SDA SRS 2 upsize to an 18" Passive Radiator??

Just a thought I had, there is certainly plenty of room for the larger PR on the sda's I was thinking perhaps it would play lower and gain some efficiency? I am looking at the Dayton from Parts Express, it comes with weights for tuning not sure how that works either, thoughts?

Comments

  • Nightfall
    Nightfall Posts: 10,042
    There are very smart people here that wouldn't touch it.
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

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  • mhardy6647
    mhardy6647 Posts: 32,927
    edited October 2020
    Drtynels wrote: »
    Just a thought I had, there is certainly plenty of room for the larger PR on the sda's I was thinking perhaps it would play lower and gain some efficiency? I am looking at the Dayton from Parts Express, it comes with weights for tuning not sure how that works either, thoughts?

    umm, no. The size of the PR per se has (EDIT, AFAIK) relatively little to do with its behavior -- its moving mass is the most important parameter (EDIT: well, OK, it's a little more complicated than that -- see below)

    https://www.diyaudio.com/forums/subwoofers/296276-passive-radiator-vs-port-theory.html
  • xschop
    xschop Posts: 4,636
    Plug the PR hole and Power-Port it on the rear.
    Don't take experimental gene therapies from known eugenicists.
  • Emlyn
    Emlyn Posts: 4,346
    edited October 2020
    Drtynels wrote: »
    Just a thought I had, there is certainly plenty of room for the larger PR on the sda's I was thinking perhaps it would play lower and gain some efficiency? I am looking at the Dayton from Parts Express, it comes with weights for tuning not sure how that works either, thoughts?

    Is the stock passive radiator damaged and no longer functioning? If not, there's no reason to mess with it. Cut a bigger hole and you're just left with a bigger hole and a driver mismatched to the cabinet and the rest of the drivers in the cabinet.

    There are forum tested methods for tightening the bass with the existing driver by using hurricane nuts instead of the original little wood screws to more firmly couple the big driver to the cabinet. Another thing to do is to dampen the metal basket on the passive radiator and midwoofers with Dynamat or another similar product. Also test for cabinet leaks.

    The beauty of the big SDA speakers is how perfectly the midwoofers, passive radiator, and cabinet are tuned and carefully integrated to be seamless and fast.

    Lower bass frequencies for home theater are possible with a separate subwoofer. Just make sure it's a good one to keep up.

  • invalid
    invalid Posts: 1,271
    You may as well design your own speakers if you try to change to a bigger passive radiator.
  • audioluvr
    audioluvr Posts: 5,420
    VR3 wrote: »
    Im digging the power port idea personally

    Is the power port 18" in diameter?
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  • VR3
    VR3 Posts: 27,970
    It can be!
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • xschop
    xschop Posts: 4,636
    edited October 2020
    Post edited by xschop on
    Don't take experimental gene therapies from known eugenicists.
  • xschop
    xschop Posts: 4,636
    edited October 2020


    Wouldn't that technically render it open baffle? Lol
    VR3 wrote: »
    It can be!

    Don't take experimental gene therapies from known eugenicists.
  • engie490
    engie490 Posts: 425
    VR3 wrote: »
    Im digging the power port idea personally

    You can change any speaker to a ported design, the question is: Should you? In other words, the engineers usually select a cabinet design that works for the given drivers. If you want to change a sealed design to a ported configuration, you might as well dump all the cone drivers that share that space with the woofer and start over.

    In the case of the SDAs, you would be porting much more than just the bass, since the MW drivers cover the response out to 2Khz. You would also change the rule of thumb for positioning these speakers in a room as ported designs generally hate boundaries (i.e., walls).
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  • Any depth gained in deep bass will be offset by a loss of upper bass ranges so that your resulting frequency response will no longer be smooth or even across its range.

    Take note that Polk didn't increase the size of the radiator on the top models SRS when it added 4 more midbass drivers. It gained a deeper bass from cabinet volume and radiator tuning, not radiator size.
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  • xschop
    xschop Posts: 4,636
    edited October 2020
    "You would also change the rule of thumb for positioning these speakers in a room as ported designs generally hate boundaries (i.e., walls)."

    Maybe the reason why the new Legend SDAs are bottom Power-Ported?
    Don't take experimental gene therapies from known eugenicists.
  • engie490
    engie490 Posts: 425
    xschop wrote: »
    Maybe the reason why the new Legend SDAs are bottom Power-Ported?

    Maybe. Keep in mind that the L800 is a wholly different design from the ground up with active, ported woofers and the midrange drivers in a separate sealed, internal enclosure.

    In the manual, the recommended setup is basically the same as for all other SDA speakers. In the Sound & Vision review, the L800s ended up about a foot from the back wall, so not a big difference.

    Also, the LSiM floorstanders have the powerport on the bottom of the speakers. In reviews of the 707 and 705, both sets of speakers ended up 12 inches from the wall.
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  • xschop
    xschop Posts: 4,636
    I know from experimenting, that a Power-Ported enclosure is more efficient than a PR for it's tuned frequency. I believe that was part of the original question.
    One day when parts are NLA, I'm sure we'll see some more creative thinking, rebuilding these classics.
    Don't take experimental gene therapies from known eugenicists.
  • Emlyn
    Emlyn Posts: 4,346
    The L800 is more like an evolution of the old SRT system than the original passive radiator SDAs. The designers figured out what was necessary and what was not for the price point.
  • VR3
    VR3 Posts: 27,970
    Definitely have to agree with that sentiment from what I have seen
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