It’s important to us that we design and assemble our tonearms in-house. This gives us a deeper understanding of how the product works and allows us to continuously improve.
For Theory, we wanted to take our OA2 gimbal bearing design to the next level by further reducing points of resonance in the tonearm. Practically speaking, this meant using more rigid materials and minimizing the number of connection points between parts.
To do that, we designed an armtube that combines the headshell, tube, and pivot housing into a single, continuous piece. This design leaves no connection points for resonances to creep in between the headshell and tonearm pivot. But what material would this be made of? We needed something light enough to preserve the low effective mass of the armtube yet strong enough not to resonate during play.
The answer was magnesium. Not only does magnesium have an incredible strength-to-weight ratio, but it can also be molded into complex shapes using a process called thixoforming. This process made it possible to combine the different tonearm elements into a single piece, preserving the arm’s effective mass and low center of gravity.
The tapered armtube design keeps vibration away from the stylus and ensures the walls of the armtube are as thin as possible, keeping mass low. We also increased the effective length by 7mm for lower angular tracking error and less distortion.
OA3 Pro didn’t happen overnight. We worked closely with our Wisconsin-based magnesium molder for over a year to develop and build the complex tool required to manufacture the armtube. The result is an exceptionally strong, low resonance armtube that is made right here in the USA.