Soundsmith Strain Gauge Cartridge Systems

Soundsmith's Strain Gauge cartridge system is a breakthrough in high end vinyl playback. The system comprises a cartridge (with user replaceable stylus) and a dedicated preamp unit.

The Strain Gauge redefines the capability of the phono cartridge. (Model shown SG-200).

The Strain Gauge gives an heightened sense of realism, low surface noise and class-leading channel separation and imaging. First time listeners comment on how veiling is removed and how fast music sounds. Seasoned commentators have noted how the strain gauge gets closer to the master than CD or any other cartridge.

How the Strain Gauge works

The cantilever is terminated in a pair of tiny silicon elements. As the stylus is moved by the record groove, the cantilever bends the two pieces of silicon.

A property of the silicon is that its electrical resistance changes with strain - as its shape is changed. This property is used in engineering for measuring expansion due to temperature changes and the effects of loads on structures.

The dedicated Soundsmith preamp supplies the cartridge with a small current. As the resistance of the two silicon elements change the current is modulated with the signal from the record. LEDs in the cartridge show that the cartridge is connected and functioning.

The advantage of this technology is that what you hear is directly related to the stylus displacement. Magnetic cartridges induce a voltage by the relative movement of coils and magnets with an air gap in between. So the voltage generated by a magnetic cartridge is not a direct representation of the modulations in the groove.

Strain Gauge Cartridge Model range

All models utilise the same cartridge design, the same audio circuitry and the same fault protection. The designer claims they sound identical. See the table showimg a summary of key features.

The SG-200 provides the cartridge, power supplies and preamp that delivers a line level output suitable for connecting to a preamp line level input.

The SG-400 model and above are built on a full width chassis and offer a choice of fixed and variable outputs, both balanced and single ended with one line input.

The SG-410 adds remote control volume and muting.

The SG-500 is designed to serve as a system preamp unit, having the features of the SG-400 plus four line inputs and tape output/monitor.

The SG-510 adds remote volume and muting.

The SG-600 has the features of the SG-400 with the addition of cartridge performance displays. These indicate vertical tracking force, instantaneous force per groove wall (for eccentricity and anti-skate performance) and the vertical component of tracking force (record warp).

The SG-610 adds remote volume and muting.

The SG-810 has the inputs of the SG-510 with the addition of cartridge performance displays.

Why the Strain Gauge sounds better

The effective moving mass of the stylus/cantilever assembly is approximately one tenth of the lowest moving coil cartridge. That means less inertia so the stylus can more faithfully track the modulations in the record groove, particularly noticeable on transients, which sound faster.

A further advantage of the low effective moving mass is that the mechanical resonance frequency of the cantilever/stylus is pushed outside of the audio band.

Because the Strain Gauge is a displacement device, it naturally exhibits a falling frequency response of 6 dB/octave. This closely follows the RIAA curve over a large part of the audio frequency range, meaning that filter circuits are not required. The consequence is high phase accuracy in the audio range, resulting in excellent transient attack, pinpoint imaging and wide soundstaging. It is widely recognised that the ear is more sensitive to timing anomalies than amplitude anomalies.

Read independent reviews

The Absolute Sound issue 201 by Anthony Cordesman
Hi Fi Choice issue 324 by Paul Messenger

The Soundsmith Strain Gauge won the Hi Fi Choice Best Innovation Award 2009.