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Passive Radiators -- pros and cons

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  • Passive Radiators -- pros and cons

    I'm a novice speaker builder but advanced woodworker and need some big speakers for new shop (32'x48'x12') {yes, I've posted about this before but this is more specific}

    I had some KLH 5001's (lost in fire 15 years ago) that had a 12" woofer and 12" PR and really liked the sound and would like to build something similar. I really liked the way the vocals sounded and the clarity of the guitar strings fading off. I've got some Tanzenite bookshelf speakers and they sound great but aren't big enough (and are staying in my office!)

    But with the new woofer designs do I need a PR or will the new designs sound even better with a PR?

    Any existing designs out there that I can copy? (especially the XO )

    Looking at "Rally Sports" but they sound like they are best at higher volumes and harder rock than I listen to -- I'm more into vocals, jazz, classical, instrumentals and acoustic folk than rock.

    Any other suggestions??

  • #2
    http://techtalk.parts-express.com/fo...nge-sarcophage
    Last edited by howard; 06-24-2019, 07:51 PM. Reason: wrong link

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    • #3
      http://techtalk.parts-express.com/fo...rs-based-3-way

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      • #4
        What you liked about your KLH had nothing to do with their being passive radiators. PRs operate in essentially the same way that ported cabs do, and what PRs and ported cabs both do is to affect how the speaker works below roughly 100Hz, while the qualities you liked from your KLH were in the mids and highs.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          Originally posted by mikec View Post
          I'm a novice speaker builder but advanced woodworker and need some big speakers for new shop (32'x48'x12') {yes, I've posted about this before but this is more specific}

          I had some KLH 5001's (lost in fire 15 years ago) that had a 12" woofer and 12" PR and really liked the sound and would like to build something similar. I really liked the way the vocals sounded and the clarity of the guitar strings fading off. I've got some Tanzenite bookshelf speakers and they sound great but aren't big enough (and are staying in my office!)

          But with the new woofer designs do I need a PR or will the new designs sound even better with a PR?

          Any existing designs out there that I can copy? (especially the XO )

          Looking at "Rally Sports" but they sound like they are best at higher volumes and harder rock than I listen to -- I'm more into vocals, jazz, classical, instrumentals and acoustic folk than rock.

          Any other suggestions??
          I would argue that a 12" passive radiator isn't quite large enough for a 12" woofer, but, like Mr. Fitzmaurice said, the Passive Radiator had little if anything to do with the pleasantry and presentation of the vocals you were enjoying.

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          • #6
            Agree with what Bill and AEIOU said. And I'll point out that, unless you need a PR because the port is ridiculously long, they cost considerably more than a port.
            Francis

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            • #7
              Since you asked about pros and cons, we've covered the cons. On the pro side, PRs do a better job suppressing midrange radiation out of the cabinet than a port. That's really not a big pro because a rearward or downward facing port can accomplish the same thing.
              Francis

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              • #8
                If the port entrance is correctly placed and the cabinet properly damped it won't pass any more midrange than a PR. Where a PR is really different is that it doesn't have port resonances. But if that was a major factor you'd see a lot more PRs and far fewer VBs. IMO the most significant reason to use a PR is so your advertising can say it's a PR, and you can claim all sorts of reasons why it's better than a VB, which usually translates to more expensive than a VB.
                www.billfitzmaurice.com
                www.billfitzmaurice.info/forum

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                • #9
                  One of the things i’ve had issues with ports over the years is port noise (chuffing). To make port fit, you have to make the diameter smaller, but that increases the likelyhood of port noise. Make a bigger diameter port and now you have to make an even longer port in the cabinet.

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                  • #10
                    Originally posted by westrock2000 View Post
                    One of the things i’ve had issues with ports over the years is port noise (chuffing). To make port fit, you have to make the diameter smaller, but that increases the likelyhood of port noise. Make a bigger diameter port and now you have to make an even longer port longer in the cabinet.
                    Sure. When the port gets excessively long, a PR is a solution.
                    Francis

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                    • #11
                      Very interesting. Lots to think about. Thanks for the help!

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                      • #12
                        Without knowing the environment in your shop, a possible advantage of a PR might be to prevent "stuff" from making it's way into (and living) in the speaker cabinet. Sawdust, bugs, mice, etc??

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                        • #13
                          Wolf's volcanic subwoofer and Tom Zarbo's Tenacious design use PRs. Both very compact and high performance.

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                          • #14
                            Very compact subwoofers are the natural home for PRs.
                            Francis

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                            • #15
                              Originally posted by mikec View Post
                              I'm a novice speaker builder but advanced woodworker and need some big speakers for new shop (32'x48'x12') {yes, I've posted about this before but this is more specific}

                              I had some KLH 5001's (lost in fire 15 years ago) that had a 12" woofer and 12" PR and really liked the sound and would like to build something similar. I really liked the way the vocals sounded and the clarity of the guitar strings fading off. I've got some Tanzenite bookshelf speakers and they sound great but aren't big enough (and are staying in my office!)

                              But with the new woofer designs do I need a PR or will the new designs sound even better with a PR?

                              Any existing designs out there that I can copy? (especially the XO )

                              Looking at "Rally Sports" but they sound like they are best at higher volumes and harder rock than I listen to -- I'm more into vocals, jazz, classical, instrumentals and acoustic folk than rock.

                              Any other suggestions??
                              If you like the sound of that particular KLH speaker then I suggest you mimic them as close as possible. Its every driver working in sync which includes the PR's that give you that signature sound you liked in your KLH 5001's.

                              IMO PR's and Ports sound different regardless if they operate similarly. Also from my experience Ive never heard a port sound cleaner and or more controlled them a PR......One more thing IMO/experience with PR's they sound best when placed in front/forward as to me they don't sound as good when placed on the sides, back, or bottom/down firing.

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