Center channel bass output

[Erik Mandaville]

Here is something I didn't notice very much before, but do now that I don't have the Lexicon's capability of setting crossover points to the center and other surround channels: It seems to be deriving bass from both channels, and pooling those together at the center. Earlier this afternoon I thought, "Wow, that sounds kind of cool, maybe I don't need a subwoofer, afterall!" the problem is peaky bass, where the rest of the mid and and HF response are balanced with that of the Klipschorns.

I need to build a speaker level filter for that, because it didn't sound this way at all with the Lex. processor here. I have had this lesson in life many times -- sometimes you don't know how much you care/like/appreciate something until it's gone!

I really didn't notice this excessive bass before, but maybe it was just the recording??? Somehow, I don't think so.

[D-MAN]

Erik, maybe you could get by by "capping" it for a 70Hz bandpass? At least that would be relatively cheap.

DM

[Erik Mandaville]

Hey,

A cap to block the bass is what I was thinking about -- I appreciate your advice! I'm going to look at it tomorrow when I'm not so tired. My eyes started going crossed looking at this crossover table I have...

Erik

[sfogg]

Erik,

" It seems to be deriving bass from both channels, and pooling those together at the center."

Yup, the minibox would since it is just blending both left and right together and sending it to the center. The Las can't keep up with the bass from your mains so it would probably make it peaky over the range it covers (being reproduced from 3 woofers in that range) but wouldn't be able to go as deep as the K'Horns so that area wouldn't be boosted by the same amount. This might be compounded by the center not being time aligned with your L/Rs any more.

Also bass from the center channel (which is typically in the center of the room) is a bad idea as it has the lowest ITDs and is also equidistant from both side walls which will reinforce some room modes much worse then in other locations.

I'd put a basic high pass on the center amp around 100hz or so to help tame this somewhat. The Lexicon's high pass filter was second order if you wanted to try to duplicate it.

Shawn

[Daddy Dee]

Somewhere, maybe Dope from Hope? I read about the L+R bass output being a challenge for the center.

[sfogg]

Erik,

Forgot to mention that the Lexicon's modes (like most matrix modes) preserve the total energy in the recording. What that means is the total amount of energy put into the room by x number of speakers is equivalent to what that recording would have done played back in 2 channels. You might have noticed when you switch back and forth from 2 channel to Music Logic that your L/Rs would have been a little louder in 2 channel mode. This is why.

The minibox wouldn't do this, it will alter this relationship somewhat depending upon where the center channel reinforces the output of the L/Rs the best. I'd guess this might alter the tonal quality somewhat compared against 2 channel.

Shawn

[sfogg]

" I read about the L+R bass output being a challenge for the center. "

It would. The center in the minibox setup is getting twice the bass level of the L/Rs. The Las isn't going to keep up with a pair of K'horns.

Shawn

[Erik Mandaville]

Shawn:

"You might have noticed when you switch back and forth from 2 channel to Music Logic that your L/Rs would have been a little louder in 2 channel mode. This is why."

I noticed exactly that. Switching from Music Logic into two-channel produced a really big difference in sound, which to some might perceived as 'better' at first. I wanted to make note of the differences between the two, because as I said, even two-channel with the Lexicon was great. Both Music Logic and 2-channel only provided clear and detailed sound, but I think I mentioned that 2-channel in comparison sounded 'flat' and even slightly harsh (probably because it was quite a bit louder) than in surround Music Logic mode. The main victim of jumping into two channel, though, seemed to me to be imaging. With two channel, we got a really large and spacious sound, but the reference points for instruments were not nearly so distinct.

Thanks for the explanation (and Dee for mentioned the D From H info.)on the bass issue. I need to work something out with that, because it's really noticable on certain pieces of music. Bass just leaps out says "Look at me!"

I'm half way done with the Moth!

(oops!)