prem@eagle.UUCP (Swami Devanbu) (09/23/85)
*** REPLACE THIS LINE WITH YOUR MESSAGE *** I've been looking at Turntables in the 200-350$ range (excl. cartridge). Here's some assorted ramblings, with questions. In a TT, you look at the suspension, the tone-arm, and the pick-up. The function of the suspension isto de-couple structure-borne mechanical vibrations. There seem to be two ways of doing this. One is to use soft feet on the turntable, and make the turntable itself a massive monolithic structure, using materials with good vibration damping properties, such as wood, composites, ceramics, etc. The advantage to this approach seems that it is cheaper; the natural frequency is apparently a little higher, about 10-20 Hz; This could supposedly cause "muddying" of base, whatever that is. (probably intermodulation distortion). Also, the cover could act as an acoustic pickup, and pass the signal on nicely to the cartridge. This won't happen in the "float" approach, below. The other approach isto float the platter, arm altogether on high-compliance springs, with the resonant frequency well below audible range (eg, 4 Hz). The rationale here is that the resonance characterestics "clamp down" mechanical pickup starting way below the audible range. The disadvantage here would be the difficulty of damping low-frequency vibrations. Additionally, 4 Hz is right about the range of footfalls and dancing feet on wood floors; so this might jar the tone arm, cause skipping etc. Its difficult to damp slow oscillations; Now if you had a HEAVY subchasis, and had a piston attached to it, in a jar of say, molasses, it would be great. I wonder if anybody (SOTA, Oracle, Linn Sondek) goes to THIS extent. Comments ? I looked at 5 TT's that used a floating subchasis. The NAD 5120, at $180, the Systemdek IIX, at ~$320, the Beogram 1800, ~$200, The AR's, the older one at $330, and the new at $210. All tonearm included, except the IIX. The most striking design was the NAD. (also the cheapest). The specs where comparable, as was the subjective sound quality, on cartridges in $100 range, and response to an adhoc tap-here-and-there-on-a-blank-groove isolation test. The NAD charmed me the most - a strange beauty hath it, even as Caliban. NAD has, as always, moved in mysterous ways in this design, their wonders (blunders?) to perfrom. The tonearm is FLAT (!), cut out of a multilayer PC board. The signal wires are etched therein (!), and whole arm PLUGS into a mount on the subchasis, proving mechanical and electrial carriage. I read a rather technical (if immodest) piece written by the NAD designers in "AUDIO": They claim to have tuned the flat arm's cantilever resonance to "conduct" cartridge resonance into the (static balance) weight. They also claim that PCboard damps oscillation on a vertical plane very well, and is totally inflexible on a horizontal. Not knowing much about the mechanics of arms, I humbly believe. Overall, this TT seems best value for money. As ugly as sin her(him?)self, but it tracks well, sounds just fine to my Leaden ears, and resists knocks and taps as well as TT's costing twice as much. Questions: a) Has anyone heard/seen the NAD ? What do you think ? b) Is Subchasis isolation really better ? Then why doesn't everybody use that ? c) What exactly do I get for the extra $200 in a systemdek or an AR ? d) Are there any other tables in this price I should look at ? e) Is there anyway of getting the best of both the "softfeet" and floating subchasis designs ? (In my price range, of course). Perhaps graftable feet ? f) Any recommendations for cartridges in the $100 range ? Thank you. Prem Devanbu, (....eagle!prem)
mojo@kepler.UUCP (Morris Jones) (09/27/85)
In line with this discussion, I'd like to know what the performance
differences are between linear tracking turntables and conventional
(radial?) tracking.
--
Mojo
... Morris Jones, MicroPro Product Development
{dual,hplabs,glacier,lll-crg}!well!micropro!kepler!mojo