Heresy II cabinet stuffing...

[Rootpusher]

When removing the crossovers on the '89 Heresy IIs I recently acquired (I'm sending the crossovers to Bob Crites for an upgrade, and also getting the titanium tweeter diaphragms), I noticed inside each cabinet a large piece of light greenish-grey foam -- maybe 1.5" thick, open cell -- wrapped in a "U" shape, with the round side of the "U" following the curve at the top of the woofer, and each long side of the "U" terminating at the interior floor of the cabinet; this foam "U" runs the full front to back dimension of the cabinet.

1.) Is this stock?

2.) How would the sound change if I removed it?

3.) Has anyone experimented with removing this foam and instead loosely packing the cabinet with something like PartsExpress "Acousta Stuf," or some other form of loose fiber packing?

Thanks!

[Daddy Dee]

The U shaped foam is indeed stock.

Never have compared to see if I could hear a difference. In the original Heresy the cab is empty, except for drivers and crossover.

[colterphoto1]

replace it exactly as it is, do not add or delete anything. it should have a slit for the wiring and is usually in an upside U shape around the woofer. This reduces internal reflections inside the cabinet.

[Rootpusher]

I never even took it out -- I was able to thread the wires out through that slit.

Judging from your response: Would I be correct to assume that Klipsch arrived at that exact (and presumably optimal) configuration after a lot of trial and error, and that nothing can or need be done to further damp any reflections inside the cabinets?

Thanks again,

[Islander]

I never even took it out -- I was able to thread the wires out through that slit.

Judging from your response: Would I be correct to assume that Klipsch arrived at that exact (and presumably optimal) configuration after a lot of trial and error, and that nothing can or need be done to further damp any reflections inside the cabinets?

Thanks again,

Batting or foam inside a speaker cabinet does more than damp reflections. It also provides "virtual volume", giving the effect of a larger cabinet. The amount is precisely calculated, so changing it will likely reduce the sound quality.

[colterphoto1]

I never even took it out -- I was able to thread the wires out through that slit.

Judging from your response: Would I be correct to assume that Klipsch arrived at that exact (and presumably optimal) configuration after a lot of trial and error, and that nothing can or need be done to further damp any reflections inside the cabinets?

Thanks again,

Yes, Klipsch has acoustical engineers who figure this stuff out using test equipment, trial and error, math, and ouija board.

[lakedmb]

Would it be beneficial to stick the same size foam from the Heresy II's into a set of Heresy I's?

[Groomlakearea51]

Tried that, but no real effect (that I could tell). Reason probably has to do with the cabinet material. Birch plywood for the H-I, and MDF for the H-II. Different resonating freq's. That I have noticed. When I refinish a pair of H-I's, the cabinets will resonate (loudly) at a certain frequency when orbital sanding the front edges, but that sound is different for a H-II. Also, the H-II crossover is on the terminal cup, and not on a separate board like the H-I. The H-I crossover board, when screwed onto the side panel, likely dampens any resonance. Sorta' like ringing a bell with your finger (or anything else for that matter) on the bell.....