Not in the biblical sense. What do you want to know about it?

GM

You're welcome!

There are different 'Onken' designs, with the most visible being the Jensen Ultraflex 'clone', which in turn is derived from Thuras's 1932 bass reflex patent. Yes, Jensen 'killed two birds with one stone' WRT wanting a vent area = driver Sd and brace the cabs well too boot. Factor in using 3/4" void free plywood and cleat reinforced joints and all that's left is to add a brace/support system for the heavy driver(s) and some stuffing to damp down the harmonics of the (summed) large vent.

The Onken 'W' OTOH is just a large reflex with standard vents, but it's 'claim to fame' is sand filled double wall construction to damp the cab's resonance.

The 416-8A articles with plans/ measurement:

http://ebenisterie.musique.free.fr/RDS/Divers/Audiophile1977.pdf

http://ebenisterie.musique.free.fr/RDS/Divers/Audiophile1982.pdf

How big any cab needs to be is dependent on the driver's specs, total system impedance, and the desired F3, Fb, so this alignment may not be suitable for your app..

For example, SS amp driven 416-8C Onken alignment (n = 6.34): Net Vb ~10.5 ft^3/~35 Hz F3, Fb with overall dims: 36.5" h x 23.5" w x 26.38" d. Driven with a 300B: Net Vb ~19.5 ft^3/~26 Hz F3, Fb with overall dims: 36.5" h x 40.13" w x 26.38" d.

Folks tout the big vents increased bass output, but they don't mention the downside, which is the chopped up response above the cab's BW where their harmonics comb filter with the driver's lower mids output if not properly damped, which of course damps down the extra gain, and then some. Bottom line, Onken's got the sexy look, but a simple

You're welcome! Correct, I used a 3.2 DF (2.5 ohms output impedance) to get the alignment, but ideally you would design around your amp's DF. ?? I mean this is what the measured specs I have calcs, and of course the big vents is what makes the Vb calc'd from the posted dims somewhat greater. Using published specs I get ~8.97 ft^3 net/~38 Hz Fb, so should still work fine in a slightly oversized/lower Fb cab.

GM

The M19 has a classic Altec alignment, peaking around 50 Hz with the -8B, and requires the room to fill in the rest if need be, while the Onken peaks lower based on a percentage of its (Fs/Qts) spec to help the driver above Fs where it runs out of excursion, but rolls off at a steeper rate, so it just depends on the room, speaker location and how much bottom end you need.

GM

Yeah, Altec offered some duplex cabs with a shelf vent variant which I initially used in my 20 ft^3 dual 515B 'subs', but with the advent of real LF capability I tuned it much lower, first with a longer shelf that extended up the back wall, and later with a T/S vent to get around the strong TL action's upper harmonics mucking up the lower mids when I began using them with a higher XO point.

Some folks believe the Onken is mildly loaded this way, but it's not, though its vent system does have some resistive damping due to the large summed surface area Vs one or two large round vents of equivalent CSA.

GM