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  • 12" Ultimax or Reference


    My box I have to work with is 4.7 cu. ft. net internal with a 4" Precision port 17" long effective length. This gives a tuning of approx 19Hz. My amp is a BASH 300. I am just about to buy the Ultimax 12" driver but I read of a few experiences of scraping voice coils, excursion noises, and adhesive failure with some Ultimax subs (seems mostly 12" and 10" ones). Is this still an issue or has it been resolved in recent production runs? I'm specifically interested in the 12" size.

    This is the driver I was planning around all these months but I'm giving thought to the alternate choice of the 12" High Fidelity series RSS315HF-4 (4 ohm) or RSS315HFA-8 (8 ohm) - both of these having exemplary reviews, and would also work well in the same enclosure I have. The only downside for me would be these don't offer the same very low F3 in an unboosted sealed configuration.






  • #2
    Its been solved best i know. My friend has a pair of them with 15"PRs. Deep and clean.
    https://www.facebook.com/Mosaic-Audi...7373763888294/

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    • #3
      W/the B300's mild boost @ around 30Hz, I like the 315HF-4 best in your box.

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      • #4
        In WinISD beta, using the recommended/default sealed box size, RSS315HFA-8 (8 ohm) shows an F3 of 35Hz, while the RSS315HF-4 (4 ohms) is 44Hz. That seems like too great a difference...is that right? I only entered Fs, Vas and Qts.

        Dayton's box recommendations (using BassBox 6 Pro) both give 40Hz.

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        • #5
          I have that combination (box size, vent, Bash 300, RSS315hf-4) and it works very well. The same amp, and a newer RSS315hf-4 in a 2ft sealed box works very good as my bedroom sub.

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          • #6
            I get the same results (WinISD Pro) within a Hertz or 2. Bottom end rolloff is determined by Qts and Fs. Box size is determined by Qts and Vas.

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            • #7
              So the 8-ohm version does extend a bit lower in a sealed box than the 4-ohm. And considering that my now-broken JL 10W6 wired at 12 ohms and powered by my BASH 300 fit in perfectly in terms of output with my main bookshelf speakers (I didn't need to wire it for 3 ohms to get it loud enough to blend in) ...it seems the 8-ohm will be the better choice for me. I only need moderate SPL (will be in a mid-sized bedroom). Considering this, are there any reasons I would regret choosing the 8-ohm over the 4?

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              • #8
                Originally posted by top40 View Post
                My box I have to work with is 4.7 cu. ft. net internal with a 4" Precision port 17" long effective length. This gives a tuning of approx 19Hz. My amp is a BASH 300. I am just about to buy the Ultimax 12" driver but I read of a few experiences of scraping voice coils, excursion noises, and adhesive failure with some Ultimax subs (seems mostly 12" and 10" ones). Is this still an issue or has it been resolved in recent production runs? I'm specifically interested in the 12" size.

                This is the driver I was planning around all these months but I'm giving thought to the alternate choice of the 12" High Fidelity series RSS315HF-4 (4 ohm) or RSS315HFA-8 (8 ohm) - both of these having exemplary reviews, and would also work well in the same enclosure I have. The only downside for me would be these don't offer the same very low F3 in an unboosted sealed configuration.




                When you factor in the room, deepest unassisted F3 is really not a major factor.

                That said, the Ultimax offers more linear throw and more total low distortion output than the same size Reference series.
                R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio

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                • #9
                  Originally posted by top40 View Post
                  I only entered Fs, Vas and Qts.
                  Insufficient data. WinISD Beta is better than nothing, but barely. Use 0.7.

                  Between the two the Ultimax 12 has higher maximum SPL in the vicinity of 25Hz, which I assume is important to you, otherwise why would you use that large a box?

                  www.billfitzmaurice.com
                  www.billfitzmaurice.info/forum

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                  • #10
                    Originally posted by Pete Schumacher View Post

                    When you factor in the room, deepest unassisted F3 is really not a major factor.

                    That said, the Ultimax offers more linear throw and more total low distortion output than the same size Reference series.
                    Would that be the Reference HF or HO? Or Both? I was contemplating buying a 10" Reference HO to measure it up against a 10" Ultimax and speculated it would do better due to triple shorting rings.

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                    • #11
                      I have used all sizes of the Ultimax and RS HF line, I would go with the RS HF.
                      Guess xmax's age.

                      My guess: 15. His grammar is passable. His trolling is good.

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                      • #12
                        Originally posted by guitar maestro View Post
                        I was contemplating buying a 10" Reference HO to measure it up against a 10" Ultimax and speculated it would do better due to triple shorting rings.
                        Shorting rings are of dubious value with subs, as where they're effective with respect to inductance tends to be well above the subwoofer pass band.

                        www.billfitzmaurice.com
                        www.billfitzmaurice.info/forum

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                        • #13
                          Originally posted by billfitzmaurice View Post
                          Shorting rings are of dubious value with subs, as where they're effective with respect to inductance tends to be well above the subwoofer pass band.
                          And if they low-passed above the typical 80Hz subwoofer LPF? What if they're allowed to operate as subwoofer-woofers into the hundreds of Hz?

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                          • #14
                            Originally posted by billfitzmaurice View Post
                            Shorting rings are of dubious value with subs, as where they're effective with respect to inductance tends to be well above the subwoofer pass band.
                            In any event, the Ultimax has some attempts at inductance reducing rings, too:

                            A large copper sleeve and copper pole cap in the motor reduce energy storage from inductance, with the side benefit of lowering distortion for "faster" response.
                            Francis

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                            • #15
                              The very mention of 'faster response' with a subwoofer driver indicates ad copy written by a marketeer with limited, if any, engineering chops.
                              And if they low-passed above the typical 80Hz subwoofer LPF? What if they're allowed to operate as subwoofer-woofers into the hundreds of Hz?
                              It would be extremely rare that one would want to operate a sub into directionally locatable frequencies.
                              www.billfitzmaurice.com
                              www.billfitzmaurice.info/forum

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