Subwoofer terms inquiry (1 Viewer)

[Jedd]

1) What is Q? Should I look at the group delay graph or at the Q value? i.e sealed Q=9 has max delay 13, ported Q=6 has 20
2)What would be the best driver for 120L sealed enclosure? What numbers should I look at? Qts, Xmax?
3)with given enclosure (122L, sealed) and given driver (Tempest), how much power do I need, what changes when I tripple it from 250W to 750W? What will be the optimum value? What about coils?
4)When I look at the "SPL in room&cabinet" graph there are 3 kinds of lines - bold "in box", blue - "free air", and one unmarked - ? (room response??) - which one of these is important?
5)When I load Adire Q=0.7 sealed design and do Box->Optimize->Table Optimize -> 0.707 it doubles the enclosure.
6)They say that you need to eq your sub (of any design?) to get flat response in your room. Does it mean that I have to get separate equalizer for it, or is something already done in the amplifier?
Thanks

 

[Kerry Hackney]

Jedd, you may do better with some of these questions in the basics area... but here are a couple of answers.

Q is the suspension compliance of the driver. Think of it like a shock on a car. Lower Q is stiff, higher Q is less controlled. Higher Q designs in subs can be "boomy" and somewhat less musical.

As for drivers for a 120L box, a lot depends on what you want it to do. If you're after max spl it may be different than if you want something for music. You may want to look at some existing designs before you try to roll your own.

Power requirement are also dependent on your goals. Double power doesn't equal double volume. Tell us what you want it to do.

In room is what you are predicted to hear. The rest are tools to tell you what is happening with the driver.

In many rooms a sub will not be flat because the room has such a huge effect on bass frequencies. Parametric EQs like the Behringer are added to the system to correct the peaks in response. Your amp can't do what the eq does.