Monthly Archives: May 2016

Automatic voltage reduction!

There is one final feature that will make it into the final firmware: automatic voltage reduction.

During playback in “live quartz mode”, MagicQuartz can reduce the motor voltage to reduce motor hum. I’ve worked on this due to request from a “future” user. I was sceptical at first if this has any benefit at all. But it has! My Dual 1219 is dead silent when running at 70 Volts! 🙂

Implementing this was a bit tricky. At such low voltages, the motor status detection (if the motor is turned on or not) is not properly working. During normal operation, MagicQuartz is using the current draw to determine the motor status, and at a dramatically reduced voltage, this becomes unreliable.

But in live quartz mode, MagicQuartz can rely on the optical sensor signal to determine the motor status. Whenever MagicQuartz detects a deviation from nominal speed (i.e. when the platter stalls or the turntable’s automatic start/stop funtions are in operation), it automatically boosts the voltage back to normal. This works very well.