KAB RF1 Rumble Filter
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KAB RF1 Rumble Filter

  (7 Reviews)
£149.04 Exc. VAT |  


Kab RF-1 Rumble Filter

Getting into LP's and startled at the big speaker cone movements that you're seeing? Thinking a better turntable will help? It may not! This very low frequency energy is called rumble. Much of it is actually cut into the record groove when the master disc was made. Other sources are mis matched tonearms, poorly damped tonearms and acoustic feedback. Often, the only way to suppress rumble is with a really good rumble filter. 
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.


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.



Two important things to know:

1. When records are made, frequencies below about 150Hz are combined to mono. This is done to avoid large out of phase groove excursions. 

2. 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 takes advantage of this by electronically combining the left and right channels together below 140Hz. In so doing the filter effectively cancels vertically modulated noise. Vertical rumble comes generally from bearing noise of the disc cutting system. But since the music below 140hz is already mono on the disc, the musical information is unaffected. Below 20Hz, all signals are quickly attenuated at 18dB/Octave.

The RF-1 is a must for vinyl enthusiasts.

The KAB RF-1 is easy to install. Place it in between the phono preamp and control amp or in a process loop. It requires no attendance. It is happy to remain powered up at all times.

Average Rating (7 Reviews):  
Write a Review and share your opinions!

11 June 2022  | 

I started investigating subsonic filters when I first noticed some very "scary" woofer excursions (I have some transmission line speakers with 10 inch woofers that go down to -2 dB at 21 Hz) caused by actual signals recorded within the grooves of some of my records (the start of track 1 on side C of the 2016 repressing of Urban Hymns is a real woofer-killer!). I put in a passive second-order high-pass CR filter (-3 dB at 20 Hz and a slope of 12 dB per octave) between my pre- and power-amps and this suppressed around 90% of the visible excursions. However, using the active KAB RF1 filter has now completely removed all the visible distortions and led to a remarkable improvement in sound - the lower end is now very tight and tuneful, and I am finally hearing what my speakers are really capable of. There is no discernible reduction in bass response and the rest of the spectrum is completely transparent to my ears. So, a highly recommended product.

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great product and service
20 March 2020  | 

The product works as described. Fast shipping and great service from Analogue seduction.

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08 March 2020  | 

It's easy: it does exactly what they claim: reducing cone pump and no loss in bass. To be specific:
I live in an old house with very springy floors and the turntables can't be mounted on a wall, so they rest on a midcentury couch table. To make matters worse, the table is situated right between the speakers. They offer generous amounts of bass, so without a rumble filter, it is no fun listening loud or even walking around in the room. Of course I could have bought a phono amp with integrated rumble filter, but I wished to keep my existing Brystons. My vintage Marantz PH22 phono amp is also fine and has to be used on a regular basis. The KAB makes it possible.

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Halleljuah, rumbles gone
23 March 2019  | 

l had a big problem With wandering woofers on some records and the problem actually increased after upgrading my pu (hana sl) and riaa (aSR mini basis mk2). my thorens 320 is placed on a sollid wall shelf in safe distans to the speakers so its hard to say why l had this problem.
The sweet thing is that doesn't matter anymore, after installing the KAB RF1 in my system the problem is 100% solved. if you haveing any wandering woofers issue don't hesitate, just by this one!

highly recommended indeed.

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Hallelujah... the rumbles gone
22 March 2019  | 

Had a big issue With wandering woofers before l received my KAB RF1 and now the problem is 100 percent solved. if you have simular problems, don't hesitate, just by it! for me it was Worth every penny. fast shipment and good communication by AS.

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1 of 1 people found this review helpful.

It works!
31 January 2019  | 

Oh happy days! Finally I can listen to my new 180 grams vinyls at maximum volume! And it sounds great! The bass sounds more distinct and clean. And, of course, no more rumble and flutter. Now the cones of my woofers only moves when they are supposed to... I have spent a whole lot of money on my audio equipment and I must say the KAB RF1 filter is the most valuable addon in terms of money spent versus audio enhancement achieved!

Thanks a lot!

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It really works!
19 May 2015  | 

I had big rumble problems, especially when playing Classic Music.

The woofers of both my B&W 804S and of my REL Strata5 could "swing" without control during some passages. This happened quite often and bothered me a lot.

My "vinyl chain": VPI Scout-->Ortofon Quintet Black, --> Park SUT (Cinemag 1254) --> GS Reflex M -->Hegel preamp-->Hegel Power amp-->B&W804S+Rel Strata5

By introducing the RF1 into the chain I have definitly solved all my rumble problems: I have to admit that I was a little skeptical regarding this product, but it does what it promises!

All rumble is gone. Period.The bass is quicker and faster and, to my ears, even the midranges and the highs are better, focus, soundstage all these parameters get better by a wide upgrading the amp or the cart.

I highly recommend this product and give it five stars.

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8 of 8 people found this review helpful.

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