Harrison LabsFMOD Inline Crossover Pair 20 Hz High Pass RCA

very good one

These inline rca style filters are an easy way to cut out infrasonic noise (20hz high pass)or with more than one connected in each input terminal (mabey 20hz high pass and 50hz low pass for ex) give a sepfic range of frequency respones to your amp. These filters come in a varitey of frequencys. In my expeience these filters did not cause distortion but did give a flat sound to my subwoofers but i would still recomend them for many applications for ex. if you are getting infrasonic noise, want a narrow band of frequency response or if your amp dose not have high pass or low pass filter built in.

I have the classic problem with rumble when starting my records. No record is perfect and wanted to prevent speaker damage for songs at the outer edge. While these do tame down subsonics they do take away from the clarity of my system. They can be a cheap bandaid but long terms something else is needed.

Harrison Lab FMOD-900073 (20 Hz high-pass filter)Gold-Plated20 Hz High-Pass Filter-3 dB point @ 20 Hz@25 Hz : 25% frequency increase at 10K ohms@17 HZ : 15% frequency decrease at 47K ohmsThis high-pass filter is supposed to cut frequencies below 20 Hz, as we know the human ear can hear from 20 Hz to 20,000 Hz, so frequencies below the 20 Hz point can't be heard, and usually most speakers will not be able to produce that low frequency --most speakers don't produce audible sound below 25 Hz--. With that said, the frequencies below 20 Hz are still reproduced and amplified by your amplifier, so first you may damage your speaker feeding it power that won't be heard and make only cause your voice coils to get extra hot. Second your waster amplifier power by producing sound that won't be heard.The FMOD solves this, you insert it before your amplifier so that the AMP will never get sound below 20 Hz.This high-pass filter has other names like (crossover, rumble-filter and sub-sonic filter). Nowadays you find most amplifiers with sub-sonic filters built-in, so if you have one of those you don't need this FMOD high-pass filter.Anyhow, my personal take on this filter is negative. As soon as it was inserted it caused audible noise -to the sensitive ear with high quality equipment-- and caused the bass to sound bad, soft and distorted. I removed it the next day after confirming this many times.With low grade equipment you may want to give it a try as you may not feel the difference, but if you're an audiophile and can sense any change in sound then don't go for this and get yourself a decent amplifier with built-in Sub-Sonic filter.

Absolutely, 100% gimmick! I’ve been around this Audiophile game long enough to know when I’ve been duped. I’ve been duped by these essentially chokes. They choke out low medium and high frequencies. Do not be fooled by these purveyors of fiction.

Works as advertised and will keep your ported sub from bottoming out. I think they are kind of pricey, but they are the only game in town for subsonic filter if your amp doesn't have one.

These definitely worked out great for me. I've got 4 vented 18" subs with no way to have prevented them from bottoming out till now. They did provide just enough cut for me at their tuning point and I can crank my subs out just a bit more and get more out of em. I'd highly recommend these for anyone just wanting a simple plug and play option. When you factor in the price as well they can't be beat. :)

Killed all the rumble from my turntable which came from the speakers. Perfect!