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Lamb to the Slaughter....first timer

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  • Lamb to the Slaughter....first timer

    Hello everyone - just joined, first-time poster. Started dabbling and researching and trying to learn. I've gotten far enough along that I thought I'd ask for some input on what I've got so far, and take my beatings.

    The drivers are Dayton Designer Series 5" woofers for mids (DS135-8), Dayton Classic Series 10" subwoofer (DCS255-4), and the tweeter is the Dayton Reference Series 1 1/8" fabric dome (RST28F-4). I don't mind some height, but wanted a relatively narrow footprint, so decided to explore a side-firing sub. The enclosure incorporates some design cues inspired by the Solstice speakers, namely the shaped front baffle and the slot port. XSim indicated I was dissipating too much power in the 5" driver, so I moved to twins to get the power handling in line with the amp channel output (200W @ 4 ohms). Targeted crossovers frequencies of around 250Hz for the sub to mid, and about 2000Hz for the mid to tweeter.

    I've attached a screenshot of the XSim windows displaying the crossover schematic, frequency response, and impedance graphs. I've also attached a graph showing power dissipation at full output. Crossovers ended up all being pretty basic second orders, with some mild attenuation on the mids and tweeter. Frequency response seems pretty flat, almost always within + or - 1db, and it bumps up 3-4 db below 150Hz to somewhat compensate for baffle step.

    I used WinISD to get internal volumes and port dimensions. It called for a much larger volume than I expected with the sub - 60 liters. I ended up compromising a little there and giving up some of the lowest frequencies and arrived at what I think is a decent solution at about 45 liters, with a slot port at the bottom - similar to the Solstice. It also called for a larger than desired volume for the mids, but realizing I didn't need them to extend very low, I was able to get a decent looking transfer function with a much much smaller volume. I looked at both sealed and ported - they were extremely similar at this volume, with just a 10Hz shift or so...for now I've left the port in, passing through the other chamber and out the back of the cabinet. I've attached shots of the transfer function that WinISD spits out for the volumes shown, and some pictures of the cabinet as well.

    Flame on....

    Thanks for looking! Trying to learn.

    Mike

  • #2
    Posting to attach pics of the speaker...

    Mike

    Comment


    • #3
      Stacking two 5" midranges will narrow the vertical directivity at your 2000Hz crossover. That's usually not a great idea, unless it solves other problems. Do you want two just for power? Do you listen really loud? Personal preference here: if I had two mids I'd MTM the arrangement.
      Francis

      Comment


      • #4
        With a side mounted woofer near the floor it's almost impossible to get the response and spl correct without measuring. No reason to port the mids. You should try to add in the baffle step to the mids and the tweeter. Max power is typically determined by the x-max of the woofer. Phase alignment again is going to be mess without measuring. You should make some educated guesses of the offsets to improve the simulation.
        John H

        Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

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        • #5
          Agreed about not porting the mids. Won't accomplish much except to possibly allow midrange energy to go out the port (bad).
          Francis

          Comment


          • #6
            Have you considered a 2 way, and running the subwoofers off separate amps?

            Comment


            • #7
              Alright, port for the mids is gone. The transfer function was almost identical with or without it, and losing it will just make it easier to build anyway. Thanks for the suggestion.

              Good call about the baffle step...with the narrow baffle it'll have a much higher frequency I guess? 600 Hz or so by the math I've seen. I'll tweak the crossover and see what I can do with that.

              John, you mentioned the woofer near the floor...would it be better/more predictable if it were higher? Nothing preventing it from moving much higher in the enclosure.

              For the mids, at max amp output XSim said it was more than twice the rated power for that speaker...and I do tend to listen loud. As far as stacking the mids, I was under the impression that keeping them closer together would net a better off-axis response, which is important to me as these will not be used with a single "listening position", but will likely be listened to as I move about the area. I may be way off track there, as I said, I'm new to this hobby.

              Thanks for the replies!

              Mike

              Comment


              • #8
                your midrange enclosure does not have much depth. I can't give you any fact based data or measurements, but backwave colouration is a possibility - even with damping. I'll let other correct me on the reality or the minimum depth recommended (if any) for a given XO point and excursion. I personally "oversize" midrange enclosures to a Qtc of 0.5. If you do this - you will get enclosure losses (that is the F3 will go up in frequency and add to the highpass transfer function for the midranges). You may need to allow for this in your sims - by adding in the box effect when you derive your inbox response.

                PS: go MTM to keep lobing pattern symmetrical and reduce destructive interference of a TMM layout with a traditional 2 way crossover.

                Comment


                • #9
                  Cool design!

                  I might recommend going larger on the mid enclosure to lower its Q, losing the mid port and going sealed. I’d also consider angling the back wall of the mid enclosure so it’s not parallel with the baffle.

                  I also like the idea of going active on the sub for this build, with a smallish plate amp for each one. Go active on the sub and leave the sub on the side and by the floor. This will make it infinitely easier to dial in to blend with the mid woofers and to tune your bass to whatever you are listening to and whatever room you are in.

                  just my opinions, and we all know what they say about opinions

                  Comment


                  • #10
                    I don't think your sim looks bad, but w/the woofer that near the floor, +6dBSC won't be needed. I'd cut the BSC in half.
                    Your box models (& woofer Fb) look okay to me.
                    My sim (as yours) showed normal polarity on the woofer, and reverse on the tweeter, but it also indicates the mids are reversed (although I'm sure my phase data probably isn't as accurate as yours).

                    Comment


                    • #11
                      Thanks for all the comments guys - appreciate the help. I made a few tweaks over the weekend based on the suggestions. I added some volume to the sealed mid enclosure and angled the back wall (I had ditched the port previously). I also spent some time messing with how close I could get the drivers - with the tweeter now much closer to the mids, I am thinking it should push the destructive interference to a frequency well above the crossover point. Getting the mids closer to each other should be an improvement as well.

                      I also played with the crossover some - unfortunately, I don't have screenshots of that handy. I was trying to move the BSC up to around 600 Hz and keep it to +2 to 3 db). I got it looking really flat, but it carried the extra db up to a little more than 1000 Hz. I couldn't get it to my targeted 600Hz without it getting lumpy. So basically, it's pretty flat from 40 up to 1000-1100 Hz, drops 2 db and stays flat up to the tweeter high end. Is that too high of a frequency for the step? I'm worried it might be fatiguing to listen to.

                      I'm also worried that I might be going a little overboard for my use case....I listen primarily to loud punk/rock music after all...lol. I'm far from an audiophile.

                      Comment


                      • #12
                        Originally posted by T311 View Post
                        Thanks for all the comments guys - appreciate the help. I made a few tweaks over the weekend based on the suggestions. I added some volume to the sealed mid enclosure and angled the back wall (I had ditched the port previously). I also spent some time messing with how close I could get the drivers - with the tweeter now much closer to the mids, I am thinking it should push the destructive interference to a frequency well above the crossover point. Getting the mids closer to each other should be an improvement as well.

                        I also played with the crossover some - unfortunately, I don't have screenshots of that handy. I was trying to move the BSC up to around 600 Hz and keep it to +2 to 3 db). I got it looking really flat, but it carried the extra db up to a little more than 1000 Hz. I couldn't get it to my targeted 600Hz without it getting lumpy. So basically, it's pretty flat from 40 up to 1000-1100 Hz, drops 2 db and stays flat up to the tweeter high end. Is that too high of a frequency for the step? I'm worried it might be fatiguing to listen to.

                        I'm also worried that I might be going a little overboard for my use case....I listen primarily to loud punk/rock music after all...lol. I'm far from an audiophile.
                        For your uses, you may be close enough to just build it and see if you're happy. But don't be surprised if, in time, you get the urge to tweak things just a little better. It's the blessing and curse of DIY.
                        Francis

                        Comment


                        • #13
                          Rory Buszka designed a system with a low mounted side firing woofer, you might try to PM him about the design. He knows his stuff. He's on this board.

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