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18" Ultimax Infinite Baffle instead of sealed???

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  • 18" Ultimax Infinite Baffle instead of sealed???

    I got some advice here the other day that drove me from the Ultimax15 to the Ultimax18. I am replacing a single sub with two, intending to reduce amplitude variation throughout the listening room. The 18 wants a relatively large enclosure at 4-6cf. That's really not that large for an 18" woofer, but it's a big thing to have two of in your family room. I had previously considered an IB arrangement mounted under the floor. I don't want to buy 4 or 8 of these things to get the SPL without over-excursion. My thought for IB is more about getting the boxes out of the room than it is about the super low extension and uncolored response that makes some people love IB designs. If I mount two Ultimax18's in opposite corners of the room, vented through the floor, with appropriate high-pass filters, I can get the same performance as the sealed design I would otherwise have taking up space in the room. I have attached a graph of the SPL at a power where the driver reaches maximum excursion for both the sealed and filtered IB alignment. Is there a good reason why I should not do the IB installation?
    Attached Files

  • #2
    They are ideal for it due to their massive stroke. I think PE says they should be manifold mounted. The power handling will probably be cut in half or so.

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    • #3
      Just to clarify, what exactly do you mean by "vented through floor"? What is beneath your floor?

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      • #4
        Originally posted by vapor602
        Just to clarify, what exactly do you mean by "vented through floor"? What is beneath your floor?
        This may have been poor wording. I would plan to make a manifold in the basement that bolts under the floor. A 12"x16" floor return vent will cover the hole in the floor. Sent from my SAMSUNG-SGH-I337 using Tapatalk

        Comment


        • #5
          Originally posted by make_some_noise
          They are ideal for it due to their massive stroke. I think PE says they should be manifold mounted. The power handling will probably be cut in half or so.
          With the high pass filter my model shows the driver reaching max excursion and the same SPL at about the same power. Without the filter, i get lower extension but significantly reduced power handling and SPL due to severe excursion at ultra low frequencies. In that respect I'm kind of defeating one major advantage of IB, but I'm getting (according to the computer model) performance equal to the sealed design without having the enclosure in the room. Sent from my SAMSUNG-SGH-I337 using Tapatalk

          Comment


          • #6
            I love my IB ... just kidding. The bass is pretty clean and deep though. The sheetrock in my house hates it; lots of cracks.

            Take this with a grain of salt as this is my personal experience, and yours may vary.

            With IB you are going to need eq'ing. It's the nature of the beast. Generally they have to go where they have to go, there's usually little, or no choice, in placement. This means liberal amounts of eq to flatten. But by all means, if you can optimize placement, do it. My thoughts; you will still need liberal amounts of eq.

            Power, power, and more power.

            In the 'Shed' home theater setup, there were 4 15" Dayton IB's in a cube open to the theater room on one side, and another room on the back. They could take everything the Behringer ep2500 could dish out. No problem with the woofers bottoming. With the right material, the air felt like jelly.

            Due to new neighbors moving a mobile home (we call em' trailers) right against the shed, that system was dismantled to 'keep the peace'. Now the system resides upstairs in the house, but with two 18" Stereo Integrity woofers (comparable to the Ultimax 18) which reside in a 'kick wall' running the length of the house. Those big a$$ subs have never come close to bottoming with the Behringer ep2500 driving them. Measurements were taken with REW, for eq'ing purposes, but I never measured max spl. Let's just say, in a ~20x26 room, it's bloody loud ... and clean ... and deep, when the material is there.

            I know a lot of people run the sims and worry about how much power the IB's can handle at fs, or below; In my experience, this has been a non-issue.

            If you eq (you probably should) I found it easier to go lightly when adding boost. It worked better to cut peaks than raise valleys.
            http://techtalk.parts-express.com/fo...khanspires-but
            http://techtalk.parts-express.com/fo...pico-neo-build
            http://techtalk.parts-express.com/fo...ensation-build

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            • #7
              Originally posted by Kornbread View Post

              I know a lot of people run the sims and worry about how much power the IB's can handle at fs, or below; In my experience, this has been a non-issue.

              If you eq (you probably should) I found it easier to go lightly when adding boost. It worked better to cut peaks than raise valleys.
              Depending on the room and the gain one gets, it is likely that the really deep stuff will need to be cut some, which also will help with cone excursion. Unless he has a massive room, I wouldn't worry about an HP filter and if the the power handling is reduced he's probably still more than ok. The UM 18's are tough beasts and I'd love a couple of them sealed as they would be far smaller than my two subs are now. My 18" in a 12 cu ft EBS box and my 15" sub are overkill for my small 13x17' room and I just have 300 watts each. I've done damage to the house, broken windows, and pissed off my neighbors a few times in the last 15 years. A couple UM18's on 2k RMS of power in an IB config would be unreal in my little house, lol.

              Comment


              • #8
                Originally posted by Kornbread
                I love my IB ... just kidding. The bass is pretty clean and deep though. The sheetrock in my house hates it; lots of cracks. Take this with a grain of salt as this is my personal experience, and yours may vary. With IB you are going to need eq'ing. It's the nature of the beast. Generally they have to go where they have to go, there's usually little, or no choice, in placement. This means liberal amounts of eq to flatten. But by all means, if you can optimize placement, do it. My thoughts; you will still need liberal amounts of eq. Power, power, and more power. In the 'Shed' home theater setup, there were 4 15" Dayton IB's in a cube open to the theater room on one side, and another room on the back. They could take everything the Behringer ep2500 could dish out. No problem with the woofers bottoming. With the right material, the air felt like jelly. Due to new neighbors moving a mobile home (we call em' trailers) right against the shed, that system was dismantled to 'keep the peace'. Now the system resides upstairs in the house, but with two 18" Stereo Integrity woofers (comparable to the Ultimax 18) which reside in a 'kick wall' running the length of the house. Those big a$$ subs have never come close to bottoming with the Behringer ep2500 driving them. Measurements were taken with REW, for eq'ing purposes, but I never measured max spl. Let's just say, in a ~20x26 room, it's bloody loud ... and clean ... and deep, when the material is there. I know a lot of people run the sims and worry about how much power the IB's can handle at fs, or below; In my experience, this has been a non-issue. If you eq (you probably should) I found it easier to go lightly when adding boost. It worked better to cut peaks than raise valleys.
                Thanks for telling me about your experience. I would plan to power these with an inuke 6000. I would also plan to use dsp for eq. I expect to use eq regardless of the enclosure type. In terms of placement i plan to put them in opposing (diagonal) corners. The purpose for this is to tame some nasty room modes and provide more even response throughout the room. I hope this will allow me to effectively eq the system. Currently my single sub can't be equalized because the response is so different in different room positions. I think i can just cut and not boost. My biggest problem is with huge peaks around 31Hz (long room dimension). These get overwhelming at room boundaries, but when i cut the peak with eq it's dead at other room positions. I hope to suppress these room modes with the placement and get smoother response and then finish with eq. Sent from my SAMSUNG-SGH-I337 using Tapatalk

                Comment


                • #9
                  Originally posted by Kornbread
                  I love my IB ... just kidding. The bass is pretty clean and deep though. The sheetrock in my house hates it; lots of cracks. Take this with a grain of salt as this is my personal experience, and yours may vary. With IB you are going to need eq'ing. It's the nature of the beast. Generally they have to go where they have to go, there's usually little, or no choice, in placement. This means liberal amounts of eq to flatten. But by all means, if you can optimize placement, do it. My thoughts; you will still need liberal amounts of eq. Power, power, and more power. In the 'Shed' home theater setup, there were 4 15" Dayton IB's in a cube open to the theater room on one side, and another room on the back. They could take everything the Behringer ep2500 could dish out. No problem with the woofers bottoming. With the right material, the air felt like jelly. Due to new neighbors moving a mobile home (we call em' trailers) right against the shed, that system was dismantled to 'keep the peace'. Now the system resides upstairs in the house, but with two 18" Stereo Integrity woofers (comparable to the Ultimax 18) which reside in a 'kick wall' running the length of the house. Those big a$$ subs have never come close to bottoming with the Behringer ep2500 driving them. Measurements were taken with REW, for eq'ing purposes, but I never measured max spl. Let's just say, in a ~20x26 room, it's bloody loud ... and clean ... and deep, when the material is there. I know a lot of people run the sims and worry about how much power the IB's can handle at fs, or below; In my experience, this has been a non-issue. If you eq (you probably should) I found it easier to go lightly when adding boost. It worked better to cut peaks than raise valleys.
                  I'm also encouraged to hear you are satisfied with the output with only two drivers. I see alot of discussions on here where people are using 4 or more. Sent from my SAMSUNG-SGH-I337 using Tapatalk

                  Comment


                  • #10
                    Originally posted by make_some_noise
                    Depending on the room and the gain one gets, it is likely that the really deep stuff will need to be cut some, which also will help with cone excursion. Unless he has a massive room, I wouldn't worry about an HP filter and if the the power handling is reduced he's probably still more than ok. The UM 18's are tough beasts and I'd love a couple of them sealed as they would be far smaller than my two subs are now. My 18" in a 12 cu ft EBS box and my 15" sub are overkill for my small 13x17' room and I just have 300 watts each. I've done damage to the house, broken windows, and pissed off my neighbors a few times in the last 15 years. A couple UM18's on 2k RMS of power in an IB config would be unreal in my little house, lol.
                    My room is 14x18x9. One of the long walls is only 1/3 the length with the remainder open to the rest of the house. The room is not huge but it's open on the one side. I hope to get high SPL with only two drivers. Sent from my SAMSUNG-SGH-I337 using Tapatalk

                    Comment


                    • #11
                      My room on the long side has a 4' wide opening to the rest of the house. Not quite 1/3rd like yours, but I get more than enough SPL and a lot of gain down low. The gap in the wall is the biggest cause of your room modes, I have the same issue. Difference for me is that I am the only one in the house that cares so I setup my subs for my usual listening position.While in positions other than where I sit I may have some holes where the bass is leaner, it equally shakes everything in the room and that is what most non audio folks care about. I never get a lack of bass complaint from people. If anything even sitting where a room mode is much leaner than my position, people who have never heard my system before usually gasp when something nasty in a movie happens. My areas with holes in the response are mid bass issues, say 60-100hz or so.. The deep stuff is equally strong through out most of it. Luckily my kids are old enough now to not bash in my speakers so I can go back to a big set of mains instead of bookshelfs on stands which will solve my midbass room mode problems.

                      Comment


                      • #12
                        Thanks everyone. So far sounds like IB is an OK plan. I plan two locations with only two drivers, so no opposing drivers in each manifold. Hopefully i can reinforce the manifold enough to prevent problems. Sent from my SAMSUNG-SGH-I337 using Tapatalk

                        Comment


                        • #13
                          Originally posted by make_some_noise
                          My room on the long side has a 4' wide opening to the rest of the house. Not quite 1/3rd like yours, but I get more than enough SPL and a lot of gain down low. The gap in the wall is the biggest cause of your room modes, I have the same issue. Difference for me is that I am the only one in the house that cares so I setup my subs for my usual listening position.While in positions other than where I sit I may have some holes where the bass is leaner, it equally shakes everything in the room and that is what most non audio folks care about. I never get a lack of bass complaint from people. If anything even sitting where a room mode is much leaner than my position, people who have never heard my system before usually gasp when something nasty in a movie happens. My areas with holes in the response are mid bass issues, say 60-100hz or so.. The deep stuff is equally strong through out most of it. Luckily my kids are old enough now to not bash in my speakers so I can go back to a big set of mains instead of bookshelfs on stands which will solve my midbass room mode problems.
                          I'm curious about your comment that the severity of room modes is related to the open wall. I had only been considering the distance between the solid walls. The single sub is in the front corner at the intersection of the wall that is open on the other end. The highest response peak occurs in the opposite diagonal corner. I wonder what would happen if i move the sub to the other front corner where the room has no opposite diagonal corner. Sent from my SAMSUNG-SGH-I337 using Tapatalk

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                          • #14
                            When eq'ing, I'm only worried about the listening position.

                            What is the freq. response of the iNuke? IIRC, some pro sound amps have a subsonic filter, pretty sure the ep2500 does.

                            Found this on Inuke frequency response, looks like it starts to roll off around 40hzl, but it's only down ~2db by 10hz.

                            http://forum.speakerplans.com/behrin...202_page2.html

                            If I can help, just let me know.
                            http://techtalk.parts-express.com/fo...khanspires-but
                            http://techtalk.parts-express.com/fo...pico-neo-build
                            http://techtalk.parts-express.com/fo...ensation-build

                            Comment


                            • #15
                              Originally posted by Kornbread
                              When eq'ing, I'm only worried about the listening position. What is the freq. response of the iNuke? IIRC, some pro sound amps have a subsonic filter, pretty sure the ep2500 does. Found this on Inuke frequency response, looks like it starts to roll off around 40hzl, but it's only down ~2db by 10hz. http://forum.speakerplans.com/behrin...202_page2.html If I can help, just let me know.
                              Yeah I'll have to carefully review the inuke specs although what you describe above sounds perfectly acceptable. I also need to look at the DSP. I have heard it doesn't have any adjustment below 20Hz so i may need to use something else like a mini dsp. Sent from my SAMSUNG-SGH-I337 using Tapatalk

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