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Discussion Starter · #1 ·
probably been asked before, but why is it commonplace to have your receiver/processor crossover higher than your speaker's freq response capability?


currently i have a 2.5 way towers for my fronts, rated down to 40 Hz. i would like to take advantage of the speaker's full capability. i have set all my speakers to xover at 60 Hz, and am currently using the option of the fronts (L and R) receiving full range info, in conjunction with the sub putting out anything below 60 Hz. i can only do this with the front l and r set to large, if i set them to small, the xover setting specified will apply to all speakers, including the front L and R


i know that one reason is to avoid overworking the receiver power-wise (power-hungry bass region?), but is there any other benefit? how do the other HT owners with full or semi-full range fronts set their crossovers? it would be a pity not to use the bottom end of your speakers, if you set the xover too high.


ultimately, the answer would be "to evaluate different settings and combinations, and run with what sounds best", but i just wanna know why most have this setting
 

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Notwithstanding your receiver "problem", the main reason is that freq response tends to roll off. If you look at a graph for your speaker, you'll see a curve down to 40Hz. It doesn't just provide 100% freq response to 40Hz and then drop off like a straight vertical line.


So you generally want the x-over setting well above the speakers lowest frequency rating if you are using a sub, since the sub should easily reproduce sound in that range.


Though, it does sound like you want a receiver with better bass management. (though there might be ways around that .. hard to tell with the info you posted.)


-David
 

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Quote:
Originally Posted by hwakin
probably been asked before, but why is it commonplace to have your receiver/processor crossover higher than your speaker's freq response capability?


currently i have a 2.5 way towers for my fronts, rated down to 40 Hz. i would like to take advantage of the speaker's full capability. i have set all my speakers to xover at 60 Hz, and am currently using the option of the fronts (L and R) receiving full range info, in conjunction with the sub putting out anything below 60 Hz. i can only do this with the front l and r set to large, if i set them to small, the xover setting specified will apply to all speakers, including the front L and R


i know that one reason is to avoid overworking the receiver power-wise (power-hungry bass region?), but is there any other benefit? how do the other HT owners with full or semi-full range fronts set their crossovers? it would be a pity not to use the bottom end of your speakers, if you set the xover too high.


ultimately, the answer would be "to evaluate different settings and combinations, and run with what sounds best", but i just wanna know why most have this setting



I use Large main speaker settings, and small for all other speakers.


My mains are rated at 40HZ low end -3dB, and I have no problems at all.


There are three camps on this issue.


Camp 1 indeed has small main speakers, and they are required to set all speakers to small.


Camp 2 has large main speakers, and they PREFER the sound of large main speaekr settings. The problem comes in on differences in implementation of the bass management schemes for a particular receiver. Some BM schemes and lack of knowledge by the end user can result in poor performance in this mode. If done properly, this setup works great.


Camp 3 has large main speakers and they PREFER to use small settings for the main speakers. The reasons given are somewhat true, but are not always important enough so you can hear a difference. I don't care how hard my receiver has to work. My receiver has never complained to me about working too hard, nor does it belong to a union!!!


A lot of the above also has to do with how hard you are pushing your system. If you are running at near full output capacity (play very loud), then camp 3 has a point.
 

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More of it has to do with the fr cancellations when having the same fr come out of your mains and out your sub @ same time.
 

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Bass is only localized down to 80hz, below that you can't tell where it's coming from.

Like Icarus said, the crossover is not a brick wall, your speakers will receive signals lower than the x-over point.

Unlike J_Palmers' non-union equipment... ;-) .. most set-ups will benefit from reducing the work-load of the lower frequencies on the amps, especially in large 7.1 configurations or when playing full range 5.1 like DTS.
 

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I have my crossover set to what my speakers can handle, only because my subwoofer performs so poor that it might as well not even exist.


80hz all the way when I get my SVS.
 

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Lots of hobbyist opinions on preference and the Small/Large thing. If the lowest distortion/widest dynamic range/most even FR is desired, though, it's best to cross over all speakers an octave above their reach. For most systems, even with large-appearing speakers, this mean setting them to small and applying BM at 80Hz or so.

http://www.harman.com/wp/pdf/multsubs.pdf


"In this investigation, bass management is assumed, i.e.

there is one and only one audio low frequency channel,

which is sent to all subwoofers. There are many

advantages to bass management and only questionable

advantages to using multiple bass channels (“stereo†bass

etc.). There is much debate on this subject. Much of it has

to do with the implementation of the bass management –

headroom, mixing of LFE etc. This is another subject

entirely, and is not considered here.

Some have argued that there is a subtle envelopment at low

frequencies which is enhanced when out of phase material

is reproduced at the left and right side of the listener [9].

This has not been shown conclusively, and in any case this

subtle effect is likely outweighed by the more immediate

advantages of bass management."
 

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Quote:
Originally Posted by mboy
More of it has to do with the fr cancellations when having the same fr come out of your mains and out your sub @ same time.
Very important advice here. Having duplicate frequencies in both the mains and the sub will introduce phasing and cancellation issues that simply will not be worth the trouble to solve. Some of these issues won't be solvable at all and you will compromise some part of your response curve.
 

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Quote:
Originally Posted by cnjvh
Very important advice here. Having duplicate frequencies in both the mains and the sub will introduce phasing and cancellation issues that simply will not be worth the trouble to solve. Some of these issues won't be solvable at all and you will compromise some part of your response curve.
Not so much "will" introduce issues as "may" introduce issues.
 

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Quote:
Originally Posted by DonoMan
Not so much "will" introduce issues as "may" introduce issues.
True, I suppose nothing is certain. But unless you have an auto setup that can accurately set your distances/phasing and use it, I think you are more likely to have issues that not. Something to be aware of and informed about at any rate...
 

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Quote:
Very important advice here. Having duplicate frequencies in both the mains and the sub will introduce phasing and cancellation issues that simply will not be worth the trouble to solve. Some of these issues won't be solvable at all and you will compromise some part of your response curve.
True. Unless you're really lucky.
 

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Quote:
Originally Posted by Jack Gilvey
Lots of hobbyist opinions on preference and the Small/Large thing. If the lowest distortion/widest dynamic range/most even FR is desired, though, it's best to cross over all speakers an octave above their reach. For most systems, even with large-appearing speakers, this mean setting them to small and applying BM at 80Hz or so.

http://www.harman.com/wp/pdf/multsubs.pdf


"In this investigation, bass management is assumed, i.e.

there is one and only one audio low frequency channel,

which is sent to all subwoofers. There are many

advantages to bass management and only questionable

advantages to using multiple bass channels (“stereo†bass

etc.). There is much debate on this subject. Much of it has

to do with the implementation of the bass management –

headroom, mixing of LFE etc. This is another subject

entirely, and is not considered here.

Some have argued that there is a subtle envelopment at low

frequencies which is enhanced when out of phase material

is reproduced at the left and right side of the listener [9].

This has not been shown conclusively, and in any case this

subtle effect is likely outweighed by the more immediate

advantages of bass management."



I set my mains to large and also use an additional dedicated subwoofer. Bass is much more even due to elimination of some room modes (width), and reduction of the number of room modes in another direction (length).



One part of the trick is you must deliver a SIMILAR signal to all three speakers, and the speakers must be properly placed in the room. This is similar to "In this investigation, bass management is assumed, i.e. there is one and only one audio low frequency channel, which is sent to all subwoofers." The EXACT same signal is not required, but it must be very similar.



Methods used are per:

http://www.harman.com/wp/index.jsp?articleId=122.0



A second part of the setup means you must know EXACTLY what your receiver does with bass management in the various speaker size setup schemes. Some BM schemes are helpful, and others are not. This is related to the statement "There is much debate on this subject. Much of it has to do with the implementation of the bass management – headroom, mixing of LFE etc. This is another subject entirely, and is not considered here."



The use of MULTIPLE dedicated subwoofers will also work very well. That is, if you can fit them into your room!!!
 

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Quote:
Originally Posted by Jack Gilvey
Lots of hobbyist opinions on preference and the Small/Large thing. If the lowest distortion/widest dynamic range/most even FR is desired, though, it's best to cross over all speakers an octave above their reach. For most systems, even with large-appearing speakers, this mean setting them to small and applying BM at 80Hz or so.

http://www.harman.com/wp/pdf/multsubs.pdf


"In this investigation, bass management is assumed, i.e.

there is one and only one audio low frequency channel,

which is sent to all subwoofers. There are many

advantages to bass management and only questionable

advantages to using multiple bass channels (“stereo†bass

etc.). There is much debate on this subject. Much of it has

to do with the implementation of the bass management –

headroom, mixing of LFE etc. This is another subject

entirely, and is not considered here.

Some have argued that there is a subtle envelopment at low

frequencies which is enhanced when out of phase material

is reproduced at the left and right side of the listener [9].

This has not been shown conclusively, and in any case this

subtle effect is likely outweighed by the more immediate

advantages of bass management."
How much is an octave? 20hz?
 

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Quote:
The use of MULTIPLE dedicated subwoofers will also work very well. That is, if you can fit them into your room!!!
I can see multiple full-range speakers working well along these lines if they're sent "similar" (do some receivers do this?) bass and if the best positions for bass also happen to work well for higher frequencies. That's the "lucky" part. I run a pair of subs at 1/3-2/3 spacing across my front stage . All three Athena towers, while verifiably strong to below 40 Hz, are set to "small".

Quote:
How much is an octave?
A doubling or halving of frequency
 

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Nice setup Jack. Did not realize you were in Verona, I am in West Paterson.
 

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Quote:
Originally Posted by Jack Gilvey
if the best positions for bass also happen to work well for higher frequencies.
Which, in my experience, is very rarely true (or the reverse, where the best positions for higher frequencies work well for bass). That's why you have "bass management", so you don't have to depend on luck...


John
 

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Quote:
Originally Posted by Jack Gilvey
Cool. :) I'm at Best Buy all the time. Oh, wait, you didn't want to hear that...
Hey, it's your money. I happen not to like them over there. MOstly bad experiences with 1 or 2 good ones. I won't shop there anymore.

To each his own tho :)

Somehow, I do not see you making big ticket purchases their since they do not carry the stuff you would be into (or me for that matter except TV and receiver maybe).
 

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I currently have 5 Rocket RS850s, crossed at 80 Hz. Kris Deering has 5 Ref 3s, crossed over at 80 Hz...heck lots of people do this.


You wanna know why?


Try moving your sub to each of the 5 mains positions and in the position your sub normally is in, and plot your freq response curve from 20 to 80 Hz...not all the same, probably not close (exception being the main compared to each other in a symmetical room) unless you are freakishly lucky or have an extremely well designed setup.


Now if you understand that the response is all over the place, how do you feel knowing that at any time any speaker could be tossing out either the same or different sound in those freqs? How predictable and even is your response then? You will end up with all types of different interference both constructive and destructive, causing different peaks and nulls depending which speakers are playing.


Contrast this with a mono bass signal, you know what you got, your bass all comes at you the same way all the time, and is easy to work with placement, multiple subs, room treatments and EQ.


This doesn't even address the issue that you usually can't place the mains for a good response and if you do you have hurt the higher freqs and imaging....or the fact you have less strain on your amp, or that drivers now need to handle less of the lower freqs...or that many don't have identical speakers all around.


My ideal situation is running identical full range speakers all around, crossed over at 80 Hz, bass is now mono. Use multiple subs and placement to get a good curve, room treatments for 80Hz+ control, throw in an EQ for the finishing touch.


*Edit* I'm preempting the question of why have full range mains at all and here are my reasons:


1. Looks, WAF, Stability...they look nicer and the dog/kid won't knock em over

2. Psychoacoustics...it sure is harder to tell where the bass is coming from without the visual clue that all the speaks are small

3. Speaker quality...it is tough to find monitors that are up to snuff with top floor standers

4. SQ...I like to not have the speakers producing a lot of signal where they are at their limits. If your speaks have a -3 dB point at 55 Hz, chances are they won't be as distortion free when you ask them to produce reference levels at 60 Hz....but would fare much better at 80 Hz
 

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Discussion Starter · #20 ·
thanks guys, good info all over the thread

got some bass mgmt work cut out for me...


cheers :)
 
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