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What is the function of the "power rectifier filter?"

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  • What is the function of the "power rectifier filter?"

    I've sort of cobbled together amp boards and power supplies and just made things work with remedial knowledge... mostly out of necessity. When you've all the sudden fabricated a dozen pair of speakers, a bunch of amplifier solutions come in handy.

    I came across some ebay product called a "Double Power Rectifier Filter Amplifier Rectification Filtration Board." I looked up what the circuit is for, and it turns out it converts AC power to DC. OK. We're learning... good. But what for? In the amp world, that is.

    I get lost with the half wave / full wave stuff. I know very little about power and electricity. Like I said, I have stumbled through it and am lucky to not have been shocked with 110v more often. I've blown stuff up out of ignorance. Learned enough not to blow stuff up, and moved on.

    So what is this for? Should I add these to the power supply + amp board equation? The only reason I can think to ever condition the power in any way is to get cleaner sound with less distortion and noise. I mean... that's ALL we are trying to do here, right?

    Here is the specific product that started me wondering:

    https://www.ebay.com/itm/1pc-Double-...-/362833185900

    Somebody who knows more than me: please explain these things in the moron language I can understand.

    If the number is large, the size can be small, and there is no need for a large rectifier bridge with a heat sink., affecting the appearance and space of the chassis, the overall size and specifications are more uniform.
    My Studio Music Production Gear: http://equipboard.com/spaker
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  • #2
    Those boards will convert A.C. ( alternating current ( as out of the wall ) ) to plus and minus D.C. ( needed by most amplifier circuits )
    Between the wall and the board , you would also need a transformer to convert the 110 Volts ( in U .S . ) to your required value ,
    and isolate the earth ground from your amplifier chassis ground . ( to prevent possible danger )
    https://www.circuitlib.com/index.php...ircuits-design

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    • #3
      Active circuits like amplifiers run on DC, but our power distribution is AC. AC power allows us to use transformer to raise and lower voltage for transmission over long distances, the main reason Tesla won over Edison back in the day.

      The standard (non-switching) power supply steps down the 120VAC from your wall to a lower voltage, then rectifies it using diodes to a single polarity but lumpy half sine wave (ignoring full wave rectification for now). That needs filtered to a nice steady and clean single DC voltage.

      That circuit does just that, and gives you a nice DC output for an amplifier board.
      Electronics engineer, woofer enthusiast, and musician.
      Wogg Music
      Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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      • #4
        Originally posted by wogg View Post
        Active circuits like amplifiers run on DC, but our power distribution is AC. AC power allows us to use transformer to raise and lower voltage for transmission over long distances, the main reason Tesla won over Edison back in the day.

        The standard (non-switching) power supply steps down the 120VAC from your wall to a lower voltage, then rectifies it using diodes to a single polarity but lumpy half sine wave (ignoring full wave rectification for now). That needs filtered to a nice steady and clean single DC voltage.

        That circuit does just that, and gives you a nice DC output for an amplifier board.
        Lacks the xfmr though ..

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        • #5
          Originally posted by hitsware2 View Post

          Lacks the xfmr though ..
          Well yeah... there's that. Keeping it simple
          Electronics engineer, woofer enthusiast, and musician.
          Wogg Music
          Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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          • #6
            Thanks. So I kinda knew what this was. I know about Tesla and Edison battling it out over AC and DC... killing elephants in the street and whatnot.

            OK.... so dumb question #2.

            Does a "switching" power supply do the AC to DC conversion? Is that what the "switching" is?

            Because I have just hooked switching power supplies to amp boards with nothing in between. I have to assume SOMETHING between the wall outlet and the amp board is converting AC to DC, right? This board would be for building your own power supply (kind of like described above) with a transformer, right? You wouldn't include this in a situation where AC is already being converted to DC, right?
            My Studio Music Production Gear: http://equipboard.com/spaker
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            • #7
              Right .

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              • #8
                Switching refers to a 'switch mode' power supply. Basically, it turns off and on thousands of times a second... so fast that the equipment it's connected to continues to function just fine. But, since the power supply is only "on" half the time, the transformer can be much smaller. Oversimplified of course.
                TomZ
                *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

                *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

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                • #9
                  It ' s the higher frequency that allows the smaller xfmr ...

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                  • #10
                    A switch mode power supply provides the constant DC voltage that amplifier circuits require. In the ideal world it's a constant DC voltage, no gaps, no half-wave) There are caveats such as ripple / noise. But those issues are limited mostly to the audiophile (audioholic) crowd. And at the very worst, adding a couple capacitors for demand peaks but nothing nearly as big as posted, is the rectification needed. That board is targeted at amplifier builds using transformers. A modern, moderate power amp can run just fine on an old laptop power supply.

                    Post the amplifiers your using (pics, description, links, etc). We can help you optimize the solutions as well as provide an understanding of what the amps can provide (max power, distortion, etc.).

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                    • #11
                      Originally posted by Millstonemike View Post
                      A switch mode power supply provides the constant DC voltage that amplifier circuits require. In the ideal world it's a constant DC voltage, no gaps, no half-wave) There are caveats such as ripple / noise. But those issues are limited mostly to the audiophile (audioholic) crowd. And at the very worst, adding a couple capacitors for demand peaks but nothing nearly as big as posted, is the rectification needed. That board is targeted at amplifier builds using transformers. A modern, moderate power amp can run just fine on an old laptop power supply.

                      Post the amplifiers your using (pics, description, links, etc). We can help you optimize the solutions as well as provide an understanding of what the amps can provide (max power, distortion, etc.).
                      There we go. This is all the info I was looking for, with a tip of the hat to everyone who pitched in.

                      I do not have a "problem" with amplifier boards and power supplies, per se. I have been pairing boards from Sure/ Wondom for years with the switching power supplies you typically find used for LED lighting. I have never had a distortion or noise issue, but am always looking for little improvements. I thought, perhaps, that this was some kind of passive power conditioning that was not necessary, but another little step in striving for as little noise as possible. It was a hunch, but based on another hunch on what this thing did. Now I know for sure. I can add some rectifier circuits if I wanted to, but the board from this posting would be overkill / silly.

                      I haven't built any speakers for myself that were >$700, so I don't think I am yet in the range where I would be beyond $40 amp boards and a couple hundred watts of power.

                      Thanks for the info. You guys are the bestest.

                      Pete
                      My Studio Music Production Gear: http://equipboard.com/spaker
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