Parametric And Sub-Woofer Equaliser:  (electronic schematic added 1/07)

Peak Level Indicator:  Dot-mode three-LED display.  9V battery powered portable unit (added 3/05)

Peak Reading Audio Level Meter:  indicates peak audio response on an analogue meter, similar to a tape recorder recording level meter (added 4/02)

Personal Media Player (PMP):  Intersil Application Block Diagram  (app note added 6/06)

Portable Headphone Amplifier:  (circuit added 9/04)

Pre Distortion Techniques:  Tape Linearizer and a Distortion Analyzer (added 4/02)

Precision Audio MilliVoltmeter:  Measures10mV to50Volt RMS in eight ranges Simply connect to your Avo-meter set @50µA range (added 9/04)

Rctheremin Circuit:  (schematic / circuit design added 9/02)

Removing the DC Thump from Audio Circuits:  (schematic / circuit design added 9/02)

Room Noise Detector:  One-LED monitors3-levels:50, 70 & 85 dB (added 9/04)

Satellite Radio:  Intersil Application Block Diagram  (app note added 6/06)

Satellite Set-Top Box (NTSC / PAL):  Intersil Application Block Diagram  (app note added 6/06)

Scanmate Audio Activated Recorded:  (schematic / circuit added 10/02)

Scanmate:  (electronic circuit added 10/06)

Sound Detector:  (electronic circuit added 7/03)

Sound Operated Switch:  (schematic / circuit design added 9/02)

Spatial Distortion Reduction Headphone Amp:  (circuit / schematic design added 6/06)

Speaker Microphone Circuit:  (diagram added 2/07)

Speaker Protector:  (circuit added 7/02)

Speaker Signals to Line Level Inputs:  (electronic schematic added 8/02)

Spyder an Eight Output Pedalboard Power Supply:  Outputs regulated 9V DC (added 4/02)

Stereo Broadcast Limiter:  Circuit for the Ramsey FM10a/FM25 Transmitter (added 4/02)

Stereo LED VU meter using discrete components (BC547 transistors):  (diagram added 2/07)

Stereo Width Controller:  (electronic circuit added 10/06)

Stereo Width Controllers:  (electronic circuit added 7/03)

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. (added 4/02)