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Introducing: The Pit Vipers (Ooh Yeah!!!)

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  • Click image for larger version

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ID:	1489366 Baffles inner and outer faces

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    • djg
      djg commented
      Editing a comment
      CNC is hard to beat. Looks great.

  • Perhaps I missed it, but what is the actual impedance of the Pit Viper? I've been waiting for a good DIY design like this that I could build and it'd look properly paired with a vintage 70's receiver if executed correctly. However, a lot of us stay away from "modern" speakers (of this design) because we really don't want to push ~3.4ohms with a 40+ year old receiver (looking at you Wharfedale Lintons).


    We have those memories of a friend's dad who had a Cerwin-Vega or JBL setup like this that'd slam your chest with bass. We still want that...only with a bit of actual sound-staging and accuracy now.

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    • Thanks djg

      Now that I have the enclosures pretty much figured out, I need crossover help if someone would be so kind.

      I don't have any experience with passive x-over board layout. So, if someone would please diagram how the components should be arranged, that would be fantastic.

      I can do all of the x-over on one board or 3 separate boards ( one for each driver ). Doesn't matter to me - just as long as I have the proper component layout.

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      • The XOs are pretty simple. I would make 3 separate boards. I would make them big enough so that I could lay all the parts out just as they are drawn. Lots of people drill holes and push all the parts leads through and connect them on the reverse side. I keep it all "above board". Much simpler in my mind, and the board doesn't need any standoffs to clear the wiring.

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        • Click image for larger version

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          The only part that might be confusing is on the LH side of the schematic where wires cross without little dots. That means they are not connected. For each part of the XO, the top line is the plus wire, the bottom, the minus. If you are new to schematics, try placing a piece of paper over the LH side where the wires cross, and then label each pair top +, bottom -.

          All 3 + and- wires can meet at the terminal connectors

          I use 5 minute epoxy to glue the components. I remove the ty raps on the air coils for better contact. The shellac should hold them fine If you ended up with an iron core woofer coil you might want to screw that down or ty rap it.

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          • Meniscus made these for me. They have nice terminals in and out, but they aren't necessary. The tape covers component values of a proprietary design.

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            Some XOs I did with strain relief for the wires done by gluing them down.

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            Edit: the schematic for the 3 XOs above

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            Last edited by djg; 08-14-2022, 06:20 PM.

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            • And read this RE: the two coils on the midrange XO board.

              http://troelsgravesen.dk/coils.htm

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              • Thanks for these posts and pics. That does help answer alot of my questions.
                One more tho - I think I read it before, but just want clarification......
                None of these components have a positive and negative side correct ? Meaning, they can be oriented with the lead wires in either direction . No way to connect them backwards right ?

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                • djg
                  djg commented
                  Editing a comment
                  Correct. Speakers operate on AC, alternating current. The + and - on the XO diagrams are to show how the amp power is input.

                  The speaker drivers themselves DO have polarity. They must be hooked up according to the XO diagram. Note the + and - on each driver symbol. Sometimes the drivers will be specified reverse polarity, and the + and - will be switched. All 3 Pit Viper drivers are normal polarity.

                  So, amp power in has polarity, driver hookup has polarity. XO components have no polarity.

              • I'm pretty new at speaker building so hopefully someone will double-check this.
                This is the Tweeter and Woofer on a 3.5 x 5 board and the midrange on a 3.5 x 5 board.
                Probably could all be squeezed together on a 5 x 7 board easy enough but keeping track of the wires was a pain for me to figure out.
                (Note PE has nice "perforated crossover boards" in 3.5 x 5 and 5 x 7 that look nice, but some 1/8" or 1/4" hardboard or mdf works fine.)

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                • Regarding inductor placement...

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                  • I would love to see some in depth stuff on the mid range stuffing. IME the stuffing in the midrange box can have a huge impact on it's response.

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                    • Originally posted by a4eaudio View Post
                      I'm pretty new at speaker building so hopefully someone will double-check this.
                      This is the Tweeter and Woofer on a 3.5 x 5 board and the midrange on a 3.5 x 5 board.
                      Probably could all be squeezed together on a 5 x 7 board easy enough but keeping track of the wires was a pain for me to figure out.
                      (Note PE has nice "perforated crossover boards" in 3.5 x 5 and 5 x 7 that look nice, but some 1/8" or 1/4" hardboard or mdf works fine.)

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                      That's exactly the kind of thing I'm looking for !!!
                      Thank you for posting this picture.
                      Can someone please confirm its accuracy ?

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                      • marvin
                        marvin commented
                        Editing a comment
                        Nice layout drawing. I like to take one more step to keep me from getting confused. I number all the wires/junction points on the schematic, and then also the junction points where the components meet on the circuit board. Then I can verify that the number of wires soldered at each junction matches the number on the drawing. Just helps me double check my work and prevent confusion.



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                      Sorry. Double post

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                      • Originally posted by joshshetter View Post
                        I would love to see some in depth stuff on the mid range stuffing. IME the stuffing in the midrange box can have a huge impact on it's response.
                        This is a good question. I really hadn't thought about this before, but I can understand how the amount of stuffing is important to the midrange response.

                        And speaking of stuffing, if using fiberglass mat on the rear panel of the cabinet ( as Paul mentions ) should the raw fibers be covered with material of some kind to keep them from getting into the woofer ?

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                        • djg
                          djg commented
                          Editing a comment
                          There's a fire and bug proof recycled denim insulation material a lot of people use. Rock wool also. It's an entire subject of "discussion". The problem with most insulation is just getting the small amount needed. You might have some leftovers from the bath remodel.

                          I have used suspended ceiling panels of bonded fiberglass. Peel off the surface, cut with an X-Acto knife, no loose insulation. Most people who worry about loose fiberglass in the enclosure worry about fibers being ejected from ports.

                          "Egg carton" mattress topper foam also another favorite.

                          I got a box of sawtooth profile one foot square acoustic wall tiles on closeout from PE, used that up.

                          I most often use WalMart polyester pillow stuffing. I tend to go cheap. You can spend quite a bit on specialized acoustic treatments. As a Psych major in college, I tend to relate personality type to a person's approach to speaker building in general. That's just me.

                          If you want your speakers to sound like Paul's, build them like Paul's. Unless of course if you're going to worry about his insulation specs.

                        • djg
                          djg commented
                          Editing a comment
                          I have a theory that old school hairspray would work on loose fiberglass batts to immobilize the deadly fibers. Just a theory.

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