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  • #31
    This forum software ... ugh ...

    One um18 in 8ft³ sealed.
    Click image for larger version  Name:	8ft um18 sealed.JPG Views:	1 Size:	131.0 KB ID:	1382256

    One um18 in 4ft³ ported.

    Click image for larger version  Name:	4ft um 18 ported.JPG Views:	1 Size:	154.3 KB ID:	1382257



    One um18 in 8ft³ ported.

    Click image for larger version  Name:	8ft um 18 ported.JPG Views:	1 Size:	147.9 KB ID:	1382258










    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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    • #32
      Sent message to OP but thought this might be useful here also.

      Just my ramblings ...

      While the Unibox models are very close to PE's, the sealed are pretty far off in qtc. Not sure why, maybe they are taking into account its intended auto environment? Since PE lists impedance as 4 ohm I assumed both 2 ohm coils are being driven in series (listed as 4 ohm) so unless mistaken, all other t/s parameters are as listed by PE.

      Also, (this part also confuses me so I may very well be wrong here, do ask others on the list to verify/refute) both voice coils being driven by two different amps with 1100 watts each doesn't equal more than driving both voice coils with 1100 watts from one channel of the same amp.

      But ... if you wire the coils in parallel impedance would halve, which in theory would double power available from the amp, if it's stable and capable of dumping that much current into 1ohm (which isn't really a flat 1ohm). Wired in series would in theory double the impedance and halve the amp's output. So, if your amps are not stable into 1 ohm I can see where you are coming from using two separate amps to drive both voice coils.

      ^ Don't be afraid to ask the question of others for I have never really understood the intricacies of driving multiple voice coils in the same driver.

      A sealed box will be easiest to build, or you could go the extra trouble of building a ported box knowing you might wind up plugging the ports because it sounds better sealed.


      Guys, whatdaya think???
      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


      • #33
        Originally posted by Kornbread View Post
        Sent message to OP but thought this might be useful here also.

        Just my ramblings ...

        While the Unibox models are very close to PE's, the sealed are pretty far off in qtc. Not sure why, maybe they are taking into account its intended auto environment? Since PE lists impedance as 4 ohm I assumed both 2 ohm coils are being driven in series (listed as 4 ohm) so unless mistaken, all other t/s parameters are as listed by PE.

        Also, (this part also confuses me so I may very well be wrong here, do ask others on the list to verify/refute) both voice coils being driven by two different amps with 1100 watts each doesn't equal more than driving both voice coils with 1100 watts from one channel of the same amp.

        But ... if you wire the coils in parallel impedance would halve, which in theory would double power available from the amp, if it's stable and capable of dumping that much current into 1ohm (which isn't really a flat 1ohm). Wired in series would in theory double the impedance and halve the amp's output. So, if your amps are not stable into 1 ohm I can see where you are coming from using two separate amps to drive both voice coils.

        ^ Don't be afraid to ask the question of others for I have never really understood the intricacies of driving multiple voice coils in the same driver.

        A sealed box will be easiest to build, or you could go the extra trouble of building a ported box knowing you might wind up plugging the ports because it sounds better sealed.


        Guys, whatdaya think???
        the amp is stable at 2 or 4 ohms. not one ohm.. the birth sheets state 1168 at 14.4 volts into a 4 ohm load for one amp and and 1170ish into 4 ohms at 14.4 volts for the second amp. and this has been verified with a scope and true rms meter. they are solid little amps. they are not linkable amps with master/slave capabilities.. I have heard of people running stereo amps into a dual voice coil subwoofer. while it may not be any more than the power from one channel as you state.. it damn sure couldnt hurt.. i may end up just using one of the amps for the sub. but my thoughts are have it ready tp wire one cil per amp.. as everything i have read indicates thatr the ultimax subs really shine with about 3 k rms.

        Comment


        • #34
          i have the ability to dial in each amps output very precisely. with an oscope and meter. I have seen several guys do this over the years. it may not be optimal. but at that kind of power level.. it is a difference you can feel and hear.. assuming of course the amps put out a clean signal.. which these do.. very efficient amps and very low thd. I actually tested them with a power supply from work and cranked up the voltage to 16 voltgs as alpine rates them for 12-16 volts.. and they really liked that. output went to almost 1300 with a 40 hz sine wave.. either way, once the entire system is dialed in and tuned with rew I doubt i will be using their full output.. but I did that for a reason, they never run hot, they are already 10 years old and frequently see full volume for 30 minute car rides to and from work. and they are just like a mule.. they keep pulling.

          Comment


          • #35
            Headroom is a good thing, just gotta be careful with so much power going into a 3" coil. UM's are not DD9500's. I used to have two amps (RF bd1000.1's) going into an RE XXX 12" Quad-1.4 Ω back in the day. So long as the voltages are set as accurately as possible, the overall operation will be fine.

            Comment


            • #36
              Here are a couple of articles that help explain cabin gain and the vehicle resonant frequency. Both are short reads and have some very good information in them.

              Learn how to build a high output subwoofer enclosure. Sync the car response with the enclosure response to get the most out of your system.

              Comment


              • #37
                Ok it arrived today.. I just slapped together a 20x20x18 (very close to recommended specs) sealed box out of some Baltic birch I had left from an old project. Filled it with a big bag of polyfill and with just one amp hooked up started breaking it in. Holy hell.. 2 of them w would've been insane and impractical. Very well built driver and it is definitely closer to the sound I am wanting. Tight snappy. Can't wait to get it broke in and the other amp hooked up and the correct box modeled with lots of internal bracing. Then I will start dialing it in with rew. I sure wish I had found parts express and Dayton audio a few years ago. I know some guys that have spent 1500 plus on a set of 3 way components.. And for the money the Dayton stuff just plain works.

                I am going to take the time to learn to model a box myself. But after I do some sweeps with it the way it is.. And hopefully get some good direction from some of you more knowledgeable folks here at tech talk.

                Comment


                • #38
                  Try these two tracks on repeat for breaking in subs. Bassotronics Bass I Love You and Bass I Love You Too
                  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


                  • #39
                    Vented boxes need WAY more "design" than sealed ones. If you've already got around 4cf (or 3cf - stuffed), going bigger won't change too much (doubling the size could drop the final "Q" down from .80 to .70, but the F3 is in the lower 30s - either way).

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