Understanding bass in a Home Theater system.

chris2456

I am new to this site so go easy on me if my questions seem trivial.

Qualifier - My home theater systems front speakers and rear surround speakers each have a dedicated Polk Audio powered subwoofer (3 subs) via speaker level in/out connections.

1) BASS in general – In a 7.1 home theater system is there a difference in the bass directed to the front channels verses the rear surround channels, or is bass just bass? I have always used speaker level connections to all my speakers which allow the low frequencies to be filtered at the sub of each individual speaker. Assuming the surrounds receive a different signal level than the front speakers during the decoding of a movie would the bass level be different at the various speakers at any given moment? If I switch from “speaker level” to “line level” connections how will this effect the front bass level verses the rear surround level? Line level does not allow me to specify front -vs- rear connection. I guess my question is how do you control the bass between the front and back if you use a line level connection verses a speaker level connection?

I am running a Sunfire Theatre Grand IV preamp, Sunfire Cinema Grand 7-400, with LSi25's front, 2 LSiC's, and a pair of LSiFX with a PSW-1000 in the rear.

Thanks

chris2456

Everyone probably already knows this but I'll place it anyway for those who may have read my thred and did not know...
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Hi Christopher,

Thank you for contacting Crutchfield Technical Support. In this type of system, you can have discrete information for each channel.

However, the Bass information for the entire soundtrack is typically encoded in the .1 channel in these systems. Depending on how the receiver is set up, the subwoofer will either receive the LFE (.1) information or it will receiver the front channel bass information and the LFE information.

This is usually dictated by the speaker size setting in the receiver.

While all of the channels are full range channels, the encoding usually doesn't include much bass information in center and surround channels. There can and will be some bass information in these channels but it is not something that can be controlled.

While having subwoofers in-line on the surround channels is ok, it is probably not making a very big difference in the overall sound.

If you were to take these subwoofers and connect them to the line level subwoofer output, you will probably hear an increase in Bass level but you could also possibly hear a decrease.

Having the subwoofers around the room could create a situation that can possibly create what is called "Destructive Interference".

Basically what this is, is sound waves in the room reaching the main listening position and being out of phase with each other. When this happens, the sound waves essentially cancel each other out, and reduce the apparent bass level in the room.

I hope this of some help to you. If you have any other questions, please let us know.
Shawn
Crutchfield Technical Support
1-800-955-9094 Ext. 5529
techsupport@crutchfield.com