Broskie Cathode Follower [BCF] now in Rev. A

Balanced to Unbalanced The BCF receives a balanced input signal and converts it to an unbalanced output. It is a unity-gain buffer that offers a high input impedance, a low output impedance, low distortion, and great CMRR. In addition, because the BCF uses a push-pull topology, its use is not limited to line-stages, as the BCF can be used as a headphone buffer-amplifier if the headphone's impedance is high enough (say, 300-ohms). In addition, much like a signal transformer, the BCF offers common-mode signal rejection (CMRR); this means that BCF passes differential input signal, but largely ignores what is common to both input signals. Why is this a feature?

Common-mode signals are extraneous to the actual input signal and usually consist of hum, power-supply noise, and RFI. The key advantage that a balanced signal offers is the chance to apply a high-CMRR transformer or circuit, which will then scrub away the added electrical contamination. The problem with using a high-quality signal transformer is cost: good transformers are both rare and expensive.

The BCF PCB, like the ACF board, is an amazingly simple affair, holding two tubes, one per channel (two triodes per per channel) and a handful of capacitors and resistors, only four by six inches. It requires an external power supply, which can hold a B+ voltage as low as 24V (6GM8/6N27P/ECC86) or as high as 300V (6CG7 or 6H30 or 12BH7 or ECC99).

Jupiter capacitors are just for display and are not included. The PS-1, PS-3, PS-4 would work well. Includes 12-page user guide.