Joseph Crowe

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Nick
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#16 Re: Joseph Crowe

Post by Nick »

I have been thinking as it happens over the weekend about 2nd order distortion cancellation in push pull systems. Unless I am missing something cancellation is not the word we should use as the distortion is transformed into 3rd Harmonic.
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JamesD
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#17 Re: Joseph Crowe

Post by JamesD »

Hi Nick,

Don't we get both effects? We get some cancelation inside the active device as the overall 2nd harmonic can be less than without the attempted cancellation but also with the remaining amount converted to third harmonic as the level of third harmonic goes up.... This is also frequency dependent I seem to remember when I measured it...

Hi Wolfgang,

I agree that they all sound different - in my experience which sounds better depends on the loudspeaker and the passive and active crossovers under test...

Interesting articles and site... Here is Troels take on driver phase again multiple pages need to be read to get the whole story..
http://www.troelsgravesen.dk/Inverted-Polarity.htm starts basic and gets more interesting as he delves deeper into drivers and crossovers...
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Nick
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#18 Re: Joseph Crowe

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We get some cancelation inside the active device as the overall 2nd harmonic can be less than without the attempted cancellation
Maybe, I am just trying to understand how. If we start with a single ended output stage then the -ve going peak will be less than the +ve ones (for some value of + and -) hence 2nd harmonic, If you add the second output device, then its +ve going peak will be less than its -ve one (with respect to the output). Now the uncompressed peak is not magically expanded, so we have the reduced -va + the full -va, on one side and the full -va + the reduced -va on the other side, so both peaks are now reduced, so its third harmonic. But nothing has cancelled the reduction on the peaks, is just that there is now a unreduced peak added to the reduced one so in effect the reduction is half'd, but not by any cancellation action.

If that makes any sense.
Little known fact, coherent thought can destructively interfere with itself leaving no thought at all, that’s why I prefer incoherent thought.
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rowuk
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#19 Re: Joseph Crowe

Post by rowuk »

Nick wrote: Sat Apr 17, 2021 4:33 pm
Because intermodulation (sum and difference tones) are very much a part of live music. Two trumpets, a brass section, massed strings, voices, a woodwind section, all cause "serious" intermodulation
How? Where is the non linear mixing in the case of live music?

Even if you say the ear or microphone is the source of the intermod, then doing it twice by repeating the process is not equivalent.

I feel you may be conflicting the wanted dissonance created by the combination of musical intervals and the intermodulation created by the non linear mixing in the reproductive chain,
He documented that in a properly tuned major chord
I guess that would require a non tempered scale then.
Multi track recordings do not normally have the acoustic intermodulation recorded. Large scale acoustic recordings will mask "major chords" and brighten up "minor" chords. Modern professional players (non keyboard) play with just intonation. My intermodulation in the chord applies.
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#20 Re: Joseph Crowe

Post by iansr »

Having read Mitchco’s articles about AudioLens I’ve decided its something I’ve just got to try and use it to implement both an active crossover and room correction. I’ll be doing that with the horn system I posted about earlier. The articles are on Audiophile Style which is the haunt of quite a few lunatics as far as I’m concerned, but Mitch is most definitely not one of them. He is an ex studio engineer and comes at it from a balanced objective / subjective standpoint. Well worth reading for anyone interested in the current SOTA DSP. If your opinions on DSP are based on MiniDSP products then you might want to put any prejudices on hold . . .
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