Prelude buffer

elektor july/august 1983 K~C3 prelude buffer In the final Prelude article, Prelude p.s. in the May issue, we described a buffer stage that can be used at the inputs and record output of the unit. As promised here we have the design for the printed circuit board (figure 2) for this buffer. The circuit diagram is repeated again in figure 1 The buffer consists of a super emitter follower, in which the actual emitter follower is formed by connecting Ti and T2 in cascode. The load of the emitter follower is a current source, consisting of another cascode con- nection (T3 and T4). The resultant circuit has excellent linearity and very low output impedance: effec- tively zero ohms. There are significant advantages to be gained by the use of these buffers: Crosstalk between the channels and between the various inputs is reduced to a negligible level (better than 60 dB). The External-In input can also be provided with level control by using one of these buffers. 1 The output impedance of T...