Stereo Tone Control with Line In + Microphone Mixer

This is an active stereo tone control circuit using very well known op-amp IC of TL072. The circuit include mic pre-amp and mixer control. In this design, we have two inputs: one for line (stereo), one for microphone and has control of the three audio frequency (high/treble, medium and low/bass). It also provide balance control between right and left channel, microphone volume control, line in volume control and master volume for both line in and mic control. The circuit is powered by a regulated symmetrical power supply. The PCB layout design for both tone control and power supply is provided here, complete with component placement. Good luck.

Stereo Tone Control Component List

INTEGRATED CIRCUIT

• TL072 : 2
• TL071 : 1

RESISTORS All 1/4W

• 22K ohm (red, red, orange) : 10
• 10K ohm (Brown, Black, Orange) : 10
• 1K ohm (brown, black, red) : 3
• 100K ohm (brown, black, orange) : 3
• 100 ohm (Coffee, Black, Coffee) : 4
• stereo/dual potentiometers 100K ohm : 3
• stereo/dual potentiometers 10K ohm : 2
• mono/single potentiometers 10K ohm : 2

CAPACITORS

• 1uF/25V electrolytic capacitor : 4
• 10uF/25V electrolytic capacitor : 1
• 4.7uF/25V electrolytic capacitor : 2
• 6.8nF (682) polyester capacitor : 2
• 1.5nF (152) polyester capacitor : 2
• 47nF (473) polyester capacitor : 2
• 1nF (102) polyester capacitor : 2
• 100nF (104) polyester capacitor : 4
• 2200uF x 25 V electrolytic capacitor : 2
• 1uF nonpolar capacitor (105) : 5

Stereo Tone Control PCB Layout and Component Placement

Power Supply Circuit

The power supply type for the stereo tone control is symmetrical and regulated and on its output we use +15 and -15 VDC. The LM7815 will deliver stabilized +15VDC and the LM7915 will deliver stabilized -15 VDC. For symmetrical source, the TL072 VCC range will be 7V up to 36V, so you may use a pair of regulator IC LM7805/LM7905 up to LM7815/7915.
Below is the schematic diagram, pcb design and component layout: