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Old 6th February 2013, 10:04 PM   #21
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Quote:
Originally Posted by ghettosynth View Post
So the alpines in sim had strong peaks at either end of the usable bandwidth.
The dual 8's in isobaric sound intriguing, but I imagine that there's no free lunch, so, reducing the box size must yield some other trade-off? If we assume that the additional complexity isn't a construction issue, what are the disadvantages to such an arrangement?
The disadvantage is isobaric uses twice the drivers and power for the same level as one driver, but the box size is smaller.

As far as sim Vs reality, look back at your other post and look at my ported box actual and sim response. The difference is huge.

Even if the sim turns out to be correct, I'd take an equalized peaky response over a light cone flapping it's guts out any day.
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Old 8th February 2013, 02:45 AM   #22
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Originally Posted by weltersys View Post
The disadvantage is isobaric uses twice the drivers and power for the same level as one driver, but the box size is smaller.

As far as sim Vs reality, look back at your other post and look at my ported box actual and sim response. The difference is huge.

Even if the sim turns out to be correct, I'd take an equalized peaky response over a light cone flapping it's guts out any day.
These were huge peaks, but, I get the general idea. As far as isobaric boxes, from what I've read, there's really not much reason to use them unless space is a serious problem and the additional driver/power cost is negligible.

I'm guessing the $16k quad 21 isobaric that goes down to 20hz is practical because the 500 pound box is small for a box that goes down to 20hz?
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Old 9th February 2013, 12:04 AM   #23
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Originally Posted by ghettosynth View Post
I'm guessing the $16k quad 21 isobaric that goes down to 20hz is practical because the 500 pound box is small for a box that goes down to 20hz?
If you are talking about MaCaully's M421, it in no way makes it to 20 Hz.
Note the lack of even a basic frequency response chart in the spec sheet.

http://soundforums.net/test-drive/18...subwoofer.html

The 421 can get very loud to around 30 Hz, but uses twice the power and drivers as the DSL TH-221, which makes it to 22Hz -3dB.

There is a lot more to a good sub than a "FEA optimized design" ;^).

Last edited by weltersys; 9th February 2013 at 12:07 AM.
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Old 12th February 2013, 03:53 AM   #24
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Originally Posted by weltersys View Post
If you are talking about MaCaully's M421, it in no way makes it to 20 Hz.
Note the lack of even a basic frequency response chart in the spec sheet.

McCauley M421 Quad 21" Subwoofer

The 421 can get very loud to around 30 Hz, but uses twice the power and drivers as the DSL TH-221, which makes it to 22Hz -3dB.

There is a lot more to a good sub than a "FEA optimized design" ;^).
Interesting read, I have no real point of reference for such systems, I was simply impressed by its massive-osity!
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Old 12th February 2013, 06:13 AM   #25
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Originally Posted by ghettosynth View Post
That's what I meant



So the alpines in sim had strong peaks at either end of the usable bandwidth. I suppose that they might work "OK" in the THAM, but I don't know. I wouldn't waste my time building them without first having a better sim.

The dual 8's in isobaric sound intriguing, but I imagine that there's no free lunch, so, reducing the box size must yield some other trade-off? If we assume that the additional complexity isn't a construction issue, what are the disadvantages to such an arrangement?
Another way of looking at it is 5-6dB more output, for 4x the cost.

Is that worth the investment?

That really depends on how much power you have. For me it's compelling for a couple reasons:

1) There are 4000 watt amplifiers at Wal Mart for $275:
Behringer Stereo Power Amplifier - Walmart.com

2) I think the Geddes multi-sub approach works really well. I would rather have 2-3 subs distributed throughout the room than one.

Personally, I wish there was an 8" sub with an FS of 35hz or so and a qts of 0.3, with a decent motor. The MCM 55-2421 comes prett close but it doesn't sound remotely as clean as the Alpine SWR 843D or the CSS Trio 8.

Last edited by Patrick Bateman; 12th February 2013 at 06:16 AM.
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Old 12th February 2013, 09:57 AM   #26
grec13 is offline grec13  United States
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Originally Posted by Patrick Bateman View Post
Another way of looking at it is 5-6dB more output, for 4x the cost.

Is that worth the investment?

That really depends on how much power you have. For me it's compelling for a couple reasons:

1) There are 4000 watt amplifiers at Wal Mart for $275:
Behringer Stereo Power Amplifier - Walmart.com

2) I think the Geddes multi-sub approach works really well. I would rather have 2-3 subs distributed throughout the room than one.

Personally, I wish there was an 8" sub with an FS of 35hz or so and a qts of 0.3, with a decent motor. The MCM 55-2421 comes prett close but it doesn't sound remotely as clean as the Alpine SWR 843D or the CSS Trio 8.
Well. Nobody mention the changing of dynamic of isobaric. They sound really different. Very fast and deep -perhaps? So the idea of isobaric TH IS very interesting.
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Old 12th February 2013, 10:13 AM   #27
tinitus is offline tinitus  Europe
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with the smaller woofers I see improved power handling as maybe the bigger advantage of isobaric
but I guess only when already at 'biggest acceptable box size limit', whatever that may be
reasoning ?
well, if power handling is crutial...
and using the more modest smaller hifi woofers...
maybe the higher cost could be compared to blown drivers as other alternative
(please, I noted maybe only when already at box size limit)

I don't need that much, so it may work with a single 8" Usher hifi woofer
but thats besides the topic
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Old 12th February 2013, 10:56 AM   #28
grec13 is offline grec13  United States
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[QUOTE=tinitus;3366553]with the smaller woofers I see improved power handling as maybe the bigger advantage of isobaric
but I guess only when already at 'biggest acceptable box size limit', whatever that may be
reasoning ?
well, if power handling is crutial...
and using the more modest smaller hifi woofers...
maybe the higher cost could be compared to blown drivers as other alternative
(please, I noted maybe only when already at box size limit)

I don't need that much, so it may work with a single 8" Usher hifi woofer
but that besides the topic[/QUOTE

For isobaric and Push-Pull you can use way cheaper woofers and have huge improvements in SQ. And as we all well know below 70hz there is 'only" maters how much air can you move and for how much $. Isobaric in this regards well undervalued.
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Old 12th February 2013, 11:12 AM   #29
tinitus is offline tinitus  Europe
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Originally Posted by grec13 View Post
For isobaric and Push-Pull you can use way cheaper woofers and have huge improvements in SQ.
'certain' important specs seems to be more limited with smaller woofers, and maybe the cheaper ones especially
and when it comes to bigger woofers, I do not feel safe with cheap ones
its much easier, faster, cheaper, and safer, to use magnet gap with big tolerances
but maybe the small ones suffer less from this
dont know enough about it
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