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DIY Rack Mountable Turn On Box For Pro Audio Gear

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  • DIY Rack Mountable Turn On Box For Pro Audio Gear

    I have some pro audio gear that I would like to be able to control with my home audio pre-amp 12v trigger. There are some options on the market that do this, such as the Xantec unit and a couple of power strips but I wanted something that was going to be a little bit more heavy duty and that would mount nicely in an equipment rack.

    I actually set out to build two boxes, one for my home theater that will control a DBX Venu360 I am using for subwoofer processing, and the other to control two Crown XLS amplifiers for a garage system I will eventual get to. I have previously added some relays to three subwoofer amplifiers (SpeakerPower sp2-8000s) that did not come with triggers, but I was able to easily add those inside the box which was nice. I was not able to obviously find a way to do this with this gear so a separate box was necessary.

    Here is the final result:



    And here is the unit in action

    https://vimeo.com/442917939

    The second box just has one outlet but I could easily add a second one in the future

    Here it is controlling the DBX (note the wiring was not cleaned up yet)

    https://vimeo.com/442602379

  • #2
    The process is pretty straight forward. First, the gear:

    3 Rack unit project box
    Omron 40a solid state relay. This is expensive, I bought a previous version on clearance for $40. Does it make a difference getting an expensive relay for something like this? I’m not sure.
    Heat sink. I bought this for really cheap used on eBay, like $5.
    12v power supply. This is not the exact one I used, it’s not available anymore. Any cheap power supply will work. I think the one I got is 8a output which is still overkill, I needed it to power two fans.
    Fan temperature control board Quiet 92mm computer fans
    Panel bonding epoxy adhesive
    Machine screws, various wire, weld nuts, powercon panel mounts, and 3.5mm panel mount plugs. Let me know if you need specifics on any of these.
    -Trevor

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    • #3
      The gear: Project box Basic layout My preferred method for attaching stuff like this to a project box is to attach the item to weld nuts and then use a panel bonding adhesive to just stick it to the metal. I use this stuff as it is very strong, it is used in place of welding auto body panels together and is actually stronger than welding for sheet metal. Plus, it makes it easy to get the attachment points perfect. I used some hole saws to drill into the back panel. The holes aren’t perfect but they will work. I also used the panel bonding adhesive to just glue the fan to the pa el directly. What if that fan needs replaced? Then the back panel would also need replaced. I just didn’t feel like drilling holes for the fans but could have easily been done. -Trevor

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      • #4
        I used the panel bonding adhesive to also adhere the thermister to the relay heat sink. Then it’s just a matter of wiring everything up. Positive and negative 12v triggers are wired to the relay input side. Hot lead 120v ac is wired from the 120v inlet to one contact of the relay. The other contact is wired to the switched outlets. I also grabbed 120v from the relay to the dc power supply. The 12v line coming off of the power supply is wired to the fan controller along with the 12v trigger outs. I used some adhesive zip tie anchors to strap down the wires And then some labels on the back panels. -Trevor

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        • #5
          You should be using a PowerCon for the power inlet, not an 8-pole SpeakOn. They are meant for different purposes.

          Later,
          Wolf
          "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
          "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
          "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
          "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

          *InDIYana event website*

          Photobucket pages:
          http://photobucket.com/Wolf-Speakers_and_more

          My blog/writeups/thoughts here at PE:
          http://techtalk.parts-express.com/blog.php?u=4102

          Comment


          • #6
            Originally posted by Wolf View Post
            You should be using a PowerCon for the power inlet, not an 8-pole SpeakOn. They are meant for different purposes.

            Later,
            Wolf
            All of the connectors are powercons...

            The chassis connectors for the outlets: https://www.neutrik.com/en/product/nac3fpx-st-top

            And corresponding plug: https://www.neutrik.com/en/product/nac3mx-w-top

            Chassis mount for the inlet: https://www.neutrik.com/en/product/nac3mp-hc

            And the corresponding plug: https://www.neutrik.com/en/product/nac3fc-hc


            No speakons here.

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            • #7
              I stand corrected! I've apparently not seen that particular connector. Why wouldn't a 20A blue-faced unit work? You only need 15-20A current capacity for 120V supply. 32A seems a bit overkill, as it's way more than a standard Edison can route.

              Later,
              Wolf
              "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
              "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
              "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
              "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

              *InDIYana event website*

              Photobucket pages:
              http://photobucket.com/Wolf-Speakers_and_more

              My blog/writeups/thoughts here at PE:
              http://techtalk.parts-express.com/blog.php?u=4102

              Comment


              • #8
                Originally posted by Wolf View Post
                I stand corrected! I've apparently not seen that particular connector. Why wouldn't a 20A blue-faced unit work? You only need 15-20A current capacity for 120V supply. 32A seems a bit overkill, as it's way more than a standard Edison can route.

                Later,
                Wolf
                Oh ya, its totally overkill and unnecessary. I chose it because I already had a couple power cords made with this connector on them. These connectors are used by SpeakerPower amplifiers so I just needed to purchase the chassis connector. The blue one definitely would have worked though, no doubt about it.

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                • #9
                  I ended up having to rebuild this box. We will call this v2.0. I was having intermittent problems with the solid state relay turning the power supply on and off intermittently with no trigger input present. I double checked all the circuits and even switched out the relay with no change. It turns out with solid state relays there is always some degree of current leakage through the relay. This was enough to flash the power supply on and off causing the issue. I could have tried wiring a resistor in parallel with the relay but just decided it would be easier to get some mechanical relays instead. It also simplified the box, no longer needing fans, it is now smaller at 2RUs instead of 3RUs. I used a couple of these relays: https://www.mouser.com/ProductDetail...rrencycode=USD

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