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Old 14th March 2008, 14:23   #211
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I built a few PR subs even one that used 3 PRs (one active driver). The drivers (woofer and PRs) I used were not great drivers (Madisound home brand). I did compare this sub to a subs using a sloted port (not round) and the sloted port souned tighter. But I believe it was just bad tuning on my part. I was expecting too much from the PR based sub.

After that my experiments with PR were in the 90s. We (a friend and I) tinkered with a few PRs that were constructed so that mass tuning could be done easily. The PRs were rear mounted. These designs were far more successful (they used better drivers built in Denmark) then my friend fell on hard times and further development stopped (I heard his accountant ran away with his wife, after bleeding his company or something insane thing like that).

B&T might know this 6' 3" "friend" (from Essen). :-)

Talking about the above Essen based experiments, Clip, one advantage we found was that when trying to couple the port to a wall (or floor) there was some ammount of non-linearities. flared ports I assume might have solved this. a PR however could be coupled to a wall/floor with fewer side effects. I dont know if these supposed effects are psychological or real as we did not ABX this.
Thanks for the info Navin.

i feel really bad for that guy.

i don't know when but i would definitely like to try a PR. Another thing added to my wish list.

cheers
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Old 14th March 2008, 14:29   #212
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Cool What is the usp of a PR ?

This might sound very bizare'

However, I always wanted to know; Why would one use a PR ?

'Generally' [this is not a thumb rule]
Sealed Bozes are 'preferred' in SQ set ups.
Ported Enclosures are 'preferred' in SPL set ups.

Where are PR's used ?
More for SQ or SPL ?
Where & When would a 'band pass' enclosure be preferred ?


Can any of the 'Guru's try and offer some form of an explaination ?

Please.

Thanks,
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Old 14th March 2008, 14:43   #213
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Originally Posted by clipto333 View Post
Thanks for the info Navin.
Clip, you learn a lot more from just doing, than worrying if the exact T/S specs if the woofer are just right. I like your sprit, let it loose. There is only so much you can gleam from forums (we are not talking of this forum as TBHP's ICE section barely graces the subject).

I wont be very wrong is saying that atleast half the DIYers do not measure their drivers (some dont care, some dont have the facility, some know that they can tune the system to compensate and some dont even know that manufacturer specs can often be off by more than 15%) before using them.

Think of the coil of the damaged woofer (you intend to use as a PR) as an added weight. In fact you could well find that you might need to add more mass to the woofer cone so the coil weight is not really something to worry about.
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Old 14th March 2008, 14:47   #214
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Originally Posted by BHAGWAN View Post
This might sound very bizare'
However, I always wanted to know; Why would one use a PR ?

Sealed Bozes are 'preferred' in SQ set ups.
Ported Enclosures are 'preferred' in SPL set ups.
Where are PR's used ?
More for SQ or SPL ?
B, from anyone else I would assume they wanted to know. Coming from you (an audio consultant) I believe you are joking/teasing. Sam and B&T really got me last time. Not again.
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Old 14th March 2008, 15:01   #215
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Smile I am asking on a serious note !!!

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Originally Posted by navin View Post
B, from anyone else I would assume they wanted to know. Coming from you (an audio consultant) I believe you are joking/teasing. Sam and B&T really got me last time. Not again.
Sirji,

I am asking on a serious note.

You see, PR's were used in Home Audio speakers more than 2 decades back.
I have not come across many in todays day & age that use PR's

Very Very few persons use Band Pass - Speed [lack of it] is the main concern.
Sealed Boxes & Ported enclosures, I may have some idea about, but PR's is an 'alien field' to me.

Kindly shed light - as per my earlier post. Appreciate the efforts.

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Old 14th March 2008, 15:58   #216
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Originally Posted by BHAGWAN View Post
Sirji,

I am asking on a serious note.

You see, PR's were used in Home Audio speakers more than 2 decades back.
I have not come across many in todays day & age that use PR's

Very Very few persons use Band Pass - Speed [lack of it] is the main concern.
Sealed Boxes & Ported enclosures, I may have some idea about, but PR's is an 'alien field' to me.

Kindly shed light - as per my earlier post. Appreciate the efforts.

Bhagwan,

Since you are a user of a PR, i would like to know why you installed it. what was the reason you went for a PR instead of a sealed or a ported enclosure. Or if anyone suggested you to install it, what was the reason given.

And i would also like to know if a PR is for SQ or SPL.

Thanks
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Old 14th March 2008, 16:11   #217
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PR's were used in Home Audio speakers more than 2 decades back.
not exactly 2 decades back but yes PR designs today are few and far between. I think the fad has passed. However that does not mean that the design is flawed.

The last commercial PR design I head was the Theil CS6. Funny at one end it had a coaxial mid-tweeter and at the other end a PRed bass.

PRs in many ways are tuned just like vented/ported boxes. Their roll offs and acousti-mechanical characteristics also are quite similar. The advantage is that there is no chuffing and the disadvantage is that the PR's output might well be out of phase (just like some vented designs) depending on the postion and freq band (read as tuning) of the PR.

Once flared and dimpled (yes the same dimples used in golf *****) ports reduced the chuffing the need for PRs died. Besides PRs are significantly cheaper than ports (a port would easily be 1/0th the cost of a PR). When you work that into the cost of a loudspeaker it can make a significant difference (we can discuss commerical aspects later).

PRs are easier to tune (ports can be tuned by changing length and/or light stuffing) than ports besides a PR can achinve a tuning where a port might be too long to fit in a box (which is suspect is your case). Ports on the other hand dont have a resonant frequecny of their own (PRs do) and this means that the roll off is slightly smoother (the Fs of the PR can cause a notch in the LF roll off). Besides Ports have no fixed Mms. Some claim that this is why PRs sound like they have poorer transient respone than ports. I believe that this is only partially true. A port when loaded just right might have as much velocitive air mass (moving air mass) as a PR. Still the air mass in a port will come to rest much faster than a PR becuase the PRs Mms is fixed, the air mass in a port is variable.

So really once the chuffing problem was eliminated the only real advantage of a PR is when a port wont fit in a box. Peerless XLS subs are common examples.

Funny, 3 decades ago a tall man in a lab coat could not stop extorting the advantages of a PR (almost all of his designs employed one) today few of his designs (if any) employ a PR.

B, I am sorry for offering such an abridged expalnation. As some of YOUR friends would tell you, I am known to rant more. But the limits of my time and warnings that I am scaring newbies have curtailed my longer essays.

Last edited by navin : 14th March 2008 at 16:13.
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Old 14th March 2008, 16:11   #218
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Quote:
Originally Posted by BHAGWAN View Post
You see, PR's were used in Home Audio speakers more than 2 decades back.

Sealed Boxes & Ported enclosures, I may have some idea about, but PR's is an 'alien field' to me.
Hay Bhagwan! Stop pulling Navin's leg. In case you havent noticed, Sam has conveniently stopped replying.

Quote:
Originally Posted by BHAGWAN
I have not come across many in todays day & age that use PR's
Anil maarega.

Quote:
Originally Posted by BHAGWAN
Very Very few persons use Band Pass - Speed [lack of it] is the main concern.
Bose/ Space/ Telome waale sab milke maarenge.
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Old 14th March 2008, 16:33   #219
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Originally Posted by BHAGWAN View Post
I am asking on a serious note.:
Navin maarega

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Hay Bhagwan! Stop pulling Navin's leg. ...Sam has conveniently stopped replying.
Sam knows what is good for him. I dont take prisoners.
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Old 14th March 2008, 17:20   #220
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Could it be that PRs are useful when the box to be used is so shallow that a port of the required length cannot be used?

Philips uses/used PRs in quite a few of their mass-consumer oriented "hi-fi" systems they called the WOOX. Probably for the bling-factor of showing two cones in a speaker box.

I remember that Kenwood had this really small (and thin/shallow) active sub that was known as the W00X (KSC-WA-62-RC if I remember right) that had a 5.25" woofer and a 6.5" (or 6") passive radiator. I mentioned this subbie because it was a very thin-mount one,and because the woofer and the PR are of two different sizes. I'd tried getting one of these as my very first subs (stealth was a major requirement then) but I could not source one.

The Basslink also had a 10" driver and a 10" PR, if I remember right.

And didn't Blau have an Active Sub (ODx something) with a 10" driver and an 8" (I think) PR?

So the point I'm coming to is, does a PR help reduce the size of the enclosure? And similarly, does a PR help give better boom at lesser size?
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Old 14th March 2008, 17:48   #221
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Originally Posted by navin View Post

B, I am sorry for offering such an abridged expalnation. As some of YOUR friends would tell you, I am known to rant more. But the limits of my time and warnings that I am scaring newbies have curtailed my longer essays.

dont do that. please. don't refrain from posting longer essays. :-)

I think we need a separate section for advanced audio. where we all can discuss technical aspects of audio.

cheers
clip
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Old 14th March 2008, 23:46   #222
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Talking I did not - B & T ordered and billed me for it !! Just Kidding

Quote:
Originally Posted by clipto333 View Post
Bhagwan,

Since you are a user of a PR, i would like to know why you installed it. what was the reason you went for a PR instead of a sealed or a ported enclosure. Or if anyone suggested you to install it, what was the reason given.

And i would also like to know if a PR is for SQ or SPL.

Thanks
Sir, I was using Illusion Luccent IM 12 Subs in my RS.
That was the 'best' enclosure I had ever constructed for any sub woofer.
The Bass was really nice. I had liked it.

Some how, I wanted to upgrade. B & T offered the GZ sub to me. So I considered & said, get me the best SQ sub that GZ makes.
This is what B & T offered to me.
So I purchased it & made and enclosure & installed it.
Simple !

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Old 14th March 2008, 23:55   #223
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Thumbs down I am not trying to pull any ones leg !!

Guys, this is a 'serious' question.

I am not trying to pull some ones leg.

I want to know.
Some one please answer the question seriously.

B & T forget the Bose & Telome examples. They are low-fi products.
The only High End person that has used a Band Pass [at least that I know of] is Ascendo Speaker - Germany - Mr. Jurgen.
The Thiel SC 6 has been stopped - I think.
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.

Sealed is still used. Green Mountain Audio - Wilson Benesch [Isobarik]
Ported is most common. 90 % + speakers in the world are Ported.

Do not give me Def Tech and the likes as an example. I am asking about 'serious' audio products.

My question still stands:-

Quote:
However, I always wanted to know; Why would one use a PR ?

'Generally' [this is not a thumb rule]
Sealed Boxes are 'preferred' in SQ set ups.
Ported Enclosures are 'preferred' in SPL set ups.

Where are PR's used ?
More for SQ or SPL ?
Where & When would a 'band pass' enclosure be preferred ?
Even Sam is welcome to answer.
I am not trying to pull any one's leg - surely not the 'moderators' !!!
So, Navin do not worry. I really want to know.

Give me an answer & give me examples - please.

Thanks.

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Old 15th March 2008, 01:44   #224
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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.
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Old 15th March 2008, 10:36   #225
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Cool PR kiya toh darna kya...

Quote:
Originally Posted by clipto333 View Post
Since you are a user of a PR, i would like to know why you installed it. what was the reason you went for a PR instead of a sealed or a ported enclosure.
Clipto, remember one very important fact:

"PR karne wale kabhi darte nahin, jo darte hain woh PR karte nahin"
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