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Composition of Mixtures - Alkmaar or similar?

PostPosted: Wed Jun 09, 2021 2:41 pm
by organsRgreat
Some while ago I came across an article which showed in detail the composition of the Mixtures on the organ at St. Lauren's Alkmaar - famous from Helmut Walcha's recordings. Yesterday I was discussing with an organist friend the way Mixtures break back, and add clarity in the lower part of the keyboard - which is particularly valuable in contrapuntal music, where those lower voices are often as important as higher ones.

I thought the article was by Stephen Bicknell, but I'm now unable to find it. Can any member help, or direct me to a site which shows the composition of mixtures on another historically important organ?

Re: Composition of Mixtures - Alkmaar or similar?

PostPosted: Thu Jun 10, 2021 12:16 am
by PCF
Good morning organsRgreat

Here is the link to Stephen Bicknell's article (which does not contain the compositions):

I have found the compositions for St. Lauren's Alkmaar on
Mixture compositions for quite a few organs have been published in this database.

Franz64 made available a summary document with the mixture compositions of a few organs as well:
The google docs link is still active.


Re: Composition of Mixtures - Alkmaar or similar?

PostPosted: Thu Jun 10, 2021 4:55 am
by organsRgreat
What a superb forum this is! Yesterday I spent at least half an hour searching for this information, then decided I might find it more quickly by posting a query here. Now you've sent me EXACTLY what I was looking for! Many thanks.
The friend with whom I was discussing mixtures has an unusual background. He gained a Master's degree in music at university, with piano as his main instrument and clarinet second. Because my route was via music college (studying piano and organ) I've been able to help him with the practicalities of piano performance. He began teaching the piano locally, and also took up the organ - relatively late, but a perfect fit for a practising Christian. He is now organist at a local church (on an Allen "Renaissance Quantum" organ) and has Hauptwerk at home. In his late thirties he is continuing his studies with an excellent local teacher, and sometimes I'm able to add to his understanding. He was aware of the basic function of mixtures, but not of the way they break back, and how this helps counterpoint.

I will send him a link to this discussion, which is exactly what he needs.

Re: Composition of Mixtures - Alkmaar or similar?

PostPosted: Sun Jun 13, 2021 2:32 am
by PCF
An easy to use online mixture 'calculator' is available:

Among others, it generates visual summaries, which makes it very easy to understand mixture compositions.

Re: Composition of Mixtures - Alkmaar or similar?

PostPosted: Sat Jun 19, 2021 7:19 am
by organsRgreat
This certainly looks an interesting site, but it seems to be available only in French and German; so at the moment I can't understand how it's meant to work. Could you offer a few instructions to get me started? Thanks.

Re: Composition of Mixtures - Alkmaar or similar?

PostPosted: Sat Jun 19, 2021 12:35 pm
by IainStinson
The HELP button on the third entry box gave me some help in English (machine translated).

Seems to work ok. I found "Number of repetitions" was the number of "breaks" (points where the composition changes).
In the second box put the composition for each of the breaks in the column below the break.
In the third window press the Outflows button to see the details of the mixture.