50hz vs 80hz what happens to LFE?

bansheesho Posts: 227
My new front speakers dig much deaper than the old ones, and I have been thinking about changing the crossover frequency from 80hz to 50hz.. I was wondering what the logic of the LFE chanel is in certain modes though, because I don't want to loose the good effects that run through it.

What is the logic when:

Front and Center speakers set to Large, Rears set to Small and the crossover set to 80hz
(As set now)

Front, Center, and Rears set to Small and the crossover set to 80hz
(Not to keen on this one)

Front, Center, and Rears set to Small and the crossover set to 50hz
(I think this might sound better for the front, but I may loose a little low frequency with the rears)

Is the LFE chanel affected by the crossover setting? Meaning if I set a 50 hz crossover will all of the LFE still be sent to sub plus whatever would normally play on the speakers below 50 hz?

I have been watching TV with the new speakers, and it seems to sound better with the sub muted which makes me wonder if reserving it for only the lower low frequencies would be good.
Pioneer SC-25 | Adcom GFA-555 | KEF q900 Front | KEF q600 Center | Polk Monitor 30 Rear | Polk CS2 Rear Surround | Polk DSWPRO 660wi sub
Post edited by bansheesho on


  • bansheesho
    bansheesho Posts: 227
    edited April 2012
    This article recommends setting the crossover to roughly 10hz above the -3db rating of the speaker...


    The kef q900's are listed
    Frequency response: 32Hz–40kHz, ?3dB

    The cs2 center and m30 rears are at 60hz and 63hz -3db limit though which means that I may have a 10hz void in those speakers if the crossover is set to 50hz

    According to that article it may be a better blend with my Front speakers to set them to 50hz rather than 80hz? Thoughts for HT and Music?
    Pioneer SC-25 | Adcom GFA-555 | KEF q900 Front | KEF q600 Center | Polk Monitor 30 Rear | Polk CS2 Rear Surround | Polk DSWPRO 660wi sub
  • evhudsons
    evhudsons Posts: 1,161
    edited April 2012
    great article, thanks!

    lfe and bass management is tricky. I finally settled on 80 crossover, but I have a nad amp that I bridged with my two 4ohm speakers wired in series to be recognized as a single 8ohm with 600 watts going to it, and then I adjust the level with the switch on the front. I can adjust it better there than going between 60 and 80 on my avr.
    I also broke down and got the ratshack spl meter for fiddy bucks and it works much better than my iphone app.

    It's just pure awesomeness now. But that article explained things well and gave me more ideas to try, and it also explained sort of why there is such a delay in my indoor versus outdoor speakers. Now I can adjust the distance so it all matches.

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  • John K.
    John K. Posts: 822
    edited April 2012
    Banshee, the article you link suggests setting all speakers "Small" and the mains at an octave(not 10 Hz)above their -3dB point. For your q900s this would be about 64Hz. As a practical matter in your case, the best overall setting for the speakers would be at 80Hz.

    Whatever crossover you select, all the LFE channel information(theoretical max of 120Hz, although not that high in reality)will be sent to the sub plus any information from speaker channels set "Small" below that selected crossover frequency.
  • bansheesho
    bansheesho Posts: 227
    edited April 2012
    Thank you for clarifying!! So an octive = 32 Hz?
    Pioneer SC-25 | Adcom GFA-555 | KEF q900 Front | KEF q600 Center | Polk Monitor 30 Rear | Polk CS2 Rear Surround | Polk DSWPRO 660wi sub
  • cnh
    cnh Posts: 13,286
    edited April 2012
    Personally, I don't pay much attention to generalized discussions about HT. I listen to my system and what my "ears" tell me. And on my set, in my room with my equipment. An 80 hz setting is just NOT the best setting for music/HT combo.

    In fact even 60 hz on the mains is too high. It does not sound as good in stereo as a lower LFE with the mains being good to 40hz. The sound relies on the sub too much for music. And I like to minimize that reliance for music because blending a sub with towers in 2.1 is not that easy (at least in my room).

    So I'd say. Read what the boys have to say; but don't let that stop you from doing a lot of other "testing" and "listening".

    Currently orbiting Bowie's Blackstar.!

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  • John K.
    John K. Posts: 822
    edited April 2012
    Banshee, an octave up from any frequency is a doubling of that frequency. For examples, 20Hz to 40Hz, 40Hz to 80Hz, etc. In the case of your q900s it would be a doubling of the 32Hz rated -3dB point up to 64hz.

    The frequently suggested 80Hz crossover point wasn't picked at random; testing showed that it's high enough to take a significant part of the bass load off the mains and put it on the sub which is designed to play those frequencies better(if it isn't better, the sub simply isn't a good enough one), but isn't so high as to make the sub easily localizable. Assuming that the mains have good response to below 80Hz, that's the appropriate crossover.
  • Dennis Gardner
    Dennis Gardner Posts: 4,858
    edited April 2012
    The 80 hz setting for multi channel HT was done to control the 60hz "room node" frequency bumps that occurs in many normal size living areas in todays homes. It simply moves the control of that frequency to a seperately powered single speaker in most cases. Large speakers all around in a small room overwhelm the area at that 60hz peak and make it very difficult to control the boost that 5-7 channels can add to this anomaly. We hear it as boomy bass. If this bass is restricted to a single location, the room affect is reduced. It is simple acoustical physics. Simple to understand, hard to manage.:biggrin:

    Soundstage in HT is all about surround balance.

    Two channel music listening is all about front stage imaging and depth. The careful integration of a sub in this application with deep digging mains may require a different setup. Time to get your listen on, and learn what your room is telling you.

    My settings: 80hz for multi channel HT even though my mains dig to below 30hz in room. Sub off for 2 channel music.
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  • gp4jesus
    gp4jesus Posts: 1,805
    edited May 2012
    I set all channels to small, XO'd 1/2 an octave or higher above the f3 spec. e.g. CC 80hz; LR 60hz; sides/rear 100z.

    W/any speaker, higher does't hurt; too low, VERY loud could blow a MW. If your systems & time allows, try listening to your CC alone; your surrounds alone, w/different XO setting at different levels. YMMV.

    Enjoy, Tony
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