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TPA3116 2.1 Amp - Step by Step Modifications

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  • TPA3116 2.1 Amp - Step by Step Modifications

    I've discussed this amp before in posts but here is it is all in one place.

    I used this dual chip, 2x50w & 1x100W amp in a 2.1 boombox build. I feed it with 26v or 25v (SLA-AGMS versus LiPos) and run it hard on the beach. One full season without any issues running 2x35W and 70w (140w total).

    The amp uses one chip for the ".1" sub channel and has a fixed, sallen-key topology 2nd order LP filter with Butterworth damping. On my board, the LP F3 was 107hz. I've successfully modified that filter by replacing 2 box poly caps. In the schematic, you can see a table of possible F3s given standard value capacitors. I added a legend to the amp's picture to cross refrence with the schematic.

    The amp has an audio frequency bandpass filter, strangely, only on the sub channel. Unfortunately, the F3 of the 1st order HP section is set at ~34Hz limiting low frequency. This is easily solved by replacing two 1uf electrolytic caps with a 4.7uf ones - same physical can size. That lowers the HP F3 to ~ 7hz.

    There are two 1uf signal coupling caps between the L-R input volume pot and the chip's input. With the chips impedance impedance (30K w/gain set at 26dB), these caps form a 1st order HP, F3 = 5hz. The schematic has a table with cap values for increasing that F3 relieving the L-R speakers from some bass duty.

    The chip's gain is set 26dB. My PC output drove to full volume as would most line outs. But my my phone's headphone out was weaker and I needed to front end it with a Sure headphone amp for additional gain. Easy enough to front end that with a Sure BT module if you care (though that requires 12v power, a issue to resolve).

    The front panel switch is Standby - On (not off on). Using this switch, there isn't a turn on/off thump. Leaving this switch in the on position and switching power will cause a thump.

    Lastly, there are similar boards based on the same core design. Most notably the version with 3 PS bypass caps instead of one. Coming from different manufacturers, the triple cap board has exhibited problems with component population causing several problems (chips not in sync mode, sub LP filter at 1Khz, etc.) And, apparently on fleabay: "what you see is what you get - NOT." One guy received a different amp than pictured. So, YMMV.


  • #2
    Nice job Mike. Looks like the perfect 2.1 amp after your mods.

    Dan
    _____________________________
    Tall Boys
    NRNP Computer Sub
    The Boxers
    The Hurricanes
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    Conneccentric
    UX3

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    • #3
      Mike, thanks for spending the time to do this. The ratio of "2" to ".1" wattage figures are right on and the adjustability of xover points makes this a pretty nice setup.
      Why, oh why don't they set these up this way from the start?

      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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      • #4
        Originally posted by Millstonemike View Post
        I've discussed this amp before in posts but here is it is all in one place.

        I used this dual chip, 2x50w & 1x100W amp in a 2.1 boombox build. I feed it with 26v or 25v (SLA-AGMS versus LiPos) and run it hard on the beach. One full season without any issues running 2x35W and 70w (140w total).
        Would love to hear more about that boombox .


        Brian Steele
        www.diysubwoofers.org

        Comment


        • #5
          I just bought the black lepai 2.1 amp from PE, it comes with a 3a power supply but it calls for a 5a power supply on the back of the amp. Maybe i overlooked its usefullness when purchasing. I kind of assumed if you set the subwoofer crossover to say 120hz i thought it would roll of the HP side of the amp there as well. I probably should have researched more about it but it was cheap enough to buy and check it out. Ill hopefully get getting my boombox project wrapped up in a week or two.
          My Build Thread's
          Carrera's / Finalist TL's / Speedster TMM's / Speedster MTM Center / Overnight Sensation Surrounds

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          • #6
            Originally posted by Mike220 View Post
            I just bought the black lepai 2.1 amp from PE, it comes with a 3a power supply but it calls for a 5a power supply on the back of the amp. Maybe i overlooked its usefullness when purchasing. I kind of assumed if you set the subwoofer crossover to say 120hz i thought it would roll of the HP side of the amp there as well. I probably should have researched more about it but it was cheap enough to buy and check it out. Ill hopefully get getting my boombox project wrapped up in a week or two.
            I take it you bought the LP-168HA. If your using 8 ohm drivers, the 3A PS will do fine. If all the drivers are 4 ohm, then you may have an issue. I suggest you try it with the existing PS. If you have an issue, there's lots of 12v 5A PSs on ebay for cheap (look for 12v LED lighting supplies).

            These small amps with a sub LP do NOT incorporate a corresponding HP on the L-R channel. My best suggestion is to use a capacitor in series with the L-R drivers to create a 1st order HP filter for them. We would need to know more about your drivers and sub to make suggestions.

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            • #7
              Originally posted by Brian Steele View Post

              Would love to hear more about that boombox .

              That kinda' opens Pandora's Box ...

              Comment


              • #8
                Hi all. New to TechTalk. I have a few questions about the mods described in the original post.

                Firstly, I am trying to find the exact board Millstonemike bought to perform the mods on. Visually, the attached board appears correct. Am I right?

                Secondly, should the board I receive be different, how can I verify which parts to replace to achieve the 2.0 channel high-pass, and .1 channel bandpass?

                Lastly, is it worth the money to buy a 2.1 amplifier, and perform these mods, or should I just get a pair of 2 channel amps and a cheap DSP?

                Thanks for any advice.
                New 50W x2+100W TPA3116 NE5532 2.1 HIFI Digital Subwoofer Amplifier Board in Business & Industrial, Electrical & Test Equipment, Other Electrical & Test Equip. | eBay

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                • #9
                  Originally posted by DuraMorte View Post
                  Hi all. New to TechTalk. I have a few questions about the mods described in the original post.

                  Firstly, I am trying to find the exact board Millstonemike bought to perform the mods on. Visually, the attached board appears correct. Am I right?

                  Secondly, should the board I receive be different, how can I verify which parts to replace to achieve the 2.0 channel high-pass, and .1 channel bandpass?

                  Lastly, is it worth the money to buy a 2.1 amplifier, and perform these mods, or should I just get a pair of 2 channel amps and a cheap DSP?

                  Thanks for any advice.
                  There are several boards with a similar circuit design for the signal. The board you show has three large PS bypass caps instead of one. The design is the same but the component values can be different. On that board, you'll still see the sub LP circuit as identical but, perhaps with different values. If you have a DVM, you can measure the specific resistors and then the LP cap replacement can be easily calculated. You can also verify the caps for the low freq bass improvement and L-R HP improvement as both these cap pairs are connected to their respective pots.

                  Having said that, you always be in good shape with a DSP.

                  Where this type of board has no equal is a 2.1 portable on batteries with significant power out - it's 90% efficient.

                  Comment


                  • #10
                    Originally posted by Millstonemike View Post
                    There are several boards with a similar circuit design for the signal. The board you show has three large PS bypass caps instead of one. The design is the same but the component values can be different. On that board, you'll still see the sub LP circuit as identical but, perhaps with different values. If you have a DVM, you can measure the specific resistors and then the LP cap replacement can be easily calculated. You can also verify the caps for the low freq bass improvement and L-R HP improvement as both these cap pairs are connected to their respective pots.

                    Having said that, you always be in good shape with a DSP.

                    Where this type of board has no equal is a 2.1 portable on batteries with significant power out - it's 90% efficient.

                    Right on. Maybe the context will help.

                    I'm trying to design a bathroom sound system so my wife can have tunes in the shower. I know that may sound crazy, but she likes it, and I like her to be happy, so I'm trying to make it happen.

                    I also overengineer everything I DIY, so it may seem like overkill, but I want to get power to a pair of small (probably 4" or 5 1/4") marine coaxes and a marine subwoofer, for the best sounding shower stall ever.

                    Thus, the 2.1 board. I figured it would be a perfect use case, and easy to wire up and get working.

                    But, if there's no reason to go with a 2.1 board for anything but battery power, I'll start looking more into the amp + DSP avenue.

                    Thanks for your help!

                    Comment


                    • #11
                      Originally posted by DuraMorte View Post


                      Right on. Maybe the context will help.

                      I'm trying to design a bathroom sound system so my wife can have tunes in the shower. I know that may sound crazy, but she likes it, and I like her to be happy, so I'm trying to make it happen.

                      I also overengineer everything I DIY, so it may seem like overkill, but I want to get power to a pair of small (probably 4" or 5 1/4") marine coaxes and a marine subwoofer, for the best sounding shower stall ever.

                      Thus, the 2.1 board. I figured it would be a perfect use case, and easy to wire up and get working.

                      But, if there's no reason to go with a 2.1 board for anything but battery power, I'll start looking more into the amp + DSP avenue.

                      Thanks for your help!


                      I'm not sure what your physical requirements (in wall, etc.). There may be much better options than marine coaxes. Most decent amps will work, but the speakers are most important.

                      Comment


                      • #12
                        Originally posted by DuraMorte View Post


                        Right on. Maybe the context will help.

                        I'm trying to design a bathroom sound system so my wife can have tunes in the shower. I know that may sound crazy, but she likes it, and I like her to be happy, so I'm trying to make it happen.

                        I also overengineer everything I DIY, so it may seem like overkill, but I want to get power to a pair of small (probably 4" or 5 1/4") marine coaxes and a marine subwoofer, for the best sounding shower stall ever.

                        Thus, the 2.1 board. I figured it would be a perfect use case, and easy to wire up and get working.

                        But, if there's no reason to go with a 2.1 board for anything but battery power, I'll start looking more into the amp + DSP avenue.

                        Thanks for your help!


                        I'm not sure what your physical requirements (in wall, etc.). There may be much better options than marine coaxes. Most decent amps will work, but the speakers are most important.

                        Comment


                        • #13
                          Originally posted by Millstonemike View Post



                          I'm not sure what your physical requirements (in wall, etc.). There may be much better options than marine coaxes. Most decent amps will work, but the speakers are most important.

                          In-wall was the plan for the coaxes, with the subwoofer mounted into the towel cabinet, inside which I would build a sealed compartment.

                          I hate to clog up your thread with this stuff; I'll start a topic. Thanks again for the help!

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