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Old 22nd May 2005, 05:53 AM   #1
fazman is offline fazman  Canada
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Default starting over again... help!

OK, My isobaric loaded sub with 2 JBL's 2235 was a nice little adventure but it just ain't gonna happen anymore because they have both been sold!
BTW Thank you Simon5 for all your help on this matter but after all said and done the JBL's were just not cutting it for me for home theater. It went low enough but just not at the levels I like to listen to.
Here is what I'm left with...
QSC amp 200 watts/channel bridged 500watts into 8, 800 watts into 4
5 cubic foot enclosure can be sealed or ported.
Paradigm x-30 active x over
Have been looking at Ascendant Audio Avalanche subs, look like some nice stuff but the fact that the subs aren't ready yet makes me a little nervous to make a pre order.
I have a budget of no more than 250 bucks to spend on a quality woofer be it 15, or maybe even 18 if it can be incorporated.
Woofer needs to be able to handle gobs of power with some high excursion capabilities.
Any suggestions? Keep in mind that the enclosure will not change.


Thanks and apologies for picking everyone's brain on the last project that didn't fly!
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Old 23rd May 2005, 05:59 AM   #2
simon5 is offline simon5  Canada
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A single Ascendant Audio Avalanche 15 would be nice in a 5 cu.ft box ported if there's any left. You should call Chad to see. Only 225$ for awesome performance.

Then if you can get a Linkwitz Transform circuit, I would step up to the Avalanche 18 at 275$ hehe!
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Old 23rd May 2005, 02:31 PM   #3
fazman is offline fazman  Canada
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Quote:
Originally posted by simon5
A single Ascendant Audio Avalanche 15 would be nice in a 5 cu.ft box ported if there's any left. You should call Chad to see. Only 225$ for awesome performance.

Then if you can get a Linkwitz Transform circuit, I would step up to the Avalanche 18 at 275$ hehe!

What's a linkwitz transform circuit?
Why would I need one?
I actually considered buying an 18 Avalanche in putting it in my 5 cubic ft. box only sealed.
I did call Chad on this and he said that would give me outstanding results.
Do you think I can get low enough with the 18 in my box? (box too small?) or do you think I would need to equalize it at the very bottom? (have an old Peavy 31 band lying around but want to sell it to help pay for a new sub)
Also would you trust that if I put my order in for an 18 Avalanche now I should have no problems recieving it. I think they said they would be ready sometime in June at the latest.


I'm just a little nervous ordering something that isn't technically done yet, but I guess if they have a good reputation I shouldn't worry too much about it right?

Sorry for all the questions, I just want to make sure I make the right decision this time!
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Old 23rd May 2005, 11:32 PM   #4
simon5 is offline simon5  Canada
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A Linkwitz Transform circuit is used to equalize the low end by changing the Q of the box electronically.

You would need one to get a more flat curve in room because the box is a bit small for a 18 inches subwoofer.

The Avalanche 18 will have quite flat output in room down to about 30 Hz. It will still be very loud under this, but less loud than stuff over 30 Hz. If you like the sound of a sealed subwoofer, you will probably like that rolloff.

That's why I was recommending the Avalanche 15, better suited to a 5 cu.ft box, you could port it and get about 4-5 dB more output at 20 Hz, but lose around 2-3 dB at 40 Hz and over. Anyway, one or the other will get extremely loud.

You will have no problems with Chad. Don't worry about that.
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Old 25th May 2005, 03:17 PM   #5
fazman is offline fazman  Canada
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Just took some exact measurements of my enclosure that use to house the JBL's.
Including the bracing I net out at exactly 5.4 cubic inches of internal space, that's not including the space the driver will occupy or the port(s).
Going the 15 inch route seems to make more sense to me as I don't want to equalize a larger driver to make it go lower.

The Avalanche 15 has an fs of 16 hertz, where should I be tuning this beast for the enclosure that I have?

Also is it necessary to have an extremely large diameter port, by that I mean 6 inches or will a 4 inch diameter work?


Will I improve the performance by using 2 ports to tune?
(Inside dimensions are 18"x25"x20.75")
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Old 25th May 2005, 06:33 PM   #6
GM is offline GM  United States
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Greets!

>The Avalanche 15 has an fs of 16 hertz, where should I be tuning this beast for the enclosure that I have?
=====
For music/HT, 16Hz is about the practical limit before the vent gets too long.
=====
>Also is it necessary to have an extremely large diameter port, by that I mean 6 inches or will a 4 inch diameter work?
=====
4" is fine.
=====
>Will I improve the performance by using 2 ports to tune?
=====
Not really.

GM
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Old 25th May 2005, 08:26 PM   #7
simon5 is offline simon5  Canada
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Since a huge displacement driver like this will move alot of air, the best would be at least a dual flared port like the Precision Port 4" diameter. You can keep it full length, for a final tuning of about 17.7 Hz.

If you want to use two 4" diameter port, you'll need to make bends in the ports.
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