Question Dirac, crossover and frequency response

Doug Pyper

Distinguished Member
I wondered what people thought of the below comment from this website (i.e. the highly regarded Markus from AVS):

Some (home theater) speakers are designed to fall off below about 80Hz. Such speakers won't work with Dirac Live because the usable speaker response needs to extend about 1 octave below the intended crossover frequency as explained above.

Markus argues that, given the xo isn't a brick wall cut off, a speaker needs to be able to extend 1 octave below (and a sub 1 octave above) the xo so that the sum effect of sub and speaker is a smooth frequency response.
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Active Member
One might look at the Dirac graphs and modify the target curves so that the sum of the responses add up (possibly to a flat response, one driver might compensate the other)
What happens if there is no Dirac Live?
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Doug Pyper

Distinguished Member
Perhaps the applicability of his assertion depends on how much a speaker falls off below 80Hz? If it's a gentle arcing decline, presumably it'll still work well enough with Dirac and sum with the sub to flat.

There's also the separate question of whether this is even a problem. The sum might not be flat, but how much of a dip are we talking about with well-designed home cinema speakers? I'll have to get around to calculating it at some point (after I've figured out how to!).

There's some relevant discussion on AVS here:

Understanding Speaker Crossover Points - AVS Forum | Home Theater Discussions And Reviews

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