A few months back I was trolling around Ebay looking for bargains in phono stages and cartridges and stumbled upon a turntable isolation box made by a small company in Texas called Aural Thrills Audio. I’d been having good results running my Rega on the top shelf of a Vantage Point four shelf rack with the help of a slab of granite and some Black Diamond Racing cones and “those things” (carbon fibre squares used with the cones). Keeping the thing perfectly level, however, was an exercise in frustration, requiring the entire rack to be adjusted. With no room for my Target wall shelf in my California apartment, I was looking for a solution that would allow me to level the table independent of the rack, quickly and easily.
The Aural Thrills box promised this and more and at US $149.99, plus US $20.00 in shipping, it was certainly cheap enough to take a chance on. Aural Thrills had very good feedback ratings for their Ebay store, and there were some promising testimonials quoted on the sales page, so I took the plunge and ordered one. A couple of weeks later I unpacked the austere looking black box and started setting it up.
And finished, since there wasn’t much setup to speak of, really. The isolation box is very simple, consisting of a 19″ x 20″ x 4″ black laminated MDF frame containing three small (around 6″ in diameter) rubber innertubes; the kind you might find in a wheelbarrow tire. A 17 3/8″ by 17 3/8″ black MDF plinth rests directly on top of the tubes and should be placed dead in the centre so that it doesn’t touch any part of the box frame. What makes the box truly easy to setup and adjust are the spring loaded valves on the front connected to each innertube, allowing individual control of air pressure without having to open up the box or remove anything from the plinth. The left and right valves allow left to right control of the balance while the middle one controls front to back. Being an avid cyclist I had a bicycle pump nearby to inflate the tubes (If you’re not a bike owner, you should be able to pick up a pump for $10 or less at a sports store). Fine tuning of the level is best accomplished by letting very small amounts of air out of one tube at a time until your turntable is exactly level (a good circular spirit level is bar far the best way to judge). The male end an AIG Cleanjack RCA plug cleaner proved to be the best way to depress the valves to release air, but any small pointed object like a pen will do the trick.
Having grown accustomed to listening to the Rega sitting on top of the Black Diamond cones/squares and they, in turn, on a 1/2″ thick slab of granite, and wanting to hear the additive effect of the isolation box in, ahem, isolation, I placed the slab of granite on top of the Aural Thrills plinth and the table and cones on top of that. Although the table was now considerably higher than before, a good 7″ off the surface of the top shelf, the weight of the granite had the added bonus of pre-loading the innertubes, compressing and damping them into a more useful operating range. A car’s suspension works in a similar way, the weight of the car itself compressing the suspension enough so that it doesn’t operate at the very top of its range of travel, avoiding a stiff, jarring ride. Since the tubes are made of relatively firm, thick rubber, relative to a bicycle tube for instance (the box is designed to hold up to 200 lbs), a light table like the Rega will compress the tubes very little on its own and the performance of the isolation box will benefit significantly from some extra mass. A piece of stone from a monument or countertop maker can work wonders under certain gear and many tweakers have had good success with heavy maple cutting boards as well. Either of these will likely make good additions to the Aural Thrills box if you’re suspending less than 10 or 15 lbs on it.
Even before sitting down to listen, some finger tapping on my rack, and even on the outside of the isolation box while playing the lead in groove of a record, demonstrated how well isolated the Rega now was. Taps on the top shelf of the equipment rack and the frame of the box elicited barely audible, distant thumps through the speakers, whereas a tap on the plinth itself got the expected result: a heavy thump. Jumping up and down right in front of the turntable on my hardwood floor caused no audible disturbances either, but the placement of the turntable in the corner of my dining room gives the floor in that spot plenty of reinforcement from two walls. The effect of footfalls, even on springy floors however, should be greatly alleviated when using the isolation box.
In terms of real world music listening the effects were similar in magnitude and character to the Origin Live tonearm modification, the Rega sounding better in every department when suspended on the Aural Thrills box. Transients and micro-dynamics were more dramatic, small sounds emerging with greater impact from blacker, quieter backgrounds. This was due in part, perhaps, to reduced surface noise, which may have been a result of the now consistently perfect level of the table (the stylus tracking more precisely in the centre of the groove). The perfect level no doubt contributed to the better imaging, phantom center images now more firmly centered with soundstages blooming wider outside the speakers. By the same token, individual instruments were better delineated and complex passages more coherent with converging musical lines easier to discern and understand than before.
The improvement in articulation and coherence also translated into the loud stuff, big crescendos more natural in their ebb and flow, and, as with the Origin Live mod, the system could play louder with less fatigue, just getting better as the volume went up. The cumulative effect of the two products was really impressive, my humble Rega 3 starting to sound like a lot more than the sum of its parts, even through a $300 phono stage. The sense of effortlessness was also a testament to the improvement in smoothness and midrange purity the isolation box brought to the Rega. What seemed at first like perhaps a touch less detail left the impression of smoother, grain-free, more analog-like sound after longer periods of listening. And listen long I did. My analog front end had never sounded better.
Although probably not as fuss-free as a Vibraplane (but less than 1/10th the cost) the Aural Thrills box did a pretty good job of staying level, requiring re-leveling every few days. Since all inner tubes leak small amounts of air over time it’s wise to check the level of the plinth right before playing some records. Over time I also noticed that the isolation box worked better with moderate air pressure in the tubes, the sound getting smoother and more dynamic as the plinth sunk further into the box (but not so far, obviously, that the tubes were deflated). This produces a similar effect to adding mass, compressing and softening the tubes, making them more supple and better able to absorb vibrations.
As you can probably tell I was very happy with the performance of the isolation box with my Rega. My analog front end sounded so good with the box I never even got around to testing it under any of my other components. Although it would chew up quite a lot of vertical space in a rack, it might be quite beneficial under CD transports, preamps and particularly tube gear, which is more likely to be susceptible to microphonics. Maybe once I stop playing so much vinyl I’ll take some time to experiment with it on digital gear. Again, a keeper.
(Page Four: Iron Audio Acrylic Platter)