Originally Posted by Luisfc1972
oh man, i didnt realize setting up dual subwoofers would be so complicated and a whole other learning experience. i am novice at home theater and it looks like dual sub setup is way too much trouble.
i think ill spend $1200 on the denon x4000 to make it easy for me. it can configure two subs and it should be a lot easier than buying spl meter and doing all the things you guys say. at least i wont have to buy another avr for 5 or so years. ill put up my denon 1712 for sale. thanks fellas for your time and effort.
Don't let the ill-informed and pointlessly argumentative put you off. It isn't all that difficult to set up dual subs and there can be substantial benefits from doing so. If you get a unit that has Audyssey XT32+SubEQ HT, then it will do most of the work for you. The only thing Audyssey cannot do is optimise the frequency response around the crossover region (the splice). It cannot do this because at no time does Audyssey measure the combined response of the subs and the mains when playing together and it obviously cannot optimise that which it doesn’t measure.
The reason this is important is because around the crossover frequency all the speakers are playing the same frequencies. This is because crossover filters act gently - that is they have a 'slope' and are not 'brick walls'. So if you have set a XO of 80Hz, then both your mains and your subs will be playing some of the frequencies around the 80Hz at the same time. You can see that it is therefore important that the subs and mains are in phase with each other at those critical frequencies because if they are not then one speaker will cancel out the effect of another speaker.
It is also important that the subs are in phase with each other, for the same reason, and sometimes this does not happen after you have run Audyssey. Unlike some, who have only a single subwoofer and no experience with setting up duals, I had this exact issue some time back (it is documented in this thread if Search is now sophisticated enough to find it). At the time I was running dual SVS PC12 NSD subs which have continuously variable phase controls from 0 to 180 degrees. After Audyssey XT32 had finished I had very weak bass. At that time I was using OmniMic (now REW) to measure my in-room response and it showed me that if I changed the phase on one of the subs that my bass became much, much better. I had to move the phase control on one sub from 0 to almost 180 degrees before it all snapped in and both my subs were in phase with each other. The audible and measurable difference was very obvious, so please ignore anyone who tells you there is never any need to adjust phase on one sub in a multiple-sub setup because they are just plain wrong.
Once the phase on the subs has been harmonised, then the sub distance tweak procedure can be used to ensure the best integration of the subs and the mains around the XO. If you download the Guide linked in my signature you will see just how spectacularly this can improve FR around the splice. You do, however, need measuring equipment to do this so that is perhaps something for the future for you.