Electronic devices distortions are of a different type of the ones produced by mechanical transducers and has been proved that they are at least one order of magnitude more audible.
Moreover, THD is not all you have to measure on an amplifier.
If that 0.003% is 9th harmonic, it worries me.
Sorry Samuel, but I had to reply this.
No, however it looks like the high-frequency distortion of the basic one-transistor VAS varies in magnitude only for the various transistors types. The relative magnitude of the harmonics seems to be nearly independent from transistor type. 2nd harmonic is dominant, with higher harmonics gradually falling in level.
Samuel
A couple of 10 kHz FFT measurements for the amplifier from figure 6 of my paper:
10kHz_FFT_2N4401.pdf
10kHz_FFT_2SC3503F.pdf
10kHz_FFT_MJE181.pdf
10kHz_FFT_MPSA42.pdf
There are some differences in spectral distribution--mainly above the 4th harmonic--but nothing as drastic as at 10 Hz.
Samuel
10kHz_FFT_2N4401.pdf
10kHz_FFT_2SC3503F.pdf
10kHz_FFT_MJE181.pdf
10kHz_FFT_MPSA42.pdf
There are some differences in spectral distribution--mainly above the 4th harmonic--but nothing as drastic as at 10 Hz.
Samuel
Hello Samuel,
What model Audio Precision were the above graphs made on, also what simulator do you use.
Regards
Arthur
I'm not sure what relevance the answer should have, but the measurements were done with a SYS-2722 and simulations with an old Protel version.
Samuel
I wonder how many amplifiers designs would have low distortion if the standard test was an input of say 100 different frequency sinewaves at various levels, some harmonically related, and not only spurious frequencies but the deviation from all the ratios of input levels were measured? i.e. use something close to a standard music-like input instead of one or two sinewaves.
It would be more than interesting to see how that might be analysed and what you could learn.
As I recall, a comb filter has already been used in the distortion analysis of the output from multiple sinewaves and other mixed
signals in the Belcher Test and commented on by JLH and DS in their publications. Somehow, the technique seems to have dropped
below the horizon or been incorporated in other techniques in recent years.
There is some discussion here
As I recall, a comb filter has already been used in the distortion analysis of the output from multiple sinewaves and other mixed
signals in the Belcher Test and commented on by JLH and DS in their publications. Somehow, the technique seems to have dropped
below the horizon or been incorporated in other techniques in recent years.
There is some discussion here
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