I have some questions concerning the 2 prolongements present on some double (and triple) manual harmoniums built by Mustel.
Please hear me out and correct me when I'm saying incorrect things
I'm doing my best understanding these magnificent instrument, so here we go:
(Short warning in advance, this is a very technical topic for the "diehards" on this forum hehe expect to be confused!)
OK, 2 manual Mustel church-harmoniums:
As the two prolongement-switches are located at the ends of the lower manual I assume the prolongement-mechanism is only
present for the lower manual (full!! keyboard). If you play WITHOUT coupled manuals you can only prolong the soft-sounding registers on the lower manual
(by using the prolongements) and keep on playing on the upper manual which contains the sharper registers.
I suspect the opposite (prolonging notes on upper manual while playing on the lower) is impossible. (also less natural soundwise)
about the coupler*:
On many double manual harmoniums you play "coupled manuals" from the lower manual. This doens't seem to be the case with Mustel.
The benefit of Mustel's system is (I think) that you have your hands constantly near the register stops (**&*** see below).
I assume that when the manuals are coupled and the prolongements are selected, all notes played on the upper manual are kept pressed down
on BOTH manuals, while playing notes on the low manual doesn't affect the upper manual.
Am I correct in stating that the use of the TREBLE
-prolongement(****) (3 1/2 octaves) is only useful when manuals are NOT coupled?..
..the splitpoint is located an octave lower than the regular pressure harmonium. As a result the "dialogue" between the left and right part seems to be
less important on these instruments, mind that the double expression mechanism is also not working between left and right but between the manuals,
resulting in the return of "sourdine" registers called "pianissimo". Using the treble-prolongement has some stunning possibilities in enforcing this unique dialogue
between soft and sharp registers when manuals are ..of course.. NOT coupled.
I can only thing of 2 benefits of using the TREBLE
1. the legato playing of big chords is a lot more easy
2. you have your hands free for a 3rd manual
..I'm referring to the 3 manual model which is the very alike 2 manual harmonium but with the addition of the celesta.
This made me wonder why the treble-prolongement is not present on the regular 2 manual harmonium-celestas. It would have been nice to play for example
a big chord (with both hands) on the lower manual (=harmonium) and have your hands free to play some arpeggios on the celesta with both hands.
all comment and/or ideas, insights etc. are very welcome.
Please also check my other post concerning the metaphone-expressif
I still have to reply to that post which is the next thing on my agenda..
all the best,
* Does anyone know why there is only one coupler on these instruments??? there are 2 buttons, but they are connected underneath the instrument..
..so when you want to have the flute and fifre (1 & 3) at the same time in the treble, you have to couple the manuals which makes it impossible to have a single 1 in the bass.
**Of course the manuals on harmonium-celesta's couple the same way, but there is it a necessity to have it working like that as the celesta-manual
(which is of course the upper manual as the celesta is located on top) needs a lot of fingerweight and is therefore the manual which should be played
when coupling the harmonium to the celesta.
***In this light it seems strange to me that you can't play harmonium-solo from the upper manual on Mustel's harmonium-celesta's, nor on harmonium-celesta's
made by any other builder. Only some player-harmonium-celesta's (Mustel "Grand Concertal", Schiedmayer "Scheola") have special knobs to turn off the celesta,
so you can play harmonium from the upper manual (close to the stops) when manuals are coupled. Mind that the player mechanism on these huge harmoniums is only working
on the upper manual. So without this "suppression celesta" there would be no way to play rolls without the celesta chiming constantly together with the harmonium.
****the bass prolongement however remains very interesting with coupled-manuals as it serves as the "missing" foot-keyboard as we know it from the organ.