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Please note this is an archived topic, so it is locked and unable to be replied to. You may, however, start a new topic and refer to this topic with a link: http://www.banjohangout.org/archive/400224
dlm7507 - Posted - 11/05/2024: 12:17:03
I thought to use audacity's capability to plot spectrums to see if it shined light on a banjo's sound. A curious thing. The banjos 2nd harmonic was a higher amplitude than the fundamental yet electronic tuners that give the octave get it right. To check for the issue being with my measurements I also did strings 4, 3 & 2 on an acoustic guitar and the note i picked was a higher amplitude than the harmonics, unlike the banjos. You can select a larger view of each with the pulldown at cell D9.
I'm guessing that it has something to do with more adjacent string ringing with banjos, but I didn't expect that.
docs.google.com/spreadsheets/d...p=sharing
davidppp - Posted - 11/05/2024: 13:13:58
You'll see the same thing (almost) even if you damp all strings but the plucked one. (Those other strings are important to the plucked string sound but not relative to this particular issue.)
An important issue is the resonant frequency spectrum of the soundboard (or drum head). You can't get strong sound at frequencies without a nearby resonance. The lowest banjo head resonance is well above the lowest playable pitches. Google "missing fundamental." Tuners that are properly designed understand this and will display the "right" octave." Even above the lowest head frequency, there are issues of efficiency. Note that some guitars will produce a missing fundamental on their lowest notes.
dlm7507 - Posted - 11/05/2024: 14:26:32
quote:
Originally posted by davidpppYou'll see the same thing (almost) even if you damp all strings but the plucked one. (Those other strings are important to the plucked string sound but not relative to this particular issue.)
An important issue is the resonant frequency spectrum of the soundboard (or drum head). You can't get strong sound at frequencies without a nearby resonance. The lowest banjo head resonance is well above the lowest playable pitches. Google "missing fundamental." Tuners that are properly designed understand this and will display the "right" octave." Even above the lowest head frequency, there are issues of efficiency. Note that some guitars will produce a missing fundamental on their lowest notes.
Thank you for your reply. A quick answer!
banjoak - Posted - 11/05/2024: 15:06:53
One thing to consider is the measuring method can affect results. For example the microphone and placement/distance, might not be a flat response; often are not. A lot of mics design boost certain frequency ranges. Some mics also have a bass roll off, or gentle high pass filter. Some tweaked to deal with cardioid pattern mics there is also proximity effect, as get closer enhances the lower frequencies, as get further away gets thin; so changing the distance will change the frequency response. On axis vs off axis is another factor. An omni mic helps with some of this. The room, room modes could also affect the measurement.
Edited by - banjoak on 11/05/2024 15:16:06
