A7 vs Model 19 for home HF use

[VolvoHeretic]

Quote" These drivers were originally designed to be driven with a ~matching impedance, ~doubling its Qts which if done with the proper coupling results in a ~current driven system where the speaker’s frequency response ~ mirrors its varying impedance, ergo can have considerable LF efficiency if tuned to Fs in a sufficiently large cab.

If some form of EQ is used with a very low output impedance, then more power is required, though with an acoustically large cab’s extra tuning capability it can be better blended to the room’s gain curve, reducing power/excursion consumption.

With all that in mind, using GPA’s 604-8G II specs, a T/S max flat alignment = ~33.9 ft^3 net Vb/24.8 Hz Fb, but for most efficient electrical coupling it would have to be slightly under-damped with an actual Fs tuning. These tunings though would typically be too high and may even need to be sealed for best room blend.

The pioneers decreed that the ‘best’ vented alignment was a net Vb that increases a driver’s Fs 1.56x in a sealed cab, then vent it to an Fb = Fs alignment or ~ 11.35 ft^3 net Vb.

Of the two, the larger cab has a bit more output around/at Fs which may/may not be worth the all the extra size/cost to the builder depending on room conditions and whether or not it’s misaligned to a lower Fb.

FWIW, in my own builds/recommendations, I generally ‘draw the line’ at Vb = Vas in these situations as an acceptable trade-off or ~16.35 ft^3 in this case.

GM"

There might be a lot of typos (in my understanding of) in that quote, but I love my A7-500's. But let's suppose I wanted to modify them. If I screwed on a sheet of plywood onto the fronts and increased the Vb to the exterior dimensions of the boxes to something like 12.5 CF (or what ever, since i can't remember), would that be perfect with the right sized port for inside listening? How wound something like that affect the horn bell box loading? Would the horn bell matter for interior dimensions?