Digital Piano Reproduction: Polyphonic Interference

This is another in a series of posts about why digital pianos often sound bad in live performance, and what can be done about it.

Sometimes when I play a chord on my digital piano (DP) the tone sounds suddenly and unexpectedly thin. Striking the same chord again might sound better, or sometimes worse… or just different. This effect is most audible on sustained chords. I find that it’s much worse with live sound, especially in mono. Stereo usually sounds better, especially in headphones where I hardly ever notice it.

This inconsistency of tone is very distracting. It feels like all the body drains out of my tone at random, making me cringe and back off of certain chords. Such haphazard tonal quality can make my playing timid and uninspired, and has made a lot of gigs not fun at all. Continue reading

Digital Piano Reproduction: Output Level

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.

Continue reading

Digital Piano Reproduction: Frequency Response

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.

Continue reading

Atlona HD570 distortion / subsonic transients

In my linux pc-based dsp system for crossover and EQ of active loudspeakers, I use a pc to send 6 channels of processed audio over hdmi, with an Atlona AT-HD570 to convert all channels to analog before amplification.  Recently I discovered that this setup can distort badly at moderately high signal levels, in a way that produces large transient subsonic signals which, when amplified, could permanently damage loudspeaker drivers.  My measurements point to a flaw in the HD570.
Continue reading

Digital Piano Reproduction: Phase Issues 1

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.

Continue reading

rt-plugins-0.0.4 released

I just posted version 0.0.4 of my LADSPA plugins for doing crossover/equalization of active loudspeakers.  Just a couple of changes to note:

  • First-order low- and high-pass filters are now available.
  • The build system has been moved to cmake; hopefully this makes it easier to build the plugins on other platforms.  Also some code cleanup and restructuring. (All thanks to Florian Franzmann.)

There’s no need to upgrade if these changes don’t affect you.

At some point the LADSPA API will become deprecated and my plugins will have to be migrated to LV2.  Any volunteers?