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My GR Research Sealed Servo Sub

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  • My GR Research Sealed Servo Sub

    I meant to post this a while ago but finally found the time for it.

    So back in early May I decide to pull the trigger on building one of Danny's subs. I bought the SW-12-04 and the 370PEQ amp. The amp was on back order which delayed me another couple of weeks. It was fine because I was too broke to do anything anyway.

    Eventually I got the amp and then I bought 2 and a quarter sheets of mdf at Home Depot for the bargain price of only $60!

    Ok, at this point I should probably disclose my skills as a woodworker.

    I don't have any.:no clue: I've built and rebuild all kinds of vacuum tube preamps and amps but never an actual speaker.

    While Danny has a very nice, well-braced box design available for this project I opted to do something completely different. Seeing as I suck at cutting wood with straight lines I decided to make the enclosure a cylinder.

    In order to make a cylinder out of mdf you need to cut rings and stack them so thats what I did. Since I essentially had no idea what I was doing I started cutting my first ring with my little Rotozip. And here is the result of that.

    As you can see it looks pretty nasty. I busted a couple of the 1/8" bits in the process. I had to concede that I really needed a router for the job.
    I also needed a proper jig for cutting the rings. There went another $180!

    This worked much better. I had the big sheets cut in half at the store to make moving them easier. Each 4'x4' section yielded 9 rings. I got a few rings cut and then tragedy struck. Let me pause a minute to explain another one of my knuckleheaded moves.

    As you can see in the above picture I don't have a workshop to do all of this in. I live in a small apartment which has a nice courtyard in the back. I also have this little wine rack which I never use for holding wine and more often use as a side table. This day it was my workbench. And not a very stable one at that. It was only a matter of time before the weight of the mdf became too much for that little table to manage.

    Sure enough, at one point I lost control of everything and the router crashed to the ground landing right on the edge of the circle jig. It cracked at one of the mounting bolt points but stayed on. I decided to simplify things for the time being and just cut the initial discs. Several pieces later the router slipped from my sawdust covered hands and landed in a way that snapped that jig right off for good.:eek:

    So that and the weather delayed me for several days. Eventually I was able to make a copy of the circle jig using some 1/4" mdf I had.

    This allowed me to tear up another sheet of mdf and this time I used a better table to keep everything from falling apart. Once again the weather kicked in to delay me but not for long.

    With the help of my friend, Cedric, I decided to simplify things further with the remaining sheets of mdf that I had left. I picked up a cheap circular saw and after measuring everything out proceeded to reduce them down to more manageable sizes.

    And once again with Cedric's help I was able to finish cutting the rest of the rings out.

    What was truly mind-boggling was the amount of sawdust this created.
    Try 40 pounds of it!

    The next step was to glue the rings together. I picked up a couple of bottles of some Gorilla wood glue and went at it. I did them in sections, let them dry, then glued the sections together.

    After several days of this I finally got it all together! With some polyfill stuffing and wiring up the cable connector it was finally finished!

    Now you might think that it looks ugly in its unfinished state. My original intention was to paint it with some fancy black pearl paint. Surprisingly the concensus of my friends and even my girlfriend was to simply sand it down and leave it bare. I still might slap some urethane on it to seal it. We'll see.

    I had some hum when I first plugged it all in but with a cheater plug that was quickly eliminated. At first I couldn't even get a signal for some odd reason so I thought I'd simplify things by moving the sub over to one of my 2-channel rigs. This worked but I was barely hearing anything. I read that there might be some need of breaking in the woofer so I let it play for a while.

    Gradually it got better and when I felt it was ready for the main rig I moved it back out to the living room. Still no dang signal to the sub.:thinking: Eventually I figured out I had the cable between the receiver and the sub in the wrong jack. Once I plugged it in the right jack everything was working fine.

    As for how it sounds.:jiggy: Holy friggen crap this thing is awesome! Once I got it all dialed in properly it does this weird disappearing act. Bass is there when playing music but it's so clean and tight and weighty that you just might think there's something wrong. There's just no boom. Just accurate bass. Since most music doesn't go real low this wasn't too surprising.

    Then I throw in our favorite shoot out scene from Open Range and look out! While not quite gut slamming it definitely whacks the air in the room but good! And when playing the entering atmosphere scene (track 3 I think) of Serenity it rumbles and shakes the whole friggen apartment just like a proper sub should! No boom unless there's supposed to be boom. Occasionally this beast scares me!

    I also have to throw out some props to Mark's x-sls encores. I set the receiver's crossover to cut them off at 80Hz and with the sub in the mix these babies have been singing like never before! The soundstage is huge and has expanded in depth as well as width. I've been throwing in all kinds of music lately because everything just plain sounds fantastic! I'm also considering ninja upgrades in the future.

    Anyway, this sub was my first attempt at building an actual speaker and while the journey was a hairy adventure, the finished product has brought more joy in my house than I would've imagined. If you have the nerve to DIY, just do it!

  • #2
    I love it! Great story too. :D

    Except for the "I got a few rings cut and then tragedy struck" part. Considering we're discussing novice plus router here, I was expecting a bloody trip to the emergency room. :eek: Not nice to scare us like that! :p :)
    "The evil that men do lives after them; The good is oft interred with their bones."


    • #3
      +1. I figured you lost a finger. Nice job, though. From the pics I agree with the folks that said to leave it natural. It looks cool like that.


      • #4
        Nice build. What did you mount the amp in?


        • #5
          Very cool. How about wrapping it in a cloth?
          PhenomeNhan Audio Video

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          • #6
            I'd agree, some nice cloth would work well for you. Great job!


            • #7
              Very nice!

              Btw, is your x-voce a special finish? Aside from the cherry the black top looks very glossy. The sls's look great too!


              • #8
                Originally posted by SnowmaNick
                Nice build. What did you mount the amp in?
                Remember how I said I can't cut straight lines? My plan was to build something similar to this:

                However it's been slow going and right now the amp is hiding behind the sub sans box.

                Originally posted by Interspy24
                Very nice!

                Btw, is your x-voce a special finish? Aside from the cherry the black top looks very glossy. The sls's look great too!
                I dusted before snapping the pic. Funny thing is both the voce and sls' were bought as B-stock.:biglaugh:

                As for wrapping cloth around it, well, that's certainly possible. But if the gf is happy the way they are then that saves me a whole lot of trouble. I don't care that they're bare. Although the glue spots all over are a bit messy and unattractive. I don't know. Maybe I'll paint it afterall. We'll see.