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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics. |
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In Reply to: Re: Boy, You Opened Up a Can of Worms.... [-; posted by tomservo on August 19, 2006 at 09:33:19:
"Fwiw, this is why the fundamental chart for musical instruments does not tell you what spectrum they are capable of playing music."I have measured the frequency spectrum of a single note from a violin with a condenser microphone and a spectrum analyzer. My girlfriend and I were curious about the spectrum generated from different violins. She had three rare ones on hand for trying out (a Guarneri del Gesu, Guadagnini, and a Stradivarius). She would play the same note (A 440hz)on each violin and I would use the peak hold function on the anaylzer to get an image of the spectrum. There was information right up to 20Khz (the limit of the analyzer.) and yet each violin's spectrum was significantly different (the Strad had more HF content than the othes for one thing).
I am wondering if it would be possible to do a numerical subtraction of waveforms. This is often done in spectroscopy where a BLANK is first acquired and then the measurement is performed. Since the start time is the indexed they are lined up and the blank is subtracted from the sample measurement to leave behind only the contribution of real signal response.Now if you could take the analog signal from the amp and fed this output into a computer (suitably padded down so you don't blow out your sound card) and recorded the waveform then this would be your blank. Incorporated in the blank is the inherent distortion of the amplifier. Then you hook up a speaker and sample the signal at the speaker terminals saving this waveform to the computer. You would then have to line up the waveforms but then a difference spectrum should be the result. This difference spectrum would be distortion generated by the amp due to interaction with the speaker would it not?
The other possibility would be to record the signal with a good microphone, directly at the speaker or measured outside and correcting for the microphones response. This is fed into the computer and subtracted from the blank.
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- Re: Boy, You Opened Up a Can of Worms.... [-; - morricab 10:44:05 08/19/06 (0)
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