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post #1 of 28 Old 05-07-2012, 12:49 PM - Thread Starter
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CSS APR 15 is only $60!


I could never get past the cost of PRs, and the mass adjustment always seemed like a headache. Compared to everything at PE this is an amazing deal, 3 of these are less then one TC 15" PR. I was considering re-building my subs as ported, but this just decided for me, I'm in for a pair of PRs! I'm going to cheat the excursion of a single PR for each sub by using my amps 25hz filter and tuning from 18hz down. That's another thing I'm excited about I can just add more discs and go from an 18hz tune to a 17/16/15/14/etc at the twist of a wing nut!
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post #2 of 28 Old 05-07-2012, 02:08 PM
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"I'm going to cheat the excursion of a single PR for each sub by using my amps 25hz filter and tuning from 18hz down."

that's not cheating (getting something for nothing). it is a compromise, just like all other compromises with subwoofer design.

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post #3 of 28 Old 05-07-2012, 02:25 PM - Thread Starter
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It makes me feel like I'm cheating because I only loose 1 db at 18hz and the PR excursion drops from 38mm to 28mm

edit: woofer excursion is higher at 14.7 vs 9.7, I guess that's the compromise.
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post #4 of 28 Old 05-07-2012, 06:07 PM
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Interesting. I'm such a sealed sub head stuck in the sand.....

I dont get PR, anyone want to give a little explaination...... Dont go crazy, i'm a bit limited....
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post #5 of 28 Old 05-07-2012, 06:11 PM
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Quote:
Originally Posted by kgveteran View Post

I dont get PR, anyone want to give a little explaination...... Dont go crazy, i'm a bit limited....

A port is a column of air tuned to a specific frequency.

A PR moves a volumes of air and is tuned to resonate at a specific frequency.

For basic purposes, you can think of them as performing the same.
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post #6 of 28 Old 05-07-2012, 06:40 PM
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Some folks like using PR's to avoid port "noise" (chuffing) when the port cross-sectional area is too small for the required output. They can also be used when port lengths get extremely long. The downside is cost.

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post #7 of 28 Old 05-07-2012, 06:54 PM - Thread Starter
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Quote:
Originally Posted by poormanq45 View Post


A port is a column of air tuned to a specific frequency.

A PR moves a volumes of air and is tuned to resonate at a specific frequency.

For basic purposes, you can think of them as performing the same.

Adding on to this info. The greater the mass of the pr the lower its resonant frequency, less mass higher frequency. Cabinet volume along with the pr setup determine the system tune.

I've also been lead to believe that while a pr unloads just below tune like ported, it regains control of the woofer further down in frequency unlike ported.
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post #8 of 28 Old 05-08-2012, 04:58 AM
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Originally Posted by Jay1 View Post

I've also been lead to believe that while a pr unloads just below tune like ported, it regains control of the woofer further down in frequency unlike ported.

This makes sense.

There is always going to be the mechanical resistance of the suspension on the PR. That should help to maintain resistance on the woofer below the tuning frequency.
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post #9 of 28 Old 05-08-2012, 05:52 AM
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One of the finest subs I've ever owned: The Definitive Technology Trinity, utilized (4) PR's and had some prodigious output, in-room. And perhaps the point raised above about it being better-behaved down low over a typical ported design had something to do with why I NEVER heard a bad sound out of it, even when seemingly pushed to its limits in my room (120+dbs).


Can someone speak then to two items re PR's:

1. Do they lower a system's sensitivity over a port due to the nature of their mechanical resistance vs the lack thereof with a port? I would think so.

2. Regarding PR's lending to increased output, in-room: I always maintained that my Trinity was capable of much more output, in-room, than its outdoor, ground-plane measurements could reveal.

For instance, I also owned an SVS Ultra and while it was ranked very close to the Trinity in GP measurements, the Trinity measured at least 5-6dbs higher in my room.

So could another benefit of PR's be to better couple the sub to surrounding room boundaries (especially with corner placement)?

It's interesting to me that there are not more offerings with them and I would guess it's largely a cost issue as they seem to be as effective (if not more in some respects) as porting with little lost elsewhere...unless, again, there's a substantial reduction in system sens due to the PR mass.

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post #10 of 28 Old 05-08-2012, 08:11 AM
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I've always wanted to do a 12" front firing SW with a 12" down firing PR (to hide the PR looks) in a relatively small 15" cubed designed.
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post #11 of 28 Old 05-08-2012, 08:25 AM
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Originally Posted by bluestang View Post

I've always wanted to do a 12" front firing SW with a 12" down firing PR (to hide the PR looks) in a relatively small 15" cubed designed.

Downfiring PR's are, IMO a bad idea. Consider that the typical serious (tuned below ~25Hz) PR sub will have an extra pound or more (sometimes a lot more!) of mass hanging off the suspension.

So you lose a good bit of PR stroke to cone-sag. And probably shorten its life a good bit due to gravity pulling on the suspension.

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post #12 of 28 Old 05-08-2012, 08:44 AM
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Speaking of PR's, what are some good sources for these? I've checked out CSS, PartsExpress, AESpeakers. Anyone else? I'd like to try a small PR box for the 15" Dayton DVC.

bg
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post #13 of 28 Old 05-08-2012, 09:24 AM
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Quote:
Originally Posted by garciab View Post

Speaking of PR's, what are some good sources for these? I've checked out CSS, PartsExpress, AESpeakers. Anyone else? I'd like to try a small PR box for the 15" Dayton DVC.

How small are you thinking? IIRC, the 15" Dayton DVC likes somewhat of a larger enclosure.
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post #14 of 28 Old 05-08-2012, 09:53 AM
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Quote:
Originally Posted by kgveteran View Post

Interesting. I'm such a sealed sub head stuck in the sand.....

I dont get PR, anyone want to give a little explaination...... Dont go crazy, i'm a bit limited....

Check this write up Josh did on comparing different designs. I think PR makes most sense if you are limited on number of cabinets you can use and space.

http://www.data-bass.com/data?page=content&id=82
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post #15 of 28 Old 05-08-2012, 11:27 AM - Thread Starter
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Quote:
Originally Posted by garciab View Post

Speaking of PR's, what are some good sources for these? I've checked out CSS, PartsExpress, AESpeakers. Anyone else? I'd like to try a small PR box for the 15" Dayton DVC.

You really wont gain anything from the DVC without at least a 5ft3 box. A single APR15 loaded with 450g will get you about a 3.5db advantage from 35hz down to 20hz over a 3 ft3 (.7 Q) sealed box.

If you really want a small box the 390HO is better, 3.5 ft3 could get the same results as the DVC in 5 ft3, you just need a little more power..

This CSS PR deal is pretty great, which is why I posted it.
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post #16 of 28 Old 05-08-2012, 11:49 AM
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For my Dayton DVC15, I was going to build something with strong output in the 40-70Hz range, just to compliment my IB. Trying to get some 'punch' added to my system.

I had modeled a box around 2.5cuft, tuned to about 32Hz, and it looked to achieve what I wanted to try. Except fitting ports is an issue. So this new thread about PR's got me wondering if I could achieve what I was after.

True, modeling a 'hi-fi' box results in about 6cu.ft, tuned in the low 20's. But I don't need the low end for this particular box.

Ultimately, if I can build this box, my IB will be low-passed around 30-35Hz, vented box will be bandpassed from there up to the receiver xover. Yeah, it's going to be an experiment more than anything. But I gots nothing better to do.

bg
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post #17 of 28 Old 05-08-2012, 01:19 PM - Thread Starter
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Quote:
Originally Posted by garciab View Post

For my Dayton DVC15, I was going to build something with strong output in the 40-70Hz range, just to compliment my IB. Trying to get some 'punch' added to my system.

I had modeled a box around 2.5cuft, tuned to about 32Hz, and it looked to achieve what I wanted to try. Except fitting ports is an issue. So this new thread about PR's got me wondering if I could achieve what I was after.

True, modeling a 'hi-fi' box results in about 6cu.ft, tuned in the low 20's. But I don't need the low end for this particular box.

Ultimately, if I can build this box, my IB will be low-passed around 30-35Hz, vented box will be bandpassed from there up to the receiver xover. Yeah, it's going to be an experiment more than anything. But I gots nothing better to do.

Ahh ok. Try 2.5 ft3 with one APR15 and 225g mass added.
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post #18 of 28 Old 05-08-2012, 02:02 PM
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"Do they lower a system's sensitivity over a port due to the nature of their mechanical resistance"

no.

results will be very similar to ported for a low tune, but no port chuffing, though higher cost.

the little "earthquake" subs were similar.

dsp to limit over excursion and you are good.

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post #19 of 28 Old 05-08-2012, 04:51 PM
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This addresses a lot of questions I get on PR's regularly.

http://www.aespeakers.com/PRFAQ.php

John

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post #20 of 28 Old 05-09-2012, 08:04 AM
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Ok, looks like I'll be building two PR boxes. Placed an order for 2 from AESpeakers, to do the classic "woofer in front, two PR's on the sides" setup, and will order one from CSS to do the "down-firing woofer, funky PR on the front" setup. I'll move the DVC15 and amp between the boxes until I can score another, maybe take advantage of their current sale. The AE PR's can really take much more woofer, so maybe I can find a better woofer for that 18" cube.

bg
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post #21 of 28 Old 05-16-2012, 02:39 PM - Thread Starter
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Got my APR 15's today! $60 ea shipped to AK makes these an even better deal for me, I was expecting to have additional shipping charges. These things are really light, I think the stack of washers weighs about the same as the big PR. They come with a black circle sticker as well, I'm guessing this is to cover the end of the weight tube, but I cant see how it would help with the looks? The packaging also could have been better, as the little box the weights were secured in was flopping around inside the box.

My project will be on the back burner for a while, but I'm committed now.
LL
LL
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post #22 of 28 Old 05-16-2012, 02:46 PM
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I got mine yesterday, and I too was happy with the whole deal. And I thought the front tube would bother me, but I think it looks cool after all. Really neat design!

I'll be building my PR box for the Dayton DVC15 this weekend. Can't wait to give it a spin.

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post #23 of 28 Old 05-16-2012, 03:31 PM
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Quote:
Originally Posted by tgse3 View Post


Check this write up Josh did on comparing different designs. I think PR makes most sense if you are limited on number of cabinets you can use and space.

http://www.data-bass.com/data?page=content&id=82

Would it not make sense as well if you have unlimited space? What I gather from your comment is that you should use this design to maximize the space that you are limited too.

What if one had enough for four cabinets of any particular size housing any particular sub(s). Would it not make sense to use PR's to maximize your setup?

I guess you could argue that if there were no space limitations it would be easier to accomodate other designs so let me rephrase my question.

Sealed vs. Sealed w/PR...

 

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post #24 of 28 Old 05-16-2012, 03:37 PM
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"I've also been lead to believe that while a pr unloads just below tune like ported, it regains control of the woofer further down in frequency unlike ported."

below tuning in a p.r. design, the cone that is receiving the power blows out of control just like in a ported design.

below tuning in a p.r. design, the p.r. does not blow out of control below tuning because there is no longer anything coupled to it, so p.r. excursion maxes out around tuning frequency, then stays at that level below tuning.

"There is always going to be the mechanical resistance of the suspension on the PR. That should help to maintain resistance on the woofer below the tuning frequency."

that's not quite how it works. below tuning, the powered driver is no longer fighting against the p.r. frequency response falls like a rock and cone excursion explodes.

"One of the finest subs I've ever owned: The Definitive Technology Trinity, utilized (4) PR's and had some prodigious output, in-room. And perhaps the point raised above about it being better-behaved down low over a typical ported design had something to do with why I NEVER heard a bad sound out of it, even when seemingly pushed to its limits in my room (120+dbs)."

many well designed commercials subs have custom designed limiters so that you don't every find out for yourself where the sub starts to sound bad.

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post #25 of 28 Old 05-16-2012, 05:17 PM
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Got mine today as well!!

Bandpass enclosure to be started this weekend if all goes well. And my 11 year old daughter WANTS to help..... I was speechless. Knew she was a cool kid but this is of course over the top!

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post #26 of 28 Old 05-16-2012, 06:46 PM
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I was just figuring up numbers and you could do (32) of these with (16) 15" Dayton titanic MK III subs for the same price as (8) FTW-21"s.

War Eagle!
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post #27 of 28 Old 05-16-2012, 09:29 PM
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oops, wrong thread. i reposted over in your build thread.

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post #28 of 28 Old 05-17-2012, 09:39 PM
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Quote:
Originally Posted by kgveteran View Post

Interesting. I'm such a sealed sub head stuck in the sand.....

I dont get PR, anyone want to give a little explaination...... Dont go crazy, i'm a bit limited....

Don't ask me, I don't even know what a PR is
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