Nothing really wrong with the Obsidian base. Many love it. BTW it is very heavy plastic composite not solid rock or glass. It is extremely dense, heavy, and well damped and has no obvious resonance--it feels more like rock than anything else. Many other companies experimented with weighted plastic composites, including Sony, Pioneer, and Kenwood. I have never seen anything from those companies better than the Obsidian base. Of course, if you worship your turntable, there is no limit to what you could spend on an Ultimate Plinth, and at some point with vast weight and technology you might make something better. But for the cost, you couldn't do significantly better than the Obsidian. I mean at the original price and current resale prices, which weren't outrageous when I got mine last year. The artisan designers of new super bases charge way more, of course, and I have not heard them. A simple birch plinth is not going to be better than the Obsidian unless the birch plinth is huger than huge.
The SL10 (SP10,Obsidian,EPA arm,dustcover) package got a bad name after a review in Hifi News claiming they had gotten feedback. Well, yes, they put speaker right next to turntable on the same table and cranked it to the max. The LP12 did better on this test. But it was unrealistic test, and with better feet or a suspension base for the SL10 it would likely have done better than the LP12 since virtually every part of the SL10 is well damped, except the little feet aren't very isolating for a big heavy table. For some reason, the reviewers thought the base was actual Obsidian, and they falsely blamed that, creating a meme that lasted through the 80's. However everyone now knows that if the SL10 has any serious problem, it's in the feet--which are fine if table is perched on an isolating stand.
The SL10 (SP10,Obsidian,EPA arm,dustcover) package got a bad name after a review in Hifi News claiming they had gotten feedback. Well, yes, they put speaker right next to turntable on the same table and cranked it to the max. The LP12 did better on this test. But it was unrealistic test, and with better feet or a suspension base for the SL10 it would likely have done better than the LP12 since virtually every part of the SL10 is well damped, except the little feet aren't very isolating for a big heavy table. For some reason, the reviewers thought the base was actual Obsidian, and they falsely blamed that, creating a meme that lasted through the 80's. However everyone now knows that if the SL10 has any serious problem, it's in the feet--which are fine if table is perched on an isolating stand.