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Rumble (again...) |
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Posted: 12 Nov 2017 at 5:12pm |
Year upon year customers question me about rumble filters on my phono stages. Actually there is one, and that can be seen from a frequency plot. However, for correct RIAA reproduction I will not compromise the bass response - I will not apply additional bass cut which attenuates, and also damagingly places the bass out of phase with the rest of the music. However, there is cut below 20Hz but it is not a steep cut - it is a natural roll-off. A rumble filter has a much sharper cut, and a sharp cut-off filter has ripple which means the filter peaks just where it does its worse to the bass. Most of the time there is no turntable rumble - a noise caused by the platter bearings, or even motor noise (in which case the user should treat the cause and not the symptom) - but the natural occurrence of sub-sonic fluctuations due to warps, eccentricity, and arm/cartridge incompatibility. These show themselves as cone flap, which is simply high compliance cones responding to the signal as amplified due to the above. I'm not a magician. I can't remove this and still keep the bass the customer wants. Show me somebody who can! And I'll show you a manipulator... (I resisted using the word liar) A filter can be arranged to mix the bass below 300Hz in a cross-feed circuit which will sometimes fix the "problem" (I personally don't see it as a problem). Purveyors of this solution say that bass below 300Hz is non-directional. They must have different hearing to me, or perhaps I'm from a different planet?? A good old low compliance bass driver wouldn't cone flap, but hey! That's not hi-fi... The problem is in the marketing. Vinyl is being marketed all wrong. True, it gets more customers, but it gets customers who simply don't understand it. I'd rather have fewer customers who understand it than more customers who have to ask questions which simply weren't an issue back in the day. |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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morris_minor
Moderator Group Joined: 27 Mar 2012 Location: Surrey Status: Offline Points: 6015 |
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Back in the mists of time I had an integrated amp with a rumble filter. I could never hear any difference with it switched in or out. Which either meant my speakers or headphones couldn't reproduce low frequencies or the switch had no circuit behind it. Or of course that rumble just wasn't a problem.
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Bob
Majestic DAC/pre-amp Accession MC/Enigma, Accession MM, Reflex M, Elevator EXP, Era Gold V Solo ULDE, Novo, Lautus USB and digital, Libran balanced, CuSat50 2 x Proprius + Spatia/Spatia Links |
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