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post #1 of 57 Old 06-06-2013, 02:29 PM - Thread Starter
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Do you have to max out the crossover on the sub before running audysssey? And if so, whats the reason.
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post #2 of 57 Old 06-06-2013, 02:32 PM
 
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...:confused"

We set our all our crossovers to 80Hz. Not sure what you mean by maxing out the subwoofer crossover.

Audyssey is run first and then manual settings are adjusted to taste.
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post #3 of 57 Old 06-06-2013, 02:32 PM
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Your receiver has a crossover as well, and if you overlap the two you end up doubling the slope and potentially losing information that should be sent to the sub.  So the recommendation is to bypass the crossover/filter on the sub itself or turn it to max.

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post #4 of 57 Old 06-06-2013, 02:48 PM - Thread Starter
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It's just something my friend noticed when i was setting up my denon 2313ci. He told me to max out the crossover on the sub. And then run audyssey. He couldn't explain why, when asked. So run audyssey first and then adjust the crossover after? Is that the correct way.
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post #5 of 57 Old 06-06-2013, 03:04 PM
 
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No.

Everything is done before running Audyssey. Then Audyssey can deal with what ever output is outputted. Finally, one tweaks settings to measured tastes.
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post #6 of 57 Old 06-06-2013, 03:14 PM - Thread Starter
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Makes sense, thank you guys.
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post #7 of 57 Old 06-06-2013, 04:28 PM
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Quote:
Originally Posted by primetimeguy View Post

Your receiver has a crossover as well, and if you overlap the two you end up doubling the slope and potentially losing information that should be sent to the sub.
Doubling the slope doesn't affect what should be coming out of the sub, only what shouldn't be. First run Audyssey with the sub filter at the highest frequency, to allow it to find the best crossover frequency. If that results in the sub producing directionally locatable harmonics set the sub filter at the same frequency, which should tame them. Then run Audyssey again. It should compensate for the reduced harmonic output from the sub by increasing those frequencies in the L/C/R and surrounds, where they belong.

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post #8 of 57 Old 06-06-2013, 05:13 PM
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Originally Posted by joe801 View Post

Do you have to max out the crossover on the sub before running audysssey? And if so, whats the reason.

It's not really a "crossover"; it's a variable low-pass filter. And, yes, theoretically, it should be bypassed altogether (unfiltered), when possible, and if not, set to its maximum value, when using an AVR with a digital crossover that will already be providing the necessary low-pass filtering to the information that is being sent to the subwoofer.

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post #9 of 57 Old 06-06-2013, 05:50 PM
 
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Originally Posted by sivadselim View Post

It's not really a "crossover"; it's a variable low-pass filter. And, yes, theoretically, it should be bypassed altogether (unfiltered), when possible, and if not, set to its maximum value, when using an AVR with a digital crossover that will already be providing the necessary low-pass filtering to the information that is being sent to the subwoofer.

Using our three sub system as an example, two of the subs are stacked and one of the subs has the LPF set to 70Hz. This setting allows for the best measured response plot. The other two subs are set to 120Hz. The point, with measuring, one may find an asymmetrical LPF setting gives the best response because the amount of energy going into a null is reduced.
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post #10 of 57 Old 06-06-2013, 06:23 PM
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Quote:
Originally Posted by BeeMan458 View Post

Using our three sub system as an example, two of the subs are stacked and one of the subs has the LPF set to 70Hz. This setting allows for the best measured response plot. The other two subs are set to 120Hz. The point, with measuring, one may find an asymmetrical LPF setting gives the best response because the amount of energy going into a null is reduced.
Wow. I'd like to see those measurements.

If you have 2 subs stacked, they will "couple" and act as one sub. In general, when you stack subwoofers, you want both subs to be set up exactly the same to optimize the coupling. If you have one of their LPF's different than the other, they won't couple properly in the frequency range where the LPF is active. Remember that all LPF's will have some affect below the LPF set point. In addition, the phase will get screwed up around the LPF set point. With a 70 Hz LPF, I would expect a significant impact from 55/60 Hz up, which is where I believe you were showing a problem with your most recent measurements.

I'm just sayin'

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post #11 of 57 Old 06-06-2013, 06:32 PM
 
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Originally Posted by craig john View Post

Wow. I'd like to see those measurements.

---snip---

With a 70 Hz LPF, I would expect a significant impact from 55/60 Hz up, which is where I believe you were showing a problem with your most recent measurements.

The microphone position was moved to the wife's chair, four feet to the right of the original listening position. She has a hole in the wall behind her and I stuffed the third subwoofer with one inch foam and pulled tuffs of poly-fil. The two stacked subs are matched subs. The upper sub's LPF is set to 70Hz.

Doing this smoothed out the response to the original position, although there's still a -3dB disparity between the two seated positions. No saved measurements on the original position based on the new setup.



In a few days, after pressing springtime yard-work is taken care of, I'll play with the subwoofers some more.

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post #12 of 57 Old 06-06-2013, 07:23 PM
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Originally Posted by sivadselim View Post

when using an AVR with a digital crossover that will already be providing the necessary low-pass filtering to the information that is being sent to the subwoofer.
Depending on how steep the slope there can be quite a lot of output as much as two octaves above the crossover frequency, and while it will be 12dB or more down from the in-bandwidth content, it may still be quite audible, due to equal loudness. Cascading the filters will address that situation.

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post #13 of 57 Old 06-06-2013, 08:22 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Doubling the slope doesn't affect what should be coming out of the sub, only what shouldn't be. First run Audyssey with the sub filter at the highest frequency, to allow it to find the best crossover frequency. If that results in the sub producing directionally locatable harmonics set the sub filter at the same frequency, which should tame them. Then run Audyssey again. It should compensate for the reduced harmonic output from the sub by increasing those frequencies in the L/C/R and surrounds, where they belong.

right, I meant that as two different issues... You would double the slope... And if you use the crossover on the sub and set it below 120hz you could be losing LFE info
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post #14 of 57 Old 06-07-2013, 05:50 AM
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Originally Posted by primetimeguy View Post

right, I meant that as two different issues... You would double the slope... And if you use the crossover on the sub and set it below 120hz you could be losing LFE info
I'm not sure what you're getting at, but if you have the AVR crossover set at 80Hz at 18dB/octave and the sub crossover also set at 80Hz at 18dB/octave the result is 80Hz at 36dB/octave. That won't affect anything below 80Hz, only above 80Hz.
With only the AVR filter in place 160Hz is down 18dB, but that makes it still very audible, due to equal loudness. Adding the sub filter as well takes 160Hz to -36dB, and even with equal loudness figured in that would be inaudible.

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post #15 of 57 Old 06-07-2013, 06:05 AM
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If you lower the LPF on the sub to say, 80Hz, don't you completely lose any material in the .1 channel that's over 80Hz? There's probably not much sent to that channel over 80Hz but it can contain material up to 120Hz or higher depending on the source.

I don't understand why one would want to set a LPF on the sub any lower than the sub is capable of playing.
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If using a three or four subwoofer system, this is not a consideration as what one is doing is controlling the conflicting output of their subwoofer system. In the end, using room measurements as one's guide, the goal is a subwoofer response plot that's flat (minimum standard), +/-3dB, 20hz - 120Hz.

In our case, we have three subwoofers. Two subwoofers are set to 120Hz and one subwoofer is set to 70Hz. I would not recommend setting a single subwoofer based system to 70Hz as yes, you'd be limiting output in the way you suggest.
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post #17 of 57 Old 06-07-2013, 06:29 AM
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Originally Posted by benunc View Post

If you lower the LPF on the sub to say, 80Hz, don't you completely lose any material in the .1 channel that's over 80Hz? There's probably not much sent to that channel over 80Hz but it can contain material up to 120Hz or higher depending on the source.
That's the point of letting Audyssey decide on the initial crossover frequency between the L/R/C and surrounds and the sub feed with the sub filter disengaged. It's that crossover frequency that you'd want to use to set the sub filter at. The higher that crossover the more critical that you do use the sub filter as well, to brick wall out as much midbass content as possible. There's also the matter of the crossover of the L/R, C and surrounds, which might not be the same. Typically the surrounds would be the highest, the L/R the lowest, the C in between. When you look at what Audyssey set the crossovers at you might decide to give up some bass content in the surrounds to get a cleaner sound from the sub, but you wouldn't want to do so with L/R or C.

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post #18 of 57 Old 06-07-2013, 07:45 AM
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Originally Posted by Bill Fitzmaurice View Post

That's the point of letting Audyssey decide on the initial crossover frequency between the L/R/C and surrounds and the sub feed with the sub filter disengaged. It's that crossover frequency that you'd want to use to set the sub filter at. The higher that crossover the more critical that you do use the sub filter as well, to brick wall out as much midbass content as possible. There's also the matter of the crossover of the L/R, C and surrounds, which might not be the same. Typically the surrounds would be the highest, the L/R the lowest, the C in between. When you look at what Audyssey set the crossovers at you might decide to give up some bass content in the surrounds to get a cleaner sound from the sub, but you wouldn't want to do so with L/R or C.

Not sure I understand your post, and I'm sure you know this, but Audyssey doesn't set the LPF, it only sets the crossovers between the speakers and the sub. The LPF is set manually on the sub and through a setting in the AVR.

The speaker crossovers you're referring to determine how the bass sent to the left/right, center, surround speakers is managed. The LPF on the sub not only affects the left/right, center, surround material that is redirected to the sub based on crossovers used but also the material coded to the LFE channel.

For example, if an 80Hz crossover is used on speakers and an 80Hz LPF on the sub, any material between 80Hz-120Hz coded to the LFE channel is lost entirely. Or if, as you mention, the surrounds are setup with a higher crossover than the other speakers - say 120Hz - then the >80Hz surround material is lost if using an 80Hz LPF.

The only reason I'd set set the LPF below 120Hz is if the sub isn't capable of playing that high. Or I guess if you find midbass offensive if produced by the sub and would prefer to forgo any coded to the LFE channel or directed to the sub via bass management.

FWIW, Audyssey recommends the sub's LPF be bypassed or set at the max on the sub itself and then set at 120Hz on the receiver.
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post #19 of 57 Old 06-07-2013, 08:02 AM
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Yah Audyssey set my crossover for my fronts to 60Hz, but I ended up using 100Hz. My PB10-NSD has significantly better response around 80-100Hz compared to my Infinity P162 bookshelf speakers. At least I liked the sound a lot better compared to using 80Hz.
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post #20 of 57 Old 06-07-2013, 08:19 AM
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Originally Posted by Shadowdane View Post

Yah Audyssey set my crossover for my fronts to 60Hz, but I ended up using 100Hz. My PB10-NSD has significantly better response around 80-100Hz compared to my Infinity P162 bookshelf speakers. At least I liked the sound a lot better compared to using 80Hz.

Audyssey sets my crossovers between 40-80Hz but I also adjust them all up to 100Hz because I prefer the sound.

The risk of using a higher crossover is that the bass becomes directional. I'm running several subs so that's not a problem for me, but in the past when I only used one sub, the directional bass bothered me even with an 80Hz crossover....I think I ended up using 70Hz which seemed to be the best middle ground for me.
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post #21 of 57 Old 06-07-2013, 09:55 AM
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Originally Posted by benunc View Post

Audyssey doesn't set the LPF, it only sets the crossovers between the speakers and the sub. The LPF is set manually on the sub and through a setting in the AVR.
That's exactly what I said. Let Audyssey determine the correct crossover frequency first, then you set the sub low pass.
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The risk of using a higher crossover is that the bass becomes directional
Contrary to popular belief even 100Hz is not directionally locatable. The problem is that filters are not brickwall, when set at 100Hz there's still plenty of above 100Hz content coming from the sub. Cascading the filters gets the slope closer to brickwall, giving far less content above the filter frequency. Lowering the crossover frequency also lowers the amount of above bandwidth content, but cascading the filters is more effective.

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post #22 of 57 Old 06-07-2013, 10:47 AM
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Originally Posted by benunc View Post

For example, if an 80Hz crossover is used on speakers and an 80Hz LPF on the sub, any material between 80Hz-120Hz coded to the LFE channel is lost entirely. Or if, as you mention, the surrounds are setup with a higher crossover than the other speakers - say 120Hz - then the >80Hz surround material is lost if using an 80Hz LPF.

Here's a post on the subject from Mark Seaton, taken from the Audyssey FAQ (the part at the bottom is from KBarnes):

"I personally tend to set the low pass on the LFE channel at 80Hz in most systems by preference. I think many forget that the difference between a 120Hz low pass and an 80Hz low pass is nothing more than a shelving filter. If the low pass is 4th order, the 80Hz filter is about 7dB lower at 100Hz and about 4dB at 80Hz. A 100Hz low pass setting would have about 1/2 that difference. The adjustment has more effect on shaping the LFE track's response than it does on cutting off content. If you're running the subs with a rising response on the low end which blends with the main speakers, experimenting with 80, 100 vs. 120Hz is basically a means to taper the top end of the LFE channel. Setting this lower than 120Hz is not hacking off content any more than setting your sub a few dB hot would destroy a soundtrack."

What this means in effect is that you do NOT lose the content between 80Hz and 120Hz if you set the LPF of LFE to 80Hz - you simply alter the way it is presented, because the filter is not a brickwall but a shelving filter. Setting it to 80Hz simply allows you to 'shape' the LFE track's response.

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post #23 of 57 Old 06-07-2013, 11:18 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Contrary to popular belief even 100Hz is not directionally locatable. The problem is that filters are not brickwall, when set at 100Hz there's still plenty of above 100Hz content coming from the sub. Cascading the filters gets the slope closer to brickwall, giving far less content above the filter frequency. Lowering the crossover frequency also lowers the amount of above bandwidth content, but cascading the filters is more effective.

I won't disagree with you because I haven't bothered doing a great deal of research on this but do know based on my personal experience when using an 80Hz XO on a single sub in the front left corner of my room, I could, at times, identify that bass was coming from that corner. Prior to that, I had the sub nearfield and could easily tell where the sub was; in that case it was probably as much tactile identification as aural though. Whether I was hearing 80Hz or frequencies above that I can't say.
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post #24 of 57 Old 06-07-2013, 11:27 AM
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Originally Posted by benunc View Post

Whether I was hearing 80Hz or frequencies above that I can't say.
I can, you were, and that's why you were able to localize it. The pass band doesn't come to a dead stop at the crossover frequency, that's just the place where output begins to roll off. If you have REW or the like run it with the subwoofer only running, the other speakers unplugged, what you'll see will be a revelation, especially at high volumes, where the movement of the subwoofer cone creates even more harmonic content.

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post #25 of 57 Old 06-07-2013, 11:36 AM
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Quote:
Originally Posted by holt7153 View Post

Here's a post on the subject from Mark Seaton, taken from the Audyssey FAQ (the part at the bottom is from KBarnes):

"I personally tend to set the low pass on the LFE channel at 80Hz in most systems by preference. I think many forget that the difference between a 120Hz low pass and an 80Hz low pass is nothing more than a shelving filter. If the low pass is 4th order, the 80Hz filter is about 7dB lower at 100Hz and about 4dB at 80Hz. A 100Hz low pass setting would have about 1/2 that difference. The adjustment has more effect on shaping the LFE track's response than it does on cutting off content. If you're running the subs with a rising response on the low end which blends with the main speakers, experimenting with 80, 100 vs. 120Hz is basically a means to taper the top end of the LFE channel. Setting this lower than 120Hz is not hacking off content any more than setting your sub a few dB hot would destroy a soundtrack."

What this means in effect is that you do NOT lose the content between 80Hz and 120Hz if you set the LPF of LFE to 80Hz - you simply alter the way it is presented, because the filter is not a brickwall but a shelving filter. Setting it to 80Hz simply allows you to 'shape' the LFE track's response.

Like he says, it's his personal preference. I don't think that's the most common approach though. And sure, you don't flat out lose everything above the LPF but if you use an 80Hz LPF, content at 120Hz might sound, say, half as loud as it was mixed. Again, in practice this might be a moot point since there's probably not much LFE content above 80Hz anyways. I'll be honest - I've never tried using an LPF below 120Hz - I've always just turned it all the way up/off and been satisfied with the sound and knowing I wasn't losing any content. I think that's the easiest/safest thing to do.... especially if one doesn't have measurement capabilities.
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Depending on how steep the slope there can be quite a lot of output as much as two octaves above the crossover frequency, and while it will be 12dB or more down from the in-bandwidth content, it may still be quite audible, due to equal loudness. Cascading the filters will address that situation.

The low-pass filter in almost all standard AVRs' crossovers is 24dB/octave.

This is not to say that you can't possibly induce a favorable affect on your FR by cascading the sub's LPF atop your AVR's, but with a LPF in the AVR that is that steep, it shouldn't be necessary. I know that you like to promote this idea, but I think some caution should be used in giving this advice.

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post #27 of 57 Old 06-07-2013, 11:55 AM
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Quote:
Originally Posted by holt7153 View Post

Here's a post on the subject from Mark Seaton, taken from the Audyssey FAQ (the part at the bottom is from KBarnes):

"I personally tend to set the low pass on the LFE channel at 80Hz in most systems by preference. I think many forget that the difference between a 120Hz low pass and an 80Hz low pass is nothing more than a shelving filter. If the low pass is 4th order, the 80Hz filter is about 7dB lower at 100Hz and about 4dB at 80Hz. A 100Hz low pass setting would have about 1/2 that difference. The adjustment has more effect on shaping the LFE track's response than it does on cutting off content. If you're running the subs with a rising response on the low end which blends with the main speakers, experimenting with 80, 100 vs. 120Hz is basically a means to taper the top end of the LFE channel. Setting this lower than 120Hz is not hacking off content any more than setting your sub a few dB hot would destroy a soundtrack."

What this means in effect is that you do NOT lose the content between 80Hz and 120Hz if you set the LPF of LFE to 80Hz - you simply alter the way it is presented, because the filter is not a brickwall but a shelving filter. Setting it to 80Hz simply allows you to 'shape' the LFE track's response.

There is a considerable difference between setting an AVRs 'LPF of LFE' lower than 120Hz, which only affects the bass encoded in the LFE channel, and setting a subwoofer's internal LPF to a setting that cascades or interacts with the AVR's low-pass filters on not only the LFE channel but the other speaker channels as well.

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post #28 of 57 Old 06-07-2013, 11:55 AM
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Originally Posted by Bill Fitzmaurice View Post

I can, you were, and that's why you were able to localize it. The pass band doesn't come to a dead stop at the crossover frequency, that's just the place where output begins to roll off. If you have REW or the like run it with the subwoofer only running, the other speakers unplugged, what you'll see will be a revelation, especially at high volumes, where the movement of the subwoofer cone creates even more harmonic content.

I understand that the filters/XOs aren't brick walls. And again, not disagreeing... I'm not arguing I can localize 100Hz... my only point is that when using a 100Hz XO, you might localize the sub. Whether it's 100Hz (at the XO) or 120Hz (above the XO) sounds I hear/localize isn't really important to me; I just don't want to hear sounds coming from a corner with a sub in it.

Next time I break out the measurement gear, I might do your test. While I'm at it maybe I can get my wife to plug/unplug subs while I'm not looking and see if I can identify where the sound comes from at various frequencies.
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post #29 of 57 Old 06-07-2013, 12:18 PM
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Originally Posted by sivadselim View Post

There is a considerable difference between setting an AVRs 'LPF of LFE' lower than 120Hz, which only affects the bass encoded in the LFE channel, and setting a subwoofer's internal LPF to a setting that cascades or interacts with the AVR's low-pass filters on not only the LFE channel but the other speaker channels as well.

I believe the excerpt from the Audyssey FAQ above is only addressing AVR settings in regards to LPF of LFE.

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post #30 of 57 Old 06-07-2013, 01:04 PM
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Originally Posted by holt7153 View Post

I believe the excerpt from the Audyssey FAQ above is only addressing AVR settings in regards to LPF of LFE.

Right. But we're not really discussing the AVR's 'LPF of LFE', here. We're talking about the subwoofer's own variable LPF which, if invoked, will affect ALL the bass that is sent to the subwoofer, and not, as in the case of an AVR's 'LPF of LFE', only the bass that is encoded in the LFE channel.

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