Surround content mix:
50% Center channel
40% L&R channel
10% Surround channels
The center channel is the most important speaker. Typically it is smaller than the L&R. A sub would help give you full range response for center channel information. In 5.1 processing each channel can receive info down to 20hz. The sub .1 channel gets special effects info that is not the same as what goes to the other 5/6/7 channels. The sales guy is giving you good advice if you have a smaller center speaker.
However, the system is now more complex. Set-up will require the sub is time aligned with your center speaker. You need another cable possibly a crossover, another amp, power cord and a place to put it. This is basically a sub/sat system for the center channel. Weigh this against buying a full range center channel that matches your L&R in the first place.
If you really want the best sound you should have identical FULL range speakers for all 5/6/7 channels. This is usually difficult due to speaker placement constraints for center and surrounds. Full range surrounds can be hard to justify as you are spending a lot of cash for that 10% of sound.
hope this helps,
50% Center channel
40% L&R channel
10% Surround channels
The center channel is the most important speaker. Typically it is smaller than the L&R. A sub would help give you full range response for center channel information. In 5.1 processing each channel can receive info down to 20hz. The sub .1 channel gets special effects info that is not the same as what goes to the other 5/6/7 channels. The sales guy is giving you good advice if you have a smaller center speaker.
However, the system is now more complex. Set-up will require the sub is time aligned with your center speaker. You need another cable possibly a crossover, another amp, power cord and a place to put it. This is basically a sub/sat system for the center channel. Weigh this against buying a full range center channel that matches your L&R in the first place.
If you really want the best sound you should have identical FULL range speakers for all 5/6/7 channels. This is usually difficult due to speaker placement constraints for center and surrounds. Full range surrounds can be hard to justify as you are spending a lot of cash for that 10% of sound.
hope this helps,