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Using a K-12 tube amp with a NAD C542 CD player, there is no need for a buffer or visit page. music which the K-12 does so easily. There was always something missing when it came to a convincing delivery. I felt a little of that beautiful valve warmth was required, so I tried a very affordable Valve Preamp kit from Silicon Chip Online. The preamp kit is based around a common 12AX7 dual triode. The line level (Hi-Fi) version of the kit has the gain set at 4 (6 dB). What makes this kit very inexpensive is that power comes a switch mode power supply, fed from a 17 volt DC wall wart!... line level preamplifier. The K-12 is a very polite and sweet amp with all the warmth of it`s `hot bottle` heritage. However, when I compare the K-12 with my monoblock chip amps (LM3875), I was never convinced that the chips amps really delivered the passion of the

While we have published a number of variations on a standard RIAA preamplifier for magnetic phono cartridges, we have not published a preamp stage for ceramic phono cartridges. Typically, these were supplied as turnover cartridges in record changers but there were higher quality versions such as the Decca Deram. These phono cartridges are piezoelectric devices which require a very high input impedance. Similarly, violin pick-ups made by Fishman, Barcus Berry and others are piezo devices. These two circuits have been requested for a violin pickup but could equally well suit a ceramic or crystal pickup. The op amp circuit uses a TL071 connected as a voltage-follower. It can run from a battery supply of ±9V. Circuit diagram: The alternative transistor circuit uses a BC549 connected as an emitter-follower but with bootstrapping of the input bias network to provide a high input impedance. Both circuits have input coupling capacitors but since the transducers are capacitive (ie, piezo) they...