volume control for lm386












3














For some context, see my earlier question:
Ceramic capacitor value for LM386N project



What I learned is that the 10k potentiometer on pin 3 (Vin) forms a voltage divider. When I carefully dial it, I find a spot where I get clean audio (the 10k pot is then at ~ 500Ω). This is the same with the ready-made breakout board that I used for comparison.



Now the point of not using the ready made module was that I wanted to add a volume control. Apparently scaling Vin is not how one supposed to do that, if I go up or down from the spot where the audio is good, I get distortions, but never a quieter signal.



I also tried to add a pot between pin 1 and the ceramic cap that goes to pin 8. The datasheet has 3 examples:




  • gain 20: by default there is a 1.35 kΩ resistor

  • gain 50: use a 1.2 kΩ resistor

  • gain 200: use no resistor


I only had a 2k pot and when I dial it from 0Ω up, the signal gets a bit quieter but I can't get it down to silence. If I remove the circuit between pin 1 and 8 to operate at gain 20, the output is pretty quiet though.



I searched the net quite a bit and I probably miss something obvious. It would be awesome to get some pointers. Thanks!






lm386 volume






share





























    3














    For some context, see my earlier question:
    Ceramic capacitor value for LM386N project



    What I learned is that the 10k potentiometer on pin 3 (Vin) forms a voltage divider. When I carefully dial it, I find a spot where I get clean audio (the 10k pot is then at ~ 500Ω). This is the same with the ready-made breakout board that I used for comparison.



    Now the point of not using the ready made module was that I wanted to add a volume control. Apparently scaling Vin is not how one supposed to do that, if I go up or down from the spot where the audio is good, I get distortions, but never a quieter signal.



    I also tried to add a pot between pin 1 and the ceramic cap that goes to pin 8. The datasheet has 3 examples:




    • gain 20: by default there is a 1.35 kΩ resistor

    • gain 50: use a 1.2 kΩ resistor

    • gain 200: use no resistor


    I only had a 2k pot and when I dial it from 0Ω up, the signal gets a bit quieter but I can't get it down to silence. If I remove the circuit between pin 1 and 8 to operate at gain 20, the output is pretty quiet though.



    I searched the net quite a bit and I probably miss something obvious. It would be awesome to get some pointers. Thanks!






    lm386 volume






    share



























      3












      3








      3







      For some context, see my earlier question:
      Ceramic capacitor value for LM386N project



      What I learned is that the 10k potentiometer on pin 3 (Vin) forms a voltage divider. When I carefully dial it, I find a spot where I get clean audio (the 10k pot is then at ~ 500Ω). This is the same with the ready-made breakout board that I used for comparison.



      Now the point of not using the ready made module was that I wanted to add a volume control. Apparently scaling Vin is not how one supposed to do that, if I go up or down from the spot where the audio is good, I get distortions, but never a quieter signal.



      I also tried to add a pot between pin 1 and the ceramic cap that goes to pin 8. The datasheet has 3 examples:




      • gain 20: by default there is a 1.35 kΩ resistor

      • gain 50: use a 1.2 kΩ resistor

      • gain 200: use no resistor


      I only had a 2k pot and when I dial it from 0Ω up, the signal gets a bit quieter but I can't get it down to silence. If I remove the circuit between pin 1 and 8 to operate at gain 20, the output is pretty quiet though.



      I searched the net quite a bit and I probably miss something obvious. It would be awesome to get some pointers. Thanks!






      lm386 volume






      share















      For some context, see my earlier question:
      Ceramic capacitor value for LM386N project



      What I learned is that the 10k potentiometer on pin 3 (Vin) forms a voltage divider. When I carefully dial it, I find a spot where I get clean audio (the 10k pot is then at ~ 500Ω). This is the same with the ready-made breakout board that I used for comparison.



      Now the point of not using the ready made module was that I wanted to add a volume control. Apparently scaling Vin is not how one supposed to do that, if I go up or down from the spot where the audio is good, I get distortions, but never a quieter signal.



      I also tried to add a pot between pin 1 and the ceramic cap that goes to pin 8. The datasheet has 3 examples:




      • gain 20: by default there is a 1.35 kΩ resistor

      • gain 50: use a 1.2 kΩ resistor

      • gain 200: use no resistor


      I only had a 2k pot and when I dial it from 0Ω up, the signal gets a bit quieter but I can't get it down to silence. If I remove the circuit between pin 1 and 8 to operate at gain 20, the output is pretty quiet though.



      I searched the net quite a bit and I probably miss something obvious. It would be awesome to get some pointers. Thanks!






      lm386 volume




      lm386 volume





      share














      share












      share



      share








      edited 8 hours ago









      SamGibson

      10.8k41537




      10.8k41537










      asked 9 hours ago









      ensonicensonic

      12816




      12816






















          2 Answers
          2






          active

          oldest

          votes


















          5














          You probably used a linear (B) taper pot. For audio you want an (A) log taper pot, so your 500 ohms will be about 25% of full electrical rotation, not 5%.



          Image from this site.



          enter image description here






          share|improve this answer





















          • I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
            – ensonic
            8 hours ago



















          3















          • Gain of 20 is too quiet

          • Gain of 200 is too distorted and can't turn it down to get quiet.


          Choose Gain =50 with 1.2k in series with cap



          Pots do not have a 60dB dynamic range so they usually gang 2 pots {pre-amp gain & power amp gain} to get 30dB in each.





          Solution



          Ganged Pot



          schematic





          But as Dave say's that needs to be an audio log pot.



          enter image description here






          share|improve this answer























          • You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
            – Sunnyskyguy EE75
            7 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            7 hours ago






          • 1




            They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
            – Sunnyskyguy EE75
            7 hours ago













          Your Answer





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          2 Answers
          2






          active

          oldest

          votes








          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          5














          You probably used a linear (B) taper pot. For audio you want an (A) log taper pot, so your 500 ohms will be about 25% of full electrical rotation, not 5%.



          Image from this site.



          enter image description here






          share|improve this answer





















          • I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
            – ensonic
            8 hours ago
















          5














          You probably used a linear (B) taper pot. For audio you want an (A) log taper pot, so your 500 ohms will be about 25% of full electrical rotation, not 5%.



          Image from this site.



          enter image description here






          share|improve this answer





















          • I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
            – ensonic
            8 hours ago














          5












          5








          5






          You probably used a linear (B) taper pot. For audio you want an (A) log taper pot, so your 500 ohms will be about 25% of full electrical rotation, not 5%.



          Image from this site.



          enter image description here






          share|improve this answer












          You probably used a linear (B) taper pot. For audio you want an (A) log taper pot, so your 500 ohms will be about 25% of full electrical rotation, not 5%.



          Image from this site.



          enter image description here







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 9 hours ago









          Spehro PefhanySpehro Pefhany

          204k4150408




          204k4150408












          • I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
            – ensonic
            8 hours ago


















          • I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
            – ensonic
            8 hours ago
















          I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
          – ensonic
          8 hours ago




          I meassured my pot an it is indeed lin, but that does not explain that it goes from noise to audio to noise. With a log one the range is easier to adjust, but I don't believe that the place where one should add the pot is where one can adjust the volume. It sounds like it should work, but then I should be able to control the volume a bit at least, right?
          – ensonic
          8 hours ago













          3















          • Gain of 20 is too quiet

          • Gain of 200 is too distorted and can't turn it down to get quiet.


          Choose Gain =50 with 1.2k in series with cap



          Pots do not have a 60dB dynamic range so they usually gang 2 pots {pre-amp gain & power amp gain} to get 30dB in each.





          Solution



          Ganged Pot



          schematic





          But as Dave say's that needs to be an audio log pot.



          enter image description here






          share|improve this answer























          • You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
            – Sunnyskyguy EE75
            7 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            7 hours ago






          • 1




            They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
            – Sunnyskyguy EE75
            7 hours ago


















          3















          • Gain of 20 is too quiet

          • Gain of 200 is too distorted and can't turn it down to get quiet.


          Choose Gain =50 with 1.2k in series with cap



          Pots do not have a 60dB dynamic range so they usually gang 2 pots {pre-amp gain & power amp gain} to get 30dB in each.





          Solution



          Ganged Pot



          schematic





          But as Dave say's that needs to be an audio log pot.



          enter image description here






          share|improve this answer























          • You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
            – Sunnyskyguy EE75
            7 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            7 hours ago






          • 1




            They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
            – Sunnyskyguy EE75
            7 hours ago
















          3












          3








          3







          • Gain of 20 is too quiet

          • Gain of 200 is too distorted and can't turn it down to get quiet.


          Choose Gain =50 with 1.2k in series with cap



          Pots do not have a 60dB dynamic range so they usually gang 2 pots {pre-amp gain & power amp gain} to get 30dB in each.





          Solution



          Ganged Pot



          schematic





          But as Dave say's that needs to be an audio log pot.



          enter image description here






          share|improve this answer















          • Gain of 20 is too quiet

          • Gain of 200 is too distorted and can't turn it down to get quiet.


          Choose Gain =50 with 1.2k in series with cap



          Pots do not have a 60dB dynamic range so they usually gang 2 pots {pre-amp gain & power amp gain} to get 30dB in each.





          Solution



          Ganged Pot



          schematic





          But as Dave say's that needs to be an audio log pot.



          enter image description here







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited 6 hours ago

























          answered 8 hours ago









          Sunnyskyguy EE75Sunnyskyguy EE75

          62.9k22194




          62.9k22194












          • You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
            – Sunnyskyguy EE75
            7 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            7 hours ago






          • 1




            They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
            – Sunnyskyguy EE75
            7 hours ago




















          • You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
            – Sunnyskyguy EE75
            7 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            7 hours ago






          • 1




            They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
            – Sunnyskyguy EE75
            7 hours ago


















          You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
          – Sunnyskyguy EE75
          7 hours ago






          You could get 20log(500/10k)= - 26dB which is not silent that's the approx 30dB limit I said in my answer
          – Sunnyskyguy EE75
          7 hours ago














          Isn't this very impractical to adjust volume using 2 potentiometers?
          – ensonic
          7 hours ago




          Isn't this very impractical to adjust volume using 2 potentiometers?
          – ensonic
          7 hours ago




          1




          1




          They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
          – Sunnyskyguy EE75
          7 hours ago






          They make stereo ganged pots which you can gang to 4 but like said in integrated receivers they gang preamp gain with power amp gain or something better like digital pots. (not for newbies)
          – Sunnyskyguy EE75
          7 hours ago




















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