good read

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#1 good read

Post by ed »

a bit of public service posting(including name dropping)....

lifted from another site...

Michael Rothacher was asking for some historic info, the gist of which was way over my head, but Nelson Pass offered this, which I thought was a cracking I thought I'd share: ... index.html
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#2 Re: good read

Post by IslandPink »

I'm working my way through it !
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#3 Re: good read

Post by Scottmoose »

Always interesting. :)

Re the section on absolute phase, Peter Aczel's reliably grumpy summary from the Spring 1979 edition of The Audio Critic may be of interest:

"A Brief Note on Absolute Phase"

When a trumpeter at a recording session blows into his mouthpiece, the first transient wave front emerging from the bell of his instrument, the initial attack, pushes the microphone diaphragm in. It's a positive-going signal and should be reproduced by a loudspeaker diaphragm moving toward the listener —a push. Similarly, a singer taking a sharp breath initially sucks the microphone diaphragm out and creates a negative-going transient signal that should be reproduced by a pull of the speaker diaphragm. If these signals are reversed in polarity, making the speaker push when it should pull and vice versa, the perceived sound won't be exactly the same. There will be a subtle loss of realism.

The audibility of "absolute phase" in music (not to be confused with stereo channel phasing!) has been known for a long time to sophisticated audio practitioners; in fact in the early vacuum-tube days it was an ironclad rule in the recording studio that there must be no phase-inverting stages anywhere in the recording and playback chain. This traditional piece of studio wisdom is now being rediscovered with wide-eyed wonder by assorted new audio gurus and cultists, who hail it as the invention of the wheel.

With the widespread use of multimike, multichannel, op-amp-console, mixed-down recording, the absolute-phase criterion has become meaningless. Not even the cleverest recording engineer knows what happens to a positive-going pulse through that maze of signal paths; even if he did, he might end up mixing his signal with inverted versions of itself on the same track.

With exceedingly simple recording techniques, however, such as are used by Mark Levinson, Proprius, the "new" Max Wilcox and a few others, there remains the possibility that the positive or negative-going character of a signal will be preserved intact. In that case an extra touch of realism can be added to the reproduction by experimenting with the plus-minus polarity of each channel, either by quickly reversing the speaker leads on each side by hand or having some kind of two-position switch in each channel. (Needless to say, it won't work with speaker systems that have the woofer pulling when the tweeter is pushing —or have any other driver out of phase.) Try it. You'll hear it. The better-sounding of the two possible connections will be the one with absolute phase.

* * *
(addendum written in 1992) If I were writing the above today, I would qualify and circumscribe the audibility of absolute phase even more carefully because when I press the Invert button on my current reference preamp I usually hear no difference whatsoever. I have been able to hear something on rare occasions, however, especially through coherent electrostatic loudspeakers (such as Quad ESL-63's). That something is never really dramatic or thrilling; "Better Sound for Free!" promises far too much.

As a minor thought from muggins here, Johnson appears to have railed against an 'audio establishment' for only printing what he termed 'orthodox views' but seems to have been rather selective in his own citations / references. Presumably he decided to write a lengthy text on the subject badly because he didn't have the time to write a short piece well.
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