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Old 14th August 2003, 07:31 AM   #1
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Question What kind of driver config for microsub?

I want to make a microsub for computer use and so forth. Probably just a gainclone type amplifier inside. Anyways I was wondering if you guys have any suggestions on the type of driver config I should use in one of these. I was thinking about maybe 9"x9"x9" or 8" cube using the new Dayton 7" Aluminum driver.

I was thinking two different options.

1. Have two drivers radiating to the outside surface. This would give me alot of radiating surface, but the internal volume would be very anemic....would probably port or something to give it some air.

2. Do a isobaric...probably one facing outside then one in the middle. The isobaric config would make the outside one happy, but the inside one would be very cramped!.

Any thoughts on these microsubs. I want something small, sorta like the Sunfire subs, but not that crazy obviously. Its my impression, that they have 1 kW amps in order to make up for ineffeciencies, but I'm also not looking to shake the foundation either.
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Old 14th August 2003, 11:36 AM   #2
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Does anyone even know of a website that has info on such projects....most subwoofer projects emphahsis on the bigger 1.0 CuFt and up....which I know is a good thing, but still.
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Old 14th August 2003, 11:48 AM   #3
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Isobaric.... sealed is probably the best for a small enclosure... get winISD and model some drivers..
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Old 14th August 2003, 11:51 PM   #4
Ilianh is offline Ilianh  Canada
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Tang band makes high excursion small drivers made for subwoofers, I think I've even seen a 5" subwoofer driver in their stuff....

In isobarik config, using their 8" subwoofer driver, you would need about 0.5 cu ft.
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Old 16th August 2003, 12:53 AM   #5
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Ok I think I know how to make these things work. Would you use equalization in order to boost the low frequencies? Like say a 12dB boost at 60Hz....that way you make up for the small box size.
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Old 16th August 2003, 07:57 AM   #6
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12db-never.

at 60hz? no

smaller speaker-less power handling,less area,less excursion = much less possibility of EQ .

you mite use 12db on a linkwitz transform on a 12inch.

i would just use a 6.5inch in small box that models well,ul probably get 45hz,make it peak very slightly if u want boom rather than smoothness and for PC games rather than music.

just get winisd,and any sub simulator,and go to partsexpress.com,try one with a few mm of excursion,Fs perhaps 45hz at most,and MID Q not super high like 0.9Q less you want an open baffle...

isobarik is good for cheep woofers,like what you want.
but remember overall,there isnt much gained.
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Old 16th August 2003, 08:21 AM   #7
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Yes after doing some research the linkwitz transform looks to be the best possible canidate, or maybe the ELF....I guess that what I was looking for in the begining, was how to make it operate below the natural level of the driver/box....but after looking at them both, the transform seems to be well suited. I might go to a 10" driver....its not that much bigger, but gives alot more room for improvement.


Does anyone make a aluminum woofer similar to the new PartsExpress 7" Aluminum...IE; good quality at a good price. ~$20 is good, but I know most aluminum ones are above that price point.
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Old 16th August 2003, 12:43 PM   #8
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Default Micro Sub Ideas

Your idea about two 6.5" drivers radiating on the exterior of the box will give you the most bang for your buck. Take into consideration the interior volume that your power supply will use up and then model your box/driver/power supply combination. You can use some equalisation. Even a program like Bob Bullock's Boxresponse will model this power over cone excursion over power. One important thing to remember about your sub is that where you sit and listen you will always be in the near field. The power versus loudness ratio will not matter all that much. Two drivers in a very small box can produce some bass. The equalisation and the low frequency cutoff to protect the little beasties will be what makes or breaks the system. If you come up with some more ideas don't be shy

Mark
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Old 16th August 2003, 05:22 PM   #9
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Check out http://www.i-mcm.com/ MCM 55-2185 for an 8 inch aluminum driver.

You can find an implementation of it here by John.
http://home.new.rr.com/zaph/audio/audio-speaker7.html
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Old 17th August 2003, 12:44 AM   #10
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Thank you so much for that link!

Thats actually right about what I'm looking for, compact, DVC that are 8 OHMS each....two Gainclones powering it

Also I have another question. I had a small enclosure (some altec lansing computer subwoofer that someone through in the dumpster ) And it had a front hole for an 8" so I put one in there, then I cut a hole on the bottom and put a second driver in. Mind you this box is like 8.5" cubed.

Anyways I wired them in push-pull (out of phase with each other) which I fugured wouldn't sound good, since it was kind of like a dipole, but it would limit the stress inside the box. This setup had very little bass, which didn't surprise me.

So then I connected them in phase, so that they would radiate the same...however I thought this might be a problem since there was so little air inside that the pressure would be quite large. This also had alot let bass than just one driver.

Then I tried leaving the bottom one unplugged...passive radiator style, and it sounded a little better, had a little more bass.

So my question is, is there a certain way you have to position the drivers? Since they were physically at 90* angles to each other does that screw up the phase and cause cancilations? I know most companies put mulitiple woofers either firing the same direction or with them facing away from each other....even these microsubs, like the Earthquake and Sunfire and Polk ones have drivers on opposite sides.
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