I just recently discovered that changing the master crossover point from 100 to 150HZ gave me way more bass in the surround modes. It also made the highs sound better. Can someone explain this. The book said 80 or 100HZ would be the usual settings. I don't have a subwoofer and I've got the mains set to large and the center and surround set to small.
Since the mains are set to large, all bass information below your crossover point will be redirected to your front speakers. Most likely, your fronts are better suited to producing bass than your surrounds. So, if you increased the amount of bass information that is fed into your fronts (which are better at making bass), you'll bet more bass.
You are correct though, between 80Hz to 120Hz is the most common crossover point, but you're supposed to set your crossover based on what your speakers can do. If your speakers can't produce anything (or anything well) under 150Hz, then that's what your crossover should be. Make sense?
Let's go one step further. The mains have an amplifier driving them at 220 RMS per channel minimum. The center and rears are only driven at 75 RMS minimum. would this make a difference in the bass content. The specs on the center and rear speakers say that they produce a flat response down to around 60 HZ. They should be able to produce the bass, no?
The difference in amplification is probably not making the difference in bass volume. All but the most extreme listening volumes are done in the 1 to 10 watt power range.
Since I don't know what speakers you're using, I can't be definitive on thier bass response, but if they're small or bookshelf sized, I can guarantee it's not a flat repsonse to 60hz. But you're right, you should get ample bass at 100 to 120Hz.
Another major factor in bass is the location and cabinet size of the front speakers. It may be that the front's position is in a spot where higher bass notes are being enforced by a wall or ceiling. As an experiment, you could take your rears and put them where your fronts are for comparison. Also, your front channel speakers may have a bigger cabinet, which will make an impact on the bass volume from the cabinet.
Don't forget about all the other variables that can have an impact as well, like whether or not the speaker is front or rear ported, the driver size and material, efficiency, unbalanced calibration, etc.
Thanks for the info I think it might help.