I used to have 2 old school punch 500a2 on 4 12's man those were the days of my life! Buy I'm wondering since I got 2 S15L7 in a ported box and I put a 800a2 or a 500a2 on each sub, which has no subsonic filter is it go sound like sh t? When going ported is subsonic filter on amps required?
The subsonic filter is used to filter out frequencies below the tuning of your box, which will damage the sub if not filtered. You should be able to find a crossover with a subsonic filter, and use that if the amp doesn't have one.
what he said. in short, the subsonic filter prevents a sub from "unloading" when it drops below the tuned frequency of a ported or bandpass box. the filter protects the speaker from damage. you can get an Fmod external RCA level SSF if the amp lacks this feature.
Wont blow your woofers without one but your amp will work harder on a bunch of lower stuff you cant hear. Amps can run hotter as well. better to use one if you can. I ran systems loud for years and never blew any woofers. I still dont have any subsonic filter with my 5 year old amps I'm using now.
you sure as sh*t will blow the subs running in a ported box with no subsonic filter. once the subs unload, it's just like playing them with no box at all. there's literally no more suspension, or resistance behind the sub, to act as a spring, so the sub over-excurts, and rips the motor structure apart.
Don't believe me? build a 6th order box some time, and make sure you miscalculate a chamber volume a little, then send the sub an ample amount of power and learn what unloading means first hand.