geigen principal stop type

To what stop family does the geigen principal belong -- the strings or the diapasons?

It's usually a stringier or thinner sounding (narrow scaled) principal (diapason) tone, not usually considered part of the string family, but often called a hybrid, which can do double duty in a principal chorus or as a mild string, and sometimes used in a string celeste.

The boundaries of the flue families aren't really that precise, so this is a matter of opinion.

Another one that falls into this categoría is the salicional. It can be a very small scale string string [early 20th cent American and English organs] to a small scale principal [French romantic and most current American examples]

John

Tonally, a Geigen Principal will usually produce more harmonic content (and less fundamental as implied above) than a standard principal because of it's narrower scale.

The Geigen Principal is often used in English Swell divisions with an 8' foundation.

My limited experience suggests that on a two manual instrument, it's most often the "minor" principal (where the Great Principal is the "major") and will tend to be voiced slightly fatter / fuller (e.g. in the principal direction). On a larger instrument with a Choir / Positiv division, there'll often be an alternative principal stop in that division, so the Swell principal will be more valuable for introducing harmonic content (like the rest of the swell) and the scale of a Geigen will tend to be narrower and the tone thinner.

This is of course complicated by different builders having their own preferences and the presence (or not) of other string, principal or hybrid stops (e.g. Gamba, Viola, Salicional, Open Diapason, Principal) where the function of the Geigen will change according to the disposition of the rest of the division / instrument.

It's worth mentioning that it's common to extend / duplicate whatever is used for the Swell 8' principal to provide the 4' principal too. This is why you quite often see combinations of Salicional / Salicet or Geigen Diapason / Geigen Principal for the 8' / 4' combination on the Swell. (More often though, the Swell 4' principal is called "principal" or "octave" and the only way to be sure what it is, is to hear it or look at the pipework.) However, in all of these cases, it's clear from the relationship between the 8' / 4' stops and their naming that the intention is for the Geigen to be considered with the other principal stops and not the strings.

Thanks for the in depth information. Very interesting.

Rgds,
Ed

Yes, thank you all for this very educational discussion. I see there is quite a bit I need to learn about organ voices, which is particularly important to me for setting up my pistons and rocker tabs. I plan to rely on this hardware rather than touch screens. I will have 24 pistons on each of my two keyboards (purchase imminent), and 32 rocker tabs along the top, so I will be having to make choices for what voices to assign to them, as well as how to organize them.