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 10 hours ago









      SamGibson

      10.8k41537




      10.8k41537










      asked 11 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
            10 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
            10 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            10 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
            9 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
            10 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
            10 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 11 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
            10 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
            10 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
          10 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
          10 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
            10 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            10 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
            9 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
            10 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            10 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
            9 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 9 hours ago

























          answered 10 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
            10 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            10 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
            9 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
            10 hours ago












          • Isn't this very impractical to adjust volume using 2 potentiometers?
            – ensonic
            10 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
            9 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
          10 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
          10 hours ago














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




          Isn't this very impractical to adjust volume using 2 potentiometers?
          – ensonic
          10 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
          9 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
          9 hours ago




















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