PE 300-794 plate amp, enclosure question

Discussion in 'Archived Threads 2001-2004' started by Sebastian, Nov 27, 2002.

  1. Sebastian

    Sebastian Second Unit

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    I will be building a seperate enclosure for the PE 300-794 amp and I wan to make the smallest foot print.
    How much clearance do you think the transformer needs from the bottom of the box.
    Do you think 1/4 is to small.
    Basically I would like to make the box 3 1/2" deep since the amp is 3 1/4" deep.
    What do you guys think? any problems with 1/4 clearance?

    Edit: I will be using 1/2" MDF
     
  2. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    It sounds like you're planning to mount this amp horizontally. And it also sounds like you're not going to have much clearance, hence the need to make the box very shallow.

    First consider that these plate amps use convective cooling. They're designed to be mounted vertically so that they can draw cool air into the heat sink from below. As the heatsink heats the air it will rise up and out the top. The motion of the rising hot air will draw in more cool air from below.

    If you're planning to mount it horizontally it won't cool as well. If, in addition, you don't have much clearance then there won't be much access to fresh air. These amps tend to run hotter than most and there are occaisional complaints of over-heating. In a case like this I'd definitely want an external fan to blow fresh air across the heat sink.
     
  3. Sebastian

    Sebastian Second Unit

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    Actually the amp box will be far away from the sub. I could make the enclosure as big as I want. However I want to make the amp box as small as possible.
    So I take it that the transformer on the back of the plate amp gets very hot?

    As for access to fresh air the amp will be on top of my entertainment center so the heat sinks will be open to fresh air.
     
  4. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    No, the transformer doesn't get very hot. But it does stay warm any time the amp is plugged into the wall. On or off doesn't seem to matter. The heat sink can get hot under hard use and warm under medium-to-hard use. The heat sink draws heat away from the output devices, not the transformer.
     
  5. Sebastian

    Sebastian Second Unit

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    Ryan or anyone else,

    The transformer on the back of the plate amp sticks out quite bit compared to the other components as you probably already know.
    Anyway, what do you think the minimum clearance for the transformer is from the MDF side walls.
    I made the box 3-3/4 deep to give the transformer a 1/2" breathing room from the back panel.
    When I did the sides, I was not thinking and I made it the exact size of the amp so the side wall will be right next to transformer.
    The amp box is 10-7/16 by 10-7/16 (1/2" thick)
    Is that to close?
    If so I can just cut a notch out where the transformer would be and glue another side wall to it.
    What do you think?
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    As far as minimum clearance ... your guess is as good as mine. I think I went with 1 inch.

    Yeah, I'd probably go with the notch idea. If you can, make the notch bigger than the side of the transformer so the air can easily escape from the "air pocket" you're creating.
     
  7. Sebastian

    Sebastian Second Unit

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    FYI,
    I recived a reply from PE tech support with my qeustions,
    here is his reply:
    Hello!

    The proximity of the power transformer to the wall of the cabinet is not critical. The transformer can get warm is the amplifier is run hard, but it will not produce enough heat to create any problems as a result of being very near a cabinet wall. Most heat is generated in the collector of the output transistors, and they are heat-sinked to the outside of the amplifier.

    Thanks! Let me know your further questions.

    Regards,

    Eric A. Chanlder
    Technical Support
     

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