Passive woofers?

[Apolek]

Putting together a system for the garage, and in my quest for speakers, I came across a pair Polk RTA11t conveniently located near me for an "meh" price. Noticed the two passive woofers and it got me wondering if I can get the earth shaking bass I'm seeking for this particular system from passive woofers. A) Never owned speakers with passive woofers, and B) a quick Google search doesn't tell me much. I assume (?) a passive woofer is simply an accumulator that works off the air column resonance of the acoustic suspension cabinet; but really, how much low frequency power can you get from this type of arrangement? The RTA11t is rated 29-20K Hz, which is pretty good, but would it compare to, say, a CV Dx9 in low frequency power and response?

 

[Braunbear66]

Two-way, floor-standing loudspeaker with two passive bass radiators.
-Drive-units: 1" silver-coil soft-dome polyamide tweeter, two 6.5" doped-pulp Trilaminate Polymer cone woofers with butyl surrounds, two 8" passive bass radiators.
-Crossover frequency: 3kHz. Crossover slopes: 12dB/octave (low-pass), 6dB/octave (high-pass).
-Frequency response: 29Hz–20kHz ±3dB. Sensitivity: 90dB/W/m. Nominal impedance: 6 ohms.
-Amplifier requirements: 30–250W.
-Dimensions: 39" H by 10.5" W by 14.5" D.
-Weight: 58 lbs each.

I think there is info on those Polk speakers on this forum. I have something similar as far as power and size. RSL Elan rated @ 300 watts. Has 12" rear facing passive radiators on each speaker. I recently had replaced with new passive's. I purchased the speakers from a person on this forum. I tested speakers with a vintage Yamaha with only 35 watts. It was earth shaking and sounded good.

 

[Braunbear66]

Putting together a system for the garage, and in my quest for speakers, I came across a pair Polk RTA11t conveniently located near me for an "meh" price. Noticed the two passive woofers and it got me wondering if I can get the earth shaking bass I'm seeking for this particular system from passive woofers. A) Never owned speakers with passive woofers, and B) a quick Google search doesn't tell me much. I assume (?) a passive woofer is simply an accumulator that works off the air column resonance of the acoustic suspension cabinet; but really, how much low frequency power can you get from this type of arrangement? The RTA11t is rated 29-20K Hz, which is pretty good, but would it compare to, say, a CV Dx9 in low frequency power and response?

Can You test them with your amp ?

 

[Apolek]

Can You test them with your amp ?

No, receiver is in the mail, so for now I'm going off reputation and published specs. Looking at CV Dx9, D9, and maybe the Polks. Even flirted with the idea of a pair of CV D18ee for sale the next town over (no doubt about those), but reality set in over my lack of suitable wattage to drive them. I'm just curious about passive woofers now... how they work, and how well do they work as opposed to active woofers.

 

[SpruceMoose]

Passive woofers (passive radiators, actually) are basically a substitute for a tuned port in a bass reflex system. Disadvantage: more cost than a port. Advantages: tunable by adding or subtracting weight, no port chuffing. Both ported and p/r enclosures roll off below resonance twice as fast as a sealed enclosure.

 

[Apolek]

Passive woofers (passive radiators, actually) are basically a substitute for a tuned port in a bass reflex system. Disadvantage: more cost than a port. Advantages: tunable by adding or subtracting weight, no port chuffing. Both ported and p/r enclosures roll off below resonance twice as fast as a sealed enclosure.

Thanks! I was wondering if a passive woofer was a technological improvement, or a shortcut/cost reduction. I see that like many things audio, there isn't an easy answer. Maybe I should get a pair of p/r speakers and judge for myself. I have both bass reflex and acoustic suspension speakers, and I'll admit that I prefer the bass on the acoustic suspension. Just sounds tighter and not so boomy to my ears, and with my equipment.

 

[Braunbear66]

When I purchased my speakers the passive radiators were toast and I removed them. I used the speakers for a while. They didn't sound bad since there was a 12" opening in the back of the cabinet. After I ordered new replacements and installing them the speakers sounded really good. Except I had to go back into one of the cabinets and free up a internal speakers wire that was touching the back of the passive and making a horrible noise. They used Monster cable on these RSL speakers and there was lots of wires. because of the tuning dial adjustments in the front and rear tweeter. I like these speakers but they will be going in the garage and waiting for a good amp one day so I can see what they really sound like.

 

[c-atle-79bay]

just got a set of the RSL Elans, passive radiator was toast, but initial testing, didn't sound that horrible with out them, low volume listening. But with this particular speaker, it has such a large volume in the cabinet I would like to try sealing the radiator opening to see how they sound.

 

[c-atle-79bay]

How can the PR be toast - it is the cone, suspension and maybe some weight on it, that is all. Nothing to burn out (unless the PR has a foam surround).

They have foam surrounds, both sit about half way down the opening resting on the insulation inside.

 

[teal'c]

No, receiver is in the mail, so for now I'm going off reputation and published specs. Looking at CV Dx9, D9, and maybe the Polks. Even flirted with the idea of a pair of CV D18ee for sale the next town over (no doubt about those), but reality set in over my lack of suitable wattage to drive them. I'm just curious about passive woofers now... how they work, and how well do they work as opposed to active woofers.

There's a set of CV AT-15 in Fayetteville, they will shake the earth with the right setup.

 

[darkblue94]

I would not play them at all before a refoam. I have never done PR refoam but woofers are not a problem so those shouldn't be bad at all.

There's no voice coil to worry about centering correctly. Easy as pie and pie is good.

 

[mars_volta]

Polk used rubber on their surrounds. They shouldn't need repair. Just make sure the main drivers are not locked up.

I would take the Polks over CV DX-9 any day. It says 29 hz and they are not kidding.

 

[toxcrusadr]

There are so many different speakers out there, I don't know how you can really say "I like/don't like the sound of ported/sealed/passive radiator speakers" based on a couple examples of the genre. In any case you certainly can't know whether another person is going to like or dislike a particular speaker.

I have all of these types and the PR's are just fine to my ears - at least, the ones I've kept.

BTW these Polks DO have active woofers - two of them. Everything you are hearing from the passive radiators is coming from the woofers originally. Perhaps this is obvious by now and doesn't need to be said.

Have fun and let us know what you decide to do.

 

[Braunbear66]

just got a set of the RSL Elans, passive radiator was toast, but initial testing, didn't sound that horrible with out them, low volume listening. But with this particular speaker, it has such a large volume in the cabinet I would like to try sealing the radiator opening to see how they sound.

Yes toast more like dust the foam. I did mine in January with this from Amazon.
ESS Speaker Passive Radiator Kit, 12" Speakers, ESS AMT-1A,
Must be carful not to pull any wires off there location best to take a photo like I did to make sure. Also make sure no wires are touching your passive or the back of your woofer. mine was and had to go back in and clear wires so they don't touch anything. Sound amazing.

 

[mars_volta]

Every speaker I've ever heard with a PR has impressive bass.

 

[damacman]

PRs rock. Deep, smooth response. I have the 15TLs in my office.

 

[CopperWizard]

Another advantage to a passive radiator is that the components don't take much away from the inside of the box dimensions. A port doesn't need to be refoamed.

 

[c-atle-79bay]

Thanks for the info on the PR source going to replace mine, I've got them in a very large space now, not reinforcing back/side walsl an the sound is different to be sure.

 

[twiiii]

Remember you can compress air. So a Passive radiator is slow to start and slow to stop. That said I have heard some speakers with PR's that were quite acceptable. A Mac 1052 for instance. But when Placed up against a XR 7 or XR 6 I am afraid the the difference became really apparent. Another choice was a B&O 5700 with a Phillips woofer and PR. But wen placed side by side with a Celstron speaker using the same MID and tweeters but with 2 active woofers the difference was easily revealed. True the units with PR were slightly more efficient. But power is isn't really an issue now days. So unless you are into classical pipe organs, PR would not be my choice. Especially if you like percussion, drums, sound effects and the like. I'm not fond of ported speakers either and there are some great ones.

 

[62vauxhall]

I bought a pair of what were a 2 way 8" with a passive 10". The previous owner ditched the passives, put in 10" car subwoofers and wired them as fullrange. They sounded like shite. Loud, but shite none the less. In the previous owner's mind louder was better.

I got some used passives, tuned them to the enclosure and they sound like a speaker system again. Much more detail but no "make your pant legs flutter" bass. Passives don't do that.