Is this design any good?

The hardest thing about a box simulator is that it will happily draw you a curve without ever telling you whether it is a good one. A clean run means only that nothing crossed a threshold, which is a long way short of approval.

Three things are going on, and they need separating.

Is this number normal?

A number on its own tells you nothing. Choose what you are building and Baffle adds the usual range beside the figures it has one for, so Qtc 0.72 becomes Qtc 0.72, usual 0.55–0.85 for a bookshelf speaker.

Those ranges are conventions, not rules: they are where designs of each kind normally land, written down so you have an anchor. A design outside one is unusual, not wrong, and plenty of good speakers are unusual deliberately.

Could I do better with this driver?

This is the question no other simulator answers, because they all show one box at a time and leave you to build the picture by dragging a slider and remembering.

The small plot sweeps box size for your driver and marks where you are. From it you can read two things immediately:

• the flattest box available: for a sealed enclosure the one nearest Qtc 0.707, for a vented one the one with the smallest bump
• where growing the box stops paying: past that point the cabinet gets bigger and the answer does not

The sealed-box surprise

The plot usually teaches the same lesson to everyone building sealed: a bigger sealed box does not buy you much depth. It buys a lower Q and a gentler rolloff.

The reason is a cancellation. A larger box lowers the compliance ratio, which lowers both the box resonance fc and Qtc together, and F3 depends on both in opposite directions, so they very nearly cancel. Doubling a sealed box might buy a hertz or two.

If you want real extension from a sealed alignment you need a different driver, not a bigger box. See Hofmann's Iron Law.

Better at what?

There is no single answer, which is why Baffle asks what you are building rather than handing out a score. Qtc 1.2 is wrong for a studio monitor and perfectly ordinary for a car subwoofer. F3 of 55 Hz is good work for a stand-mount and a failure for a subwoofer.

You will not find a mark out of ten here, and that is deliberate. A score would hide the trade behind a number, when the trade is the design.

One thing to hold on to

Prefer a design that is insensitive over one that is optimal. If a 25 L box looks beautiful but falls apart when Vas turns out 15% off, and a 32 L box is slightly worse on paper but barely moves across the whole band, build the 32 L box. Tick show how well this is actually known and you can see which one you have.