If a spring suspension is well-executed, it can be OK, but it's hard to do any suspension right. Here's one simple test: Put your stylus down on an old record, as far as possible from the turntable motor, and slowly increase the volume. (Don't turn the platter on--rumble from the bearing will then also come into play, and at this point, would just confuse matters). Also, don't use a Grado or other hum-sensitive cartridge. At some point, you might notice bass hum begin to increase rapidly. At this point, turn down the volume right away, because oscillations will begin and could send your system into a low frequency frenzy. I've had this problem with both spring-suspended and mass damped turntables, but have been able to alleviate it by using an isolation base (I use a heavy-duty bubble packaging sheet sandwiched in plywood; you can also float it on a small (e.g., snowblower)inner tube in a plywood sandwich contained in a pretty oak frame). I tried spikes, but they made the problem worse with the spring-suspended table. Sorbothane feet (purchased cheap at a military surplus store) seemed to work best. I never did beat the problem with the mass-damped table in my living room upstairs, although it worked very well in my basement (mass-damped floor, of course). Try different locations, too. If your turntable is located in a room anti-node, feedback can be a nightmare. Next, buy a cheap stethoscope ($10 at discount drug stores) and turn the platter on, placing the 'scope as near the platter as possible. If you hear anything through the 'scope, you can be sure it's also getting to the cartridge. A turntable should be dead quiet. Worst case would be a bad bearing which raises the rumble level and muddies up your sound into the midrange, but any scraping or rubbing noises (e.g., a misaligned rotor in the motor) will mess up the music. In one case, I had two identical turntables with scraping rotors, so I just switched the rotors between the two motors, and both of them aligned better and quieted down. Check your lubrication, too. If you haven't keep the bearing well really clean and freshly lubricated, dried or dirty bearing grease can also be a cause of noise, not to mention accelerated wear on the bearing and well. You can use brake cleaner to clean out a bearing well if you find dirty or dried lube. Use Q-tips until there is absolutely no residue showing, then put in the recommended lube. If no lube is recommended, I've had good luck with turbine oil (for laundry equipment)--it's very durable and is never bothered by heat, and doesn't dry up. Be sure to check what the manufacturer recommends, though. I've gone way beyond your question, but everything I've said applies to turntable problems that get blamed on the suspensions. No suspension will be immune to all problems--that would violate the laws of physics--so you need to think your way around any problems that arise.
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