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Old 7th June 2016, 11:45 PM
Infinitely Baffled Infinitely Baffled is offline
Join Date: Nov 2007
Location: Welshpool, mid-Wales
Posts: 38
Default Re: Nice phono stage with subsonic filter?

Hello, Bob. No, it's not an idler drive, but a Notts Analogue model with an ultra low torque motor, belt drive and high mass platter. It's just that, having recently switched to using some new loudspeakers that have no cloth grilles, I can see for the first time what my mid/bass speaker diaphragms are getting up to, and I don't like it at all!

What I can now see is that with some of my records I am getting slow, exaggerated wobbling motions of the cone. There is no accompanying sound, just lots of unwanted activity. I have done a bit of reading around on the subject and it seems that this unwanted subsonic information can be from a variety of sources: badly pressed records, tonearm/cartridge resonance, acoustic feedback from the speakers or heavy footfalls. You name it!

I have done some experimentation to try and eliminate some of these possibilities and haven't been able to identify the precise cause. But I keep coming back to the fact that I get it on some records and then not with the next - even though there has been no change in the set-up (same arm/cartridge combo, same turntable and loudspeaker positioning etc). I'm coming to the conclusion that it's simply down to the records themselves - some of them just carry more subsonic information than others and that's that. Only thing to do, it would seem, is to fit a subsonic filter into the setup somewhere. I prefer, if possible "single box" solutions, so would have liked to find a combined pre-amp with phono stage and subsonic filter built in. But that is a rare beast indeed so I am considering the possibility of a phono-stage with an integral filter. But they are not exactly plentiful either. Seems like it is a problem that not too many folks are worried about, and I wonder if I am getting it out of proportion. But sapping the power of the amp and overworking the loudspeaker cones and surrounds seems to me like something to be avoided if possible. Cheers. Gary.
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