Modular Input/Output Structures

Input Section

Analog Audio Inputs. The analog audio input signals are connected via detachable, balanced Euro-block connectors. The analog input section accommodates microphone, or line level signals with nominal levels of -50dBu, -40dBu, -20dBu, or +4dBu. By default, headroom is 20dB, meaning for example, that with a +4dBu reference level, signals up to +24dBu can be passed without clipping. +48V phantom power is available on each input.

Following the initial input stage, there is a digitally controlled volume control circuit that provides gain in 0.5dB steps. This is used to fine-tune the input signal level if it doesn't exactly match the dB steps provided. For example; the +4dBu, or -10dBV reference level selections may not provide the exact input gain level that you may need for a line level source. Furthermore, the user may use this chip to increase or decrease headroom. For example, if an input signal doesn't have much dynamic range, a gain could be applied so that the signal applied to the ADC is closer to 0dBFS. This arrangement allows the user flexibility in constructing the optimum gain staging for their application. The goal of the analog input section provides the analog to digital converter (ADC) with a signal that is as "hot" as possible without ever clipping.

The analog input section accommodates microphone, or line level signals with nominal levels of -50dBu, -40dBu, -20dBu, -10dBV, or +4dBu. By default headroom is 20dB, meaning for example, that with a +4dBu reference level, signals up to +24dBu can be passed without clipping. +48vDC phantom power is available on each input.

Following the initial input stage, there is a digitally controlled volume control circuit that provides gain in 0.5dB steps. This is used to fine-tune the input signal level if it doesn't exactly match the dB steps provided. For example; the +4dBu, or -10dBV reference level selections may not provide the exact input gain level that you may need for a line level source. Furthermore, the user may use this to increase or decrease headroom. For example, if an input signal doesn't have much dynamic range, a gain could be applied so that the signal applied to the ADC is closer to 0dBFS. This arrangement allows the user flexibility in constructing the optimum gain staging for their application. The goal of the analog input section provides the analog to digital converter (ADC) with a signal that is as "hot" as possible without ever clipping.

OUTPUT SECTION

The first stage of the analog output section is the digital to analog converter (DAC). Symetrix DSP utilizes advanced 24 bit 128x over-sampling sigma-delta converter. Like the ADC, an enhanced multi-bit architecture is used, which achieves wider dynamic range, but still keeps much the same superior distortion characteristics as conventional single-bit DACs. Following the DAC, there is a volume control section that provides gain changes from -72 dB to +12dB in .5dB steps. This allows the user to match the output level to a wide variety of devices, from +4dBu professional devices to microphone-level inputs with no external level-shifting required.

With the volume control set to unity gain (0dB), the analog output section is calibrated for +4dBu operation with 20dB headroom. This means that a digital signal of 0dBFS corresponds to a +24dBu output signal. If other signal levels are required, this is easily accommodated by changing the volume. Following the volume control, the signal is output on balanced Euro-block connectors with an output impedance of 200 ohms.