SmoothOperator
Gold Member
So, I tried out the equation for calculating the various frequencies of drums:
My 12x10 was an A 110, my 14x6.5 was 117.5 Bb my 22x16 was 70.20 between F# and G, my 16x14 turned out to 70.2 which was a C#.
For my resonant head I was stuck on how to tune it, so I chose to use the interval from the next highest mode, which turned out to be a fifth. This seems much higher than usually recommended, as I got closer to that interval it did sound bad, until it was all the way in tune with the mode. After which the snare had a nice bright crisp sound. I think the differences in decay time and sound radiation work between the (0,1) mode and (1,1) mode work together to shorten the decay and make a louder thump. As a side effect it seems, the (1,1) mode of the resonant head corresponds to the (0,2) mode of batter head which seems to reinforce the effect.
http://www.acs.psu.edu/drussell/demos/membranecircle/circle.html
Overall I am fairly happy with this approach to tuning. Some things that surprised me though, was how easy it was to hit the notes tuning once I knew what they were. My new tom which kind of prompted this, went into tune easiest, I even used an electric tuner, and one of those wrenches that click when the tension is too high. I was surprised that the tom was actually lower pitched than the snare, but indeed the deeper drum has more spacial volume. The 16 and 22 were a little more difficult, I used my voice which happens to be low, to find the pitch then tuned to that for the 16, then for the 22, I had to sort of guesstimate, by this time I was getting a feel for how the drum is supposed to sound when tuned to the shell volume though, and by the end the tuner showed F#0 dead on, I suspect when in tune there is enough sustain in the fundamental to pick it up.
Another thing that surprised me was how the drums tuned to the shell volume had much less sustain. I was kind of afraid it would make for a ringee sustained drum, but the opposite occurred, I suspect, it is do to the sound energy resonating more efficiently in the (0,1) mode and not getting attenuated into the (1,1) mode.
My suspission is that the two headed tom behaves more like a Helmholtz resonator than a vibrating column of air, since the wave length of the fundamental is so much longer than the drum.
If this were true, then the tom would essentially behave as a three spring system: top head, bottom head, air volume. If we assume the port area is equal to the port length, then the frequency of the air behaving as a spring would be.
F=(v/(2*pi*sqrt(V))
Where v is the speed of sound and V is the volume of the drum.
http://en.wikipedia.org/wiki/Helmholtz_resonance
You could add other springs to the system, shells etc. If the two heads were tuned identically, and were of the same composition, it would be essentially a two spring system.
My 12x10 was an A 110, my 14x6.5 was 117.5 Bb my 22x16 was 70.20 between F# and G, my 16x14 turned out to 70.2 which was a C#.
For my resonant head I was stuck on how to tune it, so I chose to use the interval from the next highest mode, which turned out to be a fifth. This seems much higher than usually recommended, as I got closer to that interval it did sound bad, until it was all the way in tune with the mode. After which the snare had a nice bright crisp sound. I think the differences in decay time and sound radiation work between the (0,1) mode and (1,1) mode work together to shorten the decay and make a louder thump. As a side effect it seems, the (1,1) mode of the resonant head corresponds to the (0,2) mode of batter head which seems to reinforce the effect.
http://www.acs.psu.edu/drussell/demos/membranecircle/circle.html
Overall I am fairly happy with this approach to tuning. Some things that surprised me though, was how easy it was to hit the notes tuning once I knew what they were. My new tom which kind of prompted this, went into tune easiest, I even used an electric tuner, and one of those wrenches that click when the tension is too high. I was surprised that the tom was actually lower pitched than the snare, but indeed the deeper drum has more spacial volume. The 16 and 22 were a little more difficult, I used my voice which happens to be low, to find the pitch then tuned to that for the 16, then for the 22, I had to sort of guesstimate, by this time I was getting a feel for how the drum is supposed to sound when tuned to the shell volume though, and by the end the tuner showed F#0 dead on, I suspect when in tune there is enough sustain in the fundamental to pick it up.
Another thing that surprised me was how the drums tuned to the shell volume had much less sustain. I was kind of afraid it would make for a ringee sustained drum, but the opposite occurred, I suspect, it is do to the sound energy resonating more efficiently in the (0,1) mode and not getting attenuated into the (1,1) mode.