DIY Sub Mission... Impossible?

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  • deewan
    Senior Member
    • Feb 2009
    • 284

    DIY Sub Mission... Impossible?

    Recent discussions on my 2RCC center channel speaker thread have got me thinking again and I thought this time I'd ask the experts for their input. I've been itching to change my sub setup but don't want to just change it for the same basic performance. For years I have wondered about mixing and matching ported sub cabinets in the same room/setup with sealed sub cabinets. It is my personal taste and feeling that ported subs give better movie bass (thunderous, rumbling, shaking bass) while sealed cabinets provide a more musical bass (high impact, tighter, cleaner). These are just MY opinions and assumptions I am going to stick with. I’ve always wondering if I could buy or build a ported large sub that might not be musical but would provide tons of earth shaking bass, and have that responsible for bass below, let’s say, 45Hz for example. And then have a second sub that is sealed and more musical play the bass from 45Hz up to 80Hz where it becomes directional. All that and after drooling over Paradigm's Sub 1 and Sub 2, gave me a crazy idea and I was hoping some of the experts here could help me answer some questions so I can determine if a DIY project/experiment is worth the time.

    QUESTION ONE - Are there any draw backs to having a sealed and a ported sub in the same room, being fed from the same setup, and playing at the same time and basically sharing the same footprint/location in the room?

    QUESTION TWO - Would a cabinet design much like Paradigm's Sub 1 or Sub 2 work if three 10 inch drivers were used around the bottom of the enclosure and ported while having three 8 inch drivers in a sealed enclosure rest on top? Both enclosures would be attached to each other basically giving the same look at the Paradigm sub.

    QUESTION THREE – Is it possible to create a semi low cost sub crossover sending bass below the exampled 45Hz to the ported 10 inch drivers and send the upper bass higher than 45Hz (I realize passive crossovers are not a hard cutoff at a certain freq) to the more musical 8 inch drivers?

    The most important question, is this all just a waste of time? Something in the back of my head is saying if the best of both worlds (port and sealed sub) can exist in the same system at the same time, then some commercial company would have already tried it.

    Am I crazy? Am I possibly on to something here? Ideas? Suggestions?
    The Old Woods Theater
    My Various Speaker Builds
    Statement II Remix build

    "Aren't you a little short for a Stormtrooper?"
  • dumaresq
    Member
    • Mar 2008
    • 96

    #2
    Question 1. No this shouldn't be an issue
    Question 2. Probably -- though for your ported sub the bigger you go the deeper it will go so you will like it more (since the sealed sub is going to do the "midbase" part of the spectrum.
    Question 3. No idea, but if I was going to do this I'd probably want an electronic crossover so I could adjust the crossover point as needed (and taste).

    Personally I have a 15 inch sub in a 300-450L enclosure (I can't remember the exact size) with a port tuned to 14.5Hz that with my full statement mains gives me more base at any frequency then I can ever see anyone needing (and I do like base!).

    Comment

    • BobEllis
      Super Senior Member
      • Dec 2005
      • 1609

      #3
      Having a single octave passband will be problematic when it comes to designing the filter. Many think that the low Q rolloff is what makes sealed subs sound more musical. If you are going to apply a filter below it, you will lose that effect.

      To my thinking, above 45Hz is woofer territory. What are your main speakers? (can they reach down into the 40s?

      If you want to experiment with ported vs. sealed subs, why not put all the money into a single sub with a plug for the port? You could switch a Linkwitz transform into the system when operating sealed if needed.

      Another possibility is an experiment in very low tuning. Don't settle for the standard tuning that the box programs suggest, go lower. Sometimes known as Large Low Tuned or shelf bass, lower tuning than required for flat anechoic response shows a droop in low end response that tends to match to the room gain. IMHO, the argument that ported bass is boomy comes from not accounting for room gain.

      For real subwoofer response, you'll want to go larger than 10" in anything but a small bedroom.

      Comment

      • ---k---
        Ultra Senior Member
        • Nov 2005
        • 5202

        #4
        There are no reasons you couldn't do it with an electrical crossover. BUT, I like Bob's idea better. Build a big ported sub (you can do the opposing drivers to cancel mechanical motion if you like), and when you're listening to music stuff a nerf in the port. For movies, pull the plug out of the port.
        - Ryan

        CJD Ochocinco! ND140/BC25SC06 MTM & TM
        CJD Khanspires - A Dayton RS28/RS150/RS225 WMTMW
        CJD Khancenter - A Dayton RS28/RS150/RS180 WTMW Center

        Comment

        • deewan
          Senior Member
          • Feb 2009
          • 284

          #5
          Thanks for the responses guys. Very helpful. The more I think about this, the more I think maybe the 8 inch subs should run full out for anything lower than 80Hz, like a typical sub. And maybe use the crossover on the plate amp to run the 10 inch subs to everything below 45Hz or 50Hz (or whatever the lowest crossover setting is).

          I understand what BobEllis is saying though about needing bigger drivers for real power. I currently have a set of Statements runnng full range for my mains. Paired with that I have a Paradigm DSP-10 sub (10 inch driver). It's a fine sub, no compliants other than I wish I had a little more bone shaking on the really low stuff.

          Perhaps I just need to go back to looking for good sub designs for the really low bass. The Statements do a fine job of producing all the musical bass I should need.
          The Old Woods Theater
          My Various Speaker Builds
          Statement II Remix build

          "Aren't you a little short for a Stormtrooper?"

          Comment

          • Hdale85
            Moderator Emeritus
            • Jan 2006
            • 16075

            #6
            Well 3 10's really isn't going to play much lower then a single 10". More then likely you will just get more output of the frequencies the single 10 is already playing. Like everyone has said bigger subs = lower output. The lower output is generally what you feel shaking your bones (although this may prove hard to achieve). Honestly for HT use I wouldn't go with anything smaller then a 12" and really a 15" is ideal.

            Comment

            • deewan
              Senior Member
              • Feb 2009
              • 284

              #7
              I really wasn't looking for that much lower of output. I just wanted more of it. But all that said, I think I have been talked out of trying this build. I don't mean that in a bad way. I am still thinking about a sealed and ported cabinet, just a different approach. I'm thinking about something more like the Velodyne 1812, only with a 15 and a 10. I'm thinking about having the enclosure sit in the storage room next to the theater and then firing into the theater in the front corner through the already present AT fabric. This will almost be like a IB sub, but with an enclosure on the other side of the wall. I want to stay away from IB subs since I don't want the subs output to fill both rooms of the house.
              The Old Woods Theater
              My Various Speaker Builds
              Statement II Remix build

              "Aren't you a little short for a Stormtrooper?"

              Comment

              • john trials
                Senior Member
                • Mar 2009
                • 449

                #8
                I haven't tried one of these (I'm tempted), but I've read very good reviews in many places.

                The best value for price home theater systems and subwoofers on the market guaranteed


                You change a switch on the sub and plug one of the ports. VTF – Variable Tuning Frequency. The bass characteristics can be varied between lower extension (‘music’ mode) or higher headroom (‘home theater’ mode).
                Statements: "They usually kill the desire to build anything else."

                Comment

                • deewan
                  Senior Member
                  • Feb 2009
                  • 284

                  #9
                  HSU subs are normally well reviewed. But of course since I am on a DIY kick, I am looking to build instead of purcahse. But maybe ideas can be "borrowed" from this commercial sub.
                  The Old Woods Theater
                  My Various Speaker Builds
                  Statement II Remix build

                  "Aren't you a little short for a Stormtrooper?"

                  Comment

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