Two transistor tone controller

john April 7, 2010 17 Comments

Description.

Here is the circuit diagram of a simple two transistor tone controller circuit. This circuit is based on the famous Baxandal tone control design. The transistor Q1 is wired an emitter follower to provide sufficient current gain and input impedance. The second transistor is used to voltage amplify the signal in. The network of resistance and capacitors connected between emitter of Q1 and base of Q2 is used to control the tone. Variation in the value of these components varies the audio response of the system.This circuit can provide a maximum attenuation and boost of 10decibel on 10KHz and 60Hz frequency ranges.

Circuit diagram with Parts list.

two-transistor-tone-controller-circuit

Notes.

  • The circuit can be powered from 12V DC.
  • The input and output must be connected with respect the ground.
  • POT R5 can be used to control bass.
  • POT R8 can be used to control treble.
  • All electrolytic capacitors must be rated at least 12V.
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Comments
  • Pascual
    October 16, 2014

    Sir can i use S9014 instead BC109C? Bcoz in my place BC109C is not available.

  • abubakar
    May 29, 2014

    hello sir sorry for asking you too many questions. with power supply of 45 0 – 45 on d 150Watt amp will d out put transistors get blown out with 4ohm 150 Watts woofer & I read from one of ur replies dat about 300 Watt can b achieved with paralleled output transistors .that is what I want to do sir,but am scared my output transistors shouldn’t get blown out. pls. sir advice me on what to do.

    • Seetharaman
      May 30, 2014

      For 4 ohms load use 2 output transistors in parallel. base and collector can be connected together only for each emitter use separate emitter resistances ( for PNP and NPN darlington pairs)with +45-0–45 volts DC supply you will get around 225 watts RMS and peak power of 450 watts. transformer should be capable of 500VA.

  • abubakar
    May 29, 2014

    sir with d recommended power supply of -45 volt on d 150 Watts amplifier, will d output transistors not get blown out when used with 4ohms load.?

  • abubakar
    May 24, 2014

    sorry I mean my mfb amplifier

  • abubakar
    May 24, 2014

    tank u sir my tone control circuit works perfectly with my 100 watt amplifier. jst tested it today…… u d best sir.

  • abubakar
    May 19, 2014

    tank u sir. I have completed my mfb amplifier and n d. 150 Watt amplifier but I want to use d 150 amplifier as subwoofer. pls advice me on d transformer which can power the two amps (d transformers voltage n amps rating )

    • Seetharaman
      May 19, 2014

      For motional feedback amplifier you require 42Volts @ 2.5 Amps (100VA) rating and for 150 watts amplifier you require for a load of 4 0hms speaker use 30-0-30 volt transformer with 5 amps capacity(300VA rating). For sub woofer you can use 2nos 80watts textile rubber 8 ohms woofers 8″ / 10″ in parallel. For MFB you can use full range 8″ 8 ohms 40 watts High quality speaker in a sealed 25 to 35 litres enclosure inner volume. For sub woofer a 30 to 40 litres enclosure with 8″ / 10″ woofers.

  • abubakar
    May 16, 2014

    I could only get bc109 instead of bc109c can I use d bc109? tanks.

    • Seetharaman
      May 18, 2014

      BC109 C will have a gain (hfe) of around 450 to 900 but BC109 will have 70 to 125 will be gain. That should not matter you can use a lower gain BC109 successfully. BC109B will be best choice. R11 should be reduced to 470K other than that no modification is required with BC109. Ensure you get around 5 volts at Q2 collector with the change of resistance R11.

  • abubakar
    May 16, 2014

    I could only get bc109 instead of bc109c can I use d bc109?

  • abubakar
    May 16, 2014

    sir if I used 4.7n & 2.2n in parallel ,will data be equal to 6.9n?

    • Seetharaman
      May 16, 2014

      In place of C6 yes, you can use 4.7n & 2.2n in parallel.

  • abubakar
    May 2, 2014

    is there substitute for c6?

    • Seetharaman
      May 2, 2014

      You can use 5n6 or 4n7, will not affect the tone control action very much.

  • Seetharaman
    April 28, 2011

    Hi Iqubal R5 also should be 47K both tone controls should be log type. if not available LIN can be used. C1 should be 10nF. Reduce R6 to 1.2K. The bass available with full boost should be ok. your main amplifier must be capable of high power not less than 40watt RMS power.

  • iqubal
    April 28, 2011

    HI ,

    WHAT IS THE VALUE OF C1 ? , ALSO 4.7K (R5) IS CORRECT ?(I MEAN IT IS 47K) WICH TYPE LOG OR LIN ? HOW WE CAN ULTER THIS CIRCUIT GETTING GOOD DEEP BASS

    REGARDS

    IQU

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