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Old 10th December 2012, 05:06 PM   #1
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Default FAST-ish enclosure help.

can i please get some help in how you would design the enclosures for the below drivers so they would work with an active-XO fast style set-up.

I have hauled the bass units from the T-TQWT towers i made a while ago to try a FAST style set-up as a plan B if my next attempt at a BLH for the 8inch driver doesn't give me something i like.

2x 8 inch full range units.
Fs - 58hz
Re - 7.6
Bl - 12.23
Sd - 216
Vas - 36.755
Qed - 0.25
Qmd - 2.97
Qtd - 0.231

4x 12 inch woofer units (need to double check params as they're crappy)
Fs - 37hz
Re - 7
Bl - 19.4
Sd - 520
Vas - 69
Qed - 0.44
Qmd - 5.28
Qtd - 0.406

thanks for your help
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Old 12th December 2012, 03:25 PM   #2
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ok, rephrase the question.

the box is going to have 2 chambers(?) each tuned differently. in terms of a mechanical crossover between them, do i design the FR's box first, then match the 'bass' box to try and crossover, or do i design the 'bass' first then try and match the FR to it?
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Old 12th December 2012, 03:43 PM   #3
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if this was the enclosure plot for the bass drivers, do i simply try and match the FR enclosure to approx 98db @ 200hz? which i think is about 6ltrs tuned to 100hz (see below).

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Old 14th December 2012, 01:05 PM   #4
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ok ignore the crossover questions.

what are the potential pit-falls in these 2 set-ups?
displacement is accounted for and the FR would be contained within its own ported 'box' internally.

what would the difference be between the 'D'Apolito' set up and the 2nd set up in terms of audible differences?


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Old 14th December 2012, 10:40 PM   #5
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Quote:
Originally Posted by gafhenderson View Post
the box is going to have 2 chambers(?) each tuned differently. in terms of a mechanical crossover between them, do i design the FR's box first, then match the 'bass' box to try and crossover, or do i design the 'bass' first then try and match the FR to it?
This will require the lower one to be a band-pass and the other a sealed or TL alignment.

Hmm, do you build a roof or foundation first?

GM
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Old 14th December 2012, 10:44 PM   #6
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Originally Posted by gafhenderson View Post
what would the difference be between the 'D'Apolito' set up and the 2nd set up in terms of audible differences?
A lot depends on where the HF is in relation to your ears and how far away you listen.

GM
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Old 16th December 2012, 11:29 AM   #7
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which is considered the foundation? the Fullrange unit or the bass units? I had assumed the FR unit, as the concept of FAST is 'full range assisted'.

also if i may further pick your knowledge; i've seen Planet10's FAST system's with side mounted woofers, can this work with any woofer and design? infact, could the woofers be mounted on the back of the box? what are the major differences in the sound produced when mounting front facing, side facing, rear facing?

thanks again for your help

edit: ignore rear mounted, just simulated it with MJK and its not pretty.

Last edited by gafhenderson; 16th December 2012 at 11:33 AM.
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Old 16th December 2012, 09:13 PM   #8
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You're welcome, though your latest Q implies that you have no idea how sound is generated, but surely you know that the lower the frequency, the longer its WL, ergo the more massive it is, right?

GM
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Old 16th December 2012, 10:44 PM   #9
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Originally Posted by GM View Post
You're welcome, though your latest Q implies that you have no idea how sound is generated, but surely you know that the lower the frequency, the longer its WL, ergo the more massive it is, right?

GM
I do understand that, I'm not entirely sure how this fits in with my question tho, sorry.
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Old 18th December 2012, 12:01 AM   #10
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if this is the sim for the above design, would the sealed plot work well enough to cross to the bass units?

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