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setting sub crossover to cut off point - Page 2

post #31 of 62
Quote:
Originally Posted by MitchFlorida View Post

you don't want to play any frequencies on your sub that can be played by your main speakers. It will sound boomy and distorted.
I would agree if you mean that you don't want to play content on BOTH your speakers and sub(s) if it would be more optimal to play it on the one that can do the best job of reproducing it.

However, if your speakers can do 60 Hz and your sub can do 60 Hz, why would it be more boomy and distorted to play 60 Hz on the sub? If the sub is properly integrated for level and distance, and the room modes have been properly tamed with acoustic treatments and EQ, there should be no difference at all in the sound quality whether the speakers or the sub(s) are reproducing the content.
post #32 of 62
Quote:
Originally Posted by murrots View Post

I know my room isn't ideal for home theatre, but I have to work with what I got. I'm just curious if the sub will reproduce the 120 hz well, being that it is the highest hz the speaker is supposed to handle.

Playing 120 Hz sounds on a subwoofer will tend to make the location of the subwoofer easier to detect by ear.
post #33 of 62
Quote:
Originally Posted by murrots View Post

Quote:
Originally Posted by arnyk View Post

Set the crossover dial on the sub as high as possible, just to make sure.

The dial goes to 150 hz, so that would mean that anything under 150 would be played through the sub? Or will the individual crossover for each speaker that audyssey came up with still be in effect.

If you set the low pass filter on the subwoofer higher than the low pass filter for the sub in the AVR, then the AVR filter rules.

That is the general rule for cascaded filters of those kinds. The lowest low pass filter rules. The other one will have some effect but the further away it is in frequency, the less significant it is.
post #34 of 62
Quote:
Originally Posted by MitchFlorida View Post

you don't want to play any frequencies on your sub that can be played by your main speakers. It will sound boomy and distorted.

There is no such rule set in stone.

Most speakers have distortion that increases somewhat above their -3 dB point.

http://www.audioholics.com/bookshelf-speaker-reviews/boston-acoustics-a225c-center/measurements





While the test results are spikey (acoustic measurements are often messy) you can see that all forms of distortion start shooting up when the test frequency goes below 150 Hz, even though the - 3dB point is somewhat lower, around 120 Hz.

Maintaining low distortion gives a justification for applying a high pass filter to a speaker at higher frequencies than its -3 dB point.
post #35 of 62
If the sound is boomy turn the crossover down, if the sound is thin, turn the crossover up.
post #36 of 62
Thread Starter 
Is it ok to just lower the gain or crossover on the sub after running audyssey if the bass is a little loud?
post #37 of 62
Quote:
Originally Posted by MitchFlorida View Post

If the sound is boomy turn the crossover down, if the sound is thin, turn the crossover up.
Again, not exactly that simple. If your sound is boomy, you have greater setup issues than the crossover. In a properly set up system, you should be able to move your crossover within a certain range and not introduce boominess.
post #38 of 62
Quote:
Originally Posted by murrots View Post

Is it ok to just lower the gain or crossover on the sub after running audyssey if the bass is a little loud?

Lowering the gain is usually not the best option. The better option is to reduce the sub trim on your receiver and leave the gain alone. Assuming the gain was set correctly in the first place. That's also a better option than changing the crossover if you feel the bass is too loud. In fact, if doing that results in it not being as loud, there's a good chance you have a mode (peak) in your frequency response that the lower crossover removes from the sub's playing range. So again, like in my previous post, the problem could very well be a setup issue.
post #39 of 62
Thread Starter 
I moved the sub, lowered the gain and re ran audyssey. Sound is much better. I'll have to give it a few days to really see if I like it.
post #40 of 62
Quote:
Originally Posted by murrots View Post

I moved the sub, lowered the gain and re ran audyssey. Sound is much better. I'll have to give it a few days to really see if I like it.
Did you use the Guide? What crossovers were set this time?

Craig
post #41 of 62
Quote:
It's great that you understand wavelengths. But this discussion isn't about wavelengths. It's about time. What you are missing is that, if the speaker distances are set correctly, then all the frequencies from the speakers and the subs will be timed correctly, no matter what frequency is being reproduced. It's not about frequency or wavelength. It's about arrival time, and arrival time is what the distance setting optimizes.

For example, if the sub is 15 ft. away from the primary listening/measuring position, and the LCR speakers are 10 ft. away, and the surrounds are 8 ft. away, then the subwoofer will fire first, the speakers will be delayed and fire about 5 ms later and the surrounds about 2 ms. after that. All the waves from all the speakers and sub(s) at all frequencies will arrive at the listening/measuring position at the same time. The different wavelengths of the various frequencies won't matter.


Who wouldn't know what distances do? But your example talks about phase aligning your sub in time domain ONLY. Where is the frequency domain?? For a sub to be in phase with mains at 80Hz, a different delay (distance) is required. And for the same to be phase aligned with CC, e.g. @ 100Hz, different delay (distance) setting works. Same goes for surrounds.
Quote:
In your example, how would you deal with surrounds that need a 100 Hz crossover, a CC that needs an 80 Hz crossover and mains that need a 60 Hz crossover?

By carefully choosing the speakers; that's what I said earlier. Choice of speakers is very important.
post #42 of 62
Quote:
Originally Posted by braveheart123 View Post

Who wouldn't know what distances do? But your example talks about phase aligning your sub in time domain ONLY. Where is the frequency domain?? For a sub to be in phase with mains at 80Hz, a different delay (distance) is required. And for the same to be phase aligned with CC, e.g. @ 100Hz, different delay (distance) setting works. Same goes for surrounds.
The Distance setting sets delays for the ENTIRE signal in a given channel. ALL frequencies are delayed the same amount of time. The Distance setting doesn't delay 80 Hz different than 100 Hz or 60 Hz. The fact that the wavelengths are different is immaterial. The 100 Hz content from the surrounds will arrive at the exact same time as the 60 Hz content from the mains and the 80 Hz content from the CC. And ALL the content from ALL the channels will be "in phase" with the subwoofer(s), which will arrive at the same time at 60 Hz, 80 Hz and 100 Hz.
Quote:
Originally Posted by braveheart123 View Post

By carefully choosing the speakers; that's what I said earlier. Choice of speakers is very important.
Even if you use the exact same speakers in all positions, each speaker will "see" different room reinforcement, especially at the lower frequencies where the crossovers come into play. Therefore, even with the EXACT SAME speakers, it may be beneficial to have different crossovers for different speaker groups. Crossovers should always be set based on the in-room response of the speakers, not the manufacturer's "specifications."

Craig
post #43 of 62
Thread Starter 
Quote:
Originally Posted by craig john View Post

Did you use the Guide? What crossovers were set this time?

Craig

Yes I used the guide. 100hz for mains, 60hz for center channel (which is to low since my cc only goes down to 67hz, so I raised it to 80hz) and 80 for surrounds. It sounds good so far. I want to watch a few movies and some football to see how the bass blends.
post #44 of 62
Quote:
Even if you use the exact same speakers in all positions, each speaker will "see" different room reinforcement, especially at the lower frequencies where the crossovers come into play. Therefore, even with the EXACT SAME speakers, it may be beneficial to have different crossovers for different speaker groups. Crossovers should always be set based on the in-room response of the speakers, not the manufacturer's "specifications."

I missed the words, "careful placement" to deal with room acoustics. Add that to careful selection of speakers.
post #45 of 62
Quote:
And ALL the content from ALL the channels will be "in phase" with the subwoofer(s), which will arrive at the same time at 60 Hz, 80 Hz and 100 Hz.

You are right till here. But sub is phase matched with the mains, not all the speakers. For example if you phase align the sub @ 80Hz both in frequency and time domains with the mains, you will set the sub distance according to mains for 80Hz.

That electrical distance of sub in avr is now constant for 80Hz only and that too for the mains. Now if you cross your surrounds e.g. @ 100Hz, you can't change the electrical sub distance in AVR that was already set to phase align the sub with mains, as surrounds will have different distance setting from MLP. If you change the sub distance in avr to bring your surrounds in phase with the sub, your mains will be out of phase. Same goes for CC.

That's the reason why the front 3 speakers must be placed along the edge of an imaginary arc such that they are equidistant from MLP. That way, if you phase align your mains with the sub, the CC will automatically be in phase as it has the same distance.
post #46 of 62
Quote:
Originally Posted by braveheart123 View Post

You are right till here. But sub is phase matched with the mains, not all the speakers. For example if you phase align the sub @ 80Hz both in frequency and time domains with the mains, you will set the sub distance according to mains for 80Hz.

That electrical distance of sub in avr is now constant for 80Hz only and that too for the mains. Now if you cross your surrounds e.g. @ 100Hz, you can't change the electrical sub distance in AVR that was already set to phase align the sub with mains, as surrounds will have different distance setting from MLP. If you change the sub distance in avr to bring your surrounds in phase with the sub, your mains will be out of phase. Same goes for CC.
You don't need to change the subwoofer distance to get different speakers sets in phase with the subwoofer because the speaker distance setting accounts for the difference. If you had set all the speakers to the same distances, then yes, you would be correct. But setting each speaker to it's proper distance accounts for the different delays.
Quote:
Originally Posted by braveheart123 View Post

That's the reason why the front 3 speakers must be placed along the edge of an imaginary arc such that they are equidistant from MLP. That way, if you phase align your mains with the sub, the CC will automatically be in phase as it has the same distance.
Again, even if the CC is a different distance from the LP than the L/R's, as long as you set the CC to it's proper distance setting, that will account for the difference and the CC wavefront will arrive at the same time as the wavefronts from the L/R's.

Craig
post #47 of 62
Quote:
Originally Posted by braveheart123 View Post

I missed the words, "careful placement" to deal with room acoustics. Add that to careful selection of speakers.
It doesn't matter how carefully you place the speakers. The CC in the middle of the front wall will "see" a different acoustic than the L/R's, which will be closer to the corners. The surrounds will also "see" a different acoustic as they are mid-side wall, (when properly placed.) You can't possibly place all the speakers in a surround sound system so that they all see the same room reinforcement. It's simply not possible. And that is WHY manufactures provide the flexibility to set different distances, levels and crossovers. It allows the user to optimize the system for each individual speakers set.

Craig
post #48 of 62
Quote:
Originally Posted by murrots View Post

Yes I used the guide. 100hz for mains, 60hz for center channel (which is to low since my cc only goes down to 67hz, so I raised it to 80hz) and 80 for surrounds. It sounds good so far. I want to watch a few movies and some football to see how the bass blends.
Can you describe you main speaker placement as well as your room and listening position? If Audyssey is setting your mains to 100 Hz or 120 Hz, there must be a null that is causing Audyssey to find a higher -3 dB point. Audyssey will set the same crossovers for both the L and R speakers. They are a speaker "set." The null would only need to occur from one of the speakers for Audyssey to "see" it and set the crossovers for both of the fronts at 100 or 120 Hz.

Craig
post #49 of 62
Thread Starter 
My room has hardwood floors and my tv is in the corner of the room. I'm sure my room needs treatment, but its my living room. My mains are 2' on either side of my tv. My wife and I sit a little off centered from the tv, but I took the mlp in between us( which is centered between the mains)and took some measurements where we sit.

My room has a ton of echo when the audyssey does its calibration. I can't move my speakers anywhere. The way it is set up maximizes the space I have to work with.

It still sounds good crossed over at 100hz. I wasn't experiencing any localization so far. I also think the sub would produce the lower frequency better anyway.
post #50 of 62
Quote:
Originally Posted by murrots View Post

My room has hardwood floors and my tv is in the corner of the room. I'm sure my room needs treatment, but its my living room. My mains are 2' on either side of my tv. My wife and I sit a little off centered from the tv, but I took the mlp in between us( which is centered between the mains)and took some measurements where we sit.

My room has a ton of echo when the audyssey does its calibration. I can't move my speakers anywhere. The way it is set up maximizes the space I have to work with.

It still sounds good crossed over at 100hz. I wasn't experiencing any localization so far. I also think the sub would produce the lower frequency better anyway.
Corner placements are always difficult. Nonetheless, if you're happy with the way it sounds, and it fits your space and aesthetics, then that's all that matters. smile.gif
post #51 of 62
Quote:
It doesn't matter how carefully you place the speakers. The CC in the middle of the front wall will "see" a different acoustic than the L/R's, which will be closer to the corners. The surrounds will also "see" a different acoustic as they are mid-side wall, (when properly placed.) You can't possibly place all the speakers in a surround sound system so that they all see the same room reinforcement. It's simply not possible. And that is WHY manufactures provide the flexibility to set different distances, levels and crossovers. It allows the user to optimize the system for each individual speakers set.


Try and watch a movie or listen to 2-Channel stereo music in "All Channel Stereo" mode where every speaker is fed the same signal and set different xo for mains, different for CC, and different for surrounds. You would know why it's a bad idea to use different crossovers for different speakers.
Edited by braveheart123 - 9/6/13 at 6:45am
post #52 of 62
How about this? Instead of all the esoteric arguments about acoustic theory, why doesn't someone take measurements with various crossovers to conclusively show how having different xovers can negatively affect the FR. I haven't seen that in any of my measurements, but perhaps someone else has had a different experience.
post #53 of 62
It's more of empirical science than just an esoteric discussion. Run a REW sweep putting the AVR in "All Channel Stereo Mode" setting differing xo points for all speakers. I did that long time ago and know what it does.wink.gif
post #54 of 62
What makes it esoteric is that you both have different interpretations of the empirical science, as is often then case on these forums. lol. Perhaps esoteric isn't the best description--theoretical is probably better. Either way, show your data. Can't argue with actual data.

Admittedly, I never use All Channel Stereo mode--but I have done sweeps with the Dolby Cinema mode and as I said, have never seen any negative effect from changing the xover. But that's just my experience.
post #55 of 62
Quote:
Originally Posted by braveheart123 View Post

Try and play a movie or listen to 2-Channel stereo music in "All Channel Stereo" mode where every speaker is fed the same signal and set different xo for mains, different for CC, and different for surrounds. You would know why it's a bad idea to use different crossovers for different speakers.
"All Channel Stereo" is a bad idea for a lot of reasons, but the crossovers is not one of them. ACS ia a comb filtered mess. I never use it. Try PLIIx Music and sit in the sweet spot. That works much better... and the crossovers are correct even if they're different.

Just to prove the point that the distance setting is what is used to get the speakers in phase with the subs, here's a measurement of the L/R speakers with a bad distance setting and a corrected distance setting:





Here is the CC, which a different distance than the L/R's, where the same subwoofer distance adjustment has been made. The subwoofer distance is the same for both the L/R's and the CC, but it was adjusted from the incorrect setting:



The speaker distance setting is what allows you to use the same subwoofer distance setting and get all the speakers aligned with the sub.

Craig
post #56 of 62
Like I said I did that and don't need repeating. It won't reveal anything different in the same room with the same speaker layout than it did a year ago.
post #57 of 62
Quote:
Try PLIIx Music and sit in the sweet spot.

It is 5.1 implementation of 2-channel stereo. Still not the correct method
post #58 of 62
I know you are tinkering with individual speakers distance setting as opposed to changing only the sub distance. I tried same thing only 2 YEARS ago and posted my findings on www.hometheaterforum.com.
post #59 of 62
Quote:
Originally Posted by braveheart123 View Post

Like I said I did that and don't need repeating. It won't reveal anything different in the same room with the same speaker layout than it did a year ago.

Was that a response to me? If so, the exercise wasn't for meant for your edification, but to let anyone following the thread see/learn. But it's your call, obviously.
post #60 of 62
Quote:
Originally Posted by braveheart123 View Post

I know you are tinkering with individual speakers distance setting as opposed to changing only the sub distance. I tried same thing only 2 YEARS ago and posted my findings on www.hometheaterforum.com.
Hmmm... no... I'm not "tinkering with the individual speaker distance settings." In those graphs the speakers were set to their proper distances and then the subwoofer distance was changed to get the speakers and subs in phase with each other. The point I was making is that, if you have different distance settings for speakers that are different distances away from the LP, then you only need one subwoofer distance setting to get all the speakers in phase with the sub.
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