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Passive radiator question
I've only used passive radiators instead of regular tube ports twice. Both times they worked out fantastic, both times because the modeled port resonance was way too high in the passband (at least in my opinion). Actually in my Indy theme project this year I measured the top port output and found its resonance to be only 5 dB lower than the driver's at around 800 Hz! The DSA215 PR totally fixed that.
I'm currently working on a new project that uses a top level midbass, the CSS LDW7. Once again when modeling in the box size I want to use, a reasonable diameter port has a somewhat high resonance right smack in the middle of the midbass's passband. So then I modeled several different passive radiators. Four different PR's work really well with this driver in this box size with a little added mass. Actually their "modeled" FR is so close I don't know if my ears could even hear a difference in F3/F6/F10.
So here is my question... all 4 of these passive radiators have plenty of Sd and Xmax. In fact by the time the LDW7 reaches its Xmax, at an output dB I'm very happy with, none of the PR's are even close to reaching their own Xmax.
The four 8 inch PR's are:
Dayton DS215-PR
Dayton DSA215-PR
Dayton RSS210-PR
SB20PFCR-20-00
Based on your experience which would you use? The two Dayton Designers model fine but to me look flimsy as all get out. The SB actually models the best of all 4 but it has that plastic frame. I'm not so sure its plastic frame is any worse than the thin stamped steel frames. The RSS210 is the most robust looking PR but do I really need its 19 mm of Xmax when the model shows it only reaches 8 mm?
I'm not opposed to any of the four. Your opinions are welcome.
Comments
I’ve used the Dayton RSS210-PRs 10in bigger brother, and they may be a bit of overkill. I looked at total displacement x Sd relative to the woofer I’d be pairing it with.
I’d think the SB20PFCR-20-00’s frame would be of no issue (possibly more stable than stamped steel for this application) and if enough extension for matching with the LDW7, better value (but I haven’t used this one).
I don't think there is much stress on a PR frame. There's no motor hanging off of it, and you don't have a motor exerting any force against it. I say use whichever one you like. I used the ds215 on my Indy project.
I used the SB16PFC with the plastic frame as a mid woofer, no issues with it apart from the odd shape. Haven't used the PR but if the frame's the same material, should work OK.
Geoff
What about the SB Acoustics SB15SFCR-00? The shape is easy to recess and can work nicely on a narrow box.
Same frame as the 8" SB fullranges I have. I don't have anything to complain about. In theory the plastic has some damping properties that steel wouldnt have. Not that it would do anything for PR duty.
If it is on the back I say whatever is cheapest that still works well. But the Dayton designers are wierd with 5 screw frame. So if you will have to stare at it I'd say SB. RS is a waste if not using the xmax potential.
Did you try modeling the SB racetrack size (5x8")? Would allow for a narrower enclosure if front/back mount.
I like the DSA PRs, have used those and the DS, and have used the RSS315 PR. I liked the SB15 5x8 in my Purveyor, and have others on hand.
InDIYana Event Website
Passives rule!!
.
... that's all I got.
Thanks for the input guys. I was kinda leaning towards the round SB 8" because it models the best. The plastic frame probably won't be an issue, especially since it uses 8 mounting screws.
I used the DS PR's in my Indy project and I have used the DSA versions and they work really good. I have several projects with PR's and haven't had a problem with them. I even have the 18" RSS PR's with my RSS390HE sub. I also have the E150HE PR's.
If all else is the same, use the one with the highest Qms as that will be the one that loses the least output compared to a port.