Convince me that crossover overlap is bad...

[Crazy Canuck]

I'm running a set of Polk LSIM 707's (behind a Crown XLS 2502, behind a Denon X3600)) and an SVS SB-3000. The Polks are good down to 30hz. I've been experimenting with crossover points on the sub and the Polks with overlaps as much as 50hz, and I can't really hear anything unpleasant. Other than the obvious bump in the curve where the overlap is (but I like bass!), what is supposed to be the downside?

 

[Old Onkyo]

I running a set of Polk LSIM 707's and an SVS SB-3000. The Polks are good down to 30hz. I've been experimenting with crossover points on the sub and the Polks with overlaps as much as 50hz, and I can't really hear anything unpleasant. Other than the obvious bump in the curve where the overlap is (but I like bass!), what is supposed to be the downside?

What do you mean when you say, “overlaps as much as 50hz?”

 

[Trebdp83]

Now, just take a deep breath and try to relax. Very good. Now, I'm going to swing this pocket watch back and forth. Follow the watch with your eyes. Very good. Now, repeat after me. Crossover overlap is baaaadddd......

Are you convinced, yet?

 

[ski2xblack]

Everything is a trade-off or compromise.

If your mains are capable, running them full range with lots of overlap can improve modal smoothing, but also results in increased modulation distortion of any higher frequencies the mains also reproduce. Such modulation distortion is a fairly subtle 'tell' in the grand scheme, but less of it is preferable. The solution is adding another sub for modal smoothing and high passing the mains to reduce IM.

But that's an expensive fix for a slight improvement.

 

[Crazy Canuck]

What do you mean when you say, “overlaps as much as 50hz?”

Sub crossed at 110, mains at 60. And many combinations in between.

 

[lovinthehd]

Sub crossed at 110, mains at 60. And many combinations in between.

You mean you have the low pass filter (lpf) on the sub overlapping with that of the avr? Are you running mains full range or with a double bass type setting?

Overlapping or double bass settings in the avr are just not my preference, but could be yours.

 

[ski2xblack]

Sub crossed at 110, mains at 60. And many combinations in between.

Subs will become more localizable the higher they extend up in frequency. If yours are not, don't sweat it, and if they are go with lower lpf settings.

 

[Crazy Canuck]

You mean you have the low pass filter (lpf) on the sub overlapping with that of the avr? Are you running mains full range or with a double bass type setting?

Overlapping or double bass settings in the avr are just not my preference, but could be yours.

Sorry I should have elaborated - the denon 3600 lets you set individual speaker crossovers, plus the LFE. I have the LFE set to 120 (the max). But then I set the SVS crossover to 100, and set the front speakers to, say, 60hz in the Denon. Does that make sense? So in that scenario, there is a 40hz overlap. And I can't say that it sounds bad. But my ears are old and ringey....

 

[Crazy Canuck]

Subs will become more localizable the higher they extend up in frequency. If yours are not, don't sweat it, and if they are go with lower lpf settings.

Hmm ok that's reasonable, and no, I don't really notice localization, but the sub is currently next to one of the mains so it would be "right" anyway. I'm also hoping to get a second sub, so that would help with localization if I decided to move one or the other around (still haven't done a proper sub crawl). Good point though! Thx.

 

[lovinthehd]

Sorry I should have elaborated - the denon 3600 lets you set individual speaker crossovers, plus the LFE. I have the LFE set to 120 (the max). But then I set the SVS crossover to 100, and set the front speakers to, say, 60hz in the Denon. Does that make sense? So in that scenario, there is a 40hz overlap. And I can't say that it sounds bad. But my ears are old and ringey....

The LPF of LFE only affects the LFE content (like a movie's ".1" ch) and is normally set to 120hz, but its not a crossover. A crossover is the point where the low pass and high pass filter slopes cross. When you're setting the speakers to 60hz in the Denon, you're crossing that speaker/channel with the sub. I would not use the low pass filter in the svs (it's not a crossover in your use), that's what's called cascading filters and generally not recommended.

 

[ryanosaur]

Since you are using Bass Magagement in your AVR, your should switch your Sub to Bypass, or just turn it all the way up to max. No reason to run it overlapping the AVR at all.

 

[ryanosaur]

The LPF of LFE only affects the LFE content (like a movie's ".1" ch) and is normally set to 120hz, but its not a crossover. A crossover is the point where the low pass and high pass filter slopes cross. When you're setting the speakers to 60hz in the Denon, you're crossing that speaker/channel with the sub. I would not use the low pass filter in the svs (it's not a crossover in your use), that's what's called cascading filters and generally not recommended.

Jinx

 

[Crazy Canuck]

The LPF of LFE only affects the LFE content (like a movie's ".1" ch) and is normally set to 120hz, but its not a crossover. A crossover is the point where the low pass and high pass filter slopes cross. When you're setting the speakers to 60hz in the Denon, you're crossing that speaker/channel with the sub. I would not use the low pass filter in the svs (it's not a crossover in your use), that's what's called cascading filters and generally not recommended.

Hmm.Just did some reading in the manual and mow I'm even more confused.
Here are the setting in the denon:
LFE (Default): The low range signal of the channel set to “Small” speaker size is added to the LFE signal output from the subwoofer.
LFE+Main: The low range signal of all channels is added to the LFE signal output from the subwoofer.

So I've always had it set to LFE+Main. And my front speakers set to "Large". So when I set the LFE to 120hz and the fronts to 60hz, what is being sent to the subwoofer?

Secondary question - people seem to use "LFE" when describing the discreet Low Frequency Effect channel (the .1 in 7.1) but is this not also outputting the lower frequencies from all sources? Stereo sources? And Atmos, which doesn't have discreet channels?

 

[Speedskater]

A long thread that sometimes touches on sub-woofer overlap.

“The Swarm” by Audio Kinesis

http://www.audiokinesis.com/the-swarm-subwoofer-system-1.html I’ve seen a few intra-thread mentions of this, but any longer-form reactions to this product? Does it offer any advantages/disadvantage over four separate subs? Can you go with smaller drive units? (E.g. Rhythmik).

www.audiosciencereview.com

 

[William Lemmerhirt]

Hmm.Just did some reading in the manual and mow I'm even more confused.
Here are the setting in the denon:
LFE (Default): The low range signal of the channel set to “Small” speaker size is added to the LFE signal output from the subwoofer.
LFE+Main: The low range signal of all channels is added to the LFE signal output from the subwoofer.

So I've always had it set to LFE+Main. And my front speakers set to "Large". So when I set the LFE to 120hz and the fronts to 60hz, what is being sent to the subwoofer?

Secondary question - people seem to use "LFE" when describing the discreet Low Frequency Effect channel (the .1 in 7.1) but is this not also outputting the lower frequencies from all sources? Stereo sources? And Atmos, which doesn't have discreet channels?

Yes and no. RE:LFE or .1. It’s ONLY present in a movie soundtrack. It’s a separate recorded track. So when watching a film, the sub produces the .1 LFE track PLUS all the redirected bass from the other channels. When listening to music, the sub is only producing redirected bass since there’s NO .1 or separate LFE track.

FWIW, the .1 track only contains content between 3-120hz.

 

[lovinthehd]

Hmm.Just did some reading in the manual and mow I'm even more confused.
Here are the setting in the denon:
LFE (Default): The low range signal of the channel set to “Small” speaker size is added to the LFE signal output from the subwoofer.
LFE+Main: The low range signal of all channels is added to the LFE signal output from the subwoofer.

So I've always had it set to LFE+Main. And my front speakers set to "Large". So when I set the LFE to 120hz and the fronts to 60hz, what is being sent to the subwoofer?

Secondary question - people seem to use "LFE" when describing the discreet Low Frequency Effect channel (the .1 in 7.1) but is this not also outputting the lower frequencies from all sources? Stereo sources? And Atmos, which doesn't have discreet channels?

The avr's LFE setting would just use the crossover setting for speakers set to small, i.e. the sub would be sent the lower frequencies, the speaker the higher frequencies per the crossover set.

The LFE+Main setting is a type of double bass, so it duplicates the bass frequencies in both the speaker (running full range, i.e. "large") as well as the sub up to the limit of the set crossover. This is where you get some overlap.

When you set the LPF of LFE you're just limiting the content to the sub for content with an LFE channel recorded (the ".1" channel). 120 is the normal upper limit of what's recorded in that channel for movies (but can vary with recording depending what was done). If you are using a crossover with a speaker/sub combo, it is in addition to any content existing in the LFE/.1 channel.

Bass management is generally what you do when you set a speaker to "small" (it really should just say turn bass management on for this channel/speaker). Other than music recorded on a disc with a .1 channel (and it may not even be used like with old quad recordings that are on dvd/bluray/sacd), but of course with 2ch music all you would have for the sub is using bass management since there's no LFE content. An Atmos soundtrack would have an LFE/.1 track recorded.

 

[mazersteven]

I'm still trying to figure out why you would do what the OP is doing.

 

[Crazy Canuck]

I'm still trying to figure out why you would do what the OP is doing.

lol I guess I'm just trying to max out the "bass power" of the system. take advantage of the good low end end of the 707's, plus the output from the subwoofer. I'm slowly starting to understand the application of each AVR setting and how they affect each other....

 

[lovinthehd]

In the end its simply preference. Some bump up their sub trim level for a bit of boost, too. Using a loudness contour type setting can help at lower volumes, too.

 

[mazersteven]

Polk LSiM707 Surround Speaker System Page 2

Finally, I did something I usually avoid in speaker reviews: I tried a variety of the manual and automated equalization options available on the Integra pre-pro. I settled on the simplest of tweaks: increasing the pre-pro’s treble control to +1 dB. This raised the measured output of the preamp...

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