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2X TDA7492 and power supply

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  • 2X TDA7492 and power supply

    I've just purchased 2 of these: https://www.parts-express.com/tda749...2x50w--320-606

    I also have purchased a MiniDSP kit and the $5 power supply plug for the MiniDSP.

    Sitting on my shelf is this power supply: https://www.parts-express.com/mean-w...pply--320-3143

    Is there a way to run both amp boards off of this power supply? How would I wire it up to do so?

    If not, I do have 2 laptop bricks laying around that I can run for power, but was trying to avoid having THREE power plugs for one amp/DSP box.

    I have 2 projects that I will be prototyping crossovers for:
    A Peerless/SVS buyout aluminum 6.5" woofer paired with SB26-STAC tweeter, and the Tang Band 1337SD with SB19 tweeters. So a bookshelf monitor and a desktop monitor. Hoping to be able to hear the difference with different crossover topologies and frequencies and test and test with the MiniDSP then settle on a topology and do passive crossovers for them. Eventually I plan to do a three way with the SB19, TB 1337sd, and an undecided woofer, but that will be down the road a bit.

  • #2
    * from a quick look at this: The output voltage of the P.S. would have to be dropped down to 26V max.
    "Not a Speaker Designer - Not even on the Internet"
    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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    • #3
      I have used several of those amp boards. They sound great and are surprisingly powerful. Unfortunately they can't run on that 48 VDC supply. Their max supply voltage rating is 26 VDC. The laptop bricks (~19.5 VDC) will work great. In fact I have the exact same test setup using a MinDSP, two of those amp boards and two laptop bricks.
      Expensive caps need time to break in. More expensive caps take a long time. Cheap caps sound great right out of the box.

      Why I don't spray in first gear: http://s1138.photobucket.com/albums/...t=100_2585.mp4

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      • #4
        As others have already noted , that 48V supply will not work with the TDA7492. You can run multiple amps from one supply, but you need to make sure the amps are physically separated (2" should be enough) so that the output inductors don't couple into each other. Each amp uses its own clock, and if there is coupling you can get a lot of audible "whine" from the difference frequency of the clocks.

        ​The easy way to power the miniDSP is to use one of those switching regulator modules like this one and run the 24V to the regulator. I've got a project using one of these along with a 6-channel TDA7492 board and a 24V power supply. I'll be posting some pictures of that project in a couple of days.
        Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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        • #5
          Ok thanks all, I was hoping that it would work that the boards would each get 24V from the PS, but that's only because I don't know much at all!
          I will use the laptop bricks and Neil, I will look at your setup to see how to use those buck converter things you have linked.

          Thanks again!

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          • #6
            I power a pair of those amp boards with this supply: https://www.parts-express.com/mean-w...upply--320-314
            Electronics engineer, woofer enthusiast, and musician.
            Wogg Music

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            • #7
              can someone school me on those switching power supplies? aren't they kinda nasty? would extra capacitance help?

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              • #8
                Originally posted by neildavis View Post
                As others have already noted , that 48V supply will not work with the TDA7492. You can run multiple amps from one supply, but you need to make sure the amps are physically separated (2" should be enough) so that the output inductors don't couple into each other. Each amp uses its own clock, and if there is coupling you can get a lot of audible "whine" from the difference frequency of the clocks.

                ​The easy way to power the miniDSP is to use one of those switching regulator modules like this one and run the 24V to the regulator. I've got a project using one of these along with a 6-channel TDA7492 board and a 24V power supply. I'll be posting some pictures of that project in a couple of days.
                Neil, do you ever have an issue with noise using the buck converter with the mini?
                http://techtalk.parts-express.com/fo...khanspires-but
                http://techtalk.parts-express.com/fo...pico-neo-build
                http://techtalk.parts-express.com/fo...ensation-build

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                • #9
                  Originally posted by Kornbread View Post

                  Neil, do you ever have an issue with noise using the buck converter with the mini?
                  ​No. The miniDSP has a linear regulator on the board that drops the 5V to 3.3V for the ADAU1701, so noise from the buck converter is not a problem. But there isn't much noise, anyway. Ripple from the switching regulator is in the millivolt range and the regulator switches at 150KHz, which is easy to filter with relatively small capacitors.
                  Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                  • #10
                    Originally posted by ontariomaximus View Post
                    can someone school me on those switching power supplies? aren't they kinda nasty? would extra capacitance help?
                    ​I think the lower priced Meanwell supplies switch at just above audio range -- 20KHz to 25KHz. Not super high tech, but they are very quiet, well regulated and reliable. Extra capacitance won't make a difference unless you have components optimized for 20KHz.

                    At one time I had an amp with relays in which you could switch between a conventional transformer/bridge or a Meanwell 48V supply, and for each option you could switch in or out an additional 60,00uF. The extra capacitance didn't make any change in the Meanwell output, and even with a fairly heavy load the Meanwell supply always looked the same on a scope: nice and quiet. Definitely not "nasty".
                    Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                    • #11
                      Thanks for the link Wogg - I will have to get one of those for the next pair.

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