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  • Speaker evaluation using scales

    I'm just interested in whether any of you use the above listening test to confirm anomalies in your designs?

    I've been going straight from measurements to test tracks.

    Of course we have sine wave sweeps, but it occurred to me I probably need to include some scale playing across instruments and synthesized material (different waveform types) to assess any inconsistency or unnaturalness.

    Good instruments with wide bandwidth that spring to mind would be piano and saxophone.

  • #2
    I believe your typical piano tops out at C8(4186.01 Hz). While it would cover a large range, you'd need something like a piccolo, synthesizer, or other instruments like hi-hats and cymbals to get up into the higher frequencies.
    "If we weren't all crazy, we'd just go insane..." -Jimmy Buffett

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    • #3
      Originally posted by Turtle View Post
      I believe your typical piano tops out at C8(4186.01 Hz).
      The fundamentals yes, but not the harmonics. I've yet to see an on-line chart of the bandwidth of instruments that takes that into consideration.

      www.billfitzmaurice.com
      www.billfitzmaurice.info/forum

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      • #4
        Originally posted by billfitzmaurice View Post
        The fundamentals yes, but not the harmonics. I've yet to see an on-line chart of the bandwidth of instruments that takes that into consideration.
        There would certainly be overtones and harmonics, but at a diminished value. I don't know enough about the subject to even guess what levels they would be at. I do know they exist, and can be heard, I just don't know at what levels. At some point(3rd harmonic and so on), they would be inaudible though.

        "If we weren't all crazy, we'd just go insane..." -Jimmy Buffett

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        • #5
          I realise this is all subjective but that's the point of this listening confirmation. My goal here is:
          a) does the instrument sound real?
          b) is it consistent throughout its range?

          Next thing is to find some test tracks.

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          • #6
            Originally posted by Turtle View Post
            There would certainly be overtones and harmonics, but at a diminished value. I don't know enough about the subject to even guess what levels they would be at. I do know they exist, and can be heard, I just don't know at what levels. At some point(3rd harmonic and so on), they would be inaudible though.
            It depends on a variety of factors. With low frequency instruments the 2nd and 3rd harmonics can exceed, sometimes by a wide margin, the fundamentals. Useful harmonic content on average extends to at least the eighth harmonic when the fundamental is 2kHz or lower. It's the harmonics that define timbre, and at the lower frequencies even pitch. At 40Hz and lower you can't tell the pitch without the harmonics. At all frequencies without the harmonics you wouldn't be able to tell one instrument from another.

            www.billfitzmaurice.com
            www.billfitzmaurice.info/forum

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            • #7
              Originally posted by billfitzmaurice View Post
              It depends on a variety of factors. With low frequency instruments the 2nd and 3rd harmonics can exceed, sometimes by a wide margin, the fundamentals. Useful harmonic content on average extends to at least the eighth harmonic when the fundamental is 2kHz or lower. It's the harmonics that define timbre, and at the lower frequencies even pitch. At 40Hz and lower you can't tell the pitch without the harmonics. At all frequencies without the harmonics you wouldn't be able to tell one instrument from another.
              That makes sense; Thanks for the info. So, if that many harmonics can be heard/measure, how useful would that be in evaluating a speaker? Is there anyway to reasonably assume what those harmonics should be measured at?
              "If we weren't all crazy, we'd just go insane..." -Jimmy Buffett

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              • #8
                Originally posted by billfitzmaurice View Post
                It depends on a variety of factors. With low frequency instruments the 2nd and 3rd harmonics can exceed, sometimes by a wide margin, the fundamentals. Useful harmonic content on average extends to at least the eighth harmonic when the fundamental is 2kHz or lower. It's the harmonics that define timbre, and at the lower frequencies even pitch. At 40Hz and lower you can't tell the pitch without the harmonics. At all frequencies without the harmonics you wouldn't be able to tell one instrument from another.
                What instruments have harmonics that exceed the fundamental ? You might have an instrument that the fundamental causes the instrument body to create a resonant frequency that is louder, but harmonics are not louder than fundamental frequencies.
                craigk

                " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

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                • #9
                  Originally posted by craigk View Post

                  but harmonics are not louder than fundamental frequencies.
                  Sorry but you're incorrect. When plucked a certain way/style, stringed instruments like guitar and bass can have harmonics louder than the fundamental. I don't know about other instruments, but I know guitars and basses for 27 years.









                  As far as using scales to "detect anomalies", I think that test would be very subjective as to the experience of the listener, and even then you'd be missing some frequencies that a particular scale would miss. In essence, trying to detect instrument harmonics within the speaker's reproduction is equivalent to frequency response in a way. If the 5th harmonic lies at say 5kHz, but the speaker has a 10dB dip there, then it would be missing and would affect the reproduced instrument timbre. If you take care of the frequency response in the first place [before trying to resort to scales/instrument timbre reproduction], then you won't have to worry about that hypothetical 5th harmonic at 5kHz; it will be there because the frequency response dictates it will be reproduced at the specified level.

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                  • #10
                    no they are not. i have been playing the guitar for over 40 years and you are wrong. you are getting the effect of the instrument body amplifying the harmonics. if you found a way to create more energy than you put into the fundamental you are breaking the laws of physics. you are creating a perpetual energy machine.
                    craigk

                    " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

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                    • #11
                      Hit the low key on a piano, it is about 20 Hz for the fundamental. What you hear is mostly harmonics.
                      As to guitars, I have programmed digital tuners for electric guitars. The level of the second harmonic often exceeds that of the fundamental, even with an unprocessed guitar. Add distortion as found in most guitar amps and the harmonics go crazy. High gain amps or preamps have shaping filters before the clipper stage to reduce the level of the fundamental even further, or else the tone will be too 'farty'.
                      "She don't love my speakers anymore..."

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                      • #12
                        Debate aside, I had been thinking scales as test material rather recently as well.

                        It would be nice to have a collection of scales played on a variety of instruments.

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                        • #13
                          Originally posted by craigk View Post
                          no they are not. i have been playing the guitar for over 40 years and you are wrong. you are getting the effect of the instrument body amplifying the harmonics. if you found a way to create more energy than you put into the fundamental you are breaking the laws of physics. you are creating a perpetual energy machine.
                          Well then agree to disagree, just like the others who also disagree with you. Nothing to do with breaking the laws of physics nor perpetual energy, that's for sure, lol.

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                          • #14
                            Originally posted by wavefunction View Post
                            Hit the low key on a piano, it is about 20 Hz for the fundamental. What you hear is mostly harmonics.
                            The same applies at A3, and all but the highest octave:



                            That's complicated, because the strings that aren't being hammered still produce sound. But that's not the case with a horn. This unspecified horn playing an A3 clearly shows 2nd and 3rd harmonic content that exceeds the fundamental, while even the fourth harmonic comes close:

                            www.billfitzmaurice.com
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                            • #15
                              Originally posted by philthien View Post
                              It would be nice to have a collection of scales played on a variety of instruments.
                              I agree. I'm sure there are some tracks available somewhere. As an alternative, I just use a good mix of tracks that include instruments like piano, mandolin, flutes, and so on. While it may not be the most "scientific" method, I prefer acoustic instruments for initial testing of speakers, then I move on to other genres to "push" the speakers.

                              "If we weren't all crazy, we'd just go insane..." -Jimmy Buffett

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