I just got a new bag for my old 3/4 concert set of pipes. Great bag! Leak free! The old set is playing again. But here’s the rub:
When I go up into the second octave, I now suddenly hear plain as day combination tones. They are actually difference tones (I’ve done the frequency math) between the 2nd octave and the tenor (small) drone. They are together producing a very noticeable triad. When I play high F# with the tenor D drone, I also hear an A in the first octave. Second octave G gives me a B, and the second octave A produces a C in the first octave (in combination with the drone). this would not be so bad, but E is a real problem. Since it has no harmonics in common with the D tenor drone, the resulting combination tones are a mess of ugly.
Any acousticians out there? Can I remedy this new-found problem? It is definately NOT psychoacoustic. I have recorded it. It is ugly and distracting.
The old set is playing again? How long was it not playing? Are the drone reeds cane or synthetic? If cane, you might need to work on them a little to get them performing normally. If can reeds are not played regularly they can give problems.
Do the tones go away when you have all three drones going? Or can you still hear them? what about if you shut off the tenor drone and keep the other two going?
How old is the reed in your tenor drone? Does it rise in pitch when you go into the second octave or does it stay steady? This is just speculation, but if the reed is weak or gone bad maybe it’s producing overtones when you add the pressure of going into the second octave, and those overtones are being amplified/accentuated when the chanter hits the notes in the triads.
I don’t know if this is relevant but I occasionally have a similar problem with my GHB Bass Drone, namely when I play the second of the scale on the chanter a harsh buzzing starts in the Drone. This buzzing noise can also occur all the time when the drone bottom section seeks to low and is rectified buy adjusting the bridle to so the Drone seeks further up.
It’s important to remember that energy transfer through the air couples the Drones and Chanter; indeed good stability would be impossible without this coupling.
combination tones (difference tones, that is) often occur inside the listener’s head. Not too much we can do about those, except de-tune your tenor (!)
As Brad suggests, this may be a matter of relative volume of the three drones - maybe your new tenor reed is a bit too loud. Combination tones are normal and usually desirable. The fact that you’re hearing them suggests to me that the pipes are in tune!
You say the tenor doesn’t have any harmonics in common with the chanter’s E but that’s not strictly true - besides, just having even ratios between harmonics is enough to present some degree of consonance. Whether you like the result is of course not subject to analysis, and it sounds like you don’t…
I second what Bill says: the second, if properly tuned, gives a very nice result in combination with drones, for UP and GHB; in fact, it’s probably my favorite chord in piping, very great sensation, but only when properly tuned (again).
So try to verify the tuning of low E. High E is not so easy to obtain.
I thank all of the repliers. One suggestion I think was relevant: the new reed for the old set may be too loud. This could account for the very plainly heard difference tones (not inside my head, as one suggestion insinuated, these are actually recordable tones, and are definitely NOT psychoacoustic, as I pointed out). This is an interesting subject, especially concerning the supertonic E, since its only common harmonic is from the bass drone. I tried to separate my last post w/HTML, but was not successful. so sorry for the long paragraph. Thank you all for your responses. If anyone would like to keep this thread alive, my slow response may be a hindrance, but I only get to a computer once a week or so. Thank you all. Peace, Cheers. Diggy
Diggy: just because the tones are recordable doesn’t mean that they are not inside your head. Faithful recordings can easily reproduce psychoacoustic phenomena, for instance.
And of course difference tones are generated at the microphone diaphragm just as they are at your eardrums. (See Benade on heterodyne components for instance) I did not expect you to take offense at the observation that your eardrums are inside your head, where they should be.
I don’t know why you keep suggesting that there are no harmonics in common between the baritone/tenor drones and the E. Are you excluding harmonics above the theoretical cutoff frequency for the exit aperture, or what?
In response to Bill’s response, I did not take offense at all at your suggestion that the combination tones are in my head. On the contrary. It puts me on a level with Helmholtz. He claimed to have heard summation/combination/subjective tones that could not be measured, and that no one else had ever or has ever heard since. What a scientist he was! He’s also responsible for giving us the method used today to tune pianos to the contradictive terms of equal and temperament. You know I am being sarcastic, Bill, and I really appreciate your interest in this thread. Can someone tell me how to create a new paragraph? Did it work this time? We’ll see.
Also in regard to Bill’s response, the only harmonics in common with the drones and the E note on a chanter are the 9th harmonic of the bass drone with the fundamental E, the 9th harmonic of the bari drone with the octave E, and the 11th harmonic of the tenor drone with the 7th harmonic of the E. None of these harmonics are of any amplitude to be of any significance. Woodwind harmonics are of such small amplitude above the 7th harmonic that they cannot beat with other tones or even be heard by the human ear. Please do not read between the lines, Bill, I really do appreciate your attention to this combination tone phenomenon. And everyone else’s response.
I still do not know why these ghost tones appear when I go into the upper octave. I have tried detuning the tenor drone while sustaining one of these upper-octave notes (thinking they may be common harmonic beat frequencies), but the ghost tone persists.
I’ll need to do some more calculations, but there may be other integer ratios between harmonics of the E and the drones. Integer ratios of harmonics are perceived as consonant by the ear just as exact “matches” are.
None of these harmonics are of any amplitude to be of any significance. Woodwind harmonics are of such small amplitude above the 7th harmonic that they cannot beat with other tones or even be heard by the human ear.
I don’t believe this is true, at least not of pipe chanters. For instance, I have measured significant harmonics up to the twenty-third on my concert pitch chanter; playing hard D, the seventh harmonic is actually the strongest of all (!) and the thirteenth seems to be stronger than the fundamental for hard D. Back d has 11 very strong harmonics. That’s just two examples. [edited to add:] Perhaps you are thinking of admittance/response curves, where the number of peaks is indeed smaller, as opposed to the actual power spectrum output. I am not sure the ear can hear beats between frequencies above a couple kiloHz.
Please do not read between the lines, Bill, I really do appreciate your attention to this combination tone phenomenon. And everyone else’s response.
I still do not know why these ghost tones appear when I go into the upper octave. I have tried detuning the tenor drone while sustaining one of these upper-octave notes (thinking they may be common harmonic beat frequencies), but the ghost tone persists.
This last observation does suggest that something odd is going on, and that “difference tones” don’t quite explain it. Beats me. Does the ‘ghost tone’ seem to alter in pitch as you change the tenor drone’s tuning? If so, “which way” does it go?
How does a flat set (narrow bore) builder make the drones less loud so that they don’t overpower the chanter? Is this done with reed techniques or is the overall bore of the drones different?
Generally the bore is considerably different - narrower, for one. Also, tone and volume can both be affected by constricting the drone exit hole, you often see flat sets with a narrower exit hole than the bore in the slide. I think this can aid stability a bit as well.
Not much on different tones and heterodyne stuff in that chapter, but all the chapters seem pretty good. (I’ll forgive them the bagpipe joke at the start of chapter 6…) There’s also a discussion/exercise on the tin whistle (called a “toy flute”) at the end of that chapter. Not written by a trad-head, it would seem…
Indeed. I was playing “Paddy’s Rambles Through The Park” last night and just for fun, brought the drones in on it. Fascinating. I’m not sure if pleasant is quite the right word, but perversely gorgeous all the same.
I like the E (B) chord too.
The tuning I use on my GHBs is
G 7/8
A 1/1
B 9/8
C# 5/4
D 4/3
E 3/2
F# 5/3
g 16/9 I’m not certain about this one but it is sharper than 7/4
a 2/1
