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Old 15th March 2008, 11:17   #226
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Originally Posted by Autophile View Post
I think its just a way to make money by selling cones & baskets w/o motor.
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Originally Posted by BHAGWAN View Post
I am not trying to pull some ones leg.
Any 'serious' High End speaker maker that has a PR in its design. Sonus Faber used to have in the 80's with its Extrema etc.
Sam is welcome to answer.
B, from what Sam and B&T tell me, you could well be teaching us than posing such questions. Hence the consensus is that you ARE pulling somone's leg (if not mine).

It is really quite simple. Outside of the elimination of chuffing (which is also rediced if not eliminated by flared/dimpled ports) and the fact that you can tune a small box pretty low PRs also offer some secondary benefits.

Passive radiator systems can produce a bit MORE SPL (2-3db) at the low cutoff than a similarly sized/tuned ported system, they exhibit an INCREASE in SPL at Fb compared to ported systems.

Like I said above since PRs are fixed Mms systems (ports are variable mass systems and the air mass in the port changes based on the how much air is moving through the port - aka volume/SPL) they might not have the same alacrity especially at lower SPLs (where the air mass in the port is small). This may well be why most better systems have stopped using PRs.

BTW Richard Vandersteen, the basoon player, still uses PRs in his loudspeakers. I am quite fond of his designs.
http://www.vandersteen.com/pages/2Celit2.html
V2W Revised Literature
"the V2W adds a front-firing 12-inch passive radiator to the 2W series' standard trio of 8-inch woofers"
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Old 15th March 2008, 12:28   #227
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Originally Posted by Autophile View Post
I think its just a way to make money by selling cones & baskets w/o motor. People get value one who wants to show off two subwoofers for the price of 1.5

Companies like Boston Acoustics are still doing it. I still can't understand why?.

I could understand this at time when high power low impedance amplifier and high efficiency drivers used to be non-existent or expensive, not today when kw power in car audio and quality sub woofers are not that expensive and neither they require big boxes like in older times.
I'm surprised you have this view. Don't folks desire a ported enclosure any longer?

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"PR karne wale kabhi darte nahin, jo darte hain woh PR karte nahin"
Somebody... Kill me... KILL ME!
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Old 15th March 2008, 13:13   #228
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Originally Posted by gunbir View Post
Clipto, remember one very important fact:

"PR karne wale kabhi darte nahin, jo darte hain woh PR karte nahin"
yeah, i agree. so you did PR when you were in 11th. lol
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Old 15th March 2008, 18:16   #229
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Originally Posted by gunbir View Post
Clipto, remember one very important fact:
"PR karne wale kabhi darte nahin, jo darte hain woh PR karte nahin"
(x20; I wish they allowed more smileys). Wah wah, subhanallah!!!

Gunbir, this is another one of your classic "Drill chahta hai..." type compositions!!! Keep it up.

Last edited by DerAlte : 15th March 2008 at 18:19.
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Old 15th March 2008, 18:27   #230
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Originally Posted by gunbir View Post
"PR karne wale kabhi darte nahin, jo darte hain woh PR karte nahin"
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Originally Posted by Bass&Trouble View Post
Somebody... Kill me... KILL ME!
Kyon boss, kabhi PR nahin kiya hai kya?
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Old 17th March 2008, 07:24   #231
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Exclamation This is my sub woofer design. Concept based on this...

[COLOR=#ffffff][COLOR=#000000]Isobarik loading: [/COLOR][/COLOR]

[COLOR=#ffffff][COLOR=#000000]This is not a new concept, having been originally introduced by Harry Olson in the early 1950's. Technically, "isobarik" is not really an enclosure type; it is a loading method. This loading method involves the coupling of two drivers to work together as one unit. This is typically accomplished either by placing two drivers face to face or by coupling them with a small chamber. The result of coupling the two speakers is that the coupled pair (iso-group) can now produce the same frequency response in half the box volume as a single speaker of the same type would require. For example, if a speaker is optimized for performance in a 40l. enclosure, one iso-group of the same speakers can achieve the same low frequency extension and overall response [/COLOR][/COLOR]characteristics in a 20l. enclosure.

I have used 2 Illusion Audio - Leccent - IM 12 [12"] Woofers in a Clamp Shell - Sealed Box - Loading. The woofer is just complete.
It shall be installed soon. Will take pictures and post soon.
[Hope it works] !!!
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Old 17th March 2008, 09:58   #232
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Other than the savings in boot-space, does the Isobarik setup sound better than a single unit of the same sub-driver in a sealed box?

I'm asking, because the setup will be just as loud as a sealed box using a single single driver, right (though you're using 2 drivers)?

I think this was discussed someplace here before, but I can't now find the discussion.
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Old 17th March 2008, 10:18   #233
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Originally Posted by hydrashok View Post
Other than the savings in boot-space, does the Isobarik setup sound better than a single unit of the same sub-driver in a sealed box?
that would depend on the box tuning and it's integration with the transfer function of the car in question. For my Skoda, for example, I have learnt a Qtc of 0.6 sounds better than a Qtc of 0.7 (what is commonly called optimal tuning). Hence my preference for aperiodics (QL>7). In fact I am of the view that variable box tuning (by controlling the "lossy-ness" of the box) maybe a very effective way of mating the box's tuning to the car's transfer function. There is no free lunch however, aperidoics have their limiations too.

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Originally Posted by hydrashok View Post
the setup will be just as loud as a sealed box using a single single driver, right (though you're using 2 drivers)? .
but it will need twice the power (as a single woofer in a sealed box) to produce the same SPL.
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Old 17th March 2008, 11:01   #234
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Cool Space Saving !!!

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Originally Posted by hydrashok View Post
Other than the savings in boot-space, does the Isobarik setup sound better than a single unit of the same sub-driver in a sealed box?
Sir, you are correct;
Isobarik only helps to reduce the enclosure 'size'

You see, in an I-10 space is at a premium.
By loading the 2 woofers in Isobarik, I can effectively 1/2 the enclosure size. This was very very important to me.

SO, cost of driver is double & construction of enclosure is more, but it saves space. So one had to decide what they want......

'Generally' ported enclosures will play 'louder' as compared to 'sealed' enclosures. Drivers being optimised for each.

But, this is not about 'loud' but about 'space' & 'clean bass' !!
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Old 17th March 2008, 11:06   #235
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Originally Posted by BHAGWAN View Post
SO, cost of driver is double & construction of enclosure is more,
...and sensitivity of the woofer is rediuced by about 3db and hence the woofers require twice the power to produce the same SPL
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Old 17th March 2008, 11:41   #236
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Angry Expensive options !!!

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Originally Posted by navin View Post
...and sensitivity of the woofer is rediuced by about 3db and hence the woofers require twice the power to produce the same SPL
Basically Isobarik is an expensive option to explore.
Only advantage is space / enclosure size.
The cost is high [extra driver] & the ampfilier requirement is double.

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Old 17th March 2008, 11:46   #237
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but it will need twice the power (as a single woofer in a sealed box) to produce the same SPL.
Yeah, I missed mentioning that too!

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Originally Posted by BHAGWAN View Post
... I can effectively 1/2 the enclosure size. This was very very important to me.

SO, cost of driver is double & construction of enclosure is more, but it saves space. So one had to decide what they want......
....
But, this is not about 'loud' but about 'space' & 'clean bass' !!
You must really need that boot space! I'd thought there must be some substantial additional benefit in sound if you need to spend about double the money (for 2 drivers and extra amp-power). And that's no ordinary box you're making either. More power to you
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Old 17th March 2008, 11:53   #238
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Originally Posted by BHAGWAN View Post
You see, in an I-10 space is at a premium.
By loading the 2 woofers in Isobarik, I can effectively 1/2 the enclosure size. This was very very important to me.
SO, cost of driver is double & construction of enclosure is more, but it saves space. So one had to decide what they want......
If its strictly a space issue, why not just do a Spare Wheel Well Sub setup...
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Old 17th March 2008, 12:03   #239
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Wink Where do you put the spare wheel ?

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Originally Posted by gunbir View Post
If its strictly a space issue, why not just do a Spare Wheel Well Sub setup...
Sir, where would I put the 'spare wheel' ?

Please do bear in mind; This is not my car.
It belongs to the lady of the house. She never wanted an 'audio set up' in her car to begin with.
I said, I will put only 1 pair of speakers in the front, so she agreed.
Now I have 2 Power Amps & a sub enclosure [24 kgs] in the boot;
She is already hopping mad....

Not to forget, she has no idea of what I have spent on it. If she gets wind of that, I will be 'cas******' [I hope this is allowed here] !!!
God only knows what I will have to buy her to passify her.....

That is a different story.
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Old 17th March 2008, 12:14   #240
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Sir, where would I put the 'spare wheel' ?
dont tell she knows how to change the tyre or is willing to do it. instructions to my wife are as follows "if you have any trouble, park and lock the car and take a cab home".
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