Using a 120hz x-over

[jimlowe]

Recently I upgraded all my speakers in my system(all but the IB, of course). Well, whereas my old set up left a big whole in the 80-95 hz range, the new set up seems tipped up in the bass and really doesn't blend well with my IB. One of the problems I think is the ported design of the new speakers. The other is the UNFORTUNATE and NECESSARY cabinet mounting in a entertainment center of the left and right channels.

My thoughts are that maybe using a higher crossover than my current receiver set 80hz will allow a better blend and get rid of the bloat in that region of bass. Before I spend the extra money on something like a new receiver with more xover options or a Outlaw ICBM I would like some opinions. My IB is a dual avalanche 18's manifold mounted in the ceiling. Would my IB be smooth enough this high??? Any help would be great, this problem is really annoying and noticiable.

[Darren]

The only way I'd even consider 120hz would be if the IB is centered between your mains in the front. I probably wouldn't do it even then personally. Are you sure a little EQ won't take care of the problem?

[ThomasW]

You really don't want to run them that high. Any sub with a highish Le is going to start rolling off as the frequencies go up. This means poor SQ as the frequencies being played go higher.

Your mains probably have baffle step compensation build in the crossover. Most speakers have this and are designed to be placed well away from any walls or boundries. So when they're placed near a boundry this causes a bloated or tubby sounding midbass.

[chrisbee]

You could try the old trick of stuffing the ports with old socks.

[jimlowe]

The socks are the cheapest option at this point. From what I've read it may not work though.

[ThomasW]

Plugging the port only effects boost at the port tuning frequency. I doubt that you have a port tuning that's anywhere near the crossover frequency to the IB.

As a test move the speakers out into the room away from the walls. If the problem goes away you know it's caused by the baffle step compensation.

There are 2 fixes. One is a bandaid, using EQ to flatten the output at the offending frequencies. The other is what's supposed to be done. That's rebuilding the crossover (removing the BSC) so it's designed for a near-wall boundry placement.

[markw]

I run my Dual manifold 2 x 15" IB up to 110hz with a 4th order crossover.

Each manifold is above the L/R speaker, an outie poking out of the ceiling.

Works fine. If I was to build my crossover again I would go lower (I went for 2 x the F3 of the mains), but it works fine.