Break backs in high pitched flues or mutations?

I'm having a bit of an argument on another forum with someone who is fairly knowledgeable about organs. However he claims that aside from Italian organs and a few other examples, that it isn't a common practice for organ builders to break back high pitched mutations and 1' stops, and that rather they usually use harmonic pipes at the very top of the compass. However, I have quite a few Hauptwerk organs where they do appear to break back. Here's the ones I have:

Salisbury Willis, Choir Tierce 1 3/5
Adlington hall - Nineteenth (2 2/3) and Twenty second (1')
Immanuel Presbyterian Schlicker: Larigot 1 1/3
Giubasco: Larigot 1 1/3
Mary the virgin Budapest - Sifflote 1' and Oberton 1 1/7​'

Also, the Pos Piccolo 1' on the Notre Dame de Metz breaks back. It's not an original stop, but presumably it's disposition is based on other organs that CC built? The person I'm arguing with claims that it breaks back because MDA ran out of samples, but I'm savvy enough programming for Hauptwerk that I know that's not the case. The added mutations to the Immanuel Presbyterian also break back, but why would Evensong have done this if it's not common practice?

Do you guys have any other examples I could use to defend my point? Or does it turn out he is right?

Personally I'm not a huge fan of those tiny overblown harmonic pipes some builders use at the top of those high pitched stops, but I admit that they are used.

In the UK, it is usually the case that Mixtures have breaks to ensure that the top pipes don’t get too small to make and maintain. Many of the detailed specifications describe the composition of the mixture stops as they ascend and very frequently top few notes of the highest rank will not be higher than a 15th. An important skill in designing organs is working out how to arrange the mixture breaks. I have noted that sometimes a 1ft will break back an octave from top F or more usually for the whole top octave.

The speaking length of the top C on a 2 ft rank would be 3/4 of an inch, for a 1ft it would be 3/8th of an inch. Manufacturing and maintaining pipes much shorter than 3/4 inch would be impractical. All of the books I’ve read on organ construction describe breaking back high ranks and top notes of mutations.

I would be interested to learn of any instruments that had harmonic mutations / mixtures.

Iain

[ Harrison & Harrison organs sometimes included a Mixture called "Harmonics" . This included the 17th, 19th, flat 21st and 22nd which broke back after the first 2 1/2 or 3 octaves. The pipes where simple flue pipes not harmonic pipes.]

Meanwhile I have sampled two organs which have built in break backs in flue ranks. Also I have noticed that reeds are often replaced by flues in higher octaves.
That‘s all not unusual.

I can confirm that observation from the organs I have recorded so far. It is definitely not unusual for a high pitched mutation or 1' rank to break in the upper octave. Replacing reeds with flues in the high pitches (like top octave of a 4ft Clairon) is also quite common pratice. In one case I had a Septime (1 1/7') that went back to the 2' pitch in the top octave. Breaking back to a 2 2/7' would not be a good option, as that is not part of the overtone series of the 8'.

A straight rank (e.g. of 1´ pitch) may extend to the top note without a break. If the key compass is only 4 1/2 octaves (56 notes, C2...G6) instead of five octaves (61 notes, C2...C7), one can build the 1´ pipes to the heighest note, whose frequency will be about 12 kHz. If you built it to top C (C7), it were c. 16 kHz and normally inaudible to older persons. Such small pipes cause several problems:
- manufacturing such a tiny pipe,
- tuning it correctly,
- stability of tuning and its speech.
In principle, such pipes are still possible to build, but theirs mouths are so tiny that minute amounts of dust will change their pitch and their speech (onset).
Thus, many organ builders build no shorter pipes than for 2´ ranks (or the Tierce 1 3/5´), espec. when the ranks extend over five octaves. For example, the John Compton Organ Co. adhered exactly to this practice. Higher pitched ranks (like a 1 1/3´ or a 1´, both used in Mixtures) ran out of pipes for the top notes. To hide this lack of pipes acoustically, these ranks faded out (i.e. their loudness decreases) upon pitch.

Talking about Mixtures is a different aspect, as their purpose is different. Mixtures of the Cornet type (Cornet, Seqsuialter etc.) do not break back usually (exceptions possible), but they might not exist in the bass part of the keyboard. However, the other Mixtures either have to fade out (the Compton approach), or they break back (most frequent method). If Mixtures (e.g. low-pitched Mixtures like 8 12 15 19) did not break back, the tonal timbre would become too bright in the treble compared to what it is in the bass part. The phrase "too bright" refers to brightness of brass instruments as the trumpet. There is an interesting study on this topic:
https://asa.scitation.org/doi/10.1121/2.0001671

Reed ranks as a Trumpet 8´ or a Clarion 4´ become too silent in the top octave despite the very broad resonators attached to the top pipes. Thus, they highest reed pipes are often replaced by one Diapason pipe (or better: two per note). You find such an example in the St. Anne´s sample set (I think the Trumpet/Clarion on the Great division) and you can try to find from which note onwards the Trumpet rank consists of flue pipes. The reason is that the sound spectra of a Trumpet rank becomes similar to that of a (Geigen) Diapason in the top octave.

I'm having a bit of an argument on another forum with someone who is fairly knowledgeable about organs. However he claims that aside from Italian organs and a few other examples, that it isn't a common practice for organ builders to break back high pitched mutations and 1' stops, and that rather they usually use harmonic pipes at the very top of the compass. However, I have quite a few Hauptwerk organs where they do appear to break back. Here's the ones I have:

Salisbury Willis, Choir Tierce 1 3/5
Adlington hall - Nineteenth (2 2/3) and Twenty second (1')
Immanuel Presbyterian Schlicker: Larigot 1 1/3
Giubasco: Larigot 1 1/3
Mary the virgin Budapest - Sifflote 1' and Oberton 1 1/7​'

Also, the Pos Piccolo 1' on the Notre Dame de Metz breaks back. It's not an original stop, but presumably it's disposition is based on other organs that CC built? The person I'm arguing with claims that it breaks back because MDA ran out of samples, but I'm savvy enough programming for Hauptwerk that I know that's not the case. The added mutations to the Immanuel Presbyterian also break back, but why would Evensong have done this if it's not common practice?

Do you guys have any other examples I could use to defend my point? Or does it turn out he is right?

Personally I'm not a huge fan of those tiny overblown harmonic pipes some builders use at the top of those high pitched stops, but I admit that they are used.

It’s pretty common practice - I’ve seen it on 1 3/5 and higher.
And no, we wouldn’t “cheat” and break back if the organ didn’t do that in real life
Interestingly enough, in some cases the upper octave are different pipes, sometimes voiced either louder or softer than the octave they’re duplicating.

Thanks everyone!

I suspected as much. It's just too common on my Hauptwerk organs to not be an accepted practice. Personally, I prefer 1 3/5 ranks and higher to break back at the top, they're a bit less screechy that way! Thanks Jonathan for your confirmation. It's good to know that some of my favourite builders like EM Skinner thought this was a good idea! I think this is one of the beauties of Hauptwerk, that you can do research on aspects of a number of organs from your seat!