KAB RF-1 – Phono Subsonic Filter

Efficiency Restored
And with rumble eliminated, the soundstage becomes more "still" and the bass actually tightens up because the woofers are no longer modulating and the power amp is no longer wasting current resources on sub audible noise..

Subwoofer's Best Friend
With todays crossover settings on video and music entertainment systems, response down to 10 Hz is common. The KAB Great Sound Escort RF-1 is a very fine transparent rumble filter that not only suppresses very low frequency (subsonic) energy, but also uses a unique active cancellation circuit that effectively suppresses vertical rumble too. Your subwoofers will thank you! Suppresses acoustic feedback too. A good rumble filter will actually improve the bass response by removing those deep subsonic dynamic swings from the system altogether. The power amp breathes easier and the woofers can concentrate on the music at hand. 

Versatile Applications
The RF-1 is a must for vinyl enthusiasts, live DJ's and when burning CD's for the car. You probably can't hear it, but your car woofers are going mad with all that subsonic rumble!.

Two Versions
There are two versions of the RF-1 available. The standard model which comes after a separate phono preamp; and the moving magnet (MM) model, which goes between the turntable with a high output cartridge and the MM phono input.

Solution to Vinyl Difficulties
When records are made, frequencies below about 150Hz are combined to mono. This is done to avoid large out of phase groove excursions. When the stereo stylus moves vertically, the two signals produced are equal, and 180 degrees out of phase. Therefore, below 140Hz, the music is in phase in the lateral stylus motion, and only out of phase noise is found in the vertical stylus motion. The KAB RF-1 provides a solution to this problem by electronically combining the left and right channels together below 140Hz, effectively cancelling vertically modulated noise. Vertical rumble comes generally from bearing noise of the disc cutting system, however, since the music below 140 Hz is already mono on the disc, the musical information is unaffected. Below 20Hz, all signals are quickly attenuated at 18dB/Octave. 

Details & Specifications

-3dB filtration @ 20 Hz with 18dB / octave slope 
Unique Active Vertical Cancellation below 140 Hz
Dimensions: 4.5" x 3" x 1.25"
Max Output: 5 Vrms
THD: <0.05%
Noise Floor: -95dB
Shipping Weight: 1 lbs.
Power Consumption: 24V DC @ 0.75A
Power Supply: 100-240VAC @ 50/60Hz (Included)