lym 1.0t - prospettiva - 980px
Two Stages Output Filter: Why is better?

filtri doppio stadioIn all class-D amplifiers, on the output to the speakers, a low pass filter must be used that extracts the audio information (analogue) from the PWM signal (digital). The accuracy and quality of sound reproduction depends on the type and the design of this filter.

For the LYM1.0T, we chose to adopt a two-stage filter (LC + LC). This solution, compared to the often used single stage one, can further reduce the high frequency noise coming from the PWM (Pulse With Modulation) which is based on the operation of a Class D amplifier, and improves THD + N to obtain an extremely accurate reconstruction of the audio signal.

The software simulations in the design phase and subsequent adjustments made to the circuit allowed for the best results. The accurate listening tests, performed by sound professionals, have proved the quality and excellence of this solution.
We did not use air-core coil filters because they have a high leakage flux and we could not meet the EU directive (EC 2004/108/EC) which stipulates the maximum limit for radiated noise (generators of potential interference to other nearby devices).
As a filter, we could have used the certainly better toroidal inductors, but due to the lower power of the LYM1.0T, we would not have obtained noticeable improvements, but only additional costs.