Originally Posted by Epelba01
Thank you. How would you handle a situation where you set the fronts and center to large and would want to set a lower frequency and the surrounds are set for small and the recommended crossover frequency for those by the manufacturer is 100. I am a little confused or not truly understanding how to properly set things up.
The speakers that I have are the Definitive Technology supertowers 8040 with subs built in, and a center 8060 with a sub as well. Would I turn the sub setting to off in the speaker settings? Please advise. Thank you.
I will try to be very basic. The theory of all this is that low frequencies can not be localized by the human body simply because the phase shift between both ears is too small, so below 120Hz it is impossible to know the source direction of the pressure wave. This is why Dolby decided that everything in all the channels, under 80Hz, is best to have go to single source in order to avoid standing wave effects in the room and to optimize the perceived power vs. supplied power. This is good for movies, games, sports or even concerts recorded in any of the Dolby multichannel formats. In this case the bass will go to the LFE channel no matter what and the xover freq is fixed by the standard.
The problem comes when you want to play an analog source or a stereo source with full spectrum signal. In this case we have to rely on the crossover circuitry of the speakers or the one inside the receiver. It depends on the response of your speakers but nowadays receivers do the calibration across the whole spectrum and the result ensures the best response taking into account the response of the speakers and the room.
In case you leave the whole spectrum to big channel speakers, then you are relying the filtering on the speaker internal xover circuit. You can do this by setting the speakers to LARGE.
What happens when you try to set speakers to large and also use the subwoofer? under this configuration you are just trying to use all the bass power in order to sum all the power. Well, the xover circuit inside the speakers adds some phase shift and it will just cancel the power coming from other speaker, and it is not the same for the whole frequency range. It is really a nightmare and there is no way to do it right even with state of the art technology. The easiest way is having a single bass signal going to 1 or more identical subwoofers. Only this way you ensure that the power is going to be in sync across the full bass spectrum and that it always be additive and never destructive. Nonetheless with more than one source you will always have standing wave effects if your room is too large. This is the reason why Dolby decided that having a fixed xover frequency is the only way to ensure the signal response.
IMHO, the best results should be obtained by setting the xover to 80-120HZ(try 100-120 in your case) in the receiver for all the channels and to the max in the back of the subwoofer. Then run full auto Advanced MCACC setting all the speakers to 'small' and sub to 'yes' and after that just tune it to your best preference. We all know that perceived fidelity is not the same than the objective fidelity and the final configuration should be the best of our ears and not for our spectrum analyzers.