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Old 24th August 2013, 12:27 PM   #1
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Default Any educated ideas about this?

Undertone ? Zu Audio

So anyone who has heard Zu subwoofers can attest to their fantastic performance and musicality..
I have only recently picked up DIY as a hobby in audio and will be finishing my first pair of speakers shortly. My next project will be an active system ( quite probably Mark Audio's 10p full range drivers and stereo sealed subs )..
Any educated guesses about the tuning of this enclosure in question? 38cmx38cmx63.5cm are the dimensions of the enclosure. It is sealed and uses Eminence's LAB 12. I haven't yet heard this specific design, but from previous experiences with Zu speakers and subs I am 100% sure the claimed frequency response is authentic. I do know that to extend to full 20hz one has to apply +3 db at around 26 hz with these..i don't really care about that. That and the fact that i'll be going for stereo subs assures me that i'll have satisfying extension.
So once again my question would be what exactly is the trick with such an enclosure? I'd love to build it.

Thanks a lot
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Old 24th August 2013, 01:02 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

A LAB12 driver simply needs a sealed box of about 50L,
or about 100L tuned to about 22Hz, to work very well.

rgds, sreten.
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Old 24th August 2013, 02:53 PM   #3
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I'm a little skeptical that they've managed to get a 12" driver in a sealed box to hit 14Hz, though if its -10dB, that could be plausible.

IMO, a large ported box is needed to get such low frequencies out of a 12"er with reasonable volume.

Chris
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Old 24th August 2013, 04:24 PM   #4
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Or a large sealed box with more drivers.
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Old 24th August 2013, 06:57 PM   #5
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Quote:
Originally Posted by KarlsMoody View Post
So once again my question would be what exactly is the trick with such an enclosure? I'd love to build it.
The trick is they don't show a chart of the cabinet's frequency response .

The chart below is a pair of Lab 12 in a sealed enclosure of about 5 cubic feet (141 liters) measured outdoors at 2 meters, the smaller Zu enclosure would roll off even more than the -20 dB at 14 Hz you see here.
Attached Images
File Type: png Lab 2x12 sealed.png (113.6 KB, 226 views)
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Old 24th August 2013, 07:24 PM   #6
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Thanks for your replies!
So as expected the claimed frequency response is rather optimistic!
I'd still love the idea of stereo sealed LAB 12s though! Given an internal volume of 50 litres, respectively, would 30-32hz be doable? I'm more interested in the sonic quality of such a solution than sheer extension!
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Old 24th August 2013, 07:36 PM   #7
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Quote:
Originally Posted by KarlsMoody View Post
Thanks for your replies!
So as expected the claimed frequency response is rather optimistic!
I'd still love the idea of stereo sealed LAB 12s though! Given an internal volume of 50 litres, respectively, would 30-32hz be doable? I'm more interested in the sonic quality of such a solution than sheer extension!
There was no claimed frequency response in Zu's specifications, only a frequency range .

If by "doable", you mean around -10 or -12 dB at 30 Hz, yes.
Take another look at the response I posted in #5, at 50 liters you can expect less LF than that, since the sealed enclosure measured has about 71 liters per driver.

That said, the mic I used for that test is around -3 dB at 20 Hz, so a 50 liter sealed cabinet actually would have response pretty similar.

Art
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Old 24th August 2013, 07:43 PM   #8
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Yeah, you're right it was only the range!
Ok then..what kind of a sealed configuration would get me down to 30hz? I would only ever do a sealed sub.
Where would a pair of LAB 12s in 140L enclosures each side get me?
Or any other drivers, for that matter? Sonic qualities come first
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Old 25th August 2013, 01:41 AM   #9
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The PAL12 at 300L or so, is about as efficient as you're going to get from a single 12" AND being able to reproduce into the 35hz range with it.

It is down at 30hz by a few db

So unless you're prepared to use 4+ drivers, don't expect a ton of 30hz bass in 50L cabinets.

Rule of thumb, you either spend more $ on drivers and amplifier power to get the response you want in a small package, or you spend a little more $ on wood, build a more efficient cabinet, use less power, and for all of that it is at the expense of cabinet volume.

Don't try to disprove Hoffmans iron law.
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Old 25th August 2013, 02:03 AM   #10
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May I ask why you're limiting yourself to a sealed sub? If its a size thing, yes, you NEED to go sealed to get that kind of response from a small cabinet. But you need EQ as well.

If its not the size issue, and only a "sonic quality" thing, have you heard other arrangements that have been properly implemented?
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