Thoughts on Passive bass Radiators

[fomoco69]

Are these a good design idea or not?

 

[Dan ʕ•ᴥ•ʔ]

Basically the same as a ported enclosure.

 

[hypertone]

They work well in the Polk monitors. My Polk 7's go pretty damn deep for a single 6" woofer.

 

[SleeperSupra]

A couple of good reads on PR's...


http://www.humanspeakers.com/whatis/PR.htm

http://www.subwoofer-builder.com/passive.htm

 

[Cosmos]

They are a valid design approach and are easily tunable. Some fine speakers and credible designers have used passive radiators.. including Polk, ESS AMT, JBL etc...

 

[fomoco69]

Ten four.......I am impressed with the Polk's more than the Klipsch's

 

[Tedrick]

Just like any other speaker design, there are good ones and not-so-good ones. If it sounds good to you, then that's all that really matters.

 

[F1nut]

Are these a good design idea or not?

An excellent idea, IMO.

 

[barkerd]

'same as ported ' : yes , but with excursion control for your woofer : incredibly important if you play vinyl ( those subsonics off of "not perfect" pressings can kill a woofer) : all other things being equal I have always preferred a PR design for vinyl ....I've seen a woofer blown on a lead-in track ....not good

 

[jhoyt]

I've had both Klipsch (Forte II) and Polk (Monitor 10) with passives, and both have been very impressive in the bass dept. One of my DIY ideas is to build a nice PR design.

 

[spkrdtr]

PR's are a good idea for smaller boxes where it's hard to squeeze in a properly sized vent. They serve the same purpose.

Vents will work quite as well for larger boxes.

 

[jimfet]

My towers have dual 6 inchers, transmission line feeding a bottom firing 8 inch PR. Very good bass indeed. I like the PR idea.

 

[guiller]

I find the bass on this type of speakers displaying very low distortion, which is a very desirable feature for listening to quiet music with a very deep bass range, like some classical music pieces. In my own experience, it could be, perhaps, the best choice for speaker design at least for the type of music of my preference. I wonder why this design principle has not been used more frequently. Perhaps the cost was an important factor.

All the best

 

[barkerd]

cost IS the factor : a plastic tube costs less than a PR , and lets face it : Joe Public doesnt really understand the full story......like I said : a PR is cheap insurance for a woofer

 

[dnewma04]

'same as ported ' : yes , but with excursion control for your woofer : incredibly important if you play vinyl ( those subsonics off of "not perfect" pressings can kill a woofer) : all other things being equal I have always preferred a PR design for vinyl ....I've seen a woofer blown on a lead-in track ....not good

Where do you propose this excursion control is coming from?

 

[barkerd]

my guess is in imperfect pressings (where no signal is a perfect circle with no movement, as seen by the stylus) what is supposed to be silence is actually mispressed as subsonic signal : they way the stylus sees it .... Ive seen it countless times on lead-in grooves to a track : the woofer (in a ported enclosure) has a compliant suspension and the stylus is passing along low end signal ....the woofer goes x-max crazy ....and there is no sound ....ive seen damage done by this : in lead in tracks with "no" signal .....doesnt happen on a PR system ....I would attribute it to the woofer being damped more in the region of its outer travel limits by the PR : a port doesnt do it .... I also think this is partly why PR's fell out of favour when digital came along ... ports were cheaper and they performed the same function ; albeit without an improper subsonic signal being passed along .....no bits of data in a lead in track..... "silence" = no subsonic woofer excursion

 

[fomoco69]

Good feedback guys..........thanx

 

[dnewma04]

I don't think you are quite understanding the behavior of a woofer in a passive radiator system. It simply will not provide any sort of protection from overexcursion.

 

[Ohighway]

 

[barkerd]

wouldnt the mass of the PR cone be greater than the mass of air in a similar port ?

Ive seen this effect : same system / same album / ported vs PR : I always assumed it was the PR that tamed the bad lead-in grooves by damping the woofer