First for Wayne, The PiAlign document contains some nomenclature I haven't seen. Vad is this the same as Vas? Where do I get Qd from? There are a number of others. If these are merely different names for the standard TS parameters, a translation table would be useful.

Second, all of the published alignments like QB3 or SBB4, produce box volumes less than half the size of the 4-5 ft^3 you (mollecon) suggested I might use for a typical high efficiency woofer (I plugged in a JBL 2206, for example.) Am I doing or interpreting something wrong? If not I assume we are deliberately misaligning the box to get more LF extension out of it by sacrificing a flat response, yes? The Loudspeaker Cookbook talks about non-flat alignments, but the examples he shows are all underdamped. I assume you could go the opposite way and overdamp. Is this what we're doing by using a much bigger box?

Thanks!

Jeff Mai

If you carefully examine the suggestions produced by PiAlign, you'll notice a trend. Generally speaking, most PiAligned cabinets are overdamped or what I would call EBS like. They are also often smaller than the box required for deepest flat response. Specifically, woofers having Qts less than about 0.4 are likely to be slightly overdamped and those with Qts greater than 0.4 are likely to be a little underdamped. Woofers with very high Q above about 0.7 tend to produce a curve that is like a shallow EBS.

I hadn't made it far enough to look at the PiAlign software.

I've got more reading to do and may discover the answer eminently, but what would be the advantages of PiAlignment vs. going for a larger enclosure (say 3 cu ft) for a 2206?

Jeff Mai

One alignment favors full range performance and the other favors deep bass, but both are acceptable design choices. Another good option would be a compromise solution: JBL suggests this in their product documentation - A 2ft3 cabinet tuned to 50Hz.

• JBL 2206 specification sheet

There is a theoretical limit as to how efficient conventional closed boxes or reflex designs can get (about 5% I believe) - & many commercial loudspeakers don't even come near to their theoretical limits even taking their bass response into account (the efficiency limit drops as one extends the bass response in any given box size as I mentioned in the earlier post).