In response to a diyAudio thread, I noted that the Altec 604-8H models to -F3=40Hz in a ported 5cuft volume, and if the port was later plugged it models to -F3=80Hz with Qtc~0.6 ---- desirable for a large area cone. This comment was meant to show the flexibility of a 5cuft cabinet which the OP was considering.
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The Altec StoneHedge-III and Hiraga 605-Alnico cabinets have about 5cuft of free internal volume after speaker+bracing+port have been figured in. There are detailed plans(too large to post) for the Altec StoneHenge-III . Visit Jeff Markwart's Corner website for this pdf plus more Atec knowledge.
Altec Stonehenge III (3577A) Cabinet plans
Altec StoneHenge-III
H44"+ legs,W18.75",D17.25“
Hiraga 605-Alnico
H41”,W20.1”,D18.1”
