Surprising development concerning dust covers on your turntable... [message #12180] |
Thu, 26 May 2005 07:15 |
Mr Vinyl
Messages: 407 Registered: May 2009
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Illuminati (1st Degree) |
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Hi, I had posted a while ago that I had a custom dust cover made for my turntable. Just to recap: It is made out of 1/2" thick Plexiglas and fits over my entire turntable which sits on top of a BillyBags Pro turntable stand. This cover also has a hinged top on it so I could open it up like a box and change records etc without having to lift it over and off the turntable. The reason I had this dust cover made was two fold. One to keep dust off but more importantly I wanted a barrier to keep air borne vibration from the speakers effecting the sound of the turntable. Made good sense to me. In any case I had a sneaking suspicion that the dust cover was actually making noise worse. My brother had a good idea. He suggested that I take my Radio Shack sound meter and place it on the platter of the turntable. Play some music and see how many decibles it was recording. Then put the dust cover over the turntable and see if the decibles went down. Which I fully expected they would. I used a Stereophile test cd to play test tones in about 10 different frequencies for my experiement. Much to my surprise the sound level more than doubled and at some frequencies tripled with the dust cover over the turntable. I could hardly believe it. The dust cover was actually amplifying the sound not blocking it. Keeping in mind that this dust cover doesn't touch the turntable in any way. My turntable also sits on a 1.5" thick maple butcher block which the dust cover also doesn't touch. The only thing I can think of to help solve this problem is to add some kind sound absorption material inside the case to soak up reflected sound but I haven't tried that yet. I will probably just leave things as they are since I can't really hear a difference with the dustcover on. I can always take it off for very critical listening if I want. But here is my point. If you have a dust cover on your turntable you might want to try this experiment. I would imagine a dust cover that is attached to the turntable would effect the sound greatly.
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Re: Surprising development concerning dust covers on your turntable... [message #12188 is a reply to message #12184] |
Thu, 26 May 2005 19:22 |
Russellc
Messages: 397 Registered: May 2009
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Illuminati (1st Degree) |
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Manual block is right on. It's not the sound that is dectectable inside the cover thats at isssue, its resonance and vibration. Sound in the room can also excite vibrations by stiking the cover which could then be picked by the cartridge/stylus. I would think your extra heavy cover would cut down on this, but it may depend on the resonant frequency of your cover. Everything, even large massive things like the planet, have a resonant frequency. You would still have the echo chamber effect spoken of by manualblock. I find mine sounds best (to me) with the cover up. But I would like a big "cake cover" like that, even with may regular cover on to eliminate dust getting on it. I usually keep a clean T-shirt thrown over it! Regards, russellc
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