Phase Cancellation: Difference between revisions

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Phase (cancellation, interference)

~~== Practical Note ==~~

"Finally, we have convinced ourselves that audible phase cancellation should not occur from two systems spaced more than about four feet apart. The combing is just too dense. " - Ken-at-Bose <ref>See: http://bose.infopop.cc/eve/forums/a/tpc/f/6806048934/m/7831003593?r=3291045593#3291045593 in

{{~~Forum~~}}~~</ref>~~

=== Theoretical Discussion ===

Running two inputs 180° out-of-phase puts the peaks and valleys of the sine wave so that they null each other out when summed (see the middle picture below). This has a tendency to cancel out both inputs, and is quite pronounced in the "far" field, but negligible in the "near" field. Normally phase cancellation is undesirable, but when you know what you want (and in this case, what you don't want) then you do it deliberately.

<html>

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<EMBED src="http://www.sfu.ca/sca/Manuals/ZAAPf/splash/phase_diagram.spl" width=490 height=174

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The illustration above is from [http://www.sfu.ca/sca/Manuals/ZAAPf/p/phase.html Phase at SFU]]. Follow the link for a very interesting discussion about Phase.

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[[Image:PhaseIn.png]]

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# Poor imaging

See: [http://www.livesoundint.com/archives/2003/july/phase/phase.php Practical Realities of Phase Interference]

See:

There is an interesting visual presentation of [https://www.youtube.com/watch?v=D7aftTF--5w how phase cancellation occurs with two sound sources].

[http://www.livesoundint.com/archives/2003/july/phase/phase.php Practical Realities of Phase Interference]

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See: [[:Category:Phase|Phase]]

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</noinclude>

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+{{Bose Reviewed}}
 Phase (cancellation, interference)
 <!-- TODO resolve circular reference to category and this page -->
-== Practical Note ==
+{{:Phase Cancellation and the L1}}
-"Finally, we have convinced ourselves that audible phase cancellation should not occur from two systems spaced more than about four feet apart. The combing is just too dense. "  - Ken-at-Bose <ref>See: http://bose.infopop.cc/eve/forums/a/tpc/f/6806048934/m/7831003593?r=3291045593#3291045593 in
-{{Forum}}</ref>
 === Theoretical Discussion ===
 Running two inputs 180° out-of-phase puts the peaks and valleys of the sine wave so that they null each other out when summed (see the middle picture below). This has a tendency to cancel out both inputs, and is quite pronounced in the "far" field, but negligible in the "near" field. Normally phase cancellation is undesirable, but when you know what you want (and in this case, what you don't want) then you do it deliberately.
-<html>
+<!-- dead link looking for replacement
+<html><br />
 <EMBED src="http://www.sfu.ca/sca/Manuals/ZAAPf/splash/phase_diagram.spl" width=490 height=174
 Loop="True" Play="True" BGColor="ffffff" Quality="Autohigh" Scale="Showall" SAlign="">
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 The illustration above  is from [http://www.sfu.ca/sca/Manuals/ZAAPf/p/phase.html Phase at SFU]]. Follow the link for a very interesting discussion about Phase.
+-->
+[[Image:PhaseIn.png]]
@@ Line 29: / Line 33: @@
 # Poor imaging
-See: [http://www.livesoundint.com/archives/2003/july/phase/phase.php Practical Realities of Phase Interference]
+See:
+There is an interesting visual presentation of [https://www.youtube.com/watch?v=D7aftTF--5w how phase cancellation occurs with two sound sources].
+[http://www.livesoundint.com/archives/2003/july/phase/phase.php Practical Realities of Phase Interference]
+----
 See: [[:Category:Phase|Phase]]
+<noinclude>
+----
+<references />
+</noinclude>