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Subwoofers 80hz and Down under!

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Old 07-12-2017, 01:11 AM
kamiraa kamiraa is offline
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Default Mixing LFE in with a stereo pair?

Is there a way to take a stereo pair of sub-woofers and mix in the LFE channel also?

For example I want to use my McIntosh MEN220 to split the signal between the tower and the sub-woofer so each towers / sub-woofer is acting as united pair. Overall the of tower / sub-woofers will act as one part of a stereo pair.

But because I also use the same setup for movies, so I want to take the LFE (0.1) channel that comes off the pre-amp and have both subwoofers play it together.

One idea that I thought may work is since my JL sub-woofers have two inputs , put each in combined input mode, run the LFE in on one input, and the output from the MEN220 on the other. Let the subwoofer itself mux the two channels together?
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Old 07-13-2017, 12:10 PM
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There are some pre/pros that will let you redirect LFE to the mains, but I would advise against it. Assuming perfect integration of the stereo subs (which takes an active cross-over and a small miracle), the impulse waves of the stereo subs will match the mains. Actually, they are probably in phase but delayed by one of more cycles (due to group delay in the subs), so there is still smearing even though they look in phase on a graph. To make matters worse, the LFE track is added sound under 80 H (the "boom track") that has nothing to do with music. The fix is to send the LFE signal to a third sub while telling your pre/pro that your mains are "full range" and further telling it that your sub is twelve or more feet further away from the listening position than it really is. The pre/pro will start the impulse wave 12 milliseconds early, which will be negated by the group delay inherent in a thirteen inch diaphragm, with the net result that the impulse wave of the LFE arrives precisely when it sounds best. Now you see why I have three subs with an active cross-over running two of them and a pre/pro sending LFE to only one of them.
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Last edited by chessman; 07-13-2017 at 12:13 PM.
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Old 02-28-2018, 02:56 PM
Killergurt Killergurt is offline
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Originally Posted by chessman View Post
There are some pre/pros that will let you redirect LFE to the mains, but I would advise against it. Assuming perfect integration of the stereo subs (which takes an active cross-over and a small miracle), the impulse waves of the stereo subs will match the mains. Actually, they are probably in phase but delayed by one of more cycles (due to group delay in the subs), so there is still smearing even though they look in phase on a graph. To make matters worse, the LFE track is added sound under 80 H (the "boom track") that has nothing to do with music. The fix is to send the LFE signal to a third sub while telling your pre/pro that your mains are "full range" and further telling it that your sub is twelve or more feet further away from the listening position than it really is. The pre/pro will start the impulse wave 12 milliseconds early, which will be negated by the group delay inherent in a thirteen inch diaphragm, with the net result that the impulse wave of the LFE arrives precisely when it sounds best. Now you see why I have three subs with an active cross-over running two of them and a pre/pro sending LFE to only one of them.
You lost me at “There are some”.... ;-)
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Old 02-28-2018, 03:19 PM
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Quote:
Originally Posted by chessman View Post
There are some pre/pros that will let you redirect LFE to the mains, but I would advise against it. Assuming perfect integration of the stereo subs (which takes an active cross-over and a small miracle), the impulse waves of the stereo subs will match the mains. Actually, they are probably in phase but delayed by one of more cycles (due to group delay in the subs), so there is still smearing even though they look in phase on a graph. To make matters worse, the LFE track is added sound under 80 H (the "boom track") that has nothing to do with music. The fix is to send the LFE signal to a third sub while telling your pre/pro that your mains are "full range" and further telling it that your sub is twelve or more feet further away from the listening position than it really is. The pre/pro will start the impulse wave 12 milliseconds early, which will be negated by the group delay inherent in a thirteen inch diaphragm, with the net result that the impulse wave of the LFE arrives precisely when it sounds best. Now you see why I have three subs with an active cross-over running two of them and a pre/pro sending LFE to only one of them.
Randy,
Thanks for this write up. I am actually planning to add a third sub when I move back to the US.
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Old 02-28-2018, 04:01 PM
clpetersen clpetersen is offline
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Originally Posted by chessman View Post
There are some pre/pros that will let you redirect LFE to the mains, but I would advise against it. Assuming perfect integration of the stereo subs (which takes an active cross-over and a small miracle), the impulse waves of the stereo subs will match the mains. Actually, they are probably in phase but delayed by one of more cycles (due to group delay in the subs), so there is still smearing even though they look in phase on a graph. To make matters worse, the LFE track is added sound under 80 H (the "boom track") that has nothing to do with music. The fix is to send the LFE signal to a third sub while telling your pre/pro that your mains are "full range" and further telling it that your sub is twelve or more feet further away from the listening position than it really is. The pre/pro will start the impulse wave 12 milliseconds early, which will be negated by the group delay inherent in a thirteen inch diaphragm, with the net result that the impulse wave of the LFE arrives precisely when it sounds best. Now you see why I have three subs with an active cross-over running two of them and a pre/pro sending LFE to only one of them.
Nice write up, thanks. In our set-up, we use REL subs which allow the full range signal from the mains as well as an LFE (".1") input, which are summed by the REL. I have tested this using test tracks and it does seem to work well enough with the active crossover in the pre/pro. However, I lose the ability to individually tailor the phase delays between the mains and LFE output. Any thoughts? It seems that placing the subs 12 feet back (electronically) should work. Will try.
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Old 02-28-2018, 04:47 PM
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Default Mixing LFE in with a stereo pair?

There are two separate discussions going on here.

The first is how to properly integrate a sub with your mains so that the time response is correct. This will involve delaying the signal to the mains the exact amount needed to match the delay in the sub.

If the MEN 220 has a straight delay capability you can use that for the mains. Never owned one so I’m not sure.

To make up for the 12 mSec delay in the subs, you’d have to move the subs physically 12 feet forward! That’s an impossibility in most rooms.

By setting the sub distance in your pre/pro 12 feet farther back than it physically is you will delay the signal to the mains and surrounds by 12 mSec to match the delay in the sub. A little counter intuitive, granted, but you can’t turn back time and create negative delay!

Finally once you have the sub/main delay thing worked out the LFE is just a matter of setting the right levels.

The way REL integrates their subs by paralleling the mains speaker connection is technically incorrect. The steady state response is fine, but transients are not properly compensated. However, their subs are loved by many, so who am I to judge?

Tom
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Last edited by W9TR; 02-28-2018 at 04:49 PM.
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Old 02-28-2018, 10:36 PM
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Originally Posted by Killergurt View Post
You lost me at “There are some”.... ;-)
A thorough explaining of subwoofer implementation can be found by Barry Ober, also known as The Soundoctor. https://jlaudio.zendesk.com/hc/en-us...udio-Subwoofer

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Old 02-28-2018, 10:55 PM
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+1
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