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Old 20th December 2005, 07:17 PM   #1
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Default True small sub

Is it possible to get a true sub with small drivers?
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Old 20th December 2005, 07:21 PM   #2
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A true sub?
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Old 20th December 2005, 07:39 PM   #3
chops is offline chops  United States
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It depends on your definition of "true sub" and what size "small drivers" you're refering to.
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Old 21st December 2005, 02:49 AM   #4
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I guess the question is - what's the smallest driver that will get below 30hz? down to 20?
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Old 21st December 2005, 03:15 AM   #5
chops is offline chops  United States
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Again, it depends. In all actuallity, the smallest of "ear bud" type headphones can easily reach down below 20Hz.

But as for subwoofer use to fill a room, if you have enough drivers of any given size, you can reach 20Hz. It's all a matter of what driver, how many, and the tuning of the enclosure they are in.


***Now people, don't start bashing me. I am only using this as an example, BUT.....***

By using nine 3.5" drivers in an enclosure riddled with tunnels and channels of various lengths, Bose is able to get those small 3.5" drivers to produce a clean 20Hz.

Yes, I know they also need special equalization to do so, but so do most compact subwoofers of today. Look at Sunfire, Earthquake, Bag End, Paradigm, etc, etc. They all use smaller than normal enclosures, hundreds or thousands of watts of power AND equalization to reach or go below 20Hz.

***Again everyone, PLEASE DO NOT start a little bash-fest just because I used Bose as an example.***
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Old 21st December 2005, 04:09 AM   #6
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Hogie,

Hello from a Lafayette native. Comeaux class of '78.

The answer to your question really depends on your room and performance goals. What do you have now?

If overall size is your primary concern and you want fairly impressive bass, then you'll likely need at least a single 12" in a small sealed cab using a plate amp that has a Linkwitz transform built in.

If you just want to use a small driver then horn loading any size driver that has an Fs in the 30hz range can get to 20hz. It just takes a very large enclosure to do it.
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Old 22nd December 2005, 01:32 PM   #7
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Get a 6.5" driver with 18mm of one way linear stroke and you at capeable of producing 20Hz in a small(er) sized enclosure ("large" ported or Transmission line or 6th order bandpass instead of a massive 20Hz horn ).
However there only 2 drivers i know of which are capeable of this, one is in production stages and the other a mere prototype. Both are designed to give usable responce IB down to 25-30Hz.

But what you are asking has so many factors. Assumeing we are speaking about a small HT (say 12x12x12 room) Usable responce for movies into the infrasonic range could be taken care of by a single, high excursion driver (18mm+ one way linear throw and your amp is capeable of driving it to that point above tuning), with a low Fs (below 30Hz preferably) in a ported enclsorue tuned low (18Hz or so).

Much larger of a room and you'll want to go up to a 12" driver.

And remember this is for usable responce.

If you want Good, Flat, Deep (infrasonic) Responce your best bet to start with is a good high excursion 12" driver (Adire Brahma for example) or a step down with a 15 or 18. The Dayton DVC 15's are wonderful HT drivers so ive heard, not a far cry from the old Adire Tempests's which had the TS params that would make it a great HT driver (good excursion, low FS, lower inductance, mediumish Qms, good power handleing, excetera).

If you really want small and good, flat responce down to 20Hz and dont want to use a 15 or 18 a driver such as the Tumult or similar with over 1" one way USABLE movement in a 10 of 12 would be needed.

I will never recomend Sealed for HT because sealed simply cannot go as low as a good driver built for going low in uber low ported enclsoures as flat. but remember that when stepping into the realm of Infrasonic frequincies with amps capeable of pushing your driver near its linear limits above tuning... 18dB/Octave Xovers are a nessesity just afew Hz below tuning (say your tuned to 16Hz, you want the signal to be down 10dB by say 10Hz.

that low with that much power below tuning will surely brake off a tensile lead, smash the coil into the back plate, or smash the spyder into the top plate or tear the surround. and then your $400 driver will be gone to the garbage or waiting 2monthsand nearly $100 or more after shipping for a recone (and if you happen to have an adire driver and are getting it reconed by adire it will be around 10 months, lol)
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Old 22nd December 2005, 02:50 PM   #8
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Quote:
Originally posted by CBFryman
I will never recomend Sealed for HT because sealed simply cannot go as low as a good driver built for going low in uber low ported enclsoures as flat.
Hmmm, and I have a different take on that... I think sealed is perfect for a small HT. To get "uber low", ported enclosures tend to be fairly big. The biggest thing sealed gives up to ported is output near the ported enclosure's tuning frequency. Once you get above the range where the ports help, they are essentially the same, and once you get below the tuning frequency, the sealed configuration will have MORE output. Once combined with room gain, the sealed enclosure will have fairly flat response lower than a similar ported enclosure, at the expense of output in the tuning range of the ported enclosure. Since we're talking about "small" enclosures, it's pretty hard to get a tuning point below the 30s. A small sealed enclosure will have more usable output below that. If the room is small, it may not need the extra output near the tuning point, but you can always use more extension. With newer movies making more and more use of infrasonics down to the Dolby spec of 3hz, there's no such thing as going too low.
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Old 22nd December 2005, 04:03 PM   #9
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3Hz is useless... to get a sensible responce at 3Hz breathing would become dificult and you would need an ungodly number of drivers. even in a small room.

Say a 15" driver can displace enough air to reach 24Hz IB
To reach 12Hz you would need another 15" driver and twice the power
6, 2 more 15's and agian, doubleing the power
3 and you would need 4 more drivers and agian, twice the power as previosuly.

so say it was using 200w before.

you would need 8 15's and 1600w.

10cuft is reletively easy to give up, even in a small room. if the room is 8ft high you can get a 16cuft enclsorue from 2 sq feet of floor area...if its 12ft wide and you want to make it say 2ft tall you can make an enclosure that is 24cuft gross by giving up only 1ft of walking room. and on top of your enclsorue you can put your L&R chanels, entertainment center in the middle, if you use projection you can use a 6ft screen and put your center chanel behind it.
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Old 22nd December 2005, 04:15 PM   #10
chops is offline chops  United States
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Quote:
Originally posted by CBFryman
3Hz is useless... to get a sensible responce at 3Hz breathing would become dificult and you would need an ungodly number of drivers. even in a small room.

Say a 15" driver can displace enough air to reach 24Hz IB
To reach 12Hz you would need another 15" driver and twice the power
6, 2 more 15's and agian, doubleing the power
3 and you would need 4 more drivers and agian, twice the power as previosuly.

so say it was using 200w before.

you would need 8 15's and 1600w.

10cuft is reletively easy to give up, even in a small room. if the room is 8ft high you can get a 16cuft enclsorue from 2 sq feet of floor area...if its 12ft wide and you want to make it say 2ft tall you can make an enclosure that is 24cuft gross by giving up only 1ft of walking room. and on top of your enclsorue you can put your L&R chanels, entertainment center in the middle, if you use projection you can use a 6ft screen and put your center chanel behind it.
If that was the case, then Bag End's InfraSub 18 wouldn't be reproducing 8 Hz with 400 watts of total power with ONLY a single 18" driver in a sealed enclosure.

So... so much for that theory.
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