Ultimate performance MM / MC phono stage
The Johann Sebastian Bach phono stage, or JSB for short, has two freely configurable inputs that can be connected via XLR or, alternatively, via cinch. The extremely simple operating concept visualizes the operating status via LEDs on the front panel. Of course, the selected configuration is saved after switching off, so that all settings are available again the next time you listen to music.
Complete signal switching with gold-plated, bistable relays. With this type of relay, the armature remains in one or the other switching position. An external voltage to maintain the magnetic field is not required. In other words, when switched, the relay acts like a mechanical switch. There are no negative influences of the control circuit on the signal. It was only through the use of these special relays that it became possible to sensibly integrate operating convenience into a phono stage.
Discrete JFET input stage connected in parallel to reduce input noise. Similar to tubes, JFET’s do not load the signal source; in particular, no direct currents (DC bias) can flow in or out of the phono input. This is particularly important to avoid magnetization of the pickup. The symmetrical structure of the input does the rest, the pickup only "sees" the selected terminating resistor and nothing else.
The passive equalization network reproduces the RIAA curve with an accuracy of ± 0.1 dB. The lower pole / zero pair (3180 μs / 318 μs) and the upper pole (75 μs) are deliberately designed separately to avoid interference between the two. An integrated low-cut filter (5 Hz, -12 dB / octave) removes excessive subsonic frequencies. It is also worth mentioning that the filter networks act between the symmetrical stages and is not connected at any point to the potentialy noisy ground.