Continuing with my aim to design a sound system for accurate reproduction of digital piano, I made some measurements to determine the required amplifier power and driver excursion capabilities. For output levels on par with a 6′ grand piano, an adequate system will need to reproduce transient peaks of at least 109dB SPL @ 1m and be capable of displacing at least 50 cm3. See below for details.
In my quest for high-quality live reproduction of digital piano, I have often heard it said that a piano needs full-range speakers. The argument is that the lowest fundamental is at a very low 28Hz, while the percussive nature of a piano generates lots of high frequencies. This claim sounds reasonable, but some measurements and spectral analysis show it doesn’t hold up.
Following up on an earlier post, I’ve been investigating why digital pianos sound so bad in stereo. I did a spectral analysis on the outputs of my Yamaha CP50 stage piano. The results confirm what I and others have been hearing: because of how they are sampled, stereo pianos don’t reproduce well except in headphones.
Musicians often complain that their digital piano sounds good through headphones but terrible through an amp/PA, describing their live piano sound as “thin”, “nasal” or “boxy”. This can be frustrating and musically uninspiring. Because the piano sounds good through ‘phones, people naturally blame their amp/speakers and seek a solution there.