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A small DIY LM3886 Chip Amplifier

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  • A small DIY LM3886 Chip Amplifier

    I got the bug to build an amp to run the tweeters on a two-way that was using MiniDSP. I had a lot of misc parts laying around, so thought, what the heck. I think most everyone is familiar with the LM3886 chip amp or Gainclone Amp. I ordered a couple of boards from Chipamp.com and the parts from Mouser.

    Mostly, this is about how simple it was to get a case together for it. I found a blown-out Marantz integrated at a local thrift store and scavenged a pair of heat sinks for it. Cost was $5. I used a 200VA toroid from Antek.com that was around $30, a PSU board from Bohemian Audio, and misc parts from Mouser. Add in the scrap wood and the sheet metal and it was an under-$100 amplifier that will play about 50Wpc or so into a 4r load without breaking a sweat on about +/-24Vdc rails. A neat, great-sounding amp. I will post a few pics and answer any questions I can. Neat project to try.

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  • #2
    Re: A small DIY LM3886 Chip Amplifier

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    • #3
      Re: A small DIY LM3886 Chip Amplifier

      Nice, that is a lot of caps... How much per rail?
      My Statement monitors
      My Piccolatas
      My LM3886 amp

      Comment


      • #5
        Re: A small DIY LM3886 Chip Amplifier

        Originally posted by Silver1omo View Post
        Nice, that is a lot of caps... How much per rail?
        They are 2200uF caps, 22,000uF per rail. A bit overkill....but why not, amirite?

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        • #6
          Re: A small DIY LM3886 Chip Amplifier

          Some of those chip amps can sound incredible ... not just good, but incredible. They flat out destroy the preconceived price to performance scale. I've been thinking about buying one, there are a few finished ones out there under $400 with beefy power supplies, nice cases, etc. But I might just build one myself. I have a bunch of big Pentium 3 heat sinks lying around that would work perfectly, and I have a torrid that's been on my shelf for years that would work.
          Vapor Audio

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          • #7
            Re: A small DIY LM3886 Chip Amplifier

            It looks like a lot more, I went with 20,000uF (2x10,000uF) per rail.
            I want to try an audiosector kit...
            Originally posted by tc View Post
            They are 2200uF caps, 22,000uF per rail. A bit overkill....but why not, amirite?
            My Statement monitors
            My Piccolatas
            My LM3886 amp

            Comment


            • #8
              Re: A small DIY LM3886 Chip Amplifier

              Very nice job. I think I may have been an influence on you but you put yours in a very nice box. I like the LM 1875 a little better but it is a lower power rating.

              Fred

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              • #9
                Re: A small DIY LM3886 Chip Amplifier

                tc, is that blue connector a Speakon?
                Some people are addicted to Vicodin. I'm addicted to speaker building.

                The Chorales - Usher 8945A/Vifa XT25TG Build
                ESP Project 101 Lateral MOSFET Amplifier
                LM4780 Parallel Chipamp
                Sonata Soundbar Project
                The Renditions - Active/Passive Towers

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                • #10
                  Re: A small DIY LM3886 Chip Amplifier

                  I have an Audiosector LM4780 kit that I have yet to build. Based on the quality of the kit parts and the online support, I would expect you to be very happy with the kit.
                  Threads like these remind me to take a break from speaker building and build some of the amp kits I have "in stock".


                  Originally posted by Silver1omo View Post
                  It looks like a lot more, I went with 20,000uF (2x10,000uF) per rail.
                  I want to try an audiosector kit...
                  I was so much older then, I'm younger than that now.
                  OS MTMs http://techtalk.parts-express.com/sh...d.php?t=220388
                  Swope TM http://techtalk.parts-express.com/sh...d.php?t=221818
                  Econowave and Audio Nirvana AN10 fullrange http://techtalk.parts-express.com/sh...d.php?t=216841
                  Imperial Russian Stouts http://techtalk.parts-express.com/sh...=1#post1840444
                  LECBOS. http://techtalk.parts-express.com/sh...ghlight=lecbos

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                  • #11
                    Re: A small DIY LM3886 Chip Amplifier

                    Originally posted by hongrn View Post
                    tc, is that blue connector a Speakon?
                    That is a powercon
                    http://www.neutrik.com/en/audio/powercon/
                    My Statement monitors
                    My Piccolatas
                    My LM3886 amp

                    Comment


                    • #12
                      Re: A small DIY LM3886 Chip Amplifier

                      Originally posted by fastbike1 View Post
                      I have an Audiosector LM4780 kit that I have yet to build. Based on the quality of the kit parts and the online support, I would expect you to be very happy with the kit.
                      Threads like these remind me to take a break from speaker building and build some of the amp kits I have "in stock".
                      I have the pcb set for that same amp from Audiosector sitting here. I'll need to make that my winter project. The mouser cart is already built and loaded, just need to click the order button.
                      Audio: Media PC -> Sabre ESS 9023 DAC -> Behringer EP2500 -> (insert speakers of the moment)
                      Sites: Jupiter Audioworks - Flicker Stream - Proud Member of Midwest Audio Club

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                      • #13
                        Re: A small DIY LM3886 Chip Amplifier

                        Very nice!
                        I like the overkill PS caps and overkill heat sinks.

                        I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                        "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                        High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                        SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                        My Voxel min sub Yet-another-Voxel-build

                        Tangband W6-sub

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                        • #14
                          Re: A small DIY LM3886 Chip Amplifier

                          Thanks Don. I like beefy PSU's and heat sinks. I see so many of the gainclones with really flimsy heat sinks. Some with just a strip of AL. I just don't get it. I want my amps to survive the nuclear holocaust....

                          Comment


                          • #15
                            Re: A small DIY LM3886 Chip Amplifier

                            Originally posted by tc View Post
                            ...I like beefy PSU's and heat sinks. I see so many of the gainclones with really flimsy heat sinks. Some with just a strip of AL...
                            from a paper on Thermal management - ie the 10 degree rule
                            "In our world of electronic product design, we live by this rule of thumb: For every 10 degrees Centigrade rise in temperature, the average reliability is decreased by 50 percent. Or, from the quality assurance department's point of view, if we can lower the temperature by 10 degrees, we'll double the reliability. In other words, we will double the expected life within any predictable failure rate. Another way to look at this, for those interested in buying products with good MTBF (meantime between failures) ratings, is that MTBF will, on average, double if the operating temperature is lowered 10 degrees."
                            "Not a Speaker Designer - Not even on the Internet"
                            “Pride is your greatest enemy, humility is your greatest friend.”
                            "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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