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From: "Ken McDonald"
Subject: Re: Is it Possible?
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 13 Jan 2003 17:59:54 GMT
NNTP-Posting-Date: Mon, 13 Jan 2003 12:59:54 EST
"Kevin McMurtrie" wrote in message
> In article ,
> "Ken McDonald" wrote:
> >"Kevin McMurtrie" wrote in message
> >> In article ,
> >> "Ken McDonald" wrote:
> >> >I want to build a circuit to eliminate the center channel from a
> >> >input. I think I can do it by inverting one channel and sum it with
> >> >other channel. Or feed both inputs into a differential amplifier. The
> >> >problem is I end up with a mono output.
> >> >
> >> >What I really want is to eliminate the center channel and still have a
> >> >separate left and right channel. Is it possible?
> >> >
> >> >Regards,
> >> >
> >> >Ken
> >> >
> >> >
> >> Not with simple linear circuits. The best you can do is to remove a
> >> fraction of the common signal and send that to the center channel. It
> >> works in moderation. The more it's done the more the sides become
> >> inverted mono, as you mentioned.
> >> Do a web search for surround sound decoders and center channel
> >> A circuit is programmed with a set of rules for adjusting the levels of
> >> each speaker to guess the sound placement. An encoder is designed to
> >> help trigger those rules. The key word here is "guess." It works for
> >> some kinds of audio but mangles others. Dolby has most of the patents
> >> there.
> >> DVD offers six independant channels. There's no placement guessing.
> >> The only limitation is that the sub channel has a 200Hz cut-off.
> >> Speaker placement has a lot to do with all of this. Driving front and
> >> rear speakers with plain two-channel stereo can sound better than
> >> two-channel Dolby decoding when all the levels, echoes, and phases are
> >> just right.
> >Thank you for the answer. I'm not going to use the circuit for my stereo
> >system. I plan on connecting it to the output of my computer and use
> >headphones. I want to listen to particular music with the common signal
> >Ken McDonald
> That's it?!
> Paint over the ground lead (at the base of the plug).
I understand that is how you can connect speakers to attenuate common
signals. However, the original question was how to remove the center channel
but, still have the left and right signals separate. I was hoping there was
a fairly simple way to extract the center channel, invert it and sum it with
the left and right signals. If I could do that, I would have the left and
right channels separate ( I think). Unfortunately, I don't know how to
extract the center channel. Removing it is fairly simple and can done in a
variety of ways ( hardware and software) but, you end up with the left and
right signals mixed together (mono).
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