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COUGAR II - boombox build

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  • COUGAR II - boombox build

    I've been commissioned to build a boombox similar to my original COUGAR but at a lower price point. Enter COUGAR II.

    The design will be very similar -- double MTMs with a sub in the middle powered by a car head unit and 4-channel auto amp. I won't be doing a slanted front baffle or flush mounting any drivers.

    Head unit - Pioneer DEH-P8400BH. Great unit with three sets of 4v RCA outs, Pandora control, CD, HD radio, Bluetooth, yada yada.

    AMP - Precision Power PPI P900.4. Class-D fullrange amp has bandpass XO capability which I will be utilizing (25hz high pass on both the MTM and SUB and perhaps a 150Hz low pass on the sub).

    The MTMs are 5.5" Seas Prestige L15RLY/P + Tang Band 25-302SH. Tuned to 47Hz via slot port in 0.40ft^3. F3 = 68Hz. Modeled with 100w it will hit 108db without excursion problems. I will also be enabling 25Hz high pass filters from the amp which will help to keep the drivers out of danger territory at frequencies below Fs. The eventual owner is a DJ, so I suspect this box will be driven very hard at times. Better safe than sorry.

    After bracing and whatnot, there's just over 2ft^3 of subwoofer volume for the JBL GTO804. The subwoofer compartment will be tuned to 30Hz via the PE buyout 11" flared port. F3 = 28Hz. Channel 3&4 of the amp will be bridged for the sub. Modeled at 200w it should output 108db with no worries.

    Since I'm not doing a slanted baffle, this is going to resemble a large monkey coffin.



    Here are the sims - MTM





    SUB





    I'm doing a second order XO at approx 2.9Khz. 9 elements in total including a notch on the woofer and L-pad on the tweeter.

    Last edited by bkeane1259; 11-26-2013, 01:05 AM.
    Bryan K.

    Midwest Audio Club

    Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

  • #2
    Re: COUGAR II - boombox build

    I'm not going to go into huge detail on the build out and bore everyone with a million pictures. The cabinet is pretty straight forward - rectangular box using 3/4" ply and 3/4" internal panels and braces. I also used some MDF for internal bracing.





    The slot ports are 11" long and the equivalent of a 2.3125" round port (5.75" x 0.75").



    A little bit of flush-trimming:



    Front of enclosure:



    Rear of enclosure:



    Using the PE 22" x 15" preformed metal grill.



    Getting ready to route out the driver holes:





    I drilled a bunch of holes in the slot port opening which I will later flush trim to the internal portion of the slot port.



    Radio mount:



    Had to notch out the subwoofer cutout so the terminals could pass thru. Wasn't expecting that.



    Finally got a REAL garage heater. No more dinky ceramic thinggy. This propane dual head jobber is amazing. I don't know why I didn't buck up for one of these years ago.



    Chamfered midbass cutouts:



    Cutout for subwoofer port and some more bracing. I did a T brace in the back which will also hold the braces for the threaded inserts so the rear panel can be removable. I cut a few 45-degree braces to tie some of the panels together. The cabinet is pretty solid.





    Routed out some rectangular openings for the Penn-Elcom spring loaded handles. The handle mounts only require like 6mm of mounting depth, so I did not cut all the way thru the side panels.




    Bryan K.

    Midwest Audio Club

    Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

    Comment


    • #3
      Re: COUGAR II - boombox build

      I might have to experiment with the subwoofer compartment stuffing a bit but I am going to use this poly-fill from an old pillow, including the mesh casing. It's about 2.5lbs of stuffing which I will jam behind the main brace and above the monster port tube.



      In the MTMs I used BH5, Ultratouch Denim from HD, and some PE Sonic Barrier. Many thanks to CraigK for tossing the BH5 my way at Iowa. You da man.



      I clamped down the front baffle and flush trimmed the MTM slot port openings.



      The Tang Band tweeter is a major PITA in so far as the cutout is concerned and I'm not even flush mounting it. It will not fit in a circular hole, so I notched out the corners and the terminals with a small flush trim bit plunged so that the bearing doesn't hit anything. I hate doing freehand router work, but it wasn't that bad at all actually.



      The tweeter flange is super thin. It almost looks flush-mounted, but nah...it ain't. The truncated faceplate makes it easy to squeeze all the drivers under the preformed metal grill. All the drivers have to fit within a 22" x 15" space.



      That's all for now. I'll post more progress in a couple days.
      Bryan K.

      Midwest Audio Club

      Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

      Comment


      • #4
        Re: COUGAR II - boombox build

        super sick. a lot of work for a boom box, it should be freaking spectacular when done. great post!

        Comment


        • #5
          Re: COUGAR II - boombox build

          Originally posted by kanemack View Post
          super sick. a lot of work for a boom box, it should be freaking spectacular when done. great post!
          Thanks. Maybe I shouldn't call it a boombox, because there's no effing way you'd be able to balance this thing on your shoulder during a casual stroll in the park. My original Cougar boombox weighs 53lbs without the battery. A 35AH battery weighs about 20lbs alone. 78lbs on your shoulder=pain. These projects are great for tailgate and/or outdoor parties though.
          Bryan K.

          Midwest Audio Club

          Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

          Comment


          • #6
            Re: COUGAR II - boombox build

            Damn! That is going to be great! What are you going to be using to power this (what battery and charging system are you going to use)? Is the battery internal or external?
            Statements: "They usually kill the desire to build anything else."

            Comment


            • #7
              Re: COUGAR II - boombox build

              Originally posted by john trials View Post
              Damn! That is going to be great! What are you going to be using to power this (what battery and charging system are you going to use)? Is the battery internal or external?
              External battery. I've tried 18AH, 20AH deep cycle and 35AH SLA batteries and I've found the 35AH one to be the best for long play time obviously, but the tradeoff is definitely weight. A 20AH battery weighs about 12lbs. The 35AH battery weighs 22lbs.

              For this one, it will be powered with an external 35AH battery, which will allow at least 6 hours of high volume listening. As you can see from the pictures, there's plenty of internal room for the battery and the volume displacement won't shift the box tuning dramatically, so that is an option for the new owner if he so chooses. For myself, I like to keep the battery separate.

              EDIT: I like the battery tender chargers. When my boombox is hooked up in the garage, I keep the charger hooked up to the battery and the battery hooked up to the boombox all the time.
              Bryan K.

              Midwest Audio Club

              Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

              Comment


              • #8
                Re: COUGAR II - boombox build

                Bryan, thanks for the info (and for posting photos). That boombox is going to be so cool.
                Statements: "They usually kill the desire to build anything else."

                Comment


                • #9
                  Re: COUGAR II - boombox build

                  Awesome!

                  I have that same straight-edge, by the way. Very handy tool.
                  Don't listen to me - I have not sold any $150,000 speakers.

                  Comment


                  • #10
                    Re: COUGAR II - boombox build

                    VERY cool project.....of course, living in Florida I have no clue what those round glowing things on top of the propane tank are for.
                    Currently resigned to living in balmy Zephyrhills, FL with the snow birds.
                    Howard H

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                    • #11
                      Re: COUGAR II - boombox build

                      Very nice work. I am excited about seeing it finished!

                      Comment


                      • #12
                        Re: COUGAR II - boombox build

                        Got a little more done on the boombox over the last couple days. My motivation sux.

                        Prepped the buyout port for mounting. I don’t trust the glue joint in these ports (yes, it’s a two-piece port, glued in the middle), so I always put a new bead of Gorilla glue over the existing glue joint and then wrap the port with some butyl-based damping material. This makes the plastic port a lot more dead.



                        Glued and screwed the front baffle.



                        Did a small roundover on all the edges except for the front baffle where a framed 22"x15" PE formed metal grill will go.



                        As always, I got a couple tearouts. Sometimes plywood really makes my blood boil. Or maybe it’s my crappy tools. Who knows?



                        I’ve learned to live with and quickly fix plywood tearouts (and voids) with a quick application of Bondo. I build up the damaged area and then redo the roundover with the router. That shapes most of the Bondo for me. Then I sand the rest of the Bondo that the router missed. I do the same for voids that appear when I flush trim. Just fill the voids with Bondo and do another pass with the flush trim bit. Make sure you have a smooth surface where the router bit bearing rides!!




                        I used a fair amount of screws for this project mainly because I do not have enough extra-large clamps to fit around this beast. Maybe Santa will be nice to me this year….hint hint. So anyway, there are several Bondo touchups to be sanded tomorrow. Then it’s Duratex time.

                        Bryan K.

                        Midwest Audio Club

                        Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

                        Comment


                        • #13
                          Re: COUGAR II - boombox build

                          That's a big-*** box!

                          I'm curious about the cutout required for the terminals of the JBL sub though. Seems weird. The terminals couldn't pass through by angling the driver a bit first when inserting it?
                          Brian Steele
                          www.diysubwoofers.org

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                          • #14
                            Re: COUGAR II - boombox build

                            Originally posted by Brian Steele View Post
                            That's a big-*** box!

                            I'm curious about the cutout required for the terminals of the JBL sub though. Seems weird. The terminals couldn't pass through by angling the driver a bit first when inserting it?
                            No not on this driver. I tried, believe me. The basket is weird. One the larger GTO-series drivers this isn't an issue at all. This is the 8" driver and it is an issue...well for me anyway.

                            If I made the driver cutout larger it would have squeezed thru, but I wanted more meat for the mounting screws, so I made the cutout very tight. Wasn't expecting to have to notch out a spot for the silly terminals. I also tried to remove the caps from the terminals, but they do not come all the way off. Multiple fails on my part I suppose, but in the end it will be fine.

                            Click image for larger version

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                            Bryan K.

                            Midwest Audio Club

                            Speedster | Sub Attachť | The Wildeman | Sean's NLA Towers | CO‹GAR, COUGAR II and CO‹GAR JR | Triton | Lithium | J-Boom | Trym MLTL | Docere MLTL

                            Comment


                            • #15
                              Re: COUGAR II - boombox build

                              "Cougar boom box"... is that an appropriate topic for this forum?

                              Nice build!!
                              "We are just statistics, born to consume resources."
                              ~Horace~, 65-8 BC

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