Concept

•The dynamic range of the TrueMatch converter exceeds the respective values of any conventional microphones.
• The 28-bit resolution includes the entire utilizable signal – from the intrinsic noise up to the clipping threshold of the microphone.
• Featuring a maximum input voltage of 22 dBu, the converter can virtually not be overdriven (@0 dB) and can therefore be used as line input for conventional studio devices, too.
• Even low levels are digitized with high resolution.
• Gain and signal-processing settings are made on the digital domain after A/D conversion, thus not affecting the signal quality. The settings merely tweak the signal level to be suitable for subsequent processing and recording.

Level and Dynamics

For the first time, the dynamic range of a microphone is not limited by a subsequent A/D converter – thanks to the TrueMatch RMC.
The ambition to provide optimum audio quality has been realized on the basis of the TrueMatch technology: The input stage is part of the 28-bit converter, while further signal-processing measures such as subsonic filtering, phase inversion, clip limiting, and gain setting are performed solely on the digital domain.
The input stage features a noise level of –137 dBu (@ 0 ohm input impedance) and can process signal levels of up to 22 dBu without clipping, thus providing a dynamic range of 159 dB. This dynamic range can theoretically be converted to even 26.5 bits.

In addition, the 28-bit conversion method deployed in the Reference Mastering A/D allows using the intrinsic noise as »natural« dithering for avoiding quantization noise.

With 26.5 bits used, quantization noise equals the A/D-converter noise, resulting in a total deterioration of 3 dB. By increasing the resolution to 28 bits, the quantization-noise level is approximately 10 dB below converter noise and is practically not perceivable anymore. This scenario does not consider the microphone noise yet – this is at least 6 dB above the converter noise floor.

The addition of the input-stage and converter noise floors sums up to a level of -134 dBu, which is equivalent to the noise level produced by a 60-ohm resistor. With an impedance of 200 ohm, a microphone already produces a noise level of approximately -128 dBu caused by such resistor; and the microphone-amplifier noise is not considered yet. Thus, the microphone-noise level clearly predominates within the total noise! The specified dynamic range of 150 dB is therefore the result mainly of the intrinsic noise of the microphone.

Target Formats

TrueMatch

Stage Tec‘s patented TrueMatch A/D-converter technology is based on a Delta-Sigma conversion method including 128 times oversampling. It has been deployed successfully in Stage Tec‘s CANTUS and NEXUS products since 1995 and is now available for the TrueMatch RMC, too.
With the TrueMatch system, the analog input signal is fed to multiple converters of different sensitivities. However, unlike the gain-ranging method where converter operation depends on the input level, a DSP permanently monitors the converter outputs and traces and eliminates any conversion errors. More than 45 parameters are considered in this process.
First-class analog circuit design and state-of-the-art DSP technology produce significant improvements compared to conventional 24-bit converters.

› Large Dynamic Range The dynamic range provides sufficient headroom even in critical situations.

› Homogenous Noise Spectrum Thanks to the homogenous noise distribution, intrinsic noise is practically not perceptible even at very low input levels.

› Minimized Conversion Errors TrueMatch converters feature a permanent sample-based conversion correction, resulting in a stable and almost perfect conversion curve even at ultra-low levels.