Wednesday 18 January 2017

Measuring stylus tracking force.

Demonstrating its continuing role as a technological innovator, Rega will soon be launching a new accessory – a weighing scale that precisely measures stylus tracking force. With tone arm set-up critical to sound performance as well as stylus and record condition, their new Atlas Tracking Force Scale will confirm tone arm adjustment to 1/100th of a gram with a working range of 3.5 to 5 gm in a simple in-situ process. As an integral component for the scale, Rega chose the Zemic Q70 series miniature load cell, supplied and fully supported in the Britain by Variohm EuroSensor.

Having identified that an accurate way to measure tracking force was desirable for the high-end audio market, Rega set out to design a scale that would be affordable and be able to be offered alongside the majority of its turntable range.

Rega design engineer, Ashton Wagner explains how the project developed, "We looked for a load cell with an accuracy to one hundredth of a gram that would fully maintain that accuracy over its lifetime; we needed excellent durability and a scale that would not require calibration by the user." 

Budget constraints were also fully considered at the outset, "To meet our target costs the use of premium digital and analogue electronics were off the table. A microcontroller with an embedded commodity ADC was chosen which meant, that to achieve the accuracy we desired, we would have to use a high gain amplification circuit with little room for adjustment. We needed a gauge that would maintain consistent performance under variance in temperature, age, stress, and from gauge to gauge as well – after technical support from Variohm and thorough testing we thus chose the Zemic Q70 series load cell."

The Q70 series miniature load sensor is available in five range options from 0 to 20 gm, up to 200 gm and is well proven in hand-held scale applications. Its semiconductor strain gauge sensing element provides a 0.05% accuracy class and an output sensitivity of 0.5 +/- 0.15 mV/V for excitation from 2 to 5 V DC supply. Its high overload capability and compensated temperature range of -10⁰C to ~+40⁰C ensures consistency in measurement and high reliability for normal ambient temperature conditions.

Rega’s Atlas Tracking Force Scale packages the Q70 miniture load sensor in an attractive case that fits the contour of the record deck’s platen. The battery operated scale has a simple on/off button and a three segment digital display.

@RegaResearch @Variohm #Audio

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