3-Band Tone w. Tunable Notch PUBLIC

3-Band Tone Circuit with Highly Adjustable Notch Filter

Highly adjustable 3-band tone-control circuit with tunable notch filter. Controls Include: Notch enable switch, Notch Bandwidth, Notch Frequency, High Gain, High Drive, Low Gain, Low Drive, Bass, Mid, Treble, and Volume. With Notch OFF, range between high and low -3 dBV corners is from 32 Hz to 18 kHz, and between the 0 dBV points is from 40 Hz to 14 kHz. Thus, the circuit is suitable for 6/7-string guitar (but not 8-string guitar or bass-guitar). Also with Notch OFF, maximum gain is +12 dBV @ 250 Hz with all control settings at 50%, or +33.2 dBV @ 100 Hz with all controls at 100%. This means the circuit provides moderately high gain with control settings > 50%. However, do not use with all controls at 100% except as a brief worst-case test while breadboarding. Again with Notch OFF, Treble can adjust between 0 dBV and +11 dBV @ 10 kHz, Mid can adjust between +9 and + 13 dBV @ 1 kHz, while Bass can adjust between +4.3 dBV and +15.1 dBV @ 100 Hz. With Notch ON, Notch Frequency adjusts from 400 Hz to 4kHz, Notch Bandwidth adjust from 980 Hz to 26 kHz, and Notch Depth adjusts from -5 dBV to -50 dBV. Yet, Notch controls are interactive with each other, and also affect response at higher frequencies. Examples Gains per Frequency with Bandwidth and Depth at 50%: -4.3 dBV @ 400 Hz, -29 dBV @ 630 Hz, -22.4 dBV @ 2.5 kHz. The power-supply is not shown in the diagram. The circuit requires a regulated dual-polarity DC supply providing +-9VDC or +-12VDC or +-15VDC at >= 40 mA of current. Project can be stomp-box or rack-mounted. And while the circuit is simulator verified, consider it experimental in nature. Thoroughly breadboard test before committing to a soldered build. House in a grounded metal enclosure.