The Aikido All-in-One octal stereo PCB contains two Aikido gain stages and both the high-voltage and heater power supplies. This FR-4 PCB is extra thick, 0.094 inches, double-sided, with plated-through heavy 2oz copper traces. In addition, the PCB is lovingly and expensively made in the USA. The boards are 8.5 by 6 inches, with five mounting holes, which helps to prevent excessive PCB bending while inserting and pulling tubes from their sockets.
The new Attn-2 stepped attenuator uses both series and ladder attenuators, with three rotary switches to yield a total of 99 possible decrements of attenuation in 0.6dB steps, which means we can step down to -59.4dB in -0.6dB decrements. The leftmost and rightmost switches hold eleven positions and are mono ladder attenuators for the left and right channels, with only two resistors switched in at a time, attenuating up to -5.4dB per channel, with a mute in the final position. The center switch cascades from the two flanking switches and it defines a stereo series attenuator with 11 resistors in series per channel, with -6dB decrements, establishing a maximum of -54dB of attenuation, with a hard mute in the final position.