HT Questions

Is there a standard freqency response output for the surrounds in a 7.1 set up?

Are tweeters need for your surrounds?

Do your LCR "NEED" to be the same?

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No speakers dont need to be matched, in a perfect world they would be ofcourse. The fronts and center if not dead on matched should atleast be from same maker and at very minimum same basic design (mixing Planar mains with a dynamic ported center may not be wise)
There should be a tweeter in surrounds as much info would be info in the higher ranges of sound (think birds, glass breaking and such).