Help with Subwoofer amp Low-Pass Filtering

[EWorkshop1708]

I'm designing a BTL subwoofer amp as part of a system.

To make it simple, I want to have the frequency cutoff fixed, around approx 100-150hz or so. It doesn't have to be perfect, just as long as voices aren't coming from the subwoofer too much.

I did some research and calculated some values, but I haven't built the circuit yet. It's an opamp preamp/filter, but also the subwoofer amplifier itself is also used as an additional filtering stage, and as a plus, should add stability.

Here's the circuit.

Will this work, and if not, what would need to be changed?

[EWorkshop1708]

I just found an interesting page on low-pass filters.

http://www.electronics-tutorials.ws/.../filter_5.html

It looks like my 10K ohm/100nf & 10nf/100K combinations were not too far off.

I see some changes I need to make to the circuit now, I see some errors, but I still wanted some input on it. I'll be changing the way my op-amps are setup slightly. I may have too much gain.

[AndrewT]

look up the esp site.
He details all that you need.
He even has a calculator to help with selecting component values.

[EWorkshop1708]

Here's the updated one. I'm going to construct it soon, but if you folks have any input on this circuit first, post your comments.

[EWorkshop1708]

Originally posted by AndrewT
look up the esp site.
He details all that you need.
He even has a calculator to help with selecting component values.

Thanks, I'll check it out.