Lint Audio KWELA TONES, Assembly Instructions Manual

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2
Introduction
The
Kwela Tones
is a South African clone of a very renowned headphone amplifier originally designed by Pow
Chu Moy.
Why
Kwela Tones
? Its made in a tin…Kwela is South African music made with a tin whistle ! So why not !
The headphone amplifier is designed around a dual-channel op amp such as TI s OPA1642 or TL 072 (page 31)
However, a wide variety of Op Amps have been successfully implemented. As the Op Amp directly drives
headphones some care should be given when choosing an op-amp, some op-amps are not suitable for such low
impedance loads and will result in poor performance.
A TL072 is supplied to experiment with and this is known as “rolling” (page31)
The amplifier's design is quite simple. It consists of only a few components, can be assembled on a small printed
circuit board, has a lower parts cost than other headphone amplifiers, and can run for many hours on two 9 volt
batteries. Our tests show at least 80 hrs on a set !
The CMoy headphone amplifier can be fitted into a Fisherman's friend tin and can often be found for sale in
Dischem. Other suitable tins are the Lindt chocolate heart shaped tin. Cigar boxes also work well.
A typical CMoy consists of two identical AC coupled non inverting amplifier circuits each with a 100k Ω input
impedance.
Power is supplied to the op amps using a dual power supply, which effectively divides the input voltage source in
half to create a virtual ground.