Audio Amplifier Projects

opto-to-coaxial audio converter
Most audio equipmentproduced in thepast five to ten yearshas digital inputs andoutputs. It is a pity,though, that there aretwo standards: opticaland coaxial, and notall equipment hasboth. Fortunately, theconnection difficultiesthat may ensue areeasily resolved by theuse of the adaptordescribed in this article.This enables anyoptical output to beconverted into acoaxial one or viceversa.

digital-audio-input selector
As the name indicates, the selector isintended to choose one of up toeight digital audio signal inputs,which it does with the aid of a multiplexer.The multiplexer, IC6 is controlledby preset up/down counter IC2. Thecounter is set with DIP switch S3(note that the MSB switch is notused in this application).The various inputs are selectedwith press-keys […]

COPYBIT INVERTER
The inverter can be included in theS/PDIF link between any digital a.f. signalsource (such as a DCC recorder, a CDplayer, a DSR receiver) and a (second) DCCrecorder without the need of opening ormodifying any of the equipment. Duringthe copying, any copybit is inverted and atthe same time the category code is altered.This means that […]

COPYBIT ELIMINATOR REVISITED
Our February 1994 issue carried anarticle describing an inexpensive andstraightforward circuit for eliminating thecopybit from a digital S/PDIF* audio signalto enable users to copy (digitally) their ownmusical work many times without degradationby the SCMS**. The present article describesan updated version of that circuit,which can be used with the latest DAT, DCCand MD players.

clipping indicator
A little while ago areader wrote to saythat he had foundoverdrive on some ofhis compact discs.This sort of newscomes of course likea thunderbolt since itis assumed by mostpeople that compactdiscs are examples ofthe quality of today’sdigital technology.The first reaction tosuch an allegation isone of outright disbeliefor at least scepticism.Moreover, it hasbeen alleged by otherreaders […]