Helius Designs Alexia turntable and Omega tonearm

Helius Designs Alexia,
Helius Designs Omega
Helius Designs Alexia turntable and Omega tonearm

Of course, it would be so easy for a tonearm designer to make a mediocre turntable that was simply a platform to showcase the tonearm, but that would ultimately be self-defeating. The Alexia is not simply there to reflect the underside of the tonearm, but is a distillation of Owen’s years of building telescopes and an understanding of how that kind of precision is relevant and applicable to making a record spin ‘right’. In Owen’s book, this means nailing platter rotation speed while reducing acoustic interference to a minimum.

Platter rotation speed is easy to get right, so long as you don’t mind a lot of acoustic interference. Simply make the platter as heavy as possible, give it a good motor, and any minor inconsistencies due to stylus friction are simply swept away. However, such designs are prone to pick up acoustic noise from the environment. It’s also easy to minimise acoustic interference by making the platter so free that any such interference is lost in the suspension system, but in the process the lightness of the design means stylus drag can influence speed stability. High torque motors help here, but power corrupts (and costs). In most cases, the answer is a compromise, and some of the more successful turntables of the last fortysomething years have been the designer’s expression of that compromise.

Helius decided not to join that continuum, but instead rethink the project through from scratch. It sounds fairly obvious to the point of being circular logic, but the way to control the platter speed is to regulate the speed of the platter: by using an optically controlled drive system that monitors the speed of the platter hundreds of times a second and applies corrective measures accordingly. Curiously, most feedback systems of this kind tend to monitor the speed of the motor, not the platter, and by shifting the locus of control to the platter itself, speed stability suddenly gets a lot more precise without having to call on over-engineered mass or motive force.

The Alexia’s suspension system also avoids the usual ‘springs and pillars’ arrangement with only platter and arm on the subchassis, because Owen feels this adds to problems rather than helps. The logic goes as follows: one spring starts vibrating, the rest join in. With these springs happily dancing around, the belt starts oscillating due to the varying tension created by its fixed position relative to the platter, and this causes pitch errors. To combat this, the Alexia has motor, platter, and arm all on the same subchassis, which is suspended on a double wishbone tuned to 1.5Hz. This can only move through the vertical plane, and any kind of horizontal movement is impossible. The bearing is a low-friction ruby design.

The overall look of the deck is timeless, in an almost Bauhaus form-follows-function way. The chassis sits on three points, and level adjustment is performed at this stage, the subchassis rests on the chassis, adjusting the ‘cruising altitude’ of the subchassis comes down to some extremely basic one-handed adjustment, and lots of the subchassis is made of Perspex specifically to prevent any high-frequency feedback from one sub-system to the others. There’s no need for a record clamp.

The Alexia’s natural partner is the Omega arm, as its clever use of non-coincident tungsten bearings and differential mass damping sing similar songs to those of the Alexia. We’ll concentrate slightly less on the Omega, because those with long memories will associate Helius with tonearms like this. It retains the clamshell like bearing housing of the Cyalene, but is more rounded. The non-coincident bearings mean greater integration of vertical and lateral components of a musical signal. In addition, the counterweight is an integral part of that housing, with a smaller downforce-only counterweight sitting on an outrigger shaft (there are two downforce counterweight options, enough to accommodate practically all cartridges).

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