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crossover settings


greggblagg

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80 Hz is the THX standard, as well as the usual Audyssey recommended crossover.  You may be able to use different crossovers for your different speakers (usually tagged "Advanced" in AVRs).  If your fronts are good, then 80 would be a good starting point for them.  People with tiny surrounds sometimes go as high as 100 Hz, or even higher, for the surrounds only.  I don't know your speakers.

 

Set your speakers to "small," even if they are large.  If you decide to try violating this, you must use the setting "LFE + Main."   Some people, with some speakers, in some rooms can get good bass by using this setting (called "double bass" by some AVR makers) and setting speakers to "Large," but others report phase problems, etc.  The standard advice is to use "small" even if your speakers are large and your AVR says "large."  It's a long story.

 

Also, for Home Theater, there is both a true crossover (X-over) setting for bass management, as well as a separate Low Pass Filter (LPF) for the special Low Frequency Effects (LFE) the movie people put on the soundtrack.  Properly set up, your sub would play the sound coming from both of these sources.  The bass management routes the music frequencies below X-over (usually 80) to the sub.  These are almost entirely from the bass range of the instruments of the soundtrack orchestra.  The LPF routes the bass part of sound effects to the sub.  This is usually labeled LPF for LFE, and the setting the filmmakers intend for you to use is 120 Hz -- some people prefer different settings for LFE.  

 

Gauge the ability of each of your speakers to play loud bass.  You can follow the standard advice, but ultimately let your ears be the judge.

Edited by garyrc
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People with tiny surrounds sometimes go as high as 100 Hz, for the surrounds only.

 

If you want to hear something weird, I can actually measure an 82 hz null in my room with RF-7ii's when crossed over at 80 hz.  If I cross over lower like at 60, the null gets worse as well as a lower frequency.  Doesn't matter how well the subs are blended, I have an infinitely adjustable delay knob on the sub amp and have tried 26 foot swings in Audessey on the sub placement.  If I cross over at 110 hz, it goes away and is pretty flat.  I'm not entirely sure what is going on with that.  

Edited by MetropolisLakeOutfitters
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I had an RC25, I crossed it at 80hz and it worked great.  The response of that speaker actually is 82hz, but with the port they included it extends down to 74.

 

What that means is that IF you intend to listen at very high volumes, it would be better to have a higher crossover for that center, in the 90-100 range.  The speaker can handle 80 I think no problem at high volume but will sound best with a slightly higher crossover so that it isn't working at its limits on the lower end.  

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MLO can you frequency test your RF7iis?  It sounds like they are causing the issue perhaps due to THEIR placement?  Sub cannot correct it no matter where placed but maybe the fronts themselves have an issue with the room at that frequency.  By changing the cross downwards, you were having the RFs do that frequency...when you moved it back up the sub took over and fixed it?

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What RK said. It sounds like either comb filtering or room modes of the mains themselves. I doubt the subs have anything to do with it.

 

At 110 XO, the mains are sending very little signal at 82Hz. At 80 XO, you are probably -6db at 82 Hz. At 60 XO, you are probably 0db at 82Hz. 

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