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  • First Build

    Alrighty, I'm scrapping the contents of this thread pretty much. I'm going to start over after some more reading. Thanks for those who helped!

    -- I'm too lazy to keep updating the first post, so keep an eye out for new info in my later posts. --
    -- X-over and box info can be found in my later posts, look for the ones with attached images. --

    Alright, I know I'm going to catch flack for doing a fully custom build for my first project, but I think with a little support from the PE community I can do it.
    I've got good experience in woodworking, good experience in basic electronics, and a fair understanding of general speaker knowledge, and the time and motivation to execute.
    I'm looking to built a center channel speaker, which I've found is a terrible first project, but that's what I'm in need of.
    Here's where I am so far:
    -Mids
    -I have 2 Tang Band W3-881SI 3"
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-113
    that I want to use as higher mids, say 1.5k-8k hz left over from a speaker repair I did.
    -Mid Woofer
    -I'm planning on using the Dayton Audio DA115-8 4" Aluminum cone woofer
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-328
    for around 150-1.5k hz. I haven't purchased this yet but for my budget + requirements I think this would work well. I may be swayed on this speaker given some coaxing.
    -Tweeter
    -For my tweeter I'm looking at the Vifa BC25SC06-04 1" Dome Tweeter,
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1028
    which I haven't picked up yet either, crossed over starting around 5k and up. I can be swayed on this one too.

    I'm using BassBox6 and X-over 3 pro for the simulation, sadly I don't have any testing equiptment yet so I'm going to have to trust the sims pretty much.

    I'll be updating this post here soon with where I am so far, screenshots, and questions.

    Feel free to comment on my speaker selection with any knowledge you may have on those selected and/or recommendations.

    As far as the arrangement, I'm thinking Mid - Woofer/Tweeter - Mid, with the woofer/tweeter arranged vertically and a mid on either side.

    Updates coming soon.


    A little clarification on what I'm trying to do:
    Right now, my system consists of the following:
    -A Bose 501 Series 4 pair for L/R, which consist of a forward + backward 3" and each has a 10" sub
    -A 12" Polk Audio PSW505, powered subwoofer.

    My goal with this center channel is essentially to make something that will have a sound that is powerful enough to stand with the Bose L/R speakers, because what I have right now is very weak. I'd like a fairly strong mid-bass / mid, especially between 200-2000, because that is where my system is weakest right now, but I also need a little voice clarity for HT use. Since I allready had $20 invested in the Tang Band 3" mids I wanted to use them in the arrangement, but they aren't particularly strong from 200-1000, which is why I went for the 4".
    Last edited by Adam_G; 01-24-2012, 09:32 AM.

  • #2
    Re: First Build

    Originally posted by Adam_G View Post
    Alright, I know I'm going to catch flack for doing a fully custom build for my first project, but I think with a little support from the PE community I can do it.
    I've got good experience in woodworking, good experience in basic electronics, and a fair understanding of general speaker knowledge, and the time and motivation to execute.
    I'm looking to built a center channel speaker, which I've found is a terrible first project, but that's what I'm in need of.
    Here's where I am so far:
    -Mids
    -I have 2 Tang Band W3-881SI 3"
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-113
    that I want to use as higher mids, say 1.5k-8k hz left over from a speaker repair I did.
    -Mid Woofer
    -I'm planning on using the Dayton Audio DA115-8 4" Aluminum cone woofer
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-328
    for around 150-1.5k hz. I haven't purchased this yet but for my budget + requirements I think this would work well. I may be swayed on this speaker given some coaxing.
    -Tweeter
    -For my tweeter I'm looking at the Vifa BC25SC06-04 1" Dome Tweeter,
    HTML Code:
    http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1028
    which I haven't picked up yet either, crossed over starting around 5k and up. I can be swayed on this one too.

    I'm using BassBox6 and X-over 3 pro for the simulation, sadly I don't have any testing equiptment yet so I'm going to have to trust the sims pretty much.

    I'll be updating this post here soon with where I am so far, screenshots, and questions.

    Feel free to comment on my speaker selection with any knowledge you may have on those selected and/or recommendations.

    As far as the arrangement, I'm thinking Mid - Woofer/Tweeter - Mid, with the woofer/tweeter arranged vertically and a mid on either side.

    Updates coming soon.
    Bad idea.

    Having 2 mids flanking on the outsides of a tweeter/woofer is exactly what you want to avoid in a horizontal CC. You'll have horrid comb filtering from 1.9k to 8k. Every other person on the couch will be ab le to hear that range, and every OTHER person will be sitting in a null. Bad idea.

    Chris

    Comment


    • #3
      Re: First Build

      @Chris:
      What do you recommend then? Anything you think will be good with 2 mids / a mid woofer? If I angle the two mids out slightly, say 5-15 degrees, do you think it would work better?
      Also: Do you have any resources on comb filtering that could help me understand it better? I didn't see any in the bible so far.

      Comment


      • #4
        Re: First Build

        With the way you want to build your first speaker a MidWooferTweeterMid arrangement breaks all the ROT of speaker design.
        A simple TM with the woofer and the tweeter you linked would work better and cheaper, and have better chances of sounding decent especially as a center channel.
        No need for complicated arrangements especially for your first build.

        but first you should probably clarify your goals.

        Comment


        • #5
          Re: First Build

          Originally posted by Adam_G View Post
          @Chris:
          What do you recommend then? Anything you think will be good with 2 mids / a mid woofer? If I angle the two mids out slightly, say 5-15 degrees, do you think it would work better?
          Also: Do you have any resources on comb filtering that could help me understand it better? I didn't see any in the bible so far.
          Sound travels at 13500 inches per second.
          (I'm making this up, but you'll get the idea.)

          A 100 Hz tone, projecting outward /\/\/\/\/\/\/\/\/\/\ will have 100 crests and 100 troughs in one second of time (which, in distance, will be 13500 inches).

          So, one wavelength is 13500/100=135 inches, or, about 11 ft.
          If you set up 2 speakers, next to each other, 11 ft from you, and play a 100Hz test tone, they will "sum" and be louder than a single one would.

          If, however, you put one 5-1/2' from you, and another one 5-1/2' directly behind it, and play that 100Hz tone, at your listening position, the troughs from one driver will fall directly on top of the crests from the other, cancelling each other out. This won't happen only at 100 Hz, but will also happen at different fractions and multiples of this freq. This is the same as the "lost bass effect" when you've got 2 stereo speakers hooked up to an amp out of phase with each other. At other freqs (in between the nulls), the two waveforms will sum, so you end up with positions that are very quiet and some that are quite loud, depending on the freq, scattered all over the listening area.

          This situation is minimized by stacking multiple drivers vertically, and adhering to the C-C spacing rule of thumb regarding your crossover frequency.

          The worst situation is to have 2 drivers lined up horizontally (like the "mids" in your CC) and then cross them (cut them off) too high. In your example, your layout would probably be OK if the C-C distance between your mids was 7", AND you kept them from playing above 1900 Hz, not at all what you're proposing.

          chris

          Comment


          • #6
            Re: First Build

            @Chris
            Thank's for the breakdown on the comb filtering.

            A little clarification on what I'm trying to do:
            Right now, my system consists of the following:
            -A Bose 501 Series 4 pair for L/R, which consist of a forward + backward 3" and each has a 10" sub
            -A 12" Polk Audio PSW505, powered subwoofer.

            My goal with this center channel is essentially to make something that will have a sound that is powerful enough to stand with the Bose L/R speakers, because what I have right now is very weak. I'd like a fairly strong mid-bass / mid, especially between 200-2000, because that is where my system is weakest right now, but I also need a little voice clarity for HT use. Since I allready had $20 invested in the Tang Band 3" mids I wanted to use them in the arrangement, but they aren't particularly strong from 200-1000, which is why I went for the 4".



            If I were to drop 1 of the TB3" mids from the setup, and make a 3-way center channel, possibly vertically arranged, would that be a better way to go about it?

            Comment


            • #7
              Re: First Build

              Something like this would work best, with all the drivers as close as you can possibly get them.



              Click image for larger version

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              Comment


              • #8
                Re: First Build

                Originally posted by Adam_G View Post
                @Chris:
                What do you recommend then? Anything you think will be good with 2 mids / a mid woofer? If I angle the two mids out slightly, say 5-15 degrees, do you think it would work better?
                Also: Do you have any resources on comb filtering that could help me understand it better? I didn't see any in the bible so far.
                Here is a site that helped me understand driver interference and diffraction. Especially the ripple tank applet.
                http://www.falstad.com/mathphysics.html

                Comment


                • #9
                  Re: First Build

                  @ Greywarden Note taken, I'll definitely consider.

                  @Morris That website is pretty awesome. I'll have to play around with it a little.

                  Thank you both!

                  Comment


                  • #10
                    Re: First Build

                    For a first build, I would recommend building a known design. Just off the top on my head I would think that an Overnight Sensation MTM would fit the bill, and you can get a flat-pack cabinet for cheap or I think they have all the parts together as a kit too.
                    Very well received.

                    my 2 cents.

                    Comment


                    • #11
                      Re: First Build

                      Alright, I've changed the tweeter because I didn't like the 4ohm load or the overall curve of the Vifa after playing with it, so I'm going to go with the Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter:
                      HTML Code:
                      http://www.parts-express.com/pe/showdetl.cfm?Partnumber=275-070
                      I also dropped one of the two TB3" mids, so it will be a 3-way system. I'm going to put a bunch of pictures up here in a second.

                      Comment


                      • #12
                        Re: First Build

                        Alright, first pictures are going to be my current X-over sim. I did this using X-over 3, and it incorporates the response curves from BassBox6 on the woofer and mid. If anyone has recommendations on anything here please let me know.

                        I'd like to smooth out the response on the tweeter a little bit if possible, but I don't quite know how to.

                        Here's the goodies.
                        First image is the x-over layout and response curve, second picture is the L-pad resistance values.
                        Attached Files

                        Comment


                        • #13
                          Re: First Build

                          Here's my box values and sim responses from bassbox for the woofer and mid. These responses were imported into the x-over to get the x-over values.
                          The woofer is in Red, mid is in Orange.
                          Attached Files

                          Comment


                          • #14
                            Re: First Build

                            Originally posted by Adam_G View Post
                            Alright, first pictures are going to be my current X-over sim. I did this using X-over 3, and it incorporates the response curves from BassBox6 on the woofer and mid. If anyone has recommendations on anything here please let me know.

                            I'd like to smooth out the response on the tweeter a little bit if possible, but I don't quite know how to.

                            Here's the goodies.
                            First image is the x-over layout and response curve, second picture is the L-pad resistance values.
                            If you are set on doing this on your own and not building a "proven" design, I still suggest going the 2-way route. I do not see the advantage of going 3-way with a 4" woofer for a bottom. The 4" woofer can easily mate with your tweeter choice. You can even parallel 2 woofers and go the MTM route to increase sensitivity but that would probably become a 4 ohm design. But this is IMO.
                            This is still DIY and you are still the one to choose...just throwing out ideas to increase the likelihood that your project will sound decent especially since this is your first attempt.

                            Comment


                            • #15
                              Re: First Build

                              Originally posted by Adam_G View Post
                              Alright, first pictures are going to be my current X-over sim. I did this using X-over 3, and it incorporates the response curves from BassBox6 on the woofer and mid. If anyone has recommendations on anything here please let me know.

                              I'd like to smooth out the response on the tweeter a little bit if possible, but I don't quite know how to.

                              Here's the goodies.
                              First image is the x-over layout and response curve, second picture is the L-pad resistance values.

                              First you're going to want to put a high pass on the tweeter, that would be much more important that trying to smooth out its response up high. I don't want to be a downer but this whole project probably needs to be approached from a diffferent angle. If you're going to go through the trouble of tackling a three way not much sense in using those two mids

                              Comment

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