Wlutke 7-24-2017
I've researched the Lyngdorf and the idea of room correction is
appealing. God knows my room could use it. On the other hand the idea
of sending square waves to the speakers and having them do the
smoothing curbs my enthusiasm. No D/A conversion? It could be the
future. I'll wait and see for now.
While Lyngdorf's writeups could be interpreted to mean that square waves are being sent to the speakers, I'm pretty certain that is not the case. If it were the case the 2170's excellent THD numbers would be absurdly poor, not to mention that it would make most speakers decidedly unhappy :-)
Most likely the design uses a combination of an inductor and a capacitor at its output to filter out the high frequency (ultrasonic and RF) content of the pulse width modulated square waves, just as is done in pretty much all other class D amps. That amounts to converting the square waves to sine waves, or in the case of a music signal, to a combination of sine waves at various frequencies.
Regards,
-- Al
