Bought four sealed 18" cabinets on a wild hare - Direct me to a driver setup at least competitive or superior to JTR Captivators... - Page 13 - AVS Forum
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post #361 of 367 Old Yesterday, 01:49 PM
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Quote:
Originally Posted by Archaea View Post
10 or 11Hz "tune" on the new Seaton might be partially dsp controlled instead of cabinet related since the ultimax 18" drivers are said to be capable of infinite baffle. That characteristic could lessen the box limitation with some fancy dynamic eq and dsp work.
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post #362 of 367 Old Yesterday, 01:49 PM
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JTR thread, mark was discussing it there ironically enough...haha

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post #363 of 367 Old Yesterday, 03:51 PM
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That ported sub looked awesome, why did Mark never actually put it into production as one of his regular products?

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post #364 of 367 Old Yesterday, 04:24 PM
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Quote:
Originally Posted by Archaea View Post
10 or 11Hz "tune" on the new Seaton might be partially dsp controlled instead of cabinet related since the ultimax 18" drivers are said to be capable of infinite baffle. That characteristic could lessen the box limitation with some fancy dynamic eq and dsp work.
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Originally Posted by beastaudio View Post
Might be able to pull the knee a little bit but a tune is a tune I would think. You pull more than 1-2hz, and dsp up that region, driver will unload awful quick. Like no warning gonna pop, fast. Of course you could then layer on a limiter to prevent it from getting to that point. Fine line there in between though if I had to guess.
DSP can only change the incoming electrical signal, not the physical resonance of a reflex port. The impedance measurements confirm a minimum at 11Hz, where visual observation with excursion & port output suggest 9.5-10.5Hz, below which excursion increases quickly, and some creative high pass filtering in the clunky, but very flexible, on-board DSP protects from nicely.

There are some tricks in the layout which help lower the tune which I originally expected to be closer to 12.5Hz and suspected should be lower, and in fact was. Testing such a large dimension box in detail showed many interesting behaviors I've been able to align models with, making for some fun potential in other designs armed with that knowledge.

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Originally Posted by gpmbc View Post
Link to this 11hz tune specimen?
dlbeck was in town and popped into the office while I was testing it and grabbed a pic that ended up in the JTR thread a few days before I had things set to post on my forum. The same and more info is now in a new thread here on my forum.
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post #365 of 367 Old Yesterday, 04:39 PM
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Awesome, thx!
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post #366 of 367 Old Yesterday, 05:17 PM
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Quote:
Originally Posted by jbrown15 View Post
That ported sub looked awesome, why did Mark never actually put it into production as one of his regular products?
The original design was a 6th order bandpass using an 18" PR and 15" driver. Itai, aka cubesys, who later founded iRule has the first prototypes. These worked quite well and in fact I'm updating them while in Michigan the next 2 days...

Jeff built a similar design as the very first Captivator which was first a bigger unit with single 18" & 15" for a customer I didn't think it was worth dealing with (I was right ). Jeff re-designed a more compact version on his own and started selling them before he diagnosed the issue/limitation of the PR we were using which worked and modeled perfectly at low levels, but had surround cavitation issues in unexpected conditions. Similar to this re-purposing, he changed to a very beefy 18" driver to keep delivering the product and so became the product many of you know so well.

I later determined what was required from a PR for this use (especially +/-30mm from an 18" in 1-2 cu.ft.!), and the off-the-shelf solutions don't fit directly in the original boxes. At the same time I ran into confidence issues with the reliable delivery of the intended drivers. Basically that product & design has been at the ready for suitable parts and suppliers who could deliver them, or time and resources to tool custom parts. Many have seen this custom project I did for Keith Yates which is a direct derivative of the Terraform cabinets using more appropriate parts. If US suppliers weren't so flaky and could make the customizations I wanted, a related product might be available now. It is possible if not likely it will be at some point in the future.
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post #367 of 367 Old Yesterday, 06:48 PM
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Quote:
Originally Posted by Archaea View Post
@popalock ,


yeah i'll play around!


I've been told by @dominguez1 and @gpmbc that the caps need to be nearfield in their 15hz tune and the sealed all up front.


But I plan to play! Yes there are eight cabs and eight drivers. Not quite enough to make a symbol of manhood like you did with your 16, but eight is sufficient output for me.
Nice! The caps in the 15hz nearfield will be killer. How far away will the be from the LP? I know you've got a new theater, how big is it? Have you fired up the caps already? Do you have an idea how your room affects your LFE FR yet?
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