bass content in surround speakers

[paulspencer]

I'm considering the idea of desiging all speakers in a surround system to have F3 down to at least 40 Hz in all speakers. I'd like some comments on this approach, especially from those who have tried it with experiences to share.

* does it give smoother in-room bass response?
* is it worth bass from the centre, main and rear channels?
* should you set your speakers to "small" even though they have good bass response in order to get more dynamic range?

[RobWells]

Hi Paul,

I think you have a good plan there as long as you can set your av processors x/o to match the 40Hz roll off.

I believe the processors amps usually x/o at 12Db hi pass around 80Hz to match a sealed roll off, creating a 24Db hi-pass at 80.

The sub outputs are x/o'd at 24Db to match.

Personally I'm heading for seperate subs for the surrounds, using the full range outs from my processor, with full range mains and my main subs just for LFE.

Cheers

Rob

[tiroth]

This is not very quantitative, but I sit and watch the FFT of the various channels on occasion, and the center/surround often seem band limited in the original mix. i.e. there is generally not very much power below 100HZ or above 10kHz. This has led me to believe that the capabilities of the surround channels need not be that great...but I wouldn't argue that adding that extra octave won't improve the sound...just that the difference might be very small. It is also going to vary a lot from recording to recording, I assume.

I AM talking about the mix on the disc; my processor is setup to go full range and I've measured the output to confirm there isn't any rolloff.

[paulspencer]

Rob,

Doesn't it concern you that there may not be very much signal going to the subs in the surround channels? What if they get bored and just sit there gathering dust?

I'm inclined to agree with using the bass from the main speakers, but subs for surround channels? hmmmmmm

How many subs? 3?

Tiroth,

What kind of movies did you look at? How much of a sample of movies are we talking about here?

The surround speakers in a comercial cinema don't look like they could handle any bass at all for a large space. Does this suggest that bass just isn't mixed to surround channels, or are DVDs mixed differently than the sound track used in cinemas?

[toonz]

I've been wondering about this as well. I've been thinking of building a small tower similar to the Creative Sound Spires, but my only concern is how much bass response I need.
The speakers I was going to use I can get to about an F3 or maybe 110Hz ...

I know my dad's Sony HT setup doesn't have much bass response in any of the channels (one of those satellite setups), so I don't think it'll be that big an issue.

[paulspencer]

Toonz,

What I'm concerned here is not so much a "problem" but rather more of a preference. Can a small (or perhaps not so small) but worthwhile improvement be made with bass through all channels ...

In your case it's just not possible or desirable as it would push those drivers too hard. (I assume you are using small TB's or similar). I wouldn't be too concerned. If you get a sealed 2nd order rolloff at 110 Hz then I'd say that will be fine.

[navin]

Originally posted by RobWells
...Personally I'm heading for seperate subs for the surrounds, using the full range outs from my processor, with full range mains and my main subs just for LFE....
Rob

in some instances i do believe there is bass information in the surroud channels yet for most applications i think if the surround channel roll off is gradual (read as sealed) one can get by with a F3 of 100hz. It all depends on your application like 5.1 audio.

if your rear sub is active then you might have to run a rather long RCA cable to the sub. this can be a problem.

[paulspencer]

Originally posted by navin

It all depends on your application like 5.1 audio.

if your rear sub is active then you might have to run a rather long RCA cable to the sub. this can be a problem.

Yes, I can see the value of bass info in the surrounds in 5.1 audio, although I don't think a subwoofer is warranted. I do expect there will be quite a number who will want subwoofers for surround channels for this application.

Why would long RCA line level cable be a problem? (I thought this was a problem, until a recent discussion regarding interference, now I'm not so sure).

[toonz]

Originally posted by paulspencer
Can a small (or perhaps not so small) but worthwhile improvement be made with bass through all channels ...

In your case it's just not possible or desirable as it would push those drivers too hard. (I assume you are using small TB's or similar). I wouldn't be too concerned. If you get a sealed 2nd order rolloff at 110 Hz then I'd say that will be fine.

Ahh.. I certainly think an improvement would be made. I'm sure in some movies, espacially war type ones or ones with explosions it would be useful.

Eg I was watching Tears of the Sun on the weekend, and I'm sure in the scenes with explosions happening all around you there'd be some spots where there should be some bass in the rear channels.

Yeah, not TB's but similar 4" drivers, I want some nice small rears as I don't have much space!

[navin]

not TB's? Fostex? Jordan? Visaton? let us know.