Audio Research Reference phono preamplifier Audio Research Tube Damping Rings
Audio Research Corp. has a very focused design philosophy: rigid design parameters and standards, with listening evaluations being the final critical step in the design process before a new product is released. The company is also not beyond developing its own stable of accessories, if it's determined that the accessories currently available in the marketplace don't meet ARC's standards. ARC released their proprietary interconnects (still available on custom order) a decade ago, and now offer for separate sale the tube damping rings that encircle the tubes in all ARC preamps and in the input stages of their power amplifiers.
ARC felt that the rubber used in most such rings did not damp with ideal efficiency the resonances generated in tubes' glass envelopes. The company then developed a proprietary polymer material that, in their view, most efficiently converts kinetic energy to heat. I discovered these rings when they were included as part of the Mk.II update of my VT100 amplifier. And when I learned that ARC was selling the rings to the general public—ie, not just to ARC product owners—for $5/pair, how could I not afford to try them on the 6DJ8s in my Audible Illusions Modulus L1 line-stage?
The effects of the rings on the Modulus L1's performance were not subtle. On all recordings tested, I noted that, with the rings applied: 1) bass was tighter, cleaner, deeper, and more dynamic; 2) transient attacks were more coherent, as in a live performance; 3) high frequencies were more crisp and extended, but without a trace of hardness; and 4) there was improvement in the reproduction of subtle gradations of low-level dynamics.
I'm impressed that Audio Research has developed such an inexpensive tweak, and that it can achieve a significant improvement in sonic performance. I'm even more impressed that ARC has demonstrated the integrity and courage to sell an accessory that can potentially improve the performance of competitors' products. I urge all owners of tube gear to give ARC's tube rings a whirl; the cost is minimal.—Robert J. Reina