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$e satelite has been reported to be 3"X5"X6.5" OD. Using 1/4 inch material, that yields an internal volume of 67.5in^3. The Aura NS-193-8A in that volume gives a Qts of .98 and could be crossed over in the 90 to 100Hz range. Wow. That doesn't just beat the B--se, it humiliates it.
The front would have to be a little wider than 3", because it's a 3" driver, not a 2.5" like the B-se. So, a little wider it will be. We are in the right ball park. And the box can be made effectively a little larger with aperiodic venting and stuffing.
Now then, there's the sub to think about.
So here we go. The Bo$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.
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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.
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?
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?
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
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
Hezz said:
Tell me more. The manufacturers specs are Qts .67, Vas 1.3L, Fs 80Hz.
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!
Dave Jones said:
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.
kelticwizard said:
Please go on. What would be better? (And better than what?)
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.
I am proposing a two way-I'll explain in a moment-with an Audax HM100CO woofer from Parts Express. Pricey, I know-$70 each. But you did say $600 for the whole system, correct?
Here are the specs:
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=296-053
In a 4.5" cube, with 3/8" walls, the 4 inch HM100CO has 53 cu inches to work with. Let's call it 45 cu inch. This is inside a 4.5 in cube.
What are the advantages?
It will be 6 dB down at 140 Hz-right where you want it to be for a 140 Hz crossover.
It will be 89 dB @1M/1W-how much more efficient is that than the others?
It will have a Qtc of 0.65-somewhare in between critically damped and the traditional Qtc of 0.7.
Here is the curve for the woofer:
Here are the specs:
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=296-053
In a 4.5" cube, with 3/8" walls, the 4 inch HM100CO has 53 cu inches to work with. Let's call it 45 cu inch. This is inside a 4.5 in cube.
What are the advantages?
It will be 6 dB down at 140 Hz-right where you want it to be for a 140 Hz crossover.
It will be 89 dB @1M/1W-how much more efficient is that than the others?
It will have a Qtc of 0.65-somewhare in between critically damped and the traditional Qtc of 0.7.
Here is the curve for the woofer:
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Oh, yes-forgot to add. The 4" has about twice the cone area of a 3". Aperiodic loading adds very little output out the port. So the 4" only has to move half as much to produce the same output level as a 3". This muddies the uppermidrange and highs less.
The less a cone has to move to produce the same SPL in the bass, the cleaner the upper mids and highs that speaker must carry.
Now for the tweeter-which means even less intermodulation distortion.
The less a cone has to move to produce the same SPL in the bass, the cleaner the upper mids and highs that speaker must carry.
Now for the tweeter-which means even less intermodulation distortion.
Here is it is:
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=275-030
It's outside diameter is only about 1.5" . that should mean that if you move the 4 inch over to one corner of the 4.5" front of the cube, this tweeter ought to come close to being able to fit diagonally in one of the top corners. I haven't drawn up the front face yet, but I believe that it will come close enough to fitting tso that at most, you wold only have to adjust the front face dimensions marginally to make it work.
You are asking the satellite midwoof to do quite a lot-move air from 140 Hz up to the upper reaches. The more the midwoof must strain to reproduce the midbass notes, the more muddied the upper mids.
Paul Klipsh's monumental article-Intermodulation Distortion in Loudspeakers-available through Email by request. I consider it on a par with the Thiele-small papers.
so any tweeter you include with this will give welcome relief to the speaker trying to reproduce the sound from 140 Hz on up. this tiny little number will give relief from 3,500 on up. And it costs 5 bucks.
No, I have not tried it, but any competent tweeter will give welcome relief to this system which has a 4" midwoof carrying the load from 140 Hz on up.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=275-030
It's outside diameter is only about 1.5" . that should mean that if you move the 4 inch over to one corner of the 4.5" front of the cube, this tweeter ought to come close to being able to fit diagonally in one of the top corners. I haven't drawn up the front face yet, but I believe that it will come close enough to fitting tso that at most, you wold only have to adjust the front face dimensions marginally to make it work.
You are asking the satellite midwoof to do quite a lot-move air from 140 Hz up to the upper reaches. The more the midwoof must strain to reproduce the midbass notes, the more muddied the upper mids.
Paul Klipsh's monumental article-Intermodulation Distortion in Loudspeakers-available through Email by request. I consider it on a par with the Thiele-small papers.
so any tweeter you include with this will give welcome relief to the speaker trying to reproduce the sound from 140 Hz on up. this tiny little number will give relief from 3,500 on up. And it costs 5 bucks.
No, I have not tried it, but any competent tweeter will give welcome relief to this system which has a 4" midwoof carrying the load from 140 Hz on up.
I still say don't try to compete with Bose size wise. She's unlikely to really appreciate the sonic difference. Do something artsy and get her involved in the design, if you can't come up with something you'll know she'll love on your own. She'll appreciate those speakers forever and remember you for them whether you're still together or not. Don't try to beat Bose at their own game. We know you can, but in her eyes you won't.
Test the waters if you don't believe me. Throw a couple of cool art related ideas her way and you'll get "oh, you can really do that" instead of "did you know that strawberries are in season?"
Test the waters if you don't believe me. Throw a couple of cool art related ideas her way and you'll get "oh, you can really do that" instead of "did you know that strawberries are in season?"
If you want to make this system sound halfway decent down low I would suggest two small subs in a stereo arangement run in stereo. If you do this you will be able to get a symetrical look to the setup, you can run the subs higher so that you get a full sound from the front speakers, and you will be able to use a little bit smaller drivers due to the fact their will be two of them. I would personaly recomend a sealed 8" enclosure. You could shape them any way you want and you will get great sound as long as you use a quality driver.
If it has to be hidden then I suggest the largest sub you can fit where you are going to hide it. I personaly would still go sealed.
If it has to be hidden then I suggest the largest sub you can fit where you are going to hide it. I personaly would still go sealed.
John in CR might have a point there, but for the intellectual exercise I would like to see how, with just a little expansion in the volume department, we can beat Bose. Besides, the 4.5" cube has less volume than two of those cubes together.
Just to give you an idea of how good this is: the 4" can move 0.64 cu inch of air. At 140, where it crosses over, that's about 100 dB SPL, more or less.
But at the crossover point, it should be about 6 dB down from the midband. So the midband output should be about 105 or 106 dB SPL.
That is mighty fine output even for larger systems, let alone a 4.5 inch cube. The trick, of course, is that crossover point. If we crossed over at 100 Hz, we can deduct 6 dB from that figure.
Making a high crossover point-but not as high as Bose's-lets us get surprising performance from a tiny box. And 140 is considered a good crossover point even among hifi aficionados. 200 Hz is not.
Just to give you an idea of how good this is: the 4" can move 0.64 cu inch of air. At 140, where it crosses over, that's about 100 dB SPL, more or less.
But at the crossover point, it should be about 6 dB down from the midband. So the midband output should be about 105 or 106 dB SPL.
That is mighty fine output even for larger systems, let alone a 4.5 inch cube. The trick, of course, is that crossover point. If we crossed over at 100 Hz, we can deduct 6 dB from that figure.
Making a high crossover point-but not as high as Bose's-lets us get surprising performance from a tiny box. And 140 is considered a good crossover point even among hifi aficionados. 200 Hz is not.
It doesn't take an intellectual excercise to beat Bose. It takes marketing. Go audition boom boxes or computer speaker systems and you'll beat Bose for only $100 or less. Or take the same size cab, put better drivers in and reinforce the cab and that will beat Bose. Sure you can go thru the gyrations to get the best sound possible out of the same size, but why? We all know that if you take the same components and put them in a larger cab with a real front baffle, the larger version of the same components is going to sound better.
John:
Well, in this case the 4.5" cube is smaller than the two Bose cubes stacked upon each other, so I wouldn't even be increasing the volume to get markedly better sound.
I think there is something to be said for taking on the big boys and seeing what you can do. In this case, the main thing Bose has going for it is smallness of size. It universally agreed upon by all, even by defenders of Bose 901's, that the Bose AV systems should have "Playskool" written on them and be stocked in the crayon department of your local Wal-Mart.
So the fun is in seeing if you can make take something the same size and actually produce a sound system of some quality. I feel that was Dave's intention in starting this thread, and various people have given good suggestions toward that goal. Don't you agree?
Well, in this case the 4.5" cube is smaller than the two Bose cubes stacked upon each other, so I wouldn't even be increasing the volume to get markedly better sound.
I think there is something to be said for taking on the big boys and seeing what you can do. In this case, the main thing Bose has going for it is smallness of size. It universally agreed upon by all, even by defenders of Bose 901's, that the Bose AV systems should have "Playskool" written on them and be stocked in the crayon department of your local Wal-Mart.
So the fun is in seeing if you can make take something the same size and actually produce a sound system of some quality. I feel that was Dave's intention in starting this thread, and various people have given good suggestions toward that goal. Don't you agree?
Some thoughts that have come to mind while reading this:
Making small sats, similar to Bose, is going to be hard to get good sound out of. Remember, those Bose cubes use paper-thin ABS, not 1/2 inch MDF. You're already losing about an inch on all sides alone from that. When we're talking about sizes on this scale, an inch on all sides is a good amount.
Plus, 140 Hz crossover point, if we want to talk good sat/sub systems, is not good, at all, IMO. Sound starts to become really directional around 150-160 Hz. If you have a second-order crossover point to the sub at 140 Hz, you'll definitely be hearing voices coming out of the sub, or at the very least be able to pick it out of the room, almost completely defeating the point of a sat/sub system.
It's generally recommended to have your sub down at least 12 dB at 160 Hz. That means a second-order crossover point at 80 Hz or lower. Hence why THX standards require main speakers to go down to at least 80 Hz.
So, I would pull away from the 140 Hz crossover point. In the sat/sub system I'm building where size is very limited, I'm doing 100 Hz.
But in your case, I would strongly agree with the idea of integrating the speakers into the room as art. This is really where you can get the full benefit of DIY! I've always wanted to do a transmission line with small woofers, and use the speaker stand, in my thoughts a PVC pipe, as the line.
If I were you, I'd get away from the small sat idea and go towards the art idea. Give her some ideas, or even let her design it! If that doesn't work, then just get the Bose cubes. After all, it's for ambient music for the studio, right?
My 2 cents.
Reece
Making small sats, similar to Bose, is going to be hard to get good sound out of. Remember, those Bose cubes use paper-thin ABS, not 1/2 inch MDF. You're already losing about an inch on all sides alone from that. When we're talking about sizes on this scale, an inch on all sides is a good amount.
Plus, 140 Hz crossover point, if we want to talk good sat/sub systems, is not good, at all, IMO. Sound starts to become really directional around 150-160 Hz. If you have a second-order crossover point to the sub at 140 Hz, you'll definitely be hearing voices coming out of the sub, or at the very least be able to pick it out of the room, almost completely defeating the point of a sat/sub system.
It's generally recommended to have your sub down at least 12 dB at 160 Hz. That means a second-order crossover point at 80 Hz or lower. Hence why THX standards require main speakers to go down to at least 80 Hz.
So, I would pull away from the 140 Hz crossover point. In the sat/sub system I'm building where size is very limited, I'm doing 100 Hz.
But in your case, I would strongly agree with the idea of integrating the speakers into the room as art. This is really where you can get the full benefit of DIY! I've always wanted to do a transmission line with small woofers, and use the speaker stand, in my thoughts a PVC pipe, as the line.
If I were you, I'd get away from the small sat idea and go towards the art idea. Give her some ideas, or even let her design it! If that doesn't work, then just get the Bose cubes. After all, it's for ambient music for the studio, right?
My 2 cents.
Reece
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