# New Passive Radiators from Creative Sound



## anidabi

It seems that CSS is offering now also passive radiators. http://www.creativesound.ca/

*PR1816* 
Fs: 4.2hz
Qms: 67.62
Vas: 1840L
Mms: 1600g
Cms: .9mm/N
Sd: 1200 sqcm
Xmax: 3" P-P

*PR1821*
Fs: 3.651 
Qms: 67.72 
Vas: 1840 L 
Mms: 2100g 
Cms: .9mm/N 
Sd: 1200 sqcm 
Xmax: 3" P-P



















Prices are for the *PR1816* $129 and *PR1821* $139.



Anyone willing to try them out? :bigsmile:


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## WillyD

*Re: New 15” Driver - CSS SDX15*

Hey anidabi - Yeah, these PRs look pretty cool. Glad there are some more options for those interested in PRs. Here is a sim for ya, using two of the PR1821s.


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## anidabi

*Re: New 15” Driver - CSS SDX15*



WillyD said:


> Hey anidabi - Yeah, these PRs look pretty cool. Glad there are some more options for those interested in PRs. Here is a sim for ya, using two of the PR1821s.


It's too bad those were not available when I bought SDX15. I was one to buy from the big SDX15 dispatch to finland. Now I have almost finished sonosub. I only have to paint that sucker. Been listening it for a few days now and I wonder if I ever will be able to finnish that?! :whistling: :R


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## vinculum

*Re: New 15” Driver - CSS SDX15*

Anyone know if those PRs use foam surrounds? I've emailed CSS this question, but nobody got back to me. They almost do look like foam, but it is hard to tell.

Thanx!
Dr V


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## coctostan

*Re: New 15” Driver - CSS SDX15*

What is the advantage to using the PRs if the box is still quite large at 225l? Wouldn't it be easier to just bump it to 300l and do a LLT?


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## vinculum

*Re: New 15” Driver - CSS SDX15*



coctostan said:


> What is the advantage to using the PRs if the box is still quite large at 225l? Wouldn't it be easier to just bump it to 300l and do a LLT?



225 Liters (8 cubic feet) is a 24"x24"x24" box. Thats not large, especially for an EBS IMHO!


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## WillyD

*Re: New 15” Driver - CSS SDX15*



coctostan said:


> What is the advantage to using the PRs if the box is still quite large at 225l? Wouldn't it be easier to just bump it to 300l and do a LLT?


You don't think 225 is much less than 300liters? Well its only 25%, but thats not bad. One real advantage is the lack of port compression that the 300liter LLT would suffer from at high output. Granted, and I know this might be what Steve would say, is for the $260 you spend on the two PRs, one could afford another SDX and might as well build two 300liter LLTs. Then the port compression thing is less of a problem since two subs are sharing the load.

So I try to be objective about it. :bigsmile:

PRs will continue as they've always been...a product for a smaller group of DIYers. So many DIYers, including me, don't care much about the size of their sub so it makes sense. But for someone who is looking for a single 200liter EBS sub (it can be a tad smaller or larger than 200, of course) the sim I posted would be a good option.


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## SteveCallas

*Re: New 15” Driver - CSS SDX15*

For the $260 you would be spending on two PRs, you'd be better off buying another driver and building a second subwoofe.....wait a minute, yeah.

Also, the thought process that using PRs saves you enclosure volume is false. I'd venture to say you may even need to go larger, as two 18" PRs may displace more volume than a 6" diameter port - the volume of the enclosure won't change whether you use a port or PRs. If you model a 300 liter ported LLT, you'd still need to make a 300 liter PRed sub to match the performance. So now you're looking at spending a lot more money, not saving any space, and maybe eliminating a couple dbs compression in the subsonic range at extreme output levels. Just doesn't make sense to me :yawn:

P.S. - Oh, and PRs aren't exactly guaranteed to provide clean output.


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## Ilkka

*Re: New 15” Driver - CSS SDX15*



WillyD said:


> One real advantage is the lack of port compression that the 300liter LLT would suffer from at high output.


You have PRs that don't cause any power compression (when using 2:1 ratio)? Please send 1000 pieces to me asap.


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## WillyD

*Re: New 15” Driver - CSS SDX15*



> You have PRs that don't cause any power compression (when using 2:1 ratio)? Please send 1000 pieces to me asap.


Might want to check your math there Ilkka. :nono:

The 2:1 doesn't just apply to a simple ratio of # of PR vs active driver. So lets see...

Two 18" PRs with 38.1mm xmax. Yeah, thats 18.28800 liters of displacement from the PRs alone.

One 15" driver with 30mm xmax, 4.8 liters of displacement. 

3.81:1 ratio. Would it still have a touch of compression? Quite possibly at full tilt, sure. A lot less than the LLT? I'd guess so.

Now with the 5400 and the TC PRs you have, you will practically have a 2:1 ratio. Thats another story.


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## WillyD

*Re: New 15” Driver - CSS SDX15*



> I'd venture to say you may even need to go larger, as two 18" PRs may displace more volume than a 6" diameter port - the volume of the enclosure won't change whether you use a port or PRs.


That'd be an incorrect guess. The port would require what, 12 liters? And going off say two 18" LMS-5400s (not PRs, mind you), they take up 9liters total. 

The real benefit of PRs is for drivers that are more optimal in smaller enclosures, so one can tune them low without being restricted by the port length. This obviously doesn't apply to the SDX-15, or quite a few other drivers. 



> If you model a 300 liter ported LLT, you'd still need to make a 300 liter PRed sub to match the performance.


Well that actually depends on the roll off one is looking for. If you moved the sim that I did to 300 liters, it actually drops the Fb to 12.9. Move it back to 250 liters for 14Hz, and the LLT vs the PR FRs look practically the same. Both have an F3 of about 25-26Hz, and an Fb of 14, but the LLT is 50liters bigger. In the scheme of things, obviously not worth it. 

As I mentioned in the post before you, since I knew what you were thinking before you posted it, with the SDX it makes sense to go big and forget PRs. There may be one case somewhere where a guy wants a lot of performance in just 200 liters and a 15.5Hz tune...this may be a route he wants to go. Then again, one could just roll with two sealed SDX-15s in 200 liters, opposed firing and all that. :bigsmile:


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## SteveCallas

*Re: New 15” Driver - CSS SDX15*

Hmm. Thinking out loud.

6" diameter port volume = (6.5"/2)^2 x 3.14 x 27" = 895"^3

Dual 18" driver volume, assuming it's roughly half a sphere = 2 x (18"/2)^3 x 3.14 x (4/3) = ~6100"^2

Now sure, a driver or PR isn't a perfect half sphere, as the driver structure is more of a skeleton, so I'll be nice and only use 1/5 of that calculated volume, giving me ~1220"^2. What I am missing here?


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## Geoff St. Germain

*Re: New 15” Driver - CSS SDX15*

The volume of 6100"^3 that you've calculated is for two 18" spheres.

TC Sounds had the displacement of their PR at about 2.25 L each (0.08 cu ft). This probably makes sense since a typical large 15" driver is in the 5 L range and has that big motor on the back. The CSS PRs are essentially flat discs (no additional displacement) with a basket around it. The basket is the only think that contributes to the internal volume displacement.


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## WillyD

*Re: New 15” Driver - CSS SDX15*



> What I am missing here?


What Geoff said. :nerd:


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## Sonnie

These posts were moved to their own thread since they are off topic to the other thread. :T


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## Guest

one more good feature of a passive radiator is that onw can lower the size of the box keep a low tuning and add some eq in the bottom (it won't require as much as a small closed box)


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## vinculum

*Re: New 15” Driver - CSS SDX15*



vinculum said:


> Anyone know if those PRs use foam surrounds? I've emailed CSS this question, but nobody got back to me. They almost do look like foam, but it is hard to tell.
> 
> Thanx!
> Dr V


Dear Sir,

Apologies for not getting back to you. The surrounds are foam.

Bob Reimer
Creative Sound Solutions

604-504-3954


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## Guest

nowadays there are practically no problems with foam surrounds...they last almost as long as a rubber dito


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## anidabi

While I understand people around here, most from the US, all you guys thinking big. In Finland people think a bit differently. All big is not so important as to you guys here(speaking of subwoofers now). :R All I am saying is that not everyone is willing to go for the more bigger enclosure. In Finland people are just to about use to the idea of an 300l enclosure, which is quite big. Mostly people are happy with their chorus vertigos and such small subs.

So when you come to think about it 225l isn't small, but its considerably smaller than 300l. Takes even more less space when you double the subs(also the price sky rocket :sarcastic. Still 225l enclosure is way too big for most people around here and only a handful would thinking of taking that thing to their home. But the nature of the PRs and some of you have a good point there, it's not practical to build one big box with way more money, because LLT takes less floor space even thought it's bigger. I guess you understand what I'm saying, right? :R


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## Ilkka

*Re: New 15” Driver - CSS SDX15*



WillyD said:


> Might want to check your math there Ilkka. :nono:
> 
> The 2:1 doesn't just apply to a simple ratio of # of PR vs active driver. So lets see...
> 
> Two 18" PRs with 38.1mm xmax. Yeah, thats 18.28800 liters of displacement from the PRs alone.
> 
> One 15" driver with 30mm xmax, 4.8 liters of displacement.
> 
> 3.81:1 ratio. Would it still have a touch of compression? Quite possibly at full tilt, sure. A lot less than the LLT? I'd guess so.
> 
> Now with the 5400 and the TC PRs you have, you will practically have a 2:1 ratio. Thats another story.


Yeah, you got me there, sort of...  While I naturally meant that they would have the same Sd, I sort of forgot that the SDX was a 15", and those PRs were 18". An Unibox simulation shows very little compression for that combination. But IF we have a true 2:1 ratio, then some compression below the tuning frequency will be present. Probably very similar to what a 15" driver has with a 6" port.


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## coctostan

Is there a sound quality difference between an LLT and a low tuned PR such as this? 

Comparing the SDX-15 in a 300l LLT tuned to 15hz and a SDX-15 with 2 18" PRs tuned to 15hz.

Also, excuse my newbness, but what exactly is compression and what should it mean to those choosing subwoofers?

Thanks to the experts. I hope I am not starting a war.


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## vinculum

Highend.nu said:


> nowadays there are practically no problems with foam surrounds...they last almost as long as a rubber dito


We can guess, but only time will tell...


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## WillyD

*Re: New 15” Driver - CSS SDX15*



Ilkka said:


> Yeah, you got me there, sort of...  While I naturally meant that they would have the same Sd, I sort of forgot that the SDX was a 15", and those PRs were 18". An Unibox simulation shows very little compression for that combination. But IF we have a true 2:1 ratio, then some compression below the tuning frequency will be present. Probably very similar to what a 15" driver has with a 6" port.


Yeah, I figured you just had a brain fart of sorts. And I completely agree about 2:1 ratio presenting some compression. You can of course do some tests concerning this very subject using your 5400 and PRs.


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## Guest

vinculum said:


> We can guess, but only time will tell...



hehe well no there are methods of accelerate ageing nowadays, but sure...i would think twice about putting it directly in the sunlight :scared:


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## vinculum

Highend.nu said:


> hehe well no there are methods of accelerate ageing nowadays, but sure...i would think twice about putting it directly in the sunlight :scared:


Yeah the UV light might have an effect on them day in and day out. I also run ionizers in my room and I'm unsure if the ozone generated by them would have an aging effect. If they were similar to TC's NBR surrounds I'd feel a little more confident.

Dr V


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## Warpdrv

Are there more companies going to go the route of making passives adjustable like the TC-Sounds passives..?


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## Geoff St. Germain

Warpdrv said:


> Are there more companies going to go the route of making passives adjustable like the TC-Sounds passives..?


The old Stryke PRs were technically adjustable. They could accept up to 3000 g of total weight. 

http://www.acoustic-visions.com/~acoustic/products/passive_radiators/stryke_pr18/indexold.shtml

I'm not sure if the CSS ones are capable of the same. I would email Bob and ask.


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## Guest

a passive radiator without the possibility to change tuning frequency is like fishing with a baseball bat...

every serious company should be obligated to have a passive radiator on which you can add weight easily...


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## Creative Sound

Hi all,

There is some adjustment available by adding mass in the tube at the back. This is not the most flexible but does allow minor changes. The PR1821 could go to 2500 grams by adding 400 grams in the tube.

This is my first entry into this product space and I'm looking at other options and models. One of the difficulties is that everyone wants this or that size, weight, features, etc. but the sales are not necessarily forth coming.

I'm also exploring kits with cabinets, subwoofers, PRs and amps so stay tuned.

Bob


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## Warpdrv

Thank you for chiming in Bob... Appreciate your filling us in on product info...

I would have to agree with Highend.nu


> a passive radiator without the possibility to change tuning frequency is like fishing with a baseball bat...


That was a good one...


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## Guest

John Janowitz from Acoustic Elegance has been working on variable mass passive radiators where mass can be added from the front; a very nice feature, indeed. I'm not sure if Bob from CSS will be selling those as well (the existing CSS PR's are built by John).

Either way, it's about time some dependable large displacement passive radiators are available to the DIY market again.


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## Sonnie

Brian Cheney of VMPS uses some sort of putty type goo to allow his PRs to be tunable. I suppose you could do the same with any PR.


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## cixelsid

Sonnie said:


> Brian Cheney of VMPS uses some sort of putty type goo to allow his PRs to be tunable. I suppose you could do the same with any PR.


He uses Moretite, aka rope caulk. And claims the amount removed by pinching some under a fingernail has profound effects on the tuning......not! 

His old school design, low excursion, resistively loaded PR's, work much differently compared to the modern design PRs being discussed here.


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## Geoff

Humm:

I think some are missing the boat here. Alot of big/giant sub fans here, thats quite obviouse.

Yup the easy loading variable mass tuning PR's that John J. designed and sold a few years back were nice. Also having a choice in SD-sizes & loading sizes were a nice plus. The new PR's Johns playing with & working on sound very interesting. Hope they do come forth now he back up and about to release his newest stuff in January. He selling some old/new stock Lambada IB drivers on the AE forum now in case some don't know with some great pricing.

Getting a bit off topic and back to the point, being CSS is about the only one offering long throw low fb PR's currently, at least their something out their. The foam surround dose not scare me. Foam has evolved a along way since the 80's. The TC's PR's very were nice but where do you find them anymore, aside from costing a ton.

As I understand things Pr'ed subs seem to work best using drivers with *lower Fs's 20-Hz or lower, with a lowish Qts-.20 to .40 and a small/er Vas*. This is where their benifit seems most desirable for those looking to get that extension, spl, and all in a *smaller encloser*.

EBS/LLT "is likely" the place where just buying another mega driver and having another big encloser is the smarter/better move. This assuming one dosen't mind & can handle another giant/large encloser.

I'm just starting to attempt to work on a quad PR based designed encloser now and bummed that the old Stryke 15" PR's are not around anymore, they'ed work nice. The new 18's from CSS are really likely more than I need. The 12" Pr's I've just located are border line for working well. Tho they have 22-mm one way linear (another 6-mm sus) but needing four and still not sure this will really work. Still tossing emails for more info & specs as he just found a few he thought were all gone. When these few are gone there will be no more period.

It's my first PR based encloser and a giant learning experience for me. Reading tons and simming is not the same as building it then fine tuning & listening. I'm a big mid/low Q-sealed fan, this project could end in a be a big let down.  I certainly hope not tho.!

I'm now basically forced into a smaller cabinet for 2 drivers considering my other single driver rather large HT vented subs will be evntually sold, & (no don't want to go sealed & LT with the new sub). Looking at using two TC-12's in an opposed mount to be used aa a LCD/Plasma stand for my up-coming TV and just plain limited to a around 6-ft³ +/- internal volume. The key is I want to use drivers & a Amp or Amps that are just piling up in the house and not purchase anything new aside from PR's. I think from the numbers I currently have, that 4 of the 12" PR's and the dual TC-12's will get me their in time, I hope. 

I want "everything opposed mounted to be sure the cab is dead from the natural canceling forces, hence the looking to do the all opposed mounting of drivers and PR's. Of course it also has to be nice looking when finished.

Time will tell, I have a good few months to work out all kinks. Might have to give the CSS PR's (two 18's) a try in the end.

Boy that turned out to be a long novel not a post. 

Cheers
Geoff


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## Mike Cason

I have installed eight of the 15" flat passive radiators similar to the CSS passives except for the color of the surrounds in my subwoofers and I had 8 other passive radiators from another project that I installed in my mains, giving me a total of 16 passive radiators in my front speakers. My subwoofer's tuning frequency is 20.4 hz, and the passives reduced the tuning of the mains' cabinets from 29hz to 23hz. There is a sharper rolloff with the passive radiators, but with the subs tuned to 20hz, they still go very low, especially with the movie explosions and other movie sounds. I have my subsonic filters set at 13hz. 

For those of you who have never heard a good subwoofer using passive radiators, you need to find one and listen to it. The bass, IMHO, is smoother and has its own deeper and richer sounding bass. You don't hear port chuffing and internal cabinet resonances that can be heard through the port which, according to Vance Dickason, can be amplified by as much as ten times through the ports.

IMHO, Bob's CSS passive radiators are as good as they get.


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