Need Subsonic filter for Home theater build.

[shizzzon 461]

I am trying to help a member here on SSA with his home theater sub project.

He is currently using a Fi 12" SSD in 1 cube sealed with polyfill running off of a 1400w Behringer amp.

He is changing his setup to a Mach5 18" running off the same amp but ported tuned to around 18hz.

His amp only has a 30hz or 50hz roll off choice.

I have searched and searched for crossovers that have a subsonic filter on them that can be tuned to roll off around 15-20hz. I'm trying to find one for under $150, $80-$120 is more ideal.

I have came across Harrison Labs 20hz FMOD adapters.

This is currently the only thing i have found. Is it ok or worth using?

IT's just for movies and the occasional song from what i understand.

[Robert_J 0]

The F-MODS are based on a specific input impedance of the amp. If his amp has a different input impedance, then the cut-off frequency can be off by as much as 50%.

Look at the Reckhorn EQ's from Creative Sound Solutions (Canada) or the Elemental Designs EQ.2.

-Robert

[Rybaudio 0]

I wouldn't even bother with a subsonic. If the box is tuned to 18 Hz, excursion probably isn't a problem until you're below 15 Hz and there's hardly anything down there. If the sub can't hard bottom I would just let the suspension do the work those few times that you might have a peak at 10 Hz... hell, the amp itself my roll off down there and do the job for you.

Secondly, I wouldn't use the Behringer "low-cut" filter under any circumstances. In the 2 amps that I tested, turning the low cut filter on not only cut out the very lows, but it put a 12 dB peak in around the cutoff!

[cobracommander 0]

FMODS suck

[slim2fattycake 85]

i went with the eQ.2. I am very happy with it besides the auto turn-on feature. This should have been taken out of the whole unit.

[95Honda 486]

There is no reason whatsover to put a high pass filter on anything tuned below 20Hz. It will be fine. I have been building H/T subwoofers for 15 years and have never, ever needed a high pass filter on something tuned that low...

[KU40 173]

I agree with Rybaudio and 95honda. There really isn't a reason to need one. When you tune that low it's almost a mix between ported and sealed, and the sub probably won't begin to unload until 10-12 hz. Which I'm not sure if I've ever heard anything that low in a movie or music.

[slim2fattycake 85]

there are a lot of movies now that have things that will go down to 5hz. i just want to be on the safe side. an example would be the parts where the alien pods come out of the ground in war of the worlds.

[KU40 173]

you could build a passive subsonic by wiring a few big inductors together. I have never thought about doing that so I'm not sure what it would take.

[slim2fattycake 85]

the thing is that i already have the eQ.2 processor. it does the job.

[KU40 173]

well I really was also addressing that to Shizzzon, who made the thread.

[slim2fattycake 85]

he made the thread for me. sorry, i didn't say anything.

[KU40 173]

oooohhhhhhh.

well, I guess discussion is over then.