Allen Chime harmonic composition

[Nutball]

Just for fun

I tried deciphering what makes up the chimes on my organ. I started by playing a continuous chime note on the pedals and listening for individual notes. I found it sounds like it is made up of several notes of a flute timbre closest to the koppel flote. But after finding several notes, I found a strange tone that was too difficult to decipher, it sounded like some sort of mixture. I had Transcribe! play a looped recording through the organ speakers while using its 31 band EQ to filter one note at a time, and this is what I found: (numbers after the note corresponds to key position based on 8' pitch, low number = low note) Lowest C of the chimes is made of: E2, C3, G3 slightly quieter, C4 similar volume, F4 barely on the sharp side as most or all the previous 4 were barely flat, A#4 flat and quieter, C5 sharp and similar volume, E5 similar volume, a note evenly between Gb5 & G5 very quiet, B5 very quiet. Higher notes exist as jumbled noise.

I think the last A,C,&G were the weird mixture I was hearing as they had unnatural tuning and were quiet.

I don't know what these chimes would sound like in a very reverberate room, but I heard bells at a large chapel once that after enough reverb accumulated you could easily listen for and pick out what sounded perfectly like the voices of women singing.

[davidecasteel]

Well, I'm not surprised. Tthe low E2 would probably be supplying the "hum tone", which should be approximately 1/1.55 of the pitch "heard" (in true pitch, the E below a C is 1 /1.6, because the tones in a CEG triad are in 4:5:6 ratio--the E2:C3 combination would be 2.5:4, and 4/2.5 = 1.6). The next 3 pitches in a chime are in a 2:3:4 ratio (very closely), and the C3, G3, C4 notes provide that. The upper tones are approximations to higher partials that are not multiples of the principal frequency.

David

[jbird604]

In analog days, most organs created their chimes by simultaneously keying an assortment of flute tones with sustain. On many analog Allen models you can easily sniff these out by looking at the keying rods and noticing which ones rotate into position with the Chime tab. On several Conn models I've seen, the chimes are enabled by turning on four separate tabs and the long sustain.

With both the Allen and Conn analogs, I believe the chimes are made up of the same four pitches, which correspond to the footages we would call 6-2/5' ("six and two-fifths foot"), 4', 2-2/3', and 2'. All of these are pure flute tone.

So when you strike middle C on an Allen analog with the chime tab drawn, you will activate four tones. Two of them are actually "C" notes (the 4' and 2' components), a third one is a "G" note (the 2-2/3 or Nazard component). The fourth one though is the one that actually makes a chime sound like a chime -- that weird 6-2/5' tone, which is the "E" note below the middle C that you are playing!

As David mentions, this pitch is referred to as "hum tone" and is certainly not a normal overtone. No other organ sound has such a component, AFAIK. But without this odd tone in the mix, you would just hear a tinkle that might vaguely remind you of a music box or something, but not tubular chimes. Adding in this peculiar pitch, your ear is fooled into thinking that you are hearing a middle C tubular chime, though in fact the pitch middle C is not even playing.

That is analog, and of course we are all in the digital world today. The chime tone on your ADC Allen is probably a carefully processed reproduction of an actual recorded chime note, though of course ADC organs don't really play back samples so much as recreate notes based on a single cycle. But even with the limited technology, as you can clearly tell, the chimes on your ADC organ sound more like the real thing than any analog organ's rough simulation made up of four flute tones.

Very clever the way you have sussed out the partials present. I don't doubt a bit that there are some extremely odd harmonics in the mix, as a vibrating chime tube surely produces an exceedingly strange mixture of tones, many of them nowhere near exact multiples of the basic pitch. Good job!

[KC9UDX]

Maybe I need to record the chimes on my Lowrey to decipher. There was something I always found peculiar about them but can't recall what it was.

[Nutball]

Go for it, and post your results here.

I need to go back and record those church bells I mentioned and see what frequencies make up their tone.

[toodles]

The 6-2/5 ft tone is the fifth harmonic of a 32 ft stop. You can easily figure out the harmonic that is represented by any mutation by expressing it as a gross or vulgar fraction--multiply the whole number by the denominator, and add the numerator; that sum is the native pitch register of the mutation and the denominator is the harmonic number.

In this example, 6 x 5 = 30, add 2 for 32 as the native pitch register and 5 is the harmonic number.

10-2/3 = 3rd harmonic of 32 ft. (which is why it is the resultant tone for 32 ft)
5-1/3 = 3rd harmonic of 16 ft.
2-2/3 = 3rd harmonic of 8 ft.
1-1/3 = 3rd harmonic of 4 ft.

etc.

[jbird604]

I never knew that fractions could be gross or ... VULGAR!!! Surely they don't belong in the dignified and proper world of organists!

Kidding aside, I wasn't aware of this little formulation. Interesting information. Thanks, toodles.

[KC9UDX]

Oh sure. Now as I finish reading the NLT this year I'm going to be obsessively scanning for values that may be fractional so I can determine which verses in the Vulgate might contain fractions. Then I'll have to try to read Latin. And I'll have to reread Genesis, Exodus, and Job to make sure I didn't miss any already. Good thing I didn't already read Numbers.

(As if I really need an excuse to reread them. Though I'll probably read a different translation.)

[davidecasteel]

I admit I'd never heard the term "vulgar fraction" so I looked it up--it is synonymous with "common fraction", which is just the representation of a numerator written above a denominator (the way everyone does it). In the case toodles is discussing, I would use the term "improper fraction", which is one in which the numerator is equal to or larger than the denominator--it's "top heavy". "Footage" numbers are generally written as "integers" or "mixed fractions": "integers" are what some call "whole numbers"--they don't have any fractional parts; "mixed fractions" are composed of "integers" plus "proper fractions" ("6 2/5" is an example). "Mixed fractions" are converted to "improper fractions" by multiplying the integer by the fraction denominator and adding the fraction numerator, then putting the sum over the fraction denominator (6 2/5 = 32/5). Once the "improper fraction" form has been created, the numerator specifies the parent footage (32) and the denominator specifies the harmonic number (5). (I've known this for several decades.) To carry things to an extreme, "32" can be expressed as the improper fraction "32/1", which just means it's the first harmonic (fundamental) of a 32' rank.

It's all so mathematically logical it's hard to believe that artists (musicians, in this case) came up with it. ;-)

David

[toodles]

The mutation pitches aren't so difficult--if you have a 16 ft pipe and you want the 3rd harmonic, that would mean a pipe 1/3 the length of the fundamental pipe, getting you to 5-1/3 ft. That's just the physics of it.

What is stunning to me is that intervals of a third support the fifth harmonic and intervals of a fifth support the 3rd harmonic. Alas, intervals of a seventh just support the 7th harmonic.

[KC9UDX]

Go for it, and post your results here.

Here you go. But naturally, the single hour I get to do something like this just isn't enough. So I forgot to turn off an effects processor. I have the mic'd audio but didn't mix I with the video because it has a significant amount of reverb. The video has the audio from the camera (phone).
If you want the reverb audio (with some random popping from my cheapy mixing board) I can email it to you. Else I can try to make a better video some other night.

The good part is that this meant I had to finally fix the power cord on the Lowrey, so I can play it again, if ever I get time.

[jbird604]

Though the Lincolnwood chimes may not be as consistent as what you'd hear on a large Allen, Conn, or Rodgers of the same era, you do hear the "hum" tone clearly when the full chimes are engaged. That odd-ball pitch is apparently necessary to make the brain think we're hearing a real tubular chime sounding.

I seem to recall that certain Hammond models in the 60's perhaps had a "chime" stop that simply didn't cut it because they tried to make a chime tone without the hum component, since of course that pitch is not part of the standard Hammond tone series.

[davidecasteel]

Yeah, I think the brown drawbars are the equivalent of 16' and 10 2/3'.

David

[toodles]

Yeah, I think the brown drawbars are the equivalent of 16' and 10 2/3'.

David

Subfundamental and sub-third harmonic, corresponding to 16 ft and 5-1/3 ft.

[davidecasteel]

I stand corrected.