Pioneer HPM-1100

Later version of the HPM-100 (and HPM-150) and well-known but rare loudspeaker for the 1980s.
Said to cope perfectly with the increasingly present PCM recordings, Polymer Graphite is the center of the HPM-1100.

PG is a chemical compound holding microscopic particles of graphite cristals produced by vaporisation, all held together by a special polymer.
Graphite is almost as hard as diamond but has a low density, low internal loss and high rigidity.
Furthemore, PG is easy to work with, stable in time and insensible to temperature or humidity extremes.

All three conventional drivers of the HPM-1100 are made of PG, while the two serial-connected ribbon super tweeters are of a High Polymer variant.
The smaller HPM-900 and HPM-700 only have one super-tweeter.

Not to be missed either is the 40cm woofer !
The HPM-1100 is a big boat which needs lots of room to breathe properly to delivers its fast and low-distortion response, up to 50Khz.