Passive radiators

polkfan38
polkfan38 Posts: 360
edited May 2010 in Speakers
I have some Infinity SL50 speakers. It has the 3/4 inch tweeter and a 8 inch woofer. Below them are two passive radiators. My question is this. How effective are passive radiators? On these models, it seems like they don't really "kick in" until the volume is at a medium level. Is this common with all models with such a set up?
Things are more like they are now than they ever will be!
Post edited by polkfan38 on
· Share on FacebookShare on Twitter

Comments

  • Litz
    Litz Posts: 111
    edited May 2010
    On Polk audio, Klipsch heritage and VMPS speakers, the PR's are tuned to reinforce the existing output of the active drivers. They kick in from low volume up. The Infinity Sl50's are not as well designed.

    A properly executed PR (like those I mentioned) will add response and performance without port noise. (PR is considered a port BTW). They are very effective when properly executed. problem is, many companies are clueless about them, much like phase plugs.
    · Share on FacebookShare on Twitter
  • polkfan38
    polkfan38 Posts: 360
    edited May 2010
    Yeah, I know the Infinity SL series was about at the bottom of there product line back then. But, thanks Litz! With the exception of the Polk SDA line, I don't think I will get anything else with them.
    Things are more like they are now than they ever will be!
    · Share on FacebookShare on Twitter
  • PerfectCreature
    PerfectCreature Posts: 1,456
    edited May 2010
    The deal with a passive radiator is it doesn't actually move my itself. It needs the air from the other speakers to move...I kinda reduces the sound of the bass and you feel more of a rumble with radiators than you feel a punch...
    So that could explain why it only happens when you turn it up is because maybe you speakers just don't move enough air?
    At least that what I was told anyway....
    Receiver
    Harman Kardon HK 3490
    Speakers
    Polk Audio Monitor 50s
    Subwoofer
    Klipsch KSW-100
    Cables
    AudioQuest Rocket 33s 10ft
    AudioQuest Optilink1 2m
    AudioQuest Alpha-Snake 25ft Interconnect
    AudioQuest HDMI-1 2m

    Alienware X51 R2
    PS4
    Samsung Smart TV 40" 1080p 3D
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    PerfectCreature wrote: »
    The deal with a passive radiator is it doesn't actually move my itself. It needs the air from the other speakers to move...I kinda reduces the sound of the bass and you feel more of a rumble with radiators than you feel a punch...
    So that could explain why it only happens when you turn it up is because maybe you speakers just don't move enough air?
    At least that what I was told anyway....

    That would be a fairly poorly designed one, but much like a turbocharger...it is dependant on the back motion (air) of the active woofer. Matthew Polk used to called them "Fluid coupled passive radiator" The fluid...is air.

    Polk and others made the PR such that it's not sluggish, and responds quite easily to small inputs. This also explains why some PR's don't do all that well when you crank the snot out of the system. I bought them just because Polks PR's work so well at a low to medium volume. that's why I get detail, body and bass from a Polk without having to play loudly.
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2010
    Polk's PR's sound fantastic. Vintage Monitors and SDA's have some of the cleanest, tightest, authoritative sounding bass I've ever heard. My 2A's have enough bass output to rattle your teeth. I could only imagine the sheer output of some of the bigger SDA's.
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    comfortablycurt wrote: »
    Polk's PR's sound fantastic. Vintage Monitors and SDA's have some of the cleanest, tightest, authoritative sounding bass I've ever heard. My 2A's have enough bass output to rattle your teeth. I could only imagine the sheer output of some of the bigger SDA's.

    I have heard the SDA-SRS. They indeed produce bass in the 20-hz range. One of the first demos I heard was Enya: orinoco flow/longships. While other speakers of the day played, you'd hear cannon shots as a kind of flat "bang". With the SRS, you'd get a cannon shot that flapped your pants legs. The output there is between 21-28hz depending who you take measurements from. The bass was clean, without doubling. That 15" PR works like a champ!
    · Share on FacebookShare on Twitter
  • polkfan38
    polkfan38 Posts: 360
    edited May 2010
    Would replacing the PRs with real drivers be a bad idea?
    Things are more like they are now than they ever will be!
    · Share on FacebookShare on Twitter
  • dorokusai
    dorokusai Posts: 25,577
    edited May 2010
    A PR is an expensive port.

    Yes, replacing them with a real driver, since it isn't really a driver at all, would be a bad idea.
    CTC BBQ Amplifier, Sonic Frontiers Line3 Pre-Amplifier and Wadia 581 SACD player. Speakers? Always changing but for now, Mission Argonauts I picked up for $50 bucks, mint.
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    polkfan38 wrote: »
    Would replacing the PRs with real drivers be a bad idea?

    Very bad idea.
    1. An active driver has a voice coil and spider
    2. An active driver is not tuned to work like a PR.
    ( A PR can be mass weighted)
    · Share on FacebookShare on Twitter
  • polkfan38
    polkfan38 Posts: 360
    edited May 2010
    Was just a thought. I wont try it.
    Things are more like they are now than they ever will be!
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2010
    polkfan38 wrote: »
    Would replacing the PRs with real drivers be a bad idea?

    Terrible idea.
    polkfan38 wrote: »
    Was just a thought. I wont try it.

    Good call.
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    Here is a blurb about PR's: (VMPS AUDIO)
    The Passive Radiator (PR) located in the bottom of the cabinet already has a certain amount of mass attached to the center, by the factory. By adding or subtracting mass from the PR, it is possible to make system tonal balance warmer (higher Q) or tighter (lower Q).

    Moving mass of PR is very low. Since a PR is driven equally over its entire surface by the active woofer's backwave, the diaphragm will move pistonically even if it is not rigid.
    · Share on FacebookShare on Twitter
  • RuSsMaN
    RuSsMaN Posts: 17,986
    edited May 2010
    I don't have first hand experience with your particular SL model, but a general rule of thumb, make sure everything is tightened down, active (mid)bass drivers, and pr's. If the pr's or active woofers have foam surrounds, they may need to be replaced, even if they aren't to the point of breaking up and falling away.

    Other than the things mentioned above, try to tweak placement in the room, different speakers respond differently, try to avoid equal or halved distances from the side / rear walls. You can move them around to avoid cancelling out the half or quarter wave (most common) due to room boundries.

    Cheers,
    Russ

    Litz, the general membership doesn't need to be schooled on everything, just a side note to make your time here easier. ;) Polk has been using PR's since it's inception with the Model 9, original Mini Monitor, and the one that 'put Polk on the map', the Monitor 7. At the end of the day, with all things equal, it's just that - an expensive port.
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    RuSsMaN wrote: »
    I
    Litz, the general membership doesn't need to be schooled on everything, just a side note to make your time here easier. ;) .

    Sounded like the poster had no knowledge of PR's...silly me for providing information cut and pasted from an authority to help clarify. My bad for being helpful, no good deed goes unpunished---or uncomplained about. Not all of us need schooling on polk history.
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2010
    RuSsMaN wrote: »

    Litz, the general membership doesn't need to be schooled on everything, just a side note to make your time here easier. ;) Polk has been using PR's since it's inception with the Model 9, original Mini Monitor, and the one that 'put Polk on the map', the Monitor 7. At the end of the day, with all things equal, it's just that - an expensive port.


    I'm not trying to argue that, but I've seen Litz provide quite a bit of useful information since he joined up.

    He's taught me a thing or two that I didn't know...this in particular...

    "By adding or subtracting mass from the PR, it is possible to make system tonal balance warmer (higher Q) or tighter (lower Q). "

    Interesting stuff! I wonder if anyone's ever played around with adding/subtracting weight from the PR's in SDA's.:confused::cool:
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • heiney9
    heiney9 Posts: 25,217
    edited May 2010
    comfortablycurt wrote: »
    I'm not trying to argue that, but I've seen Litz provide quite a bit of useful information since he joined up.

    He's taught me a thing or two that I didn't know...this in particular...

    "By adding or subtracting mass from the PR, it is possible to make system tonal balance warmer (higher Q) or tighter (lower Q). "

    Interesting stuff! I wonder if anyone's ever played around with adding/subtracting weight from the PR's in SDA's.:confused::cool:

    Nothing that hasn;t been covered ad nauseum elsewhere multiple times. He should dial it down a bit. He comes off as a know it all name dropper.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    heiney9 wrote: »
    Nothing that hasn;t been covered ad nauseum elsewhere multiple times. He should dial it down a bit. He comes off as a know it all name dropper.

    H9

    And you come off as a scolding , snobbish blowhard. What kind or idiot posts in a thead as if I am not able to read the post? Get over yourself windbag! You aren't exactly an audio God yourself.
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2010
    Litz wrote: »
    And you come off as a scolding , snobbish blowhard. What kind or idiot posts in a thead as if I am not able to read the post? Get over yourself windbag! You aren't exactly an audio God yourself.


    I retract my previous statement.:rolleyes:
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • Litz
    Litz Posts: 111
    edited May 2010
    comfortablycurt wrote: »
    I retract my previous statement.:rolleyes:

    and I don't care... :rolleyes:
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2010
    Litz wrote: »
    and I don't care... :rolleyes:


    Cool.

    I can already tell that you're not going to make many friends here. Better get in leagues with our resident trolls while you still can.:rolleyes:
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • RuSsMaN
    RuSsMaN Posts: 17,986
    edited May 2010
    So we are basically done here.

    Polkfan38 (and others), please feel free to start a new thread, same topic. Again, it's not always the information, as much as it is the delivery.

    This one is a wrap for obvious reasons, and will move to the Hall of Shame after Polk review tomorrow.

    Carry on...and thanks for your contributions to the board!

    Cheers,
    Russ
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
    · Share on FacebookShare on Twitter
This discussion has been closed.