Also, how can I figure out the diameter of a pipe from it's scale number? How much is the diameter of a pipe of "42" scale, and what do those numbers mean? Does this system apply to both Flues and Reeds? Ho does one figure out the scale of a tapered pipe? Is their a chart in which I can find these scale numbers?
This is a deep topic, which would take a while to explain. If one is not extremely carefulthings can be misinterpreted. [:)]
Two ways to think of scaling - how large isa singlepipe on a given note, such as bottom "C"? Going from small to large diameters progresses from a string, to a diapason, to a flute timbre for a given note. Then there isthe halving ratio, which tells us ifthe pipes within a given rank decrease quicklyor slowly as you go up the scale.
Fortunately there are some sources of information on the Internet,though I'm amazed that the information takes so much searching! Here is a Wikipedia article about Normalmensur. It discusses a 'normal' halving ratio on the 17th pipe; there are other halving ratios too. If the halving point is on the 16th pipe then the pipesare relatively largeras you gotowards the top; an 18thhalving ratio means the pipes are relatively smaller as you go up. Relative is the keyword here- a pipe that has a diapason bass and a slow halving ratio will end up with flutey trebles;if you apply that same halving ratio to a string stop, the trebles might end up as diapasons (or flutes, if the ratio is very slow).
This applies to fixed scaling, where the progression can be plotted in a straight line. With variable scaling the pipes progress in a manner as specified by the builder, usually in order toaccount foracousticalanomolies in a given space. There is also something known as fixed/variable scaling, where only a certain portion of the compass of a given rank will deviate from the normal scale.
One of the confusing things is that there are several systems for indicating the scale of a pipe. You might see the word "Normalmensur", and/or a symbol for the halving ratio, and symbols such as "NM+1, NM, NM-1" to indicate steps of deviation away from NM.
Another system assignsnumbers,with "44" for the bottom C ofthe 'normal'8' Principal. This system is a little easier to comprehend, but it does not convey if the rank is based on fixed or variable scaling, or what the halving ratio is. It is convenient, in that you can just count scale numbers to see what the scale of any given pipe is (assuming fixed scaling). If Iam scaling a 4' Octave,I could just count 12 scale degrees up from the measurement of the 8' rank; ifthe 4' Octaveis to be one scale smaller than the 8' Principal, I count up 13 steps; one scale larger,I count up 11 steps.
Another system pays no heed to scale at all, but simply notes the dimensions of the pipe in either inches or millimeters.
Whenever possible I always measure the inner diameter of a pipe, as it has slightly more bearing on the sound of the pipe than does the outer diameter (sometimes notated as "OD").
For non-cylindrical pipes, it is best to measure the diameter at the mouth and at the top;either that, or list the diameter at the mouth and the ratio of the taper.
Reed pipes do not use the same system of scaling.
Here is an extremelyhandy chart listing Normalmensur, pitch names, the numeric system equivalent, and the diameters in millimeters: Organ Supply Industries Catalog-it isat the bottom of page three. By the way, there are numerous resources on the Internet which will help you convert millimeters to inches, if you need to do that.
Chartscan be veryhandy, butthere is a risk ofgetting a bit confused if you don't know what you are seeing. For example, this chart shows bottom C of an 8' pipe being 155.5mm or scale 44. A set of pipes one scale smaller (than the scale specified in this chart) would have the C at 148.9mm, whichcorrelates to aC# in this chart; however for your purposes, this note is your "C". For this reason itmight behelpful to think of the left column of note names as being 'moveable'.
Thanks for getting this information, It was very helpful. I searched the internet for a long time on this topic, but the search yielded hardly anything. (Except some really confusing articles [:S]) I must say, that OSI catalog chart is a very good thing.
Do reed pipes have any scaling system? If possible could any inforation be provided on that?
You are welcome. [:)] Hopefully someone else will come along and can elucidate even further
By the way, I continued to wordsmith what I wrote so you might want to read it again.
[quote user="Violoncello"]Do reed pipes have any scaling system? If possible could any inforation be provided on that?[/quote]
A measurement system? I think this information is a bit more difficult to track down (frome those builders who do their own scaling[:|]). If you look on page 17 of the OSI catalog you will see some typical measurements for reed resonators (which are typically shown in inches or millimeters). Bottom "C" of a standard 8' Trumpet from the OSIshop can be anywhere from 3" to 5" in diameter at the topof the resonator. This is a pretty large range, although in comparison to flue pipes the difference seems relatively small indeed.
Reeds are a special case as they have so many measurements; just knowing the diameter of the resonator tells you very little. Some resonators also have compound or complex shapes. Equally important (if not moreso) are the measurements and treatment of the shallots and reed tongues.
It is also helpful to know if theresonators are fractional, half, full, harmonic, or double/tripleharmonic length - this will have a bearing on the diameter.
Also, how does slotting a pipe change its timbre? (Principal pipes in particular.) There are a few organs in my area with Diapasons that have "slotted pipes". Is the slotting carried up into the higher pitches ( 1/2' C, 1/4' C?) and can one make a Mixture of slotted pipes? (Would it even sound good?)
[quote user="Violoncello"]Also, how does slotting a pipe change its timbre? (Principal pipes in particular.) There are a few organs in my area with Diapasons that have "slotted pipes". Is the slotting carried up into the higher pitches ( 1/2' C, 1/4' C?) and can one make a Mixture of slotted pipes? (Would it even sound good?)[/quote]
Here is an interesting page that discusses slotting; many of your questions are answered there.
It is quite difficult to describe timbre in writing, especially as it is a very subjective thing.
My suggestion is to go to those organs in your neighborhood that have slotted pipes, and listen. [:)]
...and I really liked what I heard, too. It gave the Diapasons body, but they were not round or extremely tubby in tone, they also had a distinct clarity in their timbre. They did not sound stringy in tone at all. If you're curious, the stops were called: 8' Diapason, 4' Principal, and 2' Plein Jeu V. I do not know if the mixture was slotted or not, but it blended perfectly with the 8' and the 4'. The pipes sounded almost as if they were trying to explain something to you.
New question: Are English Diapasons slotted? Slotted Diapasons seem to fit Audsley's description of "an ideal stop of Diapason-tone". Does the slotting of a pipe impart the special "English tone" to Diapasons? Did companies like Moller, Buzard, Wicks, etc. use slotted pipes for for their so-called "English Diapason" stops?
In building wooden pipes, what are the differences in between German Blocks and English Blocks? (Construction wise) Do they effect the tonality of the pipe? What kind of sound do each cause the pipe to sound like?
The block is the square piece of wood that is affixed to the front of the pipe and covers the area beneath the mouth and forms the front lwer section of any wooden pipe. Sanding the inside part of the block is a technique used to affect the tone.
You both do realise you're talking about something different? Sesquialtera means the block on the outside that closes the foot and forms part of the mouth while Violoncello means the block inside that forms the windpassage in the foot.
I do have somewhere an article where they measured the differences between different types of blocks (the Violoncello types). The differences are in the way the pressure buils at the slit of the mouth and turbulence losses due to directional changes and sudden volume changes. So it will likely affect the attack of the pipe.
The article in question is by Dr. Andreas Richter and was published in "Die Hausorgel" edition 9/89 titled "Strömungsmechanische Aspekte in der Kernkammer einer Orgelpfeife"
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