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In Reply to: Isolation posted by lipmanl on May 4, 2007 at 10:44:32:
When I was fiddling with the support system for my TT, I made CD-Rs of each set-up to evaluate the degree to which they provided acoustic isolation. A CD-R made with the speakers off provided an example of the most I could hope for. I never got there. Even if you eliminate all acoustic feedback coming up though the shelf or plinth to the record surface, you cannot eliminate feedback so long as your record and cartridge can "hear" the music. And since this component of the feedback is in constant proportion to the loudness of the speakers ( except for some possible non-linear effects at very low volumes), it is always there at the same percentage, regardless of volume. The very first hi-fi system I heard at a friend's house nearly 50 years ago had the turntable in a small, separate room that was acoustically pretty isolated from the main room. The TT was near the wall, so that the ICs could be kept short by feeding them through a small hole in the wall to the nearby preamp in the main room. This guy was way ahead of his time.Also, as John points out, this feedback is a form of distortion, and it has been claimed many times that this "feedback distortion" is part of the appeal or "magic" of vinyl sound, along with other distortions that generally go with vinyl playback. While there are many doubters, my experience along with John's is that one can make CD-R copies of vinyl records that are virtually indistinguishable from the original. However, in addition to being careful to make a good copy, two other things are important for the two to sound the same: the CD-R should be played back on an excellent player, and the speakers should be left on when making the CD-R. As John says, it can be easy to distinguish between the CD-R and the vinyl if the CD-R was made with the speakers off. However, which you prefer- speakers on or speakers off- is another matter. I've found a number of people who have a definite liking for distortion when it is done in a nice way. At the volume levels one friend likes to drive his SET amplifiers, the distortion can reach several percent, quite audible to me. He loves the sound. Each to his or her own, or whatever floats your boat or whatever phrase you prefer. All the above said, I spend most of my time listening to vinyl, irrespective of the higher inherent distortions.
Follow Ups:
Actually the graphs you produced indicate your TT/setup has exceptional isolation properties.The comparison I just now performed of Pete Fountain's "The Blues" on my TT vs. your recording (with OC9 cartridge) of same however was not as flattering. Mind you the recording is not bad but it is clearly inferior; and again I have to wonder if you check (by ear) LPs before dropping the needle for a silent recording as I'm near certain that your LP would have benefitted from a spin on your RCM... my LP is not mint either by the way, but yours' clearly needs a little help at least in some sections.
Now, if my TT was head and shoulders above yours there'd not be much cause for concern but I have to imagine that your much newer and expensive SOTA should really outdistance my going on 20-year-old Roksan Xerxes; as far as phono stages go again I'd expect yours to outdistance mine, at least one would hope so!
I'd suggest you start thinging seriously about getting a better cartridge, one of a calibre to match your table.
I myself wouldn't rule of the recording itself being at least a partial limiting factor but you have, of course, stated many times that your recording are indistinguishable from the LPs played live. BTW, if that's true then it indicates you have no issues with feedback while playing LPs live, i.e. perhaps the feedback distortion is present down 40-60db yet you apparently can't hear it!
You obviously have a better copy of The Blues that I. None of my Pete Fountain records have exceptional fidelity and most of them have a lot of noise and clicks. Why don't you send me some CD-Rs of your LPs?If you have any Reference Recordings or Sheffield Lab direct-to-discs, they would be nice for a comparison. I own many of them.
I don't do recordings; it's something I'd eventually like to explore for creating discs for the car but certainly won't be in the near future.I'll check for Reference Recordings and/or Sheffield Lab stuff (I know I have a Harry James/Sheffield Lab) and provide a list. If you're interested in my doing a compariosn then you could send out a CDR.
I'd certainly be willing to send you an exceptionally fine direct to disc LP (*) that you could record (and return), then at least we'd both have the opportunity to compare LP/CDR albeit on our own systems. Email me if interested.
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(*)
UltraFi label, Special Limited Edition ULDD12 (direct to disc)featuring:
Stravinsky - L'Histoire du Soldat
Paul Hoffert - Concerto for Contemporary ViolinConducted by Paul Hoffert (founding member of the group 'Lighthouse').
BTW, IMHO the Hoffert piece is not out of place alongside the Stravinsky.
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