DIY

Welcome to my electronics page. Here's a description of the various DIY audio projects that I have done.

Phonograph turntable

• Details of my DIY direct-drive turntable

• Brushed DC motor speed stabiliser 

Audio circuits

Pre-amps/crossovers

• Phono pre-amp - 1 

• Phono pre-amp  - 2

• 3-way active crossover network

• 2-way active crossover network

• 3-way active crossover - version 1

Power amplifiers

• • 18W/4Ω (9W/8Ω) power amplifier [I have updated the amp to use a better biasing scheme for the o/p stage. Check Version-1 (darlington pair o/p stage) and Version-2 (compound pair o/p stage) for the new versions]

  • 50W/8Ω (100W/4Ω) power amplifier

  • 15W/8Ω (30W/4Ω) power amplifier

• 56W/8Ω amplifier based on LM3875

• 20W/8Ω power amplifier based on STK4132

• 6W/8Ω power amplifier based on TDA1521

• 10W/8Ω power amplifier based on LM1875

• 50mW headphone amplifier

• 200W/4Ω power amplifier based on STK4192

Power supplies

• • ±30, ±15V power supply

  • ±35V power supply

Miscellaneous

• • Simple start-up delay circuit

Complete systems

• 50W/8Ω tri-amplified system

  • Based on

    • 3-way active crossover network

    • 18W/4Ω (9W/8Ω) power amplifier

      • System specifications:

        • Crossover frequencies: 300Hz (low-mid), 3000Hz (mid-high).

        • Crossover type: 3-way 12db/oct, active butterworth filter based.

        • Power (8Ω): Woofer amp 9W, Mid-range amp 9W, Tweeter amp 9W (Total 27W per channel, 54W Left + Right).

        • Note: This system is not being used currently, and has been superseded by the 200W system below.

        • 200W/8Ω tri-amplified system

          • Based on

            • 3-way active crossover network

              • 50W/8Ω (100W/4Ω) power amplifier

              • 15W/8Ω (30W/4Ω) power amplifier

              • System specifications:

• • • • • • • Crossover frequencies: 300Hz (low-mid), 3000Hz (mid-high).

            • Crossover type: 3-way 12db/oct, active bessel filter based.

            • Power (8Ω): Woofer amp 50W, Mid-range amp 50W, Tweeter amp 15W (Total 115W per channel, 230W Left + Right).

            • Photos and description of 3-way active system

• 50W/8Ω bi-amplified system

  • Based on

    • 2-way active crossover network

      • 20W/8Ω power amplifier using STK4132

      • 6W/8Ω power amplifier using TDA1521 (superceded by 10W/8Ω power amplifier based on LM1875 power IC)

      • ±30, ±15V power supply

      • System specifications:

        • Crossover frequency: 3.4kHz.

        • Crossover type: 2-way 12db/oct, active bessel filter based.

        • Power (8Ω): Woofer amp 20W, Tweeter amp 6W (Total 26W per channel, 52W Left + Right).

        • Photo and description of the 2-way active system (Superceded by 170W system below)

• 170W/8Ω tri-amplified system

  • Based on

    • 3-way active crossover network (version 1)

      • 56W/8Ω power amplifier using LM3875

      • 20W/8Ω power amplifier using STK4132

      • 10W/8Ω power amplifier based on LM1875

      • ±35V power supply

      • ±30, ±15V power supply

      • Simple start-up delay circuit

      • System specifications:

        • Crossover frequencies: 312Hz and 3.4kHz.

        • Crossover type: 3-way 12db/oct, active bessel filter based.

        • Power (8Ω): Woofer amp 56W, Mid-range amp 20W, Tweeter amp 10W (Total 86W per channel, 172W Left + Right).

        • Photos and description of the 3-way active system

Loudspeaker projects

• 3-way floor-standing speakers

• 3-way WMTMW speakers

• Isobaric sub-woofer

• 3-way WWMTM speakers with horizontal MTM layout

Basics of loudspeaker design

• How a loudspeaker driver works

• Loudspeaker enclosures

• Designing an enclosure

• Enclosure calculator

Audio software

• • Audio signal generator - A Windows-based program to use your computer or laptop as a signal generator. The program outputs the signal via the sound-card. Requires DirectX 8.0 or better. Download and unzip the file in order to run the installer. Read the help file after installation for more information. The help file can be launched by pressing the "F1" key after starting the program.