Mating subwoofer to fx500is for full range surrounds

Larry Chanin

Hi All,

I’m thinking about using small Carver subwoofers in combination with my fx500is to serve as full range surround speakers. I would conceal both the subwoofers and surrounds in columns to either side of the primary listening area.

The subwoofers have speaker level inputs that are designed to sample the full range main speaker inputs and pass the signal back to the mains. The problem is if I use this arrangement with my fx500is, deep bass in the full range signal could stress them beyond their design limits.

I believe I need something like separate mono high pass passive crossovers for the right and left channels between each subwoofer and surround to filter out the low bass and send a speaker level signal to the surrounds. I would like to purchase something that has inputs and outputs at speaker level voltages.

The -3dB point for the fx500i is 55 Hz. The sub's frequency response is 18 Hz - 100 Hz.

Could anyone direct me to something I can buy off the shelf to do this filtering?

Thanks in advance.

Larry

Airplay355

subwoofers usually have crossovers on them, you could use the crossover thats built into the sub amp already....unless the subs are passive then idk

Larry Chanin

Hi Airplay,

Thanks for the response.

Yes, my subs have a fixed 70 Hz crossover. However, to use them would require that I fish line level interlinks from the preamp to the subs, and then an other set of interlinks back to the amps. My equipment rack is located in the rear of the room and the columns are in the middle of the room. Running these interlinks now that the drywall has been closed in would be a difficult, whereas I already have the speaker level connections prewired to the column locations.

Refer to the link below to view a concept drawing of my home theater. The columns are to the sides of the first row of seating.

Larry

amulford

Larry,

Do you think something like this would help?

Cross overs

They're actually for car installs, but are for in line filtering after the amps.

They have other stuff, browse.

Larry Chanin

Hi amulford,

Thanks for the response.

Parts Express was the first place I looked, but to tell you the truth, I don't have enough background to select the proper part. Before posting on Club Polk, I posted a similar question on their Tech Talk discussion board. I got one response. The poster said that I was looking for a capacitor and that I should buy a bunch of them and try experimenting with various series - parallel connections until it sounded right. While I appreciated his response, it sounded too hit or miss.

Larry

Larry Chanin

Hi,

I took an other stab at the Part Express crossovers. They seem to have the same generic description for all of their crossovers, but I was wondering whether this one might work?

80 Hz HIGH PASS 8 OHM CROSSOVER

I assume I would just run my surround speaker connections from my amplifier directly to the speaker level inputs of the sub, and then connect the input of the crossover to the same sub binding posts. The output of the crossover would then connect to the inputs of the fx500is? I would then set my side surrounds on my preamp to large.

Ken and others any words of wisdom? Any chance of damaging the sub and/or surrounds with this arrangement?

By the way, for what ever its worth, in my original posting I quoted the -3dB point on the fx500is incorrectly. I said they went down to 55 Hz when they go down to 50Hz.

Larry

amulford

I really couldn't give you a definitive answer, but I would think the speakers crossovers would filter that out, no?

Larry Chanin

Hi amulford,

I didn't think the fx500is crossovers would filter out the low bass if they were fed a full range signal, but what do I know.:D

I spoke to a technical support rep at Parts Express and he said the crossover should work for my application. We didn't specifically discuss whether the surround speaker would filter out the low bass.

I think I'll start an other new thread to specifically poise the question to the club members.

Thanks again for your interest.

Larry