arnyk wrote: > That Linkwitz Lab page seems to support my claim: "The distortion > spectrum of this test signal is very discriminating and robust. It > contains not only harmonics, but also *the more serious intermodulation > components, which are of higher amplitude*. " > > If you listen to anything but simple test tones over a system with > nonlinear distortion, you will hear IM. It is probable that the IM will > predominate because of its nature. (explained by means of a simple > example, below)" > > The only way to have the HD profile be a greater factor than the IM is > to listen to pure test tones. As soon as you start listening to music, > the IM will overwhelm the harmonic distortion. > > Let's say that you have an amp that has only a second order nonlinearity > that is as large as possible. > > If you put in 1KHz, you will get out a 2 KHz tone half the amplitude of > the input wave, plus a DC signal that is also half the amplitude of the > input, but since your speakers and ears dont' respond to DC, it will be > inaudible. > > If you put in a 1 KHz tone and a 1.5 KHz tone that are together the > same amplitude, you will make each half the maximum amplitude so they > don't clip when you sum them. > > Due to the *same nonlinearity *you will get a 500 Hz tone, a 2 KHz tone, > a 2500 Hz. tone and a 3 KHz tone. * Right off you get about four times > as many audible distortion-related spurious responses.* The 500 and > 2500 Hz tones are about half the size of each input wave, and the 2 KHz > and 3 KHz tones are about half as large as them. So, the spurious > responses from the IM are all audible and when added together have a > about double the percentage as the one audible tone from the harmonic > distortion. > > Thus the IM will overwhelm the harmonic distortion. Furthermore the > harmonic distortion is likely to be masked by the natural harmonic > structure of musical sounds, while the IM distortion as you can see, is > about half tones that are not harmonically related to the source, and > won't have anything to mask them in the music. They will blare in your > ear!
Hi again Arny! You've been busy posting since I sloped off last night so I'm still catching up. Thank you for this clear & informative post on IM. Would you think that your remarks in any way justify my preference for Class A amplification since it seems to me to produce a output remarkably free from IM at least in the case of my Pathos amp (ok, it's only strictly Class A up to 30W per channel into 8 ohm but that goes a long way in my modest room). Or am I misguidedly suffering from yet another audiophile myth here, in your opinion? Dave :) ------------------------------------------------------------------------ Golden Earring's Profile: http://forums.slimdevices.com/member.php?userid=66646 View this thread: http://forums.slimdevices.com/showthread.php?t=106914 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
