Tuning and relationship to song key

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Re: Tuning and relationship to song key

Postby vxla » Wed Jul 13, 2011 2:44 pm

A good reference for this discussion is The Science of Percussion Instruments by Thomas D. Rossing. More specific pitches will only be heard when a good, solid fundamental is produced by using the fleshy portion of hand (with fingers closed) between the edge and center of the drum head. On page 36 of the aforementioned book, an example of the sound spectra of various strokes is shown. The book can be previewed on Google Books (and page 36 is available) here: The Science of Percussion Instruments.
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Re: Tuning and relationship to song key

Postby Anonimo » Wed Jul 13, 2011 3:05 pm

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Re: Tuning and relationship to song key

Postby vxla » Wed Jul 13, 2011 3:09 pm

I'll keep tuning my drums to references pitches, and you keep playing yours however you wish.
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Re: Tuning and relationship to song key

Postby jorge » Wed Jul 13, 2011 5:02 pm

vxla wrote:A good reference for this discussion is The Science of Percussion Instruments by Thomas D. Rossing. More specific pitches will only be heard when a good, solid fundamental is produced by using the fleshy portion of hand (with fingers closed) between the edge and center of the drum head. On page 36 of the aforementioned book, an example of the sound spectra of various strokes is shown. The book can be previewed on Google Books (and page 36 is available) here: The Science of Percussion Instruments.

Vxla, nice reference, thanks. That book is out of print, and the percussion chapters of Fletcher and Rossing are less detailed regarding congas.
The frequency by amplitude spectral graph (Figure 4.11 on p. 36 in the Rossing link you posted) shows graphically exactly what both Leedy2 and I agree on, that there are lots of frequencies present in the sound of a conga tone. It also shows that there is one loudest frequency peak that is the perceived tone of the drum at its current tuning. What Leedy2 is calling distortion is actually a mix of many different harmonics from the different vibrational modes of the vibrating membrane/plate that is the skin, plus the resonant responses from the shell cavity. There are many fundamental frequencies emitted by an uneven skin, each with its own set of harmonics, so the overall harmonics are extremely complex as shown in the spectral plot. Where I disagree with Leedy2 is that I would call the fundamental frequency peak, which is many times louder than any of the other frequencies, the main tone of the drum as tuned. He seems to be saying that there is no main tone and no frequency can be identified as the pitch of the drum. Leedy2, I know you will speak up if I have misstated what I understand your opinion to be. If I interpreted your previous statements incorrectly, please explain what you mean by an untuned instrument. The spectral plot directly refutes that interpretation, as the fundamental frequency peak at 240 Hz is a single identifiable pitch that is many decibels louder than all the other frequencies that are produced by the drum. This is most clear for the tone, but can also be seen in the bass, albeit the amplitude difference between the fundamental and the harmonics is much less clear.

Also, whoever played the conga for the spectral analysis in Figure 4.11 must have played a very sloppy open slap that sounded almost like a tone, since the slap graph has the same fundamental ((0,1) mode) peak at around 240 Hz as the tone, and it is almost as loud. You can damp the (0,1) mode by pressing a finger in the center of the skin to stop vibration of the center of the skin. This will greatly change the sound of the open tone and open slap, but has little effect on the closed slap.
The bass note is also very sloppy, as the harmonic at 280 Hz is almost as loud as the fundamental at 70 Hz. Poor technique, or the drum was not tipped optimally or mounted on a stand to let the bass be heard clearly.
Last edited by jorge on Wed Jul 13, 2011 5:32 pm, edited 2 times in total.
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Re: Tuning and relationship to song key

Postby vxla » Wed Jul 13, 2011 5:10 pm

I agree. It would have been nice for them to do an analysis with an implement such as a soft timpani mallet to get a reference tone and compare it against using a open tone, slap tone, etc. It's very interesting to see how quickly the fall off of a bass tone is vs. open tone, too.
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Re: Tuning and relationship to song key

Postby bongosnotbombs » Wed Jul 13, 2011 5:20 pm

How would the amplitude spectral graph of the conga compare to the amplitude spectral graph of a single note played on a guitar or piano and a chord on a guitar or piano?
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Re: Tuning and relationship to song key

Postby Anonimo » Wed Jul 13, 2011 5:23 pm

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Re: Tuning and relationship to song key

Postby vxla » Wed Jul 13, 2011 5:35 pm

A pure tone string (nearly impossible to achieve, but still theoretical) will have a near-perfect downward curve away from the fundamental pitch. A piano string is a bit different: the striking hammer will excite the first (octave) and second (fifth-above octave) overtones slightly more than a naturally-plucked string. Such is the reason that people consider harpsichord a near-perfect instrument (plucked strings with the dexterity of all ten fingers).

Other instruments that are wacky: timpani parts are written out sounding one octave above the actual pitch. What you see on paper is actually the first overtone (octave). Xylophones (post-1920s) are "quint-tuned" and the most prominent overtone above the fundamental is the second overtone (fifth-above octave). Marimbas are tuned so the third (two octaves above fundamental) is prominent.
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Re: Tuning and relationship to song key

Postby jorge » Wed Jul 13, 2011 5:45 pm

Thanks Leedy2. From Wikipedia on Percussion Instrument, section on Indefinite Pitch
http://en.wikipedia.org/wiki/Percussion_instrument
this seems to be a useful definition of untuned percussion:
"Instruments in this group are sometimes referred to as "non-pitched", "unpitched", or "untuned". This phenomenon occurs when the resultant sound of the instrument contains complex frequencies through which no discernible pitch can be heard."

In my opinion, a well tuned conga drum does not fit this definition, since I and most other conga players can hear a "discernable pitch" when we play an open tone. So a conga is not an untuned or non-pitched instrument. You are right that if you overtune or undertune the drum, you can get a different sound that does not have as clearly defined a pitch. The spectral frequency plot posted by Vxla confirms that there is actually a real frequency peak that we are hearing, and this is not imaginary.

I am sure this could be demonstrated with a simple Real Time Analyzer (at least 1/12 octave or better yet 1/24 octave resolution) and a conga and a tuning wrench. When I get time I will try this. For now, common sense and a musical ear are all we need to conclude this discussion.
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Re: Tuning and relationship to song key

Postby bongosnotbombs » Wed Jul 13, 2011 5:48 pm

There was a guy here that claimed he knew a technique where he also tuned the overtones of his conga, I think it might have been BMac.
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Re: Tuning and relationship to song key

Postby jorge » Wed Jul 13, 2011 5:53 pm

When you tune a conga you change the fundamental frequency of the tone along with all of its harmonics (which you are calling overtones). Harmonics are integer multiples of the fundamental frequency (eg, fundamental 80 Hz has harmonics 160 Hz, 240 Hz, 320 Hz, 400 Hz, etc). Real cuero heads complicate things a bit, since there are many slightly different fundamental frequencies forming a broader peak than if the skin were perfectly even and perfectly circular like an ideal tympani.
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Re: Tuning and relationship to song key

Postby Jerry Bembe » Wed Jul 13, 2011 8:19 pm

Unfortunately, synthetic heads the best heads for this tuning method. Natural skin has better tone but synthetic is more consistent and stable.

A chromatic conga set is achievable (but too many $$). The length and size of the shell would need to vary beyond current standard sizes to achieve more than 2 octave range (25 congas).

I have found because of these dominant overtones that a Conga, Tumba, Tumba combination is advisable rather than a Quinto, Conga and Tumba combination. The Quinto does not have the tuning range of the Conga or Tumba.

I have found with a C fundamental, G, E and F as the dominant overtones. With a D fundamental, A, F# and G as dominant overtones. These overtones make sense and as long as the tuning of the head takes these into consideration I have found the best tunings for the congas. The overtones make using a simple digital tuner a difficult task.

A person with a good ear for what the congas should sound like can achieve similar tonal results as well.
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Re: Tuning and relationship to song key

Postby Thomas Altmann » Wed Jul 13, 2011 10:27 pm

I suggest that you take into consideration that a definite and definable pitch in instruments that are primarily meant for rhythmic percussion within a given harmonic arrangement is regarded undesirable! Even a double-headed drum of a drum set can be tuned in a way that a clear central note is discernable, even though it is subsummed under instruments of indefinite pitch. At the same time that the human ear recognizes this note, it is no longer heard as an indefinite percussion sound; it is mistaken as harmonically relevant, which is an error. In this case the drum interferes with the tonal intent of the music, and if this is not exactly arranged, it sounds disturbing.

So if you have the time, say, in a studio, before you record, find a tuning that fits the tonality of the respective piece of music. Don't look for pitch in harmonic orientation. And forget about it on stage, because you cannot tune your drums for every other number. It is already hard enough with tympani, so, practically spoken, don't try it with congas or bongos, and not even timbales. Be glad you don't have to deal with that. Make your drum sound beautiful in itself and tune your set in intervals that make sense and harmonize separate from the harmonies of the song.

My tip.

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Re: Tuning and relationship to song key

Postby Anonimo » Thu Jul 14, 2011 12:27 am

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