Phono Cartridge Reviews

Editor: Thank you, Michael Fremer and Stereophile, for a careful and insightful review. Seldom do we get the chance to read a review which so accurately describes what we hear in our own systems. Well done!

There are only a few points which we will clarify here, none of which affects Michael's listening impressions: The Lyra Atlas and Etna share the same design philosophy, which is to have a completely solid and seamless connection between cantilever and headshell. This is for two reasons:

One is as Michael wrote—to drain away any excess vibrational energy that the stylus picked up from the LP groove, but either was not converted into electrical signal, or was not fully dissipated within the damping system. Otherwise, the cartridge has the built-in equivalent of an echo chamber, which cannot be correct.

Two is to ensure that the pivot that is the reference point for the cantilever's motion is as clearly defined and immobile as possible. The cartridge's job is to measure the LP groove, and any unwanted motion of the pivot point means that the measuring process will not be accurate.

The Atlas connects the cantilever seamlessly to the headshell by offsetting to one side the screws and voids needed to mount the magnet system. The Etna accomplishes the same, but by offsetting the magnet-mounting system far forward in the cartridge structure. Same philosophy, different means of accomplishing it.

Previous Lyra cartridges had the same goal of mounting the cantilever directly in the cartridge body, but the magnet-mounting system was interposed between the cantilever and headshell, an area subject to a never-ending stream of vibrational energy. Although not occupying much space, the screws and voids were a source of internal reflections, and the threads could be provoked into sympathetic resonances due to the constant vibrational energy. The design of the Atlas and Etna circumvents these remaining issues.

Lyra's use of a double-knife-edge method to more securely mount the cantilever directly in the cartridge body dates all the way back to the Parnassus DCt, but this feature has been used only on our titanium-bodied cartridges (Parnassus DCt, Titan, Atlas, and Etna). This is because the manufacturing process used to fabricate the knife-edge mount, and the mounting method itself, impose severe stresses on the material used. A weaker material than titanium (such as the duralumin of the Kleos) would buckle and be unusable.

When it was time to design the Atlas, we increased the stiffness of the knife-edge components as much as feasible, again with the goal of creating a more clearly defined and immobile reference point for the cantilever's motion. The Etna uses a double-knife-edge cantilever-mounting system of similarly high stiffness.

Regarding the 93° stylus-rake angle that Michael measured, in reality there is no SRA specification in the cartridge industry. Even on the LP-cutting side of things, documentation regarding SRA is sparse and not particularly clear. Some documents suggest that the SRA cutting range for present LPs may be from 91° to 95°, but there doesn't seem to be any single document published by the LP-manufacturing industry that spells this out clearly. Also, there are at least three different, commonly used methods for securing a stylus to a cantilever, and each has its positives and negatives. One method has tight SRA and zenith tolerances, at the cost of broader tolerances for azimuth and height; another method is good at SRA, azimuth, and height, but at the cost of zenith; and a third is good at azimuth and zenith, but requires looser tolerances for SRA and height.

The tightest SRA accuracy that we have been able to get our cantilever fabricator (Ogura Jewel Industry) to agree to is ±2°, which, as in the LP industry, is a 4° range.

It would be a boon to the entire cartridge industry if there were a database—hosted on AnalogPlanet.com, perhaps—where audiophiles and reviewers could report on which SRA gives the best sound in their audio systems. However, it should be kept in mind that the design of most tonearms ensures that changing the SRA will also alter the tracking force and the tonearm's effective length, and these need to be compensated for when making SRA adjustments.—Jonathan Carr, Lyra