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Old 17th June 2009, 11:42 PM   #611
fb is offline fb  Australia
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Top view of S2/chamber
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Old 18th June 2009, 12:30 AM   #612
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Quote:
Originally posted by fb

No.... Have you had a look at the sketchup model?
Nope, don't even know which design this is and don't have/use Sketchup or any of the other fancy programs available since I don't have time to learn any of them unless ya'll prefer I not post on the forums for a long time because I'll take the time to learn AkAbak inside out first and it's getting seemingly tougher everyday for this old dog to learn new tricks.

Regardless, Atc is in essence a cutout for the driver in that it's a baffle that has to be at least as big as the cutout if you don't want to compression load Vtc, ergo it's normal to the axis of the driver, so don't really care where it is in relation to the horn unless DB tells us otherwise.

Ditto, it's assumed that the S2 side of the chamber is normal to the axis of the horn, but even if the horn path isn't parallel or perpendicular to Atc, the program doesn't know or care since it's viewed as just a 'X' amount of confined vibrating air mass connecting the two, i.e. its shape means nothing to it since it's an acoustically simple 1D solution.

Anyway, check for yourself what Atc represents, use the TH Wizard to make a chamber to prove that the vertical red line is the Sd's diameter by making Atc somewhat > Sd, than add some Vtc to give it some visible depth and you'll notice that the red line has been extended equally at both ends with black extenders to make the chamber.

BTW, which driver, sim is this? I don't have time to keep up with the threads like I use to.

GM
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Old 18th June 2009, 01:11 AM   #613
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Thanks GM, I'll get my head wrapped around it soon enough


Driver is Acoustic Elegance IB12A, $129 each or 4@$104

Link to driver, and sim in post 490
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Old 18th June 2009, 03:13 AM   #614
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You're welcome!

I hate to 'rain on your parade', but the driver's published specs lists BL as 18.8 Tm along with a 0.38 Qes which doesn't compute, so assuming Qes is correct since the BL generated one is a ridiculously low 0.13, BL = 10.8 Tm, making your design's response quite a bit different. Hope you haven't burned any wood yet.

Bottom line, best to use the basic T/S specs and let HR calc the rest.

Edit: posted a correction on the AE forum.

GM
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Old 18th June 2009, 04:03 AM   #615
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Thank you GM for the correction.

I corrected parameters on the forum posted by John and alerted him about the typo.

Sorry for that...
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Old 18th June 2009, 05:32 AM   #616
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You're welcome! OK, I see you changed it to 10.9 Tm.........

GM
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Old 18th June 2009, 12:27 PM   #617
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Quote:
Originally posted by GM
You're welcome!

I hate to 'rain on your parade', but the driver's published specs lists BL as 18.8 Tm along with a 0.38 Qes which doesn't compute, so assuming Qes is correct since the BL generated one is a ridiculously low 0.13, BL = 10.8 Tm, making your design's response quite a bit different. Hope you haven't burned any wood yet.

Bottom line, best to use the basic T/S specs and let HR calc the rest.

Edit: posted a correction on the AE forum.

GM

There goes my free lunch Thanks again GM.


I'm well and truly back to the drawing board now.... I'll revisit my AV12 sims....

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Old 18th June 2009, 07:14 PM   #618
simon5 is offline simon5  Canada
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Originally posted by GM
You're welcome! OK, I see you changed it to 10.9 Tm.........

GM
Well, like you did, I backcalculated it with WinISD Pro Alpha to 10.86 Tm so I rounded up to 10.9 Tm...

But since it's the same motor it's probably 10.8 Tm like others IB-A...

I will let John double check it, 10.8 Tm or 10.9 Tm won't make a difference anyway considering most T/S parameters move much more than ~1% usually...
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Old 27th June 2009, 11:41 AM   #619
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I'm looking at the impulse response of some designs I'm coming up with.... It's atrocious.... but what about within the passband? The attached pic is -3db at 30hz-120hz. The group delay and phase plots look benign in this region as far as I can tell.


What should I be looking for? I don't need super wide bandwidth....



Ta
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Old 27th June 2009, 11:43 AM   #620
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Phase
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