[Bob in St. Louis]

Hey guys,
Just curious as to what kind of low frequency content is sent to the rear channels.
Very soon, I'll be purchasing new rear surround drivers (open baffle of course  ) and knowing what kind of content that's sent back there will help my buying decision.

Thanks in advance fellas.
Bob

[bpape]

Just for clarity - LFE is a separate channel of it's own and is not sent to any of the speakers other than the sub unless you tell the processor you don't have a sub.  Now, general bass content is present in all channels.  In a home theater environment though, you should be cutting the mains and surrounds off at 80Hz and feeding all that to the sub anyway.  If you do that, then anything that will do 80hz effectively is sufficient (say 60Hz just to be safe).

Bryan

[Bob in St. Louis]

LFE is a separate channel of it's own and is not sent to any of the speakers other than the sub unless you tell the processor you don't have a sub. 

Very true Bryan. Poor use of wording on part, sorry about that. My subject line should have said "LF", not "LFE".....

Thanks for the information Bryan regarding cutting thier balls off at 70Hz +/-10Hz, and letting the subs take over below that. That'll help me decide which route to go.

Thanks again, (when are you coming over to the house??  )
I have beer. 

Bob

[JBLsince1990]

You’d be better of with an affordable loudspeaker management crossover system like the Behinger (DCX2496) matching amplifiers matching loudspeakers for the fronts and array of surrounds placed down the sidewalls and rear wall with a single or an array of subs placed below the fronts and useful bit of imagination to design the sound system into an aggressive beast to handle any film format with lower lows and higher highs wider dynamic range handling smoother with
smoother output frequency response.



Behringer Ultradrive Pro DCX2496
http://www.behringerdownload.de/DCX...SPECS_Rev_C.pdf





If you listen to “Planet of the Apes” (2001) chapter 3 there’s a shuddering low end on the split-surrounds @ 25Hz that would shake the seat. It should be noted that careful setting up needs to be paid close attention to make sure the lows don’t over lap each other with excessive low end audio masking or negative phase where it would cancel out slightly, providing its not "Return of Jedi" (1983) chapter 41 where "Luke and Vader" have a standoff with the (John Williams) score going completely nuts with a low end slam that comes from the split-surrounds and the fronts left and right while the centre carries a different low end or sound effect.

[ted_b]

I would say it is very dependent on what you plan on using the surround/rears for.  Yes, for movies the "thx" thinking (rolling off at 80hz and sending remainder to sub to combine with separate lfe channel at sub) is ok.  If you are, like me, a multichannel music fan, then five identical or near identical speakers, full-range, is the goal.  To each his own.  The good news on the former (movie) option:  80hz is not gospel (except to thx programs); if you find great speakers that match sonically with your front three then roll them off wherever they naturally start to knuckle down anyway.

[JBLsince1990]

There’s many ways to do this, this is one of many examples to design a four-way sound system using smaller loudspeakers for the fronts LCR with matching sub bass arrays placed below each one receiving its own low end within a degree of budget cost.

[drcruz]

Accroding to dolby.com ( http://www.dolby.com/assets/pdf/tech_library/L.mn.0002.5.1guide.pdf  - page 3-6)

The rear surround information is from 100Hz to 7kHz

Since dolby digital is set up in 5.1 discreet channels I like to run all 5 channels in full range and have 2 subs set up for the .1 LFE channel. (L/C/R freq. range is from 3Hz to 20kHz, while LFE is from 3Hz to 120Hz.)

But as has been said, there are many ways to skin the cat.

The weird thing is 5 channel music is set up a little different than 5 channel HT. If I had the money, I dream of having a dedicated multi-channel listening room w/ 5 equal full range speakers for the 5 channels, 2 to 4 subs for the .1 LFE channel all set up for 5 channel music, a good quality Universal DVD player, plus a drop down screen w/ front projector for movies. 

[opnly bafld]

Accroding to dolby.com ( http://www.dolby.com/assets/pdf/tech_library/L.mn.0002.5.1guide.pdf  - page 3-6)

The rear surround information is from 100Hz to 7kHz

That applies to the old Dolby Pro Logic, Dolby Digital is full bandwidth.

Lin

[drcruz]

OB,

I do not doubt that things are improving, can you please provide a link. I really enjoy reading this stuff. 

Thanks in advance

[opnly bafld]

OB,

I do not doubt that things are improving, can you please provide a link. I really enjoy reading this stuff. 

Thanks in advance

It is in the link you provided.

Lin

[ted_b]

OB,

I do not doubt that things are improving, can you please provide a link. I really enjoy reading this stuff. 

Thanks in advance

It is in the link you provided.

Lin

Yep, page 8 (section 1-2) describes the full bandwidth of Dolby Digital.
5.1-channel audio typically consists of five discrete, full range main channels (Left,
Center, Right, Left Surround, and Right Surround) plus an optional band-limited Low
Frequency Effects (LFE) channel for added bass (the .1). Dolby Digital bitstreams
deliver full frequency bandwidth main channels, from 3 Hz to 20 kHz, and a limited
frequency bandwidth LFE channel, from 3 Hz to 120 Hz. Current Dolby Digital
encoders accept word lengths of 16, 18, or 20 bits at sampling rates of 32, 44.1, or
48 kHz. The Dolby Digital algorithm provides 24-bit resolution, and future versions
may extend sampling rates to 96 kHz. All multichannel programs carried within a
Dolby Digital bitstream, can be downmixed (see Section 2.2) for compatibility with
Dolby Surround, stereo, or mono systems.

Now, currently we have DD and DTS, both lossy formats that put out full bandwidth 5.1, and most recently the new HD-DVD and Blu-Ray-based audio codecs that are 7.1 capable and are NOT lossy.  They are lossless compresssed formats and can handle 24/96 in eight discrete channels.  These codecs are called Dolby True HD and DTS HD Master Audio.  there are a couple of versions that are somewhere between the old and new  (Dolby Digital +, etc.), but that's enough options for now.   

[drcruz]

OOPS!