Cavaillé-Coll's four fonds
This essay first appeared on the electronic mailing list Piporg-l
I have had several requests for some kind of description of how the four typical flue foundation stops of a Cavaillé-Coll organ actually work in practice. Here goes!
First I would like to affirm that the effect is quite unlike four stops of similar type on organs made in other styles. Very few English or American romantic organs have the necessary qualities. To take an extreme example, in a vintage Harrison & Harrison one might find Open diapason I, Open diapason II, Claribel flute, and Stopped diapason, but these are not designed to be used together. The Stopped diapason might be audible when added to the Open II, but as the latter is likely to be of geigen (moderately keen) quality and slow in speech, and the Stopped diapason quick and dull, the blend will not be perfect. The Claribel will be very full and pure and will swamp the Open II or Stopped diapason; the Open I will be large and foundational with a strong bass, and will swamp the lot. It's oil and water - no wonder George Dixon, the leading exponent of the 'Imperial' style of organ design, recommended that diapasons and flutes should never be drawn together.
Cavaillé-Coll never built an organ of soft stops and loud stops, but maintained his own personal version of classical balance between the ranks throughout his career. However, there are several aspects of his style which make his recipe pecularly effective and interesting.
The Montre 8', Flûte harmonique 8' and Bourdon 8' are the invariable components of the sauce; variety, from instrument to instrument, comes from different scalings and progressons and the addition to the trio of a Viole de gambe, Violoncelle, or Salicional.
Firstly there is a uniformity in the style of voicing between these various ranks. This stems partly from the fact that Cavaillé-Coll stuck to rather 'quick' speech (a voicer's term referring to the fact that the languid is set low). This is inclined to make the pipes slightly dull in tone, allowing the nicking to be light and on the face of the languid only. Good articulation is preserved in all ranks. Though this articulation hardly amounts to an audible chiff, the Montre will speak with a trace of the octave (the basses are often made without ears, a fact which forces the speech to be set quick), the Flûte harmonique will speak with a trace of the sub-octave, and the Bourdon will speak with a trace of the octave quint (2 2/3'). The string rank will start with a characteristic 'dzzzh' consonant (if you know Russian you will know what I mean!).
Notice that we are already encountering effects of great variety and complexity. This is accentuated by the fact that each rank embodies trace elements which are related to its neighbours. The Montre will be fluty on account of generous scale, quick speech, and the unfocussed effect of having no ears, but an element of string tone may be present if the pipes are slotted. The Flûte harmonique is not an orchestral flute (although it passes well as such in the correct register); it is actually a harmonic partner to the Montre, a principal stop of large scale and double length. It has an open wooden bass of full but horny tone (modest scale, slotted, the flue cut in the block not the cap), with the harmonic section starting around middle f. The harmonic pipes have the virtue of speaking with the harmonic build-up of a true 16' register, adding the faintest trace of 'sub' tone to the entire mix (there are 5 1/3' and 3 1/5' components which only a harmonic stop can provide). Cavaillé-Coll was obsessed with melodic strength: Montre and Flûte harmonique together are designed to provide this. The bass of the Montre is likely to be gentle in power, the treble harder, brighter and louder. The Flûte harmonique fills out the bass, adds power to the treble, and gives a distinct colour to both the speech and continuation tone.
The remaining two stops are the lesser partners to this major pair. Bourdon and string together give the 'Fonds Doux' (doux = soft, sweet), in gentle imitation of their senior brethren. The combination of the two usually sounds so like a lesser principal rank as to make the provision of a small open diapason completely unecessary (just as the combination of Montre and Flûte harmonique makes the provision of a large open diapason completely unecessary). Indeed in some Cavaillé-Coll r»cit divisions the 4' ranks are Viole 4' and Flûte octaviante 4', together sounding uncannily like a single rank of 4' principals.
The string rank will add a trace of colour to either the Montre or the Flûte harmonique, but normally neither it nor the Bourdon are quite strong enough on their own to add appreciably to the Montre and Flûte harmonique (though the Bourdon thickens the sauce very slightly). But, together, the string and Bourdon are strong enough to balance either of the senior ranks on their own or to make a significant background colour in the four-rank ensemble.
The bass to treble balance of all four is that familiar from an English or American string stop, but contrasting with romantic techniques in the English speaking world there is no attempt whatever to make the basses of the principals or flutes loud enough to be heard in major combinations. The bass of the Montre will support the treble of the Montre, but the bass of the chorus with mixtures is held up by the bass of the upperwork as much as by the bass of the Montre itself, and in full organ the necessary underpinning is provided by the reeds and by the independent (but mild) pedal fluework. In the fonds the abiding impression is of a gentle, unfocussed but full bass with a very strong melodic impetus in the treble. The bass-treble crescendo is often carried to lengths that the English speaking world would believe impossible: the montres are to varied scales but sometimes the halving is as slow as the nineteenth or twentieth note.
Finally, a lot of the success of the recipe is related to the precise nature of the voicing and the speed of speech. These are characterful, articulate voices, but without any trace of neo-classical huskiness, breathiness, windiness or chiff. Please note that is a style of voicing which cannot easaily be imitated on elecro-pneumatic actions where the pallet opens much faster and the speech of the pipes has to be set slow.
Another school of organ building which can show something like this is that practiced in the Netherlands in the late eighteenth and early ninteenth centuries, where a similar effect is obtained from the three typical foundation ranks of Prestant (narrow bass but cut up high), Baarpijp (stringy spitz flute) and Holpijp (fat chimney flute). It is perhaps no coincidence that Cavaillé-Coll admired the organs of Bätz, whre the mélange also includes a full organ with mixtures, cornets and batteries of reeds 16', 8' and 4' (fine examples survive at Utrecht Cathedral, at the Lutheran Chruch in the Hague, and elsewhere).
As you can see the picture is complex and fascinating: there is more detail in these four typical Cavaillé-Coll stops than you will find in an entire organ by a less inspired builder. References to cooking have peppered this description: to extend the likeness further it would be no exaggeration to say that the Cavaillé-Coll jeux de fonds make the roux on which every registrational dish is based.