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Drivers for Basic 2-Way Speaker Build - Am I on the Right Track?

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  • #16
    Guys, it's a pair of garage speakers run off a car stereo. OP has not expressed an interest in the speaker design hobby.

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    • #17
      Originally posted by djg View Post
      Guys, it's a pair of garage speakers run off a car stereo. OP has not expressed an interest in the speaker design hobby.
      True and I actually thought mentioning PR would be worthy since it's about as basic as it gets - very little research, simple implementation, elimination of complex port research and construction, production of the type of bass he's after with a bit more bottom end vs just sealed. But, point still taken.
      Feel free to rip my assumptions apart when wrong, or fix if close.

      Passive Radiators:
      All PR(s) Vd must be at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). A combined PR(s) Vd equal or > than a combined woofer(s) Vd is usable.
      Woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax is usable.
      A PR max weight is said to be its Mms x3

      PR Systems - tight focus with key parameters.
      PR Speaker Design - thorough coverage.

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      • #18
        Originally posted by djg View Post
        Guys, it's a pair of garage speakers run off a car stereo. OP has not expressed an interest in the speaker design hobby.
        LOL! Thanks djg. Although, i wouldn't say I have no interest in it, just that I'm not likely to pursue it at this time. The more I read about the various designs and kits the more interested I become. i'm always intrigued by the thought process that leads to some of these designs but a man has got to know his limitations...

        Thanks for the suggestion Thump, I'll definitely consider it. At this time it's most likely I'll build one of the proven designs that are out there.

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        • #19
          Originally posted by djg View Post
          The design I linked is sealed. No port. You don't need 6 feet of clearance for a port. A few inches will do. How close to the opposite cab wall is the inside end of the port?

          Paul Carmody's S2000 MTM is 4 ohm, 91db sensitivity, and as everyone always says, has amazing bass output considering. DIYsoundgroup.

          Ooh, look at this, 8", sealed, cheap.

          All GRS small 3-way - Techtalk Speaker Building, Audio, Video Discussion Forum
          Does it really matter whether the port is rear or front facing? That S2000 looks really cool but rear-facing ports.

          Other than placement in my garage these will also get used outdoors on occasion so there would be nothing at all for a rear-facing port to reflect off of. Front facing would make more sense as it'll be aimed at the listener.

          That GRS 3-way is neat, but 8 ohms unfortunately.


          Would be cool if someone could cook up a crossover for the drivers I'm interested in... Project idea anyone?

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          • #20
            In theory it's not going to matter whether the port is front or rear facing. Geoff Millar's point is that an existing design may not have a front baffle with dimensions allowing the front port (which would be true for the S2000).

            Typically, if you keep the baffle width the same and the relative tweeter and woofer placements the same, you could make the speaker taller to accommodate a front port. (Also, keeping total internal volume the same.) Thus, you could get the kit but build your own cabinets if you have the tools and skills.

            Note also, that someone can simulate a reasonable crossover for you using certain drivers. But the proven designs will have had a cross-over designed, and then built, and then voiced and tweaked over some reasonable amount of listening time. For those who know what they are doing (which includes those who have kits for sale at the various sites) this is likely to be quite a bit better than a simulated crossover, no matter how good the theoretical output looks in an Excel graph.

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            • #21
              a4eaudio - thanks for your input! I was looking at the S2000 MTM over at DIYSoundgroup and those things look great. I was wondering if I could rearrange the front baffle to accommodate the ports. Yes, that is something I could do. If the baffle was made wider along it's narrowest side then the tweeter could be moved more to one side and the woofers could be moved in towards the middle and the ports could be placed at the ends. This of course assumes that the resultant loss of depth in the cabinet to keep the volume the same wouldn't interfere with the port tubes. Another option would be to simply add some kind of dead space inside the cabinet to take up the gain in volume if the depth needs to be retained.

              I understand that the placement of the speakers in the front baffle affects the overall sound the speaker delivers but I have a hard time believing that for my application it would really make a noticeable difference for the worse. I'm not going to be sitting in a listening room evaluating every little detail of these things...

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              • #22
                Will, Michael here. PM me for more info on RS225P 4A

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                • #23
                  [QUOTE=WillB;n1390298]a4eaudio - thanks for your input! I was looking at the S2000 MTM over at DIYSoundgroup and those things look great. I was wondering if I could rearrange the front baffle to accommodate the ports. Yes, that is something I could do. If the baffle was made wider along it's narrowest side then the tweeter could be moved more to one side and the woofers could be moved in towards the middle and the ports could be placed at the ends. This of course assumes that the resultant loss of depth in the cabinet to keep the volume the same wouldn't interfere with the port tubes. Another option would be to simply add some kind of dead space inside the cabinet to take up the gain in volume if the depth needs to be retained.

                  I understand that the placement of the speakers in the front baffle affects the overall sound the speaker delivers but I have a hard time believing that for my application it would really make a noticeable difference for the worse. I'm not going to be sitting in a listening room evaluating every little detail of these things...[/QUOTE

                  Hi WillB! Since you are mounting these up in your garage, other options would be to place the ports on the bottom, top, or even the side. You want the clearance from the port to other objects to be greater than the diameter of the port itself.

                  ** Strike this - noticed you want 4 ohm and higher sensitivity -
                  Since you want something that will have some decent bottom end, have you considered the Hitmakers kit? Bigger woofer and it looks like there would be enough room on those to mount the port on the baffle below the woofer.
                  Last edited by tom_s; 10-11-2018, 09:49 PM. Reason: My dummmnesss
                  Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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                  • #24
                    Originally posted by WillB View Post
                    I understand that the placement of the speakers in the front baffle affects the overall sound the speaker delivers but I have a hard time believing that for my application it would really make a noticeable difference for the worse.
                    That is likely true, and thus you can ignore the rest of this post

                    The speaker's crossover is designed for the baffle width (due to baffle step compensation "BSC"), the location of the tweeter (centered or offset) and the distance between the tweeter and woofer.
                    Why not just make the speaker taller and keep the width the same. I can't tell the diameter of the port, but if it was 2" maybe you need to make the speaker 4-5 inches taller. Then you could either decrease the depth to keep the volume constant, keep the depth the same but fill some of the internal space of the cabinet, or some combination of the two.

                    Google images of Paul Carmody's Classix II and then "front ported Classix II" and you can see examples of people that took a rear-ported speaker and built it front-ported. (I'm sure this is true of many designs, I just happen to know this will produce some good examples.)

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                    • #25
                      People have funny ideas about ports. They are tuning devices. Air does not blow out of them, it vibrates in sympathy with the speaker cones and provides a calibrated resistance to cone movement. As long as you aren't putting the port outlet right up against a wall and blocking it, there isn't a problem. It's air, not concrete. Put the ports on top if you just can't stand them in the back.

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                      • #26
                        Thanks for the additional input everyone!

                        Michaelandann - I will be in touch next week. Very busy this weekend, just a few minutes to sit at the computer while I eat a sandwich. Thanks for reaching out to me!

                        djg - understood about how ports function, at least I think so. To my understanding the purpose of the port is to generate vibrations which resonate in sympathy with the vibrations from the woofer, thus reinforcing the bass response. In order for rear or side/top ports to work they have to have something for those vibrations to reflect off of and there has to be room around the speaker to allow the vibrations to properly propagate. Since I'll be setting these on a shelf in the corners of my garage up near the ceiling there may not be enough room around the speaker, or there might be. It might work just fine. But, more problematic is their occasional use outdoors where there will be nothing for the port vibrations to reflect off of. A port on any side but the front will have the vibrations it produces just emanating off into space, away from the listeners. A front mounted port will direct it's vibrations in the same direction as the woofer - towards the listeners.

                        This and the compactness of the enclosure is one of the reasons I was leaning towards a sealed cabinet at first but it seems all the designs with high sensitivity, reasonable bass extension, and low impedance are ported.

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                        • #27
                          Port output (typically highest around the tuning freq. - Fb) is not direct at all. Freqs below 100Hz go almost everywhere, you don't need a "reflector" for the bass to bounce off of. If a ported speaker ends up being too "boomy", you can always stuff the port w/old socks (or, some use a nerf football - if it'll fit).

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                          • #28
                            Also note a 20hz wave is over 50 feet long. Low frequencies get huge.

                            This is part of why (or the reason why, not absolutely certain) low frequencies are totally non directional, and why a Sub can be placed anywhere in a room. They flood the space with those giant wave lengths.

                            Placement still needs to take the room characteristics into account or it'll sound worse, have giant spikes at certain frequencies, or get soaked up. For this I'm talking about Subs mostly, but any typical cabinet with a big enough woofer and boom factor pumping out extremely low frequencies would have these aspect apply to some degree.
                            Feel free to rip my assumptions apart when wrong, or fix if close.

                            Passive Radiators:
                            All PR(s) Vd must be at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). A combined PR(s) Vd equal or > than a combined woofer(s) Vd is usable.
                            Woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax is usable.
                            A PR max weight is said to be its Mms x3

                            PR Systems - tight focus with key parameters.
                            PR Speaker Design - thorough coverage.

                            Comment


                            • #29
                              Originally posted by Thump View Post
                              ... low frequencies are totally non directional, ...
                              That is a common Internet misunderstanding. It is more a relationship of the size of the wave and the size of the Source and what the wave encounters.
                              The large wavelengths make it difficult, but low frequency can be directed (steered), with large directional horns, or as commonly done in large concerts with careful sub array arrangement and phase control.
                              Last edited by Sydney; 10-14-2018, 08:55 AM. Reason: clarity
                              "Not a Speaker Designer - Not even on the Internet"
                              “Pride is your greatest enemy, humility is your greatest friend.”
                              "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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                              • #30
                                Bass reflex - Wikipedia

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