It has been almost three months since my last blog post. I have been busy tending to other things but I have also been busy advancing the v3.0 attenuator and the v2.1 phono preamp (more on this later). The photo below shows the rear of the right channel v3.0 attenuator. I have so far built one complete pair for testing.
Rear of v3.0 attenuator.
The v3.0 attenuator is a radical departure from the v2.0 series attenuators that used a vacuum chamber to reduce relay switching noise. Instead of a vacuum chamber, the v3.0 attenuators use tiny reed switches and a few reed relays to perform the switching duties. The use of reed switches and relays allows the v3.0 to be significantly smaller and less costly than the v2.0 series attenuators.
The picture below shows the ladder section of the v3.0 attenuator. There are two circular attenuator levels shown with 12 steps on each level. This attenuator has a total of 24 steps. The v3.0 design allows for a total of eight levels or 96 total levels if desired! The level selection is preformed using tiny magnets on a “yoke” (red part in picture) that is rotated into position with a stepper motor (silver parts just to the left of center in the picture) to ensure accurate level selection.
Ladder section of v3.0 attenuator.
The v3.0 design includes two stepper motors; one stepper motor (black part at left side of picture) for the knob and the second motor to perform the level selection. Each of the two stepper motors are controlled by a Trinamic driver in StealthChop mode to ensure silent operation.
The testing of the v3.0 attenuator is ongoing but so far the results have been spectacular!