Mixtures

[Guest]

Can someone give a definition and explanation as to what is meant by mixtureor mutation?What do the names or numbers for mixtures on a stoplist mean such as "mixture IV"? My Gulbransen President has severalstops that are combinations of various tones. Is this the same thing as a mixture or a mutation?

[jbird604]

Re: Mixtures



Mark,</p>

A mutation is a stop that sounds in between octaves.Examples include the Nazard 2 2/3 and the Tierce 1 3/5.
</p>

Stops at 16', 8', 4', 2', 1' are all octave-related, but the Nazard 2 2/3 sounds a pitch that is in between a 4' and 2' --- about an octave plus a fifth above the 8' stop. In other words, if you play middle C on the 2 2/3' stop, you will hear the G in the octave above.</p>

The 1 3/5' (tierce) sounds two octaves plus a major third above the 8' -- so if you play middle C you hear an E way up there somewhere.</p>

Of course, in a non-unified organ these stops are correctly tuned to the harmonics of the 8' stop and are not exactly a G or E. But on a unit organ, including most all analog electronics, they just borrow the G or E from the appropriate octave.</p>

Obviously you wouldn't play a mutation stop by itself because it would be the wrong notes! You add them to 8' stops for a particular tonal effect. For example, playing an 8' flute with both the Nazard 2 2/3 and the Tierce 1 3/5 will give a very clarinet-like tone color.</p>

Mixtures are stops that contain multiple ranks, usually tuned to the very high harmonics of the 8' stop. Mixtures may contain both octave-sounding pitches (such as 2' and 1' even higher tones) and fifth-sounding pitches (such as 2 2/3, 1 1/3, 2/3, etc.) Rarely do they contain third-sounding pitches (such as 1 3/5) but these are not unknown.</p>

There are all kinds of mixtures with different pitch compositions, and the ranks usually break back at various points in the scale. There should be a detailed description somewhere out there in the internet, if you want more detail.</p>

With both mixtures and mutations, some people like them and some don't. We've all played an organ sometime without any of either, and one wouldn't consider them absolutely essential. But like cooking spices and flavors, they have their place when used correctly.</p>

Now someone with more knowledge jump in and correct anything I may have mis-spoken here.</p>

John</p>

</p>

[soubasse32]

Re: Mixtures



[quote user="jbird604"]Of course, in a non-unified organ these stops are correctly tuned to the harmonics of the 8' stop and are not exactly a G or E.[/quote]Well... yes, they are still a G or an E -they just happento be tuned differently. [:)]</P>


I would add only one thing -the reason for Mixtures. If you don't use Mixtures the bass can be very muddy. Try playing a familiar melody on an 8' flue stop in the lowest octave. Unless it is a very keen string stop you will probably not even recognize the melody. If you add a Mixture, the melody becomes instantly clearer.</P>


In the treble we have the opposite problem -the pitches of theunison stops are so high as to be somewhat unpleasant. A Mixtureadds lower pitches (some via resultant tones) as you go up the scale; by the time you are at the top of the keyboard the Mixture will give the treble some weight and gravity.</P>


In the middle of the keyboard a goodMixture will enliven the tone and give complexity;it helps delineate the inner voices in polyphonic writing.</P>


Mixturesare known as compound stops, since more than one pipe plays.</P>


Mutations are sometimes called fractional stops, since the pitch designation requires a fraction.</P>


There's another type of compound stop, known as a Synthetic stop.One example would be a syntheticOboe- itdraws an 8' Salicional and a 2 2/3' Nazard. It is 'synthesizing' the harmonic structure of a reed Oboe stop.</P>

[Clarion]

Re: Mixtures



Mixtures are basically a bunch of high-pitchedtin whistles operating somewhere around the2-2/3, 2, 1-3/5, 1' range. They always sound the same whether playing mid, top, or bottomof the keyboard. Occupying about an octave or so of space at the top of the keyboard, they merely repeat themselves octave-after-octave. Mixtures sound pretty much the same, whether played on the lowest or highest octave of the keyboard.</P>


Their purpose: To contributeconsistent brilliance and definition regardless of where on thekeyboard music is being played.</P>

[MarkS]

Re: Mixtures



At a master class Peter Conte asserted that he doesn't do "fractions or Roman numerals."</P>
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[davidecasteel]

Re: Mixtures



Mutations are stops that play harmonics of the basic octavely-related voices. A harmonic is a frequency that is an integral multiple of the Foundation pitch; for example, the third harmonic is 3 times the frequency of its Fundamental. Mutation stops are tuned to those harmonics to be added to the Fundamental stops and provide additional color. SB32 has already alluded to how adding the 2 2/3' and 1 3/5' mutations to an 8' flute can simulate the sound of a clarinet quite well. Mutations "belong" to particular Fundamental footages, of which they are the harmonics. It is easy to determine both what pitch a mutation is a harmonic of and which harmonic is is by taking the footage value and converting it from anmixed number(e.g., 2 2/3') to an improper fraction (e.g., 8/3')--when this is done, the numerator (8')indicates the Fundamental pitch and the denominator (3) gives the harmonic of that Fundamental. Looking at the 1 3/5' mutation, that becomes 8/5' and it is evident that it represents the 5th harmonic of an 8' pitch. Mutations are usually expressed in reduced form--that is, with the lowest denominator possible. Of course, it is possible to use other forms of the fractions: 1 1/3' can just as easily be written as 1 2/6', for example, and that is the equivalent of 8/6' and would be the 6th harmonic of an 8' pitch. The 1 1/3' is 4/3' (same as 8/6') and that represents the 3rd harmonic of a 4' pitch. And in fact, the 3rd harmonic of a 4'pitch and the 6th harmonic of an 8'pitch have the same frequencies.</P>


As SB32 mentioned, true mutations (those for which separate ranks of pipes are provided) are tuned to be perfect multiples of the pitches they are harmonics for, and that is the most satisfactory condition. To save space and/or cost, some instruments "derive" their mutations by energizing pipes in the same or other ranks of the same pitch that are close to the multiple of the Fundamental (such as the G an octave and a half abovea played C)--because of the temperament used in tuning organs, these notes are not perfect multiples and the effect is not as good.</P>


Mixtures are compound stops that play more than one pipe when a key is pressed. Some mixtures play only 2 pipes per key, others may play 8 or more. True mixtures have separate ranks of pipes (one for each key) at each of the pitches incorporated in the mixture, and the number of ranks is shown by a Roman numberal (a Sesquialtera II invokes 2 pipes for each key, so there are 2 ranks of pipes dedicated to that purpose).</P>


Some mixtures are "straight", which means that their ranks uniformly increase in frequency from bottom to top. Sesquialtera mixtures are usually of this construction, and are made up of 2' and 2 2/3' ranks (mostly). Other mixtures have "breaks" in their frequency sequences, designed to keep the pitches of the mixture pipes mostly in the upper mid-range, where the stop is used to add clarity to the ensemble. As the notes are played up the scale, the highest pipes become too prominent and shrill and they are eliminated from the mix; at the same time, lower pitches are added at the bottom to continue to provide the desired support. A mixture that originates as a 1 1/3', 1', 2/3' grouping may progress through being a 2', 1 1/3', 1' set, then to a 2 2/3', 2', 1 1/3' set and possibly several other configurations before the top of the scale is reached. The selection of the break points is not usually at octave intervals and is one of the things left to a skilled tonal designer to determine.</P>


SB32, please feel free to criticize and correct the above as necessary.</P>


David</P>

[Menschenstimme]

Re: Mixtures

Thank you, David; I enjoyed reading that very much! I think that a "straight" mixture may also be referred to as a "progressive" mixture.

[Guest]

Re: Mixtures

Mutation in organ is like in other fields such as biological sciences. The original sound of any stop is altered to an extent by a mutation stop. The mutation is an off-unison stop: 2.2/3 1.3/5 1.1/3 1.1/7 8/9 8/11 8/13 8/15 5.1/3 3.1/5 2.2/7 1.7/9
The mere addition of a nazard 2.2/3 to a 4ft flute will between the two stops generate a light unison tone. Why? Because both the nazard and the flute at their respective pitches reinforce nartural harmonics found in the tone of an 8ft stop. The 4ft is the 2nd harmonic and the nazard is the 3rd harmonic and so when independent stops of these pitches are combined the blend in a fashion that creates a resultant tone at 8ft pitch albeit a light one.

A mixture of any sort of two or more ranks will sound a chord when a single key is depressed. Mixtures are designed so that the individual pipes blend so well with one another that they sound like a single tone when in fact they are comprised of multiple tones that coalesce so incredibly well that you are hard-pressed to be able to hear the individual elements contained therin. It is generally preferable that breaks in the mixture composition take note of whether that mixture is intended for solo playing as well as chorus playing. If it is to be used for solo line playing the ingredients in the upper ranges of the keyboard need to be such that the resulting tone remains at unison pitch; otherwise a partial of a different harmonic series say like a 5.1/3 at the very top end of the manual will transpose the melody down an octave by the resulting 16ft tone. In order to avoid that then instead of introducing a 5.1/3 at the top of the keyboard an 8ft rank is added instead so that the line remains at unison pitch when playing solo even way up there.

In 1949 in The American Organist Sen Emerson Richards of Atlantic City fame writes that his mixture designs at the now Boardwalk Hall organ reflected a lack of understanding that certain partials that were included in the mixtues in the 1930 design had the effect of creating resultant tones that actually thicken the chorus rather than clarify it. In retrospect he indicates that he would have done them differently had he known or understood back then the phenomenon of which he speaks. Iam hoping that the current authorities at Boardwalk hall might consider a revision to the organ's mixtures as per the 1949 Richards' articles so that the resurrected organ can be more utilitarian and less of a museum piece by having clear sounding mixtures sans unwanted resultants transposing the melody line to 16 and even 32 ft pitch.

In response to the ongoing ''another 7-manual'' thread as regards high pressure double-languid flue pipe construction please note that the highest at Boardwalk is the Stentor Mixture in the ceiling fanfare voiced on 35'' with all mixture pipes of enormous scale and all double-languid design.

[soubasse32]

Re: Mixtures



The only non-breaking Mixturesin common use today are to befound in Pedal divisions; this is because these Mixtures are a bit lower in composition and because there are only 30/32 notes in the Pedal division.</P>


An 8'series manual Sesquialtera typically does break, at least in the 1 3/5' rank; this is to keep the upper pipesfrom beingimpractically short. My Sesquialteragoes to3 1/5' in the top octave.</P>


I'm aware of some Mixtures from the romantic area that do not break in the octaves where one would most likely play a melody. But even thesebreak at some point.</P>


The romantic-eraProgressive Mixture (Cavaillé-Coll's Fourniture harmonique, Plein-jeu harmonique)adds more pipes as it goes up the scale; the top pitch forms a relatively lowplafond (ceiling),which does not break. As you go up the scale more pipes are added, and these would be of lower pitches. These Mixtureswere somewhat experimental and exist in very few examples.</P>

[davidecasteel]

Re: Mixtures



I stand corrected. Thank you, SB32.</P>


David</P>

[Guest]

Re: Mixtures



''The only non-breaking Mixturesin common use today are to befound in Pedal divisions; this is because these Mixtures are a bit lower in composition and because there are only 30/32 notes in the Pedal division.''</P>


Not exactly-though generally correct. The additional exception still in use and to be found is the Grave Mixture II and the rRuschquint II. Both of these do exist still in many extant organs by various builders and typically are non-breaking made of 2.2/3 and 2 principal or diapason pipes and are excellent for a tangy top to a chorus sans excessive brilliance and add a nice edge to a combination including the swell reeds 16-8-4 even if the mixture is on the great yet still it adds a nice filler to a swell reed chorus.</P>

[quantum]

Re: Mixtures



Ok I have a quesiton.</p>

What is meant when non roman numeral is placed beside the mixture name. </p>

Eg: "1/2 Cymbale III rangs" what does the 1/2 refer to?</p>

There are several such indications on this organ:</p>

http://www.nycago.org/Organs/NYC/html/AliceTully.html
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[davidecasteel]

Re: Mixtures



Normally, I'd expect that to indicate the "footage" pitch of the lowest rank of the mixture. That's a pretty high-pitched 3-rank mixture, though. (However, our Klais instrument has a 1' Scharff IV.)</P>


David</P>

[soubasse32]

Re: Mixtures



[quote user="davidecasteel"]Normally, I'd expect that to indicate the "footage" pitch of the lowest rank of the mixture. That's a pretty high-pitched 3-rank mixture, though.[/quote]That's right - it indicates the pitch of the lowest rank in the mixture.</P>


That is a high mixture, but this is not uncommon for a French Cymbale. These often start rather high-pitched, but break quite often.</P>

[cosmicpanda]

Re: Mixtures

SB32, you mention a tierce rank breaking back - if a tierce existed as an independent mutation, would this still break back in the top octave, or would the length of pipes in this case not be considered impractical?