20hz to 80hz sweep, sound from center channell - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 8 Old 07-09-10, 05:16 PM Thread Starter
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20hz to 80hz sweep, sound from center channell

When I run the test in the picture. I have sound coming from my center channell. How can that be?

I have all speakers set to small and crossover set to 100hz.
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post #2 of 8 Old 07-09-10, 05:25 PM Thread Starter
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Re: 20hz to 80hz sweep, sound from center channell

As a side note, what do you gain from this test? Can you capture and graph it?
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post #3 of 8 Old 07-09-10, 05:40 PM
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Re: 20hz to 80hz sweep, sound from center channell


Quote:
When I run the test in the picture. I have sound coming from my center channell. How can that be?

I have all speakers set to small and crossover set to 100hz.
You hear sound coming from your center channel because you have Dolby Pro-Logic engaged. Turn off all the receiver’s processing, so that you hear the sound in the left and right speakers.


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As a side note, what do you gain from this test?
Nothing I can think of.

Regards,
Wayne
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post #4 of 8 Old 07-09-10, 07:18 PM
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Re: 20hz to 80hz sweep, sound from center channell

As I wrote to you yesterday, the high and low -3db cutoffs you see in that screen are just that, the points at which the rolloffs begin. When you run your mouse over the sub cal button, the pop-up help information indicates that the REW rolloffs are -12dB/octave. So its signal is down ~12dB as high as 160Hz, well above your crossover. So I'm not surprised you hear something from other speakers.

As Wayne wrote, REW is normally sending a 2 channel signal to the AUX input on the receiver. If you are hearing something from the center speaker, you must have some Dolby or surround mode enabled. If you are hearing something only from your center speaker and not the other satellites, that would result from Dolby Pro-Logic mode.

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post #5 of 8 Old 07-10-10, 12:13 PM
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Re: 20hz to 80hz sweep, sound from center channell

When Bill says "sending a 2 channel signal" I believe he means it's meant for either L or R channels (and sub) and not meant for the C channel, just to clarify, I don't think he means to plug in both L and R channels at the same time... normally...

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post #6 of 8 Old 07-10-10, 10:41 PM
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Re: 20hz to 80hz sweep, sound from center channell

That's a good point, Greg. For Wayne's suggestion, that sound is coming from the center channel instead of the left/right channels to work, wouldn't both channels have to be fed? So it sounds to me that the current connection is using a splitter to drive both left and right. And implicitly in your observation is that, if only the left or right were driven, the sound should be in only the left+sub or right+sub, not center+sub.

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post #7 of 8 Old 07-12-10, 11:53 PM
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Re: 20hz to 80hz sweep, sound from center channell

You're probably right Bill. The only other scenario I see is if it was mistakenly connected to the C channel of the analog multi input...
But even in this scenario of both L and R were being driven, there wouldn't be output in the C channel unless surround processing was activated. There's no C channel in stereo mode.

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post #8 of 8 Old 07-12-10, 11:55 PM
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Re: 20hz to 80hz sweep, sound from center channell

I've often toyed with the idea of looking at my C channel's response this way, by feeding both L+R and using Prologic. And inverting one to feed the surround channels, even though I/we have 2 that would be getting a mono signal... you know me, I just like to play... more to the point, I like putting the ideas in other people's heads and getting THEM to play...

-Greg

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