Moduler Preamplifier Circuit


Posted on Feb 6, 2014

This Module employs an unusual topology, still maintaining the basic op-amp circuitry of the Main Module with a few changes in resistor values. A special feature of this circuit is the use of six ways switches instead of the more common potentiometers: in this way, precise `tone flat` setting, or preset dB steps in bass and treble boost or cut can


Moduler Preamplifier  Circuit
Click here to download the full size of the above Circuit.

be obtained. Tone Control switches also allow a more precise channel matching when a stereo configuration is used, avoiding the frequent poor alignment accuracy presented by common ganged potentiometers. Six ways (two poles for stereo) rotary switches were chosen for this purpose as easily available. This dictated the unusual "asymmetrical" configuration of three positions for boost, one for flat and two for cut. This choice was based on the fact that tone controls are used in practice more for frequency boosting than for cutting purposes. In any case, +5dB +10dB and +15dB of bass boost and -3dB and -10dB of bass cut were provided. Treble boost was also set to +5dB +10dB and +15dB and treble cut to -3. 5dB and -9dB. Those wishing to use common potentiometers in the usual way for Tone Controls may use the circuit shown enclosed in the dashed box (bottom-right of the Tone Control Module circuit diagram) to replace switched controls. The Tone Control Module should usually be placed after the Main Input Module, and the volume control inserted between the Tone Control Module output and the power amplifier input. Alternatively, the volume control can also be placed between Main Input Module and Tone Control Module, at will. Furthermore, the position of these two modules can be also interchanged. The preamplifier must be feed by a dual-rail, +24 and -24V 50mA dc power supply. This is easily achieved by using a 48V 3VA...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Melody Doorbell circuit
    Proximity-switch
    Ford Probe Single Wire Door Lock/Unlock Alarm System Circuit Schematic
    PLL FM Demodulator Circuit Module
    Low Power LED Battery Voltmeter
    Two-Channel PC Based Oscilloscope USB
    Simple Photoresistor Circuit
    Five uses tri-state logic audio pen CD4066 555
    XTR106 no external transistor circuit diagram of work



    Top