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myrman

Reverse phase - what does it mean?

34 posts in this topic

Following on from the Modwright thread can anyone explain what reverse phase is. There seem to be a number of manufacturers that make reverse phase products so what are the benefits of such a design?
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Only benefits for paying listener are if safely/paying listener prefers such-configured bitties.

E.g.

[url]http://www.google.co.uk/#sclient=psy-ab&hl=en&source=hp&q=audio+reverse+phase&pbx=1&oq=audio+reverse+phase&aq=f&aqi=g-v1&aql=&gs_sm=e&gs_upl=4108l4776l1l5083l4l1l0l2l2l0l66l66l1l3l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=80a9d93b87c99bdf&biw=1920&bih=797[/url]
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It flips the phase on [I]both[/I] channels, so instead of the signal going [I]up, down, up, down[/I] it goes [I]down, up, down, up[/I] etc. Thus your speaker will be going[I] in,[/I] [I]out, in, out[/I] instead of [I]out, in, out, in. [/I]Exactly the same can be achived by flipping the speaker cables at one end only, ie what was in + goes in - etc.
I had an amp with this facility, couldnt hear fuck all diffrence, you could argue for certain sounds that the first transient is always in the same 'direction' (ie either pressure or rarefacation) it is important. Such as a kick drum, where the leading edge would be going up. Temper this with all the phase errors introduced by the entire recording chain, studio mic to domestic speaker, and it's a very muddy pond.
Note it's important that this is done to both channels, flip the phase of just one & you get all sorts of cancellations & phase effects.
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Wot he says.

Though I thought Chumpy's explanation was the best.
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My old pre-amp reversed phase. As I understand it the polarity is just inverted. I just connected the output of the power amp the other way round. Otherwise I think the speakers would have been sucking instead of blowing.
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Reversing phase can move bass nodes around the room. If you were sitting in a position where bass seemed weak it could be because your were in a position where bass might be cancelled out. Reversing the phase quite can result in increase or decrease in bass but it obviously varies dependant on room and circumstances. A lot of subs come with the facility to reverse phase because it can be easier to do that than to try and site the sub optimally.
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True Henry, but with a sub, when you reverse the phase you are reversing it for the sub only, so not changing the phase of the main speakers. This will certainly have a notable effect.

Reversing absolute phase means that the phase of every speaker driver in the system is reversed. Even with a low bass note at 50hz, the speaker cone is moving backwards and forwards 50 times per second. For the life of me, I can't quite see how whether it starts off by moving forwards or backwards is going to make the slightest difference.
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[quote name='rabski']

Reversing absolute phase means that the phase of every speaker driver in the system is reversed. Even with a low bass note at 50hz, the speaker cone is moving backwards and forwards 50 times per second. For the life of me, I can't quite see how whether it starts off by moving forwards or backwards is going to make the slightest difference.[/QUOTE]

So why bother confusing the consumer with such a design. If there are no great benefits there seems little point.
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[quote name='def']I think CJ are run that way as their circuit creates an 'out of phase' signal in the pre and rather than reverse it in the amp they choose to do it via the connections.[/QUOTE]

Some of the old Linn stuff used to do that. Always made me think "if you can't get the phase right, what else is wrong?".
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[quote name='def']I think CJ are run that way as their circuit creates an 'out of phase' signal in the pre and rather than reverse it in the amp they choose to do it via the connections.[/QUOTE]

yes so far that aspect has put me off cj amps
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[quote name='hifinutt']yes so far that aspect has put me off cj amps[/QUOTE]

Why?
At least they tell what they are doing.


I had a Bryston pre-amp once that had a reverse phase switch on the front. The manual said it was so you could switch the phase for known recordings as a lot of them were out of phase. How you were supposed to know it didn't explain.

I can't see as how it makes any difference as long as everything is in the same phase.

There was a wammer a few years ago who had a bake off and people said that something wasn't right and suspected that one speaker was out of phase. All the connectors were checked and everything seemed OK.
Eventually it was found that one of the speakers had the internal wiring out of phase and that is how it had left the factory!
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I have a friend who uses a phono stage with an 'invert phase' button. Apparently, with recordings that were recorded out of phase, using the phase button makes the soundstage snap into place.
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My old Cyrus CDP had a phase invert button. It never made the slightest difference. You can invert the phase by moving your head half a wavelength nearer the speakers. Every frequency arrives at your ear with a different phase....
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