Martin Pasi is a fantastic organ builder from Roy, WA (south of Seattle) who specializes in building fine mechanical action organs and doing quality organ restorations.
The organ at St Cecilia Cathedral has 3 manuals and 55 stops. The facade of the instrument resembles closely historical Italian organs. Although this organ is spectacular in its own right, one of its most remarkable features is the ability to perform music on two different musical tuning systems (temperaments).
This organ has both well-tempered and quarter-comma meantone temperament which is especially useful if you want to play an early and later music on the same organ. The meantone temperament is based on the system of tuning perfect major thirds and it permits to hear the perfect consonant sounds from the Renaissance and the Baroque periods.
In this temperament, every key has its own character and not every halfstep is equal (like in modern equal temperament). Therefore, the dissonant chords, chromaticisms, and suspensions are especially audible in this kind of tuning.
The flip side of this system is of course that you can't really use all 24 major and minor keys and that the possibilities for modulations are limited. But since the majority of music from the 16th-17th centuries requires less than 3 accidentals, this temperament is exactely what was used in the Renaissance and Early Baroque times.
Note that the second temperament on this organ is still not equal but rather a well-tempered which means that it still has preserved some irregularity and characters of various keys. However, you can now use every key you want on this system. Therefore it works really well for more dissonant music of the 19th and 20th centuries.
Martin Pasi conceived an idea of a dual temperament organ in Omaha, NE from other 3 instruments which have the similar idea: organs at Stanford University (C.B. Fisk, Op. 85) (USA) and the Wegscheider organs at the Allstedt Schloßkapelle (Op. 1) and Dresden-Wilschdorf (Op. 21) (Germany).
While the two temperaments of the Stanford Fisk are made possible by five extra pipes per octave, and the smaller Wegscheider organs have six extra pipes per octave, 29 stops of the Pasi organ have 8 extra pipes per octave.
You can listen to the podcast in iTunes of organ and choir music where organist Marie Rubis Bauer performs with choirs from St. Cecilia Organ Festival. This music was recorded live at Saint Cecilia Cathedral on October 3, 2003 on the occasion of the inauguration of this organ. These recordings capture the experience of performers and listeners, who participated in this inaugural celebration.
I was there that day (I was a DMA student at University of Nebraska-Lincoln at that time) and remember this evening as one of the most memorable concerts ever.
If you want to know more about this organ, check out the website of Pasi Organ Builders which has detailed specifications, technical descriptions, photos, videos, and a list of CDs recorded on this fantastic instrument.
By the way, do you want to learn my special powerful techniques which help me to master any piece of organ music up to 10 times faster? If so, download my free video Organ Practice Guide.
Or if you want to learn to improvise in the style of Bach? If so, I suggest you check out my free 9 day mini course in Keyboard Prelude Improvisation.