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Hydrogenaudio Forum => General Audio => Topic started by: ppataki on 2010-07-22 12:41:48

Title: 4.0 configuration - bass redirection
Post by: ppataki on 2010-07-22 12:41:48
Dear All,

If I have a 4.0 speaker configuration and play a 5.1 or 7.1 signal through HDMI (receiver and computer are set to 4 speaker configuration)
will bass be redirected to only the front speakers or also to the rear ones?

What happens to the content of the center channel? Will it be mixed to the front speakers?

Many thanks in advance
Title: 4.0 configuration - bass redirection
Post by: probedb on 2010-07-22 12:53:32
It depends on your speaker settings. If they're all small then you won't get any bass below the crossover level. I believe if they're set to large then they get the full range. Center will be split between the two fronts.
Title: 4.0 configuration - bass redirection
Post by: DVDdoug on 2010-07-22 20:02:18
Normally, the "point one" channel does not get sent to the full-range speakers.  management normally does the opposite....  It (optionally) redirects the bass from the 5 full-range channels into the subwoofer.  (Because most people have small satellite speakers that can't reproduce bass.) 

Your receiver may have some different settings, but that's how it's usually done....

The regular channels are full-range and the "regular bass" is supposed to be mixed into these channels.  The point-one channel is the LFE channel (Low Frequency Effects) and it's supposed to contain the extra bass for "booms & explosions".  The LFE channel information is also normally left out of the 2.0 mix, but it too gets the normal bass.

So, if you have full-range speakers that can reproduce bass and you're system is configured so that it does not redirect all bass to the sub, you should still get the regular bass, but you'll be missing some special-effect bass (assuming the movie was mixed correctly). 

Since you have a non-standard setup, you might look for a test DVD so you can confirm what your system is doing with the "missing" channels.    (I have a test & demo DVD from Dolby called "Explore Our World", but apparently it's no longer available.)
Title: 4.0 configuration - bass redirection
Post by: DVDdoug on 2010-07-23 03:21:36
Good news!

I popped-in my Dolby test DVD and set my receiver to "Center Speaker = None and "Subwoofer = None".  As probedb said, the center signal was sent to the left & right speakers.    And, the LFE channel was also sent to the front speakers (with the front speakers set to "large").

So I was wrong, and if your speakers can reproduce low frequencies you will not be missing any low frequency effects.  (Assuming your receiver works like mine.)
Title: 4.0 configuration - bass redirection
Post by: ppataki on 2010-07-23 08:44:07
Hello,

That is good news!
May I ask if the LFE channel was also sent to the rear channels?
(or only to the front channels)

Many thanks in advance
Title: 4.0 configuration - bass redirection
Post by: andy o on 2010-07-23 14:24:23
What HDMI device do you have? If you have an ATI 4000 or 5000, or the newly released Nvidia GTX460 then in quadraphonic mode, you can probably set the speakers to small or large. Small means that bass will be redirected to the sub. Large means that no bass management is done. If you want the LFE channel to be output from the speakers (usually the main L and R) that's a job that usually the receiver handles.

The other HDMI solutions that exist are the Xonar HDAV, and the Auzentech Home theater HD, which have fancy options, but I don't think they offer quadraphonic. The Intel option should be as barebones in processing/bass management as the ATI/Nvidia ones, but bass management is usually redundant anyway, since pretty much all receivers offer better options.
Title: 4.0 configuration - bass redirection
Post by: DVDdoug on 2010-07-23 23:11:54
Quote
May I ask if the LFE channel was also sent to the rear channels?
(or only to the front channels)
Only to the front.