Compensating for multiple sides

Ok, first, that's one giant paragraph. In the future...

In any case, a couple things seem strange actually. I'm not sure exactly why you'd need to delay extra surround speakers, this is usually not done in most cinemas, it's just a big array. If you have multiple rows, it's fairly normal to just have arrays to the side and not have delays for the various speakers. However, I do see the thinking behind it if you are trying to align things best for a main listening position, however this seems like a slightly crude way to do it, because you're not going to get them all in phase. However, it isn't particularly a big deal IMO. I'm kind of surprised Dennis recommended adding in additional delay complications for side arrays. Never heard this done before.

The way I read the paragraph, you are NOT delaying the main surround speakers(not main as in 'dominant' but the ones nearest to the main listening position, presumably in the first row), and then for rows farther back you are adding a delay? This is backwards, you'd have no delay on the ones furthest away, and additional delay to the speakers nearest the main listening position.

Perhaps I'm reading that wrong, but that seemed backwards.

Dallas,

First things first: you need to pick a sweet spot from which to calibrate distances and levels. The speakers can't be the same distance from multiple seats, so pick one spot and stick to it. Don't use the automatic calibration routine in the Lexicon for setting distances; use a tape measure instead.

Write down the distances from the chosen sweet spot to all 11 speakers (3 pairs of side speakers). Enter the distance for all the speakers in the Lexicon. For the sides, pick the ones that are furthest from the sweet spot.

Run the side speaker outputs from the Lex to the Symnet. Run three pairs of outputs from the Symnet to their respective amps, and then to their respective side speakers. For the side speakers that are furthest from the sweet spot, dial in a delay of zero in the Symnet. For the other two pairs of side speakers, dial in the difference in distance between them and the furthest pair. So if furthest side speakers are 12 feet away, and the other pairs are 10 and 8 feet away from the sweet spot, then you'll be using the Symnet to delay them by 2 and 4 feet respectively (or whatever those distances work out to in milliseconds).

Now all your side speakers sound like they are 12 feet away. The one that is actually 12 feet away (the furthest from the sweet spot) didn't need any additional delay from the Symnet. Make sense?

The Lexicon lets you run auto distance, level and EQ all together or individually. You can either run the levels automatically or do it manually with a SPL meter. If you do it automatically, it will set levels for a spot exactly in the middle of all 4 mics. Personally, I would put a SPL meter at the sweet spot and calibrate levels manually. Whichever method you use, the three side speakers on each side will be calibrated as a single channel. If you were to calibrate the side speakers individually, then each side channel would be three times as loud compared to the other channels.

Remember to set crossovers before doing the auto-EQ. The EQ system shouldn't have a problem with multiple speakers for each channel. It seems to handle dipole speakers fine, so diffuse sound doesn't trip it up. Besides, it's actually listening to the room, not the speakers, to find out which bass frequencies linger for the most time and take the longest to decay. Keep in mind that it only works for frequencies below 250Hz, and is limited to addressing long decay times. To smoothen out low frequency repsonse, you'll need to use physical treatements (bass traps, etc) because the Lexicon doesn't really address this problem. Same for frequencies above 250Hz; passive treatments.

Good Luck,
Sanjay

Exactly! Since your front, centre and rear speakers will all be time aligned to that one sweet spot, it makes sense that all the side speakers should also be time-synched for this spot.
Correct. Measuring from the sweet spot, the closest pair of side speakers will need the most additional delay from the Symnet. The next nearest pair will need less additional delay. The furthest pair will need no delay from the Symnet. Your goal is to make all three pairs of side speaker appear the same distance away.

Sanjay

Sanjay, excellent as always!

Sanjay is da bomb!

Thanx Chris, thanx Scott. Your cheques are in the mail.

Sanjay

Man, I get PAID for letting you do all the 'splainin? What a life!

***IN between jobs today, saw that email*** You guys are a riot.

Dallas,
Correct. And I completely forgot about this in my previous posts. Each pair of side speakers should be equally loud at the sweet spot. This should be done using either the Symnet or the amps (if they have volume level control).

With proper time alignment and levels dialed in, the three speakers on each side should be heard like they're one giant side speaker (to use your words). Only after you've done that should you do the normal calibration on the Lexicon; otherwise the levels for the sides will come out wrong.
That works out to one drummer for each pair of side speakers. Wow indeed.

Keep the updates coming. I'm curious to find out how the set-up ends up sounding, especially after running room EQ.

Sanjay

Dallas,
Just to clarify, I was talking about the room EQ feature built into the Lexicon. Curious how much difference it will make in your set-up. You can toggle it On/Off on-the-fly for quick comparisons.
Pics would be nice. But no rush; post when you can.

Sanjay

Dallas,
One of the best things about it is the simplicity of use. If you've ever tried to do any measuring and EQing manually, you'll really appreciate the 'push the button and walk away' nature of the Lex EQ.
Yeah, the first thing I noticed is how much clearer dialogue was. Keep in mind that it's not EQing anything above 250Hz. However, by addressing low frequencies with long decay times, details that were previously obscured (irrespective of frequency) are now more easily heard. Whether you're using passive treatments or electronic correction, dealing with low frequency problems (especially ringing) can improve the sound over the entire frequency range.
I go back and forth between High and Max, using High more often than not.
Because the EQ system reduces some of the boominess, there can be a subjective impression of the bass suddenly sounding thin. To compensate, Lexicon built in a mild bass boost into the EQ system.

The Loudness contour is a separate feature, and is mostly useful when listening at lower volumes. As the volume gets lower, our human hearing perceives the bass as getting softer than other frequencies. The Loudness contour uses Fletcher-Munson curves to gently boost lower frequencies proportionately. This way, as you lower the volume, all the frequencies 'sound' like they are being lowered equally.
Great to hear that. I'm glad you're getting the intended result from the side speakers and the Symnet.
The rear subwoofer will be functional during music, as long as the music has a discrete .1 channel.

The MC-12 treats derived bass (filtered from any channel set to Small) and discrete bass (found in the .1/LFE channel in the source) as individual entities.

All the filtered bass from the main channels will come through the two subs (in stereo). The dedicated LFE subwoofer will play only when a .1 channel is present in the source, providing an extra bass kick (as intended).

When the LFE channel is not present, the dedicated LFE subwoofer will be silent and normal bass will be played back through the L/R subs.
Looking forward to it.

Sanjay

ddingle ... when using multiple side surrounds, set the level down (in your case) 6dB SPL for each individual speaker. Then with all speakers running, set the level for the combined lot to your reference level.

Hi Dallas,
Right. It's not to everyone's preference, which is why it's an optional feature and can be turned off. I find it useful because I tend not to listen to my system very loudly.
You're talking about the automatic calibration by the Lex? Personally, even with V4-EQ installed in my MC-12, I prefer to do levels and distances manually. I only use the EQ portion of the suite.

Sanjay

That sounds ideal. You never want the surrounds to take your attention away from the screen or distract from the front soundstage when listening to music. On properly balanced systems, I usually never notice that the surrounds are even on; that is, until they're turned off and all the sound collapses to the front wall. Sounds like it's coming along just right.

Sanjay

You may have left some processing on that splits the surround information between side and rear speaker pairs. That could make the sound in each pair a little quieter. Plus, if you have bass managements on, some of the sound may be getting re-routed to other speakers and/or the subwoofers.

When you use the internal test tones, you bypass all the processing, so you get more accurate results. Program material can vary from disc to disc (even test discs). If you calibrate based on the Grimani disc, then your levels may be off when using other test discs.

Finally, where ever the calibrated levels end up, there's no harm in seasoning to taste. If a small boost in the surround levels will make your client happy, then make him happy.

Sanjay