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Old 19th October 2007, 02:58 PM   #11
larksp is offline larksp  United Kingdom
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i want ported i know that already i like the sound..... was just thinking will i get a big improvement from using a subwoofer that is ment for films and so on rather than choosing 1 of the 2 car subs i have..... only 1 bad point i find from the monolith for me is 12inch being big but i want nice low subwoofer just will it make alot of difference
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Old 19th October 2007, 03:07 PM   #12
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Quote:
Originally posted by larksp
......and the other fs is high so cant really go below 30hz.......

the posts for the monolith i have not seen any of them try to use a pr not saying you are wrong though

this is what the site did with the driver

thanks for the post
You're welcome!

Like I said, the JL's specs should work well in the horns accurate and you have the space will be good down into the teens.

The driver's specs dictates a too large, long vent for a low vent mach to keep it from potentially 'chuffing' and/or compressing at your amp's power rating and why the PR is ideally required if you don't use the ML-TQWT or go to a proper horn.

As for what they did with it......... with no measurements, design details, etc., to know what trade-offs they made to use what appears to be a too small, short vent I have to stick with the time proven math and what I know it takes from experience to make a driver perform well in the BW you desire.
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Old 19th October 2007, 03:32 PM   #13
GM is offline GM  United States
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Quote:
Originally posted by AndrewT
Hi Gm,
could you explain this for me/us?
Vas=60L for a 12inch does not seem unusual.
Greets!

In today's 'shrinking' world you're right, but it doesn't change the fact that over the last decade or so in particular, driver manufacturers have reduced Vas to get ever smaller cabs since Qts needs to be in a relatively narrow range for best overall performance with SS based systems. This means that as box size (net Vb) shrinks, the vent size has to increase to off-set it to maintain the same low noise/compression and if the driver's Vas is acoustically small in a large enough cab to allow an acceptable size vent it will be under-damped, so manufacturers resort to various ways of 'tricking' the cab into 'feeling' a bigger/longer vent than is actually used, but other than using flared vent tubes and/or restricting the vent with some type of damping material and/or using digital EQ are normally more design /build intensive than the casual DIYer is willing to do, such as Polk's dimpled power port designs.

GM
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Old 19th October 2007, 03:44 PM   #14
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Quote:
Originally posted by richie00boy
You can't look at Vas in isolation and say the box must be small or a PR must be used. Qts directly influences box size. In this case Qts is 0.361 so a suitable box could be in the 60-90 litre range. So IMO a PR is not really needed, especially if the larger box size is used.
See my response to Andrew. As presented, IMO you're just recommending Larksp build a lower tuned version of what he already has (i.e. potentially 'chuffing'), so in both cases we'll have to agree to disagree.
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Old 19th October 2007, 03:46 PM   #15
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Quote:
Originally posted by larksp
..........but i want nice low subwoofer just will it make alot of difference
Both either of the large pipe horns and ML-TQWT I designed will do it.
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Old 19th October 2007, 04:12 PM   #16
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Quote:
Originally posted by GM
See my response to Andrew. As presented, IMO you're just recommending Larksp build a lower tuned version of what he already has (i.e. potentially 'chuffing'), so in both cases we'll have to agree to disagree.
You make a good point to Andrew. But I'm not recommending he builds a lower tuned version of what he has at all
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Old 19th October 2007, 04:15 PM   #17
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Car subs can be really good. In fact a lot of 'home' subs are car subs really.

I think you need to reconsider that you like the ported sound. IMO there is not really a ported sound, rather you like the ported boxes you have heard so far. On a budget though a ported box is usually the best way to go as it means less EQ and less power is needed. The trade is a bigger box.

With room gain you don't need to hit 20Hz.

What size is your current box? And what's the Thiele-Small parameters for the driver?
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Old 19th October 2007, 04:22 PM   #18
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Quote:
Originally posted by richie00boy

But I'm not recommending he builds a lower tuned version of what he has at all
Can't prove it from your response IMO, so what are you recommending then?
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Old 19th October 2007, 04:29 PM   #19
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I was suggesting for the Monolith which he listed the specs for. A driver he is contemplating, i.e. does not own. He hasn't really given any real info on his current box, which is why I could not comment on it.
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Old 19th October 2007, 04:55 PM   #20
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Quote:
Originally posted by richie00boy

With room gain you don't need to hit 20Hz.
Oh really?! In an HT app in general and/or in his room in particular?! Maybe in a well built/sealed large walk-in closet sized room WRT the former and unless his size room is built like a bank vault to get the theoretical 12 dB/octave room gain curve it doesn't apply either since he claims his existing 'sub' (and I use the term loosely) leaves something to be desired WRT LF performance with at least some movies.
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