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Has anyone made a bass boost circuit before?

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  • Has anyone made a bass boost circuit before?

    Guys, looking to pick someone's brain in regards to the bass boost circuit

    I'm struggling to understand where this all fits in on a setup.

    I'm looking for ways to boost the lower frequencies like Bose/JBL would do so I can keep the smaller enclosure size. Just been listening to a Bose SoundLink mini and it actually has decent lows at the lower to mid volumes, not sure about much higher as it was my folks and I didn't want to do any damage to it.
    Attached Files

  • #2
    I figured a lot of the store-bought bluetooth speakers just use a DSP EQ/bassboost from their board rather than discrete passive parts though I might easily be wrong. There are little bluetooth amp boards you can buy that have DSP built-in if you want to go that route. Otherwise you can just add something simple like a parallel paired inductor and resistor between your amp and speaker....something like a 1mH inductor (solid-core is cheaper and smaller which might make it easier to fit into a small build), and an ~8ohm resister with their legs tied/soldered together can work well for a variety of speakers for a simple bassboost around 6db. It's also totally possible to choose part values (instead of 1mH and 8ohms) based around the exact speakers you'll be using to get more accurate results that fit the frequency and boost amount you want.

    EDIT: I don't believe anything on that particular schematic is a bassboost..at least not a simple passive one that I can recognize.
    My first 2way build

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    • #3
      Originally posted by LOUT View Post
      I figured a lot of the store-bought bluetooth speakers just use a DSP EQ/bassboost from their board rather than discrete passive parts though I might easily be wrong. There are little bluetooth amp boards you can buy that have DSP built-in if you want to go that route. Otherwise you can just add something simple like a parallel paired inductor and resistor between your amp and speaker....something like a 1mH inductor (solid-core is cheaper and smaller which might make it easier to fit into a small build), and an ~8ohm resister with their legs tied/soldered together can work well for a variety of speakers for a simple bassboost around 6db. It's also totally possible to choose part values (instead of 1mH and 8ohms) based around the exact speakers you'll be using to get more accurate results that fit the frequency and boost amount you want.
      Hey thanks, you talking like a BSC?

      One of the boards i've got coming has got the ablility to configure the EQ, which i need to brush up on how to actually do that, i was thinking of making another iteration with a different bt\amp as well trying something different, but like you said it might be the path of least resistance to just get something with that ability, albeit i have found a nice breakout board that already has that OP amp on it, but then have to lost valuable internal space running with two batteries as i beleive the OP amp needs a clean power supply.

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      • #4
        It seems like a good idea at first glance, but every 6dB of bass boost doubles the cone excursion and quadruples power requirements on both the amp and speakers, so before attempting it you need to be sure the woofers have the excursion and the amp and speakers have the power available for it to work.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #5
          OEM's will build it in their embedded DSP, and likely have a sliding boost that reduces as the signal level increases in order to avoid killing the amp or speaker when it's cranked up.

          That passive circuit is a bass boost, R5 and C3 form a low pass with a gain of 9.3 (19dB) below the critical frequency of 33.8Hz. A smaller cap will raise that corner frequency. Since it's a non-inverting op-amp, the gain goes down to 1 as that capacitor takes over and shorts out the feedback loop. The defeat switch shorts the feedback loop, also leaving you with a gain of 1 regardless of frequency.

          Gain = 1+(R5/R6)
          Corner frequency = 1/(2*pi*R5*C3)
          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
            Do those smaller units actually boost the lower frequencies & do they use psychoacoustic audio processing to give the illusion of the missing fundamental?

            https://en.wikipedia.org/wiki/Missing_fundamental

            https://www.youtube.com/watch?v=AZ8qZCGg4Bk

            https://www.youtube.com/watch?v=0amvhGzeCnQ
            9 out of 10 British housewives can't tell the difference between Whizzo Butter and a dead crab.

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            • #7
              Originally posted by LOUT View Post
              I figured a lot of the store-bought bluetooth speakers just use a DSP EQ/bassboost from their board rather than discrete passive parts though I might easily be wrong. There are little bluetooth amp boards you can buy that have DSP built-in if you want to go that route. Otherwise you can just add something simple like a parallel paired inductor and resistor between your amp and speaker....something like a 1mH inductor (solid-core is cheaper and smaller which might make it easier to fit into a small build), and an ~8ohm resister with their legs tied/soldered together can work well for a variety of speakers for a simple bassboost around 6db. It's also totally possible to choose part values (instead of 1mH and 8ohms) based around the exact speakers you'll be using to get more accurate results that fit the frequency and boost amount you want.

              EDIT: I don't believe anything on that particular schematic is a bassboost..at least not a simple passive one that I can recognize.
              too bad i cant use a 2mh 18 ironcore as a have one of those in my garage....two things that would fight a solid core in the particular build mainly being able to actually fit it in. lol

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              • #8
                The Bose does boost bass at low volumes, then ramps the boost down towards the top end of the volume limit, as Wogg stated.
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                • #9
                  There are many "Loudness" circuits from years past that would provide bass boost only at lower volumes--that is an old approach that requires an extra tap on the volume control. A more modern version is easily implemented in an audio processor. There are more advanced solutions such as dynamic range control (DRC) on separate frequency bands--I believe that approach is common used in small commercial speakers, The algorithm that is probably most effective for small woofers is the psychoacoustic bass enhancement mentioned by NickS, which can give the impression of extended bass with relatively little cone movement. But these newer approaches require a fair amount of computing, either in a DSP or controller.

                  I've got the Analog Devices SuperBass algorithm--the psychoacoustic one--programmed in a low-cost ADAU1701 controller, and you can even control all of the parameters from an Android phone app (see this link). The code also has filters for bass boost, but right now it doesn't use DRC. The only board this code runs on right now is a custom board that has a lot of other circuitry that makes it expensive and too big to fit in a tiny enclosure. I've been thinking about how to make a small version of the board, but so far I don't have a good answer. And I probably wouldn't attempt such a board unless I knew there was enough demand for it.

                  So I'm curious--how much interest is there in speakers with tiny woofers?
                  Free Passive Speaker Designer Lite (PSD-Lite) -- http://www.audiodevelopers.com/Softw...Lite/setup.exe

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                  • #10
                    Originally posted by neildavis View Post
                    There are many "Loudness" circuits from years past that would provide bass boost only at lower volumes--that is an old approach that requires an extra tap on the volume control. A more modern version is easily implemented in an audio processor. There are more advanced solutions such as dynamic range control (DRC) on separate frequency bands--I believe that approach is common used in small commercial speakers, The algorithm that is probably most effective for small woofers is the psychoacoustic bass enhancement mentioned by NickS, which can give the impression of extended bass with relatively little cone movement. But these newer approaches require a fair amount of computing, either in a DSP or controller.

                    I've got the Analog Devices SuperBass algorithm--the psychoacoustic one--programmed in a low-cost ADAU1701 controller, and you can even control all of the parameters from an Android phone app (see this link). The code also has filters for bass boost, but right now it doesn't use DRC. The only board this code runs on right now is a custom board that has a lot of other circuitry that makes it expensive and too big to fit in a tiny enclosure. I've been thinking about how to make a small version of the board, but so far I don't have a good answer. And I probably wouldn't attempt such a board unless I knew there was enough demand for it.

                    So I'm curious--how much interest is there in speakers with tiny woofers?
                    For me I'm scratching an itch I've had for a while and just need to successfully complete a few different ones to close it out.....I don't think there is much of an interest in tiny drivers generally as they aren't as boomy as their bigger siblings.

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