2 Watt Amplifier 2:

3 Band Equaliser:

3 Band Equalizer:

300 Watt Subwoofer Power Amplifier:

45 Watt Single Chip Amplifier With Tone Controls:

Active Subwoofer & Controller:

Active Subwoofer:

Audio Analyzer:

Audio Graphic Equalizer: simple 7 band equalizer

Audio Level Meter:

Audio Output Level Meter:

Audio Tone Control:

Bass Amplifier:

Battery Powered Stereo Balance Control Features Low Distortion : 06/23/03 Electronic Design - Ideas for Design / low-power, low-distortion circuit that can be used to balance the left and right headphones or speakers in battery-powered automotive or computer applications.

Better Volume Control: how to create a log pot that is better than the "real" thing

Designing With the LMC835 Digital Controlled Graphic Equalizer: National Semiconductor Application Notes,04-Nov-1995

Digital Delay Unit for Surround Sound:

Digital volume control has log taper: 04/11/2002  EDN - Design Ideas /  Digital potentiometers provide a compact and convenient way to attenuate audio-amplifier signals. However, most such potentiometers suffer from at least one flaw: a nonlogarithmic step increment. To avoid this problem, a user must usually step.

Digital Volume Control: based on DS1669 Digital Pot IC

Dual Channel Digital Volume Control:

Electronic level :

Graphic Equalizer #1:

Graphic Equalizer #3:

Improved PL tone Decoder:

Inverted bipolar transistor doubles as a signal clamp: 06/07/01 EDN-Design Ideas / A number of circuits, such as level detectors and AM demodulators, benefit from a rectifier with a low offset voltage. Silicon diodes have an offset of approximately 0.6V and do not work well in low-level circuitry. A Schottky diode is a bit better...

Mic Pre Pan Pot Circuit:

Mono Audio Equalizer :

Musical Instrument (Expandable) Graphic Equalizer: standard equalizer plus bonus distortion unit

NHT Subwoofer Amp:

One Pot to Control Two Channels:

Parametric & Subwoofer Equalizer:

Passive Filters Fill the Bill At Audio Frequencies: 02/01/01 EDN-Design Ideas / PDF contains multiple circuits - scroll to find this circuit.

PC Speaker Volume Control Circuit:

Pocket Equalizer for Headphone:

Simple, Easy Parametric & Graphic EQ's, Plus Peaks & Notches:

Soft Switching Amplifier With Tone Controls:

Stereo Width Controllers:

Subwoofer Equalizer: The Linkwitz transform circuit is a hugely flexible way to equalize the bottom end of a sealed loudspeaker enclosure. A speaker that is corrected using this method is flat from below resonance to the upper limit of the selected driver. The low frequency roll off point is determined by the parameters of the transform circuit. Should the enclosure size be too small and cause a lump in the response before roll off, this is also corrected. A conventional active crossover network is then used to divide the subwoofer signal from the main channel signals. Note that there is also a separate spreadsheet calculator available for calculating component values for different situations not handled by the original circuit.

Subwoofer Filter: 12 dB/octave low pass filter for subwoofer, includes subsonic filter

Three Band Active Tone Control:

Three Band Equalizer:

Tone Control #2:

Tone Controls With 2x NE 5532: check also PCB design and notes

Tone Detector:

Tone Generator:

Tremolo:

Use Rotary Potentiometer To Drive Solid State Volume Control: 01/20/03 Electronic Design - Ideas for Design / This design idea details how a standard volume control can be replaced by its solid-state equivalent. Digital potentiometers are often advertised as replacements for rotary volume controls. To simulate these controls, many circuits employ up/down...

Voltage Controlled Panner: variable gain amplifier circuit