Wikipedia
Fontessa is a 1956 album by the Modern Jazz Quartet released on Atlantic Records. It was the first of their albums released on Atlantic. The album was released in the USA in mono on the black Atlantic label with catalogue number 1231. It was released in the USA in stereo on the green Atlantic label with catalogue number SD 1231. The prefix SD stands for Stereo Disc. The current internationally available CD release is the mono version. A Japanese CD exists of the stereo version. Additionally both mono and stereo versions were released in many other territories, for example the UK with London LTZ-K 15022 for the mono and London SAH-K 6031 for the stereo. The 11-minute title tune was released on a 45 RPM 7-inch EP with the track being split across two sides of the record.
The mono version of the album has a good recorded sound quality as one would expect from an important 1956 jazz release. The stereo version is marred by a number of technical flaws. The first of these is a very powerful mains hum consisting of a 60 Hz tone and its harmonics at 120 Hz and also 180 Hz. The second flaw is a remarkably high level of tape hiss. Lastly the level of the bass playing is much lower than the mono release. The combination of these errors would seem to suggest that the stereo recording was experimental in nature and that these recordings were probably only released after commercial pressure for a stereo version. The quality of the stereo image is high despite these flaws and it is possible to get a true sense of space and position of the players.
Track 5, "Bluesology" features a different take on the mono and stereo versions of the record. A recent multi-CD retrospective release featured the mono version of the album, with the stereo version of this tune as a bonus track.