My receiver has both large and small settings and also has the capability to set the crossover for the sub. What does the large/small setting do if I also have a crossover?
essentially, setting a speaker to SMALL in the receiver will redirect any sonic information for that channel that is below the receiver's set crossover to the subwoofer. if you set a speaker to LARGE, then none of the sonic information for that channel is redirected and the speaker is sent a "full-range" signal.
the ability to vary the crossover for the SMALL setting allows you to fine-tune the crossover to exactly how SMALL (or unSMALL) your speakers are. some "small" speakers may be fine with a 60Hz crossover, whereas a much smaller speaker, like a micro-satellite, may require a much higher crossover, like 120Hz. the crossover setting you use is determined mainly by your speakers' capabilities.
The small setting engages the crossover for a particular speaker or pair of speakers. The large setting sends the full range of frequencies to a particular speaker or pair of speakers.
As you probably know, bass frequencies are present in all the channels;
5.1 (5 speakers + sub)
6.1 (6 speakers + sub)
7.1 (7 speakers + sub)
The HT receiver/processor actually deals with two(2) different kinds of bass frequencies;
1) LFE bass - bass which is specifically recorded on the DVD as the .1 channel and designed to go to a sub. It is defined as frequencies below 120Hz, and often limited to an upper limit of 80Hz in the DVD recording process.
2) Re-directed bass - bass from any of the other speakers that are set as small in the speaker setup menu.
The HT receiver/processor typically combines these two together and sends them to the sub.
A typical HT setup has all speakers set to small with the receivers global crossover set at 80Hz. The sub should have it's internal crossover turned off or set to it's highest setting if it can't be turned off.
In your case, setting all speakers to small and setting your receiver's crossover for the sub to 80Hz probably results in the following:
1) All 5 speakers of a 5.1 system will start to reduce their output below 80Hz, because 80Hz and below frequencies are being re-directed to the sub.
2) The sub will receive all 80Hz and below re-directed bass from the other 5 speakers. The receiver will combine this re-directed bass with the #3 LFE bass below.
3) The sub will also receive all of the 80Hz and below .1 LFE bass from the DVD and the receiver's crossover will reduce any output of frequencies above 80Hz sent to it from the DVD .1 channel.
what your sub does during 2-channel playback can vary slightly from receiver manufacturer to manufacturer, and is most likely dependent upon another setting or two, besides speaker size.