210 modifications?

[valhallax]

I'm thinking about converting one of the pairs of 210's I have..these are in my shop and occupy a large part of floor space. I want to remove the lowest frequencies from my 515e's via sub in the lower portion of the cab. often times during movie explosions or bass heavy music I can hear limits. my plan would be to seal the rear chamber for the 15's and incorporate an 18 in the bottom. how much space for the rear chamber on the 515's? I know steve mac used sealed rear chambers in his mid bass horns, is this a benefit sonically? there is a lot of space in the cabs that I could use for a sub, a quick measure of the lower portion was like 30 cubic feet..

[GM]

Yes, a huge [to me] benefit, though horn bracing/mass loading made ~ as much as them not having to reproduce below ~85 Hz [used a 120 Hz/2nd order XO].

Steve's are ~3 ft^3 net if he used my recommendation that I wound up with when I converted a pair to mild compression loading [assumes a ~1 ohm total output impedance].

Biggest problem was getting a 'fast'/'powerful' enough sub, so wound up with corner loaded dual 515B/channel in a simple ~20 ft^3 vented pipe horn [aka ML-TQWT or Voigt Pipe nowadays] tuned to 30 Hz, later dropping it ~16 Hz when recordings, movies made it worthwhile.


GM