]

Originally posted by kelticwizard


As for the 3" by 5" by 6.5"-I did not realize we got to use the volume of two of those cubes. I believe that if we can do that, we can come up with something even better.

Please go on. What would be better? (And better than what?)

Where do you want to cross over to the subwoofer? The normal crossover is generally between 70 to 140 Hz. I wuld suggest the higher crossover, which is still a half octave below's Bose's 200 Hz, since it allows you to make a smaller satellite and cuts way down on intermoduation distortion.

Okay, let's say anywhere up to 140 is okay. How does the higher crossover cut down on IM distortion? Because the higher crossover is in a range where the main's group delay is flatter? Or what?

BTW, I have been assuming there would be no high pass filter built in to the mains.

[catapult]

Someone earlier mentioned in-walls. I think you should give them some consideration. You can use a real woofer and tweeter and paint the grills so they disappear visually. They should kick serious booty sound-wise compared to any enclosure of the size being discussed here.

[kelticwizard]

Originally posted by catapult
Someone earlier mentioned in-walls. I think you should give them some consideration. You can use a real woofer and tweeter and paint the grills so they disappear visually. They should kick serious booty sound-wise compared to any enclosure of the size being discussed here.

Don't be so sure. If you are willing to accept a 140 Hz crossover, wait until you see what I am proposing-it might come surprisingly close to performance in bigger boxes or in wall systems.