scale

[Robert Aulicky]

Well, Kids, I am trying to understand scale. What does this mean in English please? 16′ Bourdon 12 pipes (CCC scale 40, CC scale 54, halve on 20th, 12 pipes, ext Gt 8′)

[myorgan]

Welcome to the Forum Robert!

Try reading this book online: https://archive.org/details/gri_3312...e/754/mode/2up (pages 567-582). It's a complicated subject-both mathematically, and conceptually. Simply put, it's the measurements used to build a set of pipes which result in the desired sound. It takes the guess work out of building pipes, so the result can be more predictable rather than experimental.

Michael

[Robert Aulicky]

Thanks, Michael, I gave it a quick read to find out I need to mark the pages and reread it. I am starting a chamber organ shortly and read so much I forget 2/3 of what I read. I have both books, vol1 and vol2 along with Mark Wicks older book with the plates, and a few others. My question is why on that Bourdon is the first 12 pipes, CCC, scale 40, and the nest set, CC, scale 54? I understand why the halving on the 20th is due to strength in the higher end of the rank. Then it extends the last 12 pipes to the Great 8'? If so how is the wind chest built?

Stair building was a lot easier, now retired OMGoodness what a learn! Robert

[gtc]

Here is a reasonably straightforward discussion of this complex topic: http://www.organbench.com/444915485

Here is a discussion of the theory and math: https://en.wikipedia.org/wiki/Organ_flue_pipe_scaling

[Robert Aulicky]

Hi gtc, I have both of these printed and I am still having dificulty understanding. Firwt of all some us C as Tennor C (second C, note 13), and here are thsy using it as CC note1?

[Larason2]

Yes, welcome to the forum!

Those are all good resources, worth a look. The basic concept is that the wider the pipe is, the more it tends to sound like a flute, and the more narrow, the more it sounds like a string. Of course voicing also has a lot to do with the tone as well, but that's the basic principle.

Then to keep the tone even as the pipes get smaller, you typically want to preserve the ratio of width to length, however because of physical factors for string pipes that becomes impossible near the top of the compass. As a result, and because it keeps the pipe sound interesting, many builders vary the ratio of width to length as the pipes get smaller, and this is often represented by how many pipes the width halves.

[Robert Aulicky]

Thanks, Larason2, I saw that in the diagram in "The Art of Organ Building" where the strength of the sound changes the halving. o, the Diaposen and flute basically kee the same ratio but strings increase the halves in the upper part of the rank? Then, the smaller diameter by ht changes the sound and volume for a lesser sounding rank, right? Then what happens to the mouth and lips? Do they stay the same for the scale note?

As I mentioned to Michael, I am a retired stair builder, with 35 employees building stairs even I could not afford. So, the next challenge at 71 is a chamber organ. I must be nuts!

[Larason2]

Thanks Robert. I feel that most builders change the ratio of every type of stop, but do it differently based on what kind of pipe it is. For instance, Cavaillé-Coll used square roots, with each kind of pipe using a different square root. Flute pipes tend to get a bit too ponderous sounding, have trouble speaking, and waste too much air at the top, so even for those they do narrow the scale a bit as they get bigger. String stops in general don't narrow as much. So at the top of the range, there isn't as much difference between string and flute stops as down at the bottom. Volume does change with scale, but builders tend to adjust volume mostly by adjusting the mouth/cut up and pipe foot (though the second part mostly on romantic organs).

Now, some builders build flutes and principals to the same scale, but just have a much higher cut up on flutes than principals. Not so for Cavaillé-Coll, as I recall though, he tended to have much wider scale flutes than principals at the bottom, but I think this is true for most French builders, their principals are usually pretty narrow scale. Baroque builders too tended to differentiate flutes and principals more with scale, and I think this is why their flutes sound better. It does cost more to make flute pipes this way though, especially at the bottom! It also causes the largest flute pipes to have much slower speech, particularly at low pressures.

For the mouth and lips it's complicated. Usually mouth width depends on the type of pipe, with principals and flutes having wider mouths than strings. If mouth width is too wide, you need a lot higher pressure to make the pipe sound, and the pipe sounds like a calliope! Cut ups are variable depending on the pipe, and how its voiced for the space, but tend to be narrowest in strings and widest in flutes, principals being somewhere in between. The bigger the cut up the louder the pipe, and the more it sounds like a flute. The gap in the lips doesn't tend to vary much, as you never want it smaller than the toe hole, but much bigger than that doesn't matter as much, because the toe hole does limit the maximum amount of air that goes through it. What changes is whether the lip is smooth or has nicks in it. There are lots of other ways to adjust the mouth that affect speech and tuning, (like beards, cut up leathering, etc.), but these are mostly to adjust/tune specialized pipes and change the characteristics of speech, particularly strings/flue reeds, etc.

[myorgan]

So, the next challenge at 71 is a chamber organ. I must be nuts!

You must be!😜

My question is why on that Bourdon is the first 12 pipes, CCC, scale 40, and the nest set, CC, scale 54?

My best guess is that the first 12 pipes are generally only in the pedal in smaller instruments, and are used alone. However, the upper octaves are more likely to extend the manuals and need to blend in tone and sound quality with other manual stops.

Michael

[myorgan]

As you can see from Larason2's post above, there are many factors which affect a pipe's scale and ultimate tone quality. Personally, if I were to decide to build a chamber organ or cabinet organ, I'd probably just use published scales and voicing, or use existing pipes for the project. They are for sale on the Internet rather frequently.

Then again, you're probably more adventurous than I.

Michael

[Larason2]

Michael’s right on for that one. Existing pipes are cheap and good. There’s a pipe organ swap and shop group on Facebook, and they frequently have pretty good deals on existing pipes. Making your own is fiddly and takes a long time to learn, so unless you’re going to make a lot more of them in the future, you’ll probably save a lot of time and money just buying existing ones.