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Texas Instruments Active Crossover

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  • Texas Instruments Active Crossover

    I ran across this write up by Texas Instruments on an active two cross over using a Dayton RS 180-8 woofer and RS 28F-4 tweeter. A PCB has been designed although I have no idea if the gerber art files are available so printed circuit boards could be made. Anyway, I thought that it might be interesting to members.

  • #2
    I'm interested... but your link is to the home page :(
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music

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    • #3
      I had found this 2 Channel LR4 active XO some time ago. The "4 channel" in the description refers to HP and LP on L & R: 4 outputs from stereo input.

      IIRC correctly, the design and original source was from Russia. No telling if China now sources the same board. But my discussion with the original mfg indicated he would populate the the board for any XO point. It is designed as two cascaded 2nd order filters based on the Sallen-Key topology. And if you only wanted an LR2 filter, the second set of active XOs can be pass through.

      In reality you can design any Fc an Q you need by picking appropriate values for the two caps in a Sallen-Key topology. The standard equations for a 2nd order filter are quite simple to implement. I have not delved into the equations for 4-order but they do exsting.

      As an example ... I developed an 2nd order XO for a 2-way design in WinPCD. Based on the passive components chosen in WinPCD, I was able to find the Fc and Q of the filter using the XO section of Response Modeler. Once I had the Fc and Q, I converted that to the caps needed in the active filter (using the values of the existing resistors in the active filter). A couple of bucks for box poly caps that fit the board and I was good to go.

      LR4 Active XO.pngelectronic xo.jpg
      Last edited by Millstonemike; 12-06-2017, 06:09 PM.

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      • #4
        Mike, you need to offer your services to PE to help design their next 2.1 amp
        Brian Steele
        www.diysubwoofers.org

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        • #5
          http://www.ti.com/lit/ug/tidu035/tidu035.pdf
          9 out of 10 British housewives can't tell the difference between Whizzo Butter and a dead crab.

          http://www.youtube.com/watch?v=19CvEO3Riy0, http://www.youtube.com/watch?v=xs1aUws0Lrs
          www.rane.com/pdf/pi14data.pdf, http://www.realoldiesradio.com/docs/EV/EV_13-5.pdf, http://www.technicalaudio.com/pdf/Je...e_informer.pdf

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          • #6
            There we go, that's a really nice write up covering a whole lot of topics beyond a simple sallen-key filter. Thanks! Sent from my SM-T231 using Tapatalk
            Electronics engineer, woofer enthusiast, and musician.
            Wogg Music

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            • #7
              Related to the above post but a little different emphasis...the original post and Millstonemike's are about 2 way crossovers. What is the difference between these boards and the DIY designs at Elliot Sound Products? The LR electronic crossover (Project 09) and 18db/Octave electronic crossover (Project 123) at Elliot Sound Products? Link to ESP home page since he asks not to link to direct project pages.

              My REAL question relates to the variable rate crossover boards discussed in a few threads that all seem to have flaws. I know it wouldn't be a variable crossover, but for building a subwoofer with an amplifier board like the many Sure boards on PE, could you just use the low-filter half of these ESP designs on a breadboard (10 for $5 here at PE) and some parts from Mouser or Digikey and build a 120Hz or 80Hz or whatever crossover?

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              • #8
                Originally posted by wogg View Post
                I'm interested... but your link is to the home page :(
                ​The article was discussed here about 3 and a half years ago:

                http://techtalk.parts-express.com/fo...y-loudspeakers

                The last link in Sydney's post has the Gerber files
                Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                • #9
                  Originally posted by a4eaudio View Post
                  Related to the above post but a little different emphasis...the original post and Millstonemike's are about 2 way crossovers. What is the difference between these boards and the DIY designs at Elliot Sound Products? The LR electronic crossover (Project 09) and 18db/Octave electronic crossover (Project 123) at Elliot Sound Products? Link to ESP home page since he asks not to link to direct project pages.

                  My REAL question relates to the variable rate crossover boards discussed in a few threads that all seem to have flaws. I know it wouldn't be a variable crossover, but for building a subwoofer with an amplifier board like the many Sure boards on PE, could you just use the low-filter half of these ESP designs on a breadboard (10 for $5 here at PE) and some parts from Mouser or Digikey and build a 120Hz or 80Hz or whatever crossover?
                  Actually, the board in my previous post comes standard as an LR4 filter (Linkwitz-Riley 4th order). LR4 is obtained by cascading two Butterworth 2nd order filters (e.g., cascaded 2nd order Butterworths mathematically equal a Linkwitz-Riley 4th order). I was just giving an example of using it as a 2nd order filter.

                  And I presume your referring to the PE "sub-woofer pre-amp" board with variable sub gain and LP frequency adjustment evaluated here. That board had two issues making it mostly useless but more than fixable by replacing two components (I used Digikey). PE picked up on that and issued an updated version from the Chinese mfg. Unfortunately the prescribed fixes were "lost in translation" and the new version came back totally non-working (and harder to fix).

                  I am ready to evaluate a third party sub-woofer pre-amp board, below. In addition to sub freq. control and sub volume on the PE board, it also had overall gain control for both the sub and L-R a pass through. That feature would come in handy for some smaller digital amp modules that have low over all gain. Unfortunately my Advent Loudspeaker find has preoccupied my time as of late.

                  Coming soon ...

                  Sub Pre Amp.jpg

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