Larger box for sealed OK?

[mazeroth]

I’ll post my question first and reasoning second, so you only need to read the question but can see why below.

Are there any negatives to using a lower Qtc for a sealed speaker (non-sub)? I’m thinking of going with a 0.62 Qtc as opposed to a 0.707.

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I’m in the process of designing a set of line arrays utilizing (9) Dayton RS150 woofers, which are 6”. I would like this box to be sealed to promote better midrange. This will be used strictly for 2-channel audio. I would really like to not have to use a subwoofer and not go ported. As far as recommended enclosures go, to achieve a 0.707 an enclosure of 0.25 ft3 is required. After drawing up the plans for the enclosures, and using bracing between each driver so each driver will have its own airspace, I will have 0.35 ft3 for each driver, resulting in a 0.62 Qtc. This will, obviously, allow the woofers to go a tad lower and have a slower roll off. Here’s how they compare:

0.25ft3 F3=83 F6=64 F10=48
0.35ft3 F3=87 F6=62 F10=45

I will be using a Behringer DCX2496 for the crossover so I will have no problem boosting the low end of these speakers to promote more bass, if needs be. Seeing there will be 18 6” drivers I don’t think boosting their bass output, exponentially, from 30-80hz a few dbs will affect the sound much. What are you thoughts on boosting the bass a little with this digital crossover? Will it muddy the mids? This crossover will allow me to implement a BSC and another “mini” BSC to compensate for the bass. I had an hour to play with it last night on a test enclosure and it simply blew my mind.

Thanks for any help you guys can give me!

[5th element]

Generally going to a Qtc of 0.5 gives youthe best transient respose from the drivers.

Now a Qtc of 0.5 can sound rather cool and lifeless etc, usually going up in Qtc adds a bit of warmth to the sound mostly because of the small increase or hump in te bass you achieve by doing this. Past a certain point and the sound becomes boomy and unpleasent but this could be more to do with room coupling rather then the bass alignment.

So in short no, unless you put a "hump" of bass over flat frequency response you will not muddy the mids. It also depends on your meaning of muddy, adding warmth I would say is not muddying but could potentially sound as if it was muting detail slightly.

[Dave Jones]

There's a lot of info about sealed box Q's is here: http://www.geocities.com/kreskovs/Box-Q.html

Be careful about using EQ to boost bass in a sealed box system. High excursion = modulation distortion. I am a now a zealous believer in using a subwoofer and putting a high pass filter on the mains. With 16 drivers, excursion may not be an issue though. Woo, that's a lot of drivers.

[simon5]

This document is nice but I think this area need more testing.
Like real tests between same subwoofer with same amp, one in Q=1 and the other in Q=0.5