disco phaser - comb filter with switched resistors

disco phaser elektor december 1983 dis Phasing is an effect well known to musicians. In electronic parlance it is, in fact, a comb filter so called because the response is the attenution and amplification of a number of equally spaced frequencies in the audio spectrum. It lends itself particularly well to sounds rich in harmonics and is therefore ideal for use with recordings, musicassettes, or records containing much percussion, E-string guitar music, or choral works; it is not really suitable for solo instruments. comb filter with switched resistors The filter response which provides the phasing effect is illustrated in figure 1. From this it is easy to see why it is called a comb filter. There are a number of ways in which this can be achieved in practical terms. Studio quality systems can be very complex and therefore very expensive, but simpler methods do exist and, while not giving hi-fi performance, do give a reasonable sound quality. The easiest method, which is inci- dent...