Digital Audio Interfaces and Jitter

Our USB audio interfaces support 24bit audio up to 192kHz sampling frequency by usage of USB Audio 2.0 drivers. For technical information about our Hi-resolution USB audio, see XMOS website. Electrical and optical S/PDIF interfaces follow the same specification with respect to sampling frequencies and resolution.

The jitter performance of received digital audio is unknown. Jitter in the digital audio stream is a source of distortion when converted to an analog signal in the DAC. Digital audio with its jitter is clocked into a FIFO. The audio data output from the FIFO is clocked using an ultra low phase jitter clock (0.114ps RMS jitter). By using a good designed ASRC, the DAC will perform at it’s optimum regardless of jitter at the source. If you want to get a view of the effect of jitter for DACs and its specifications, look into this jitter performance paper.

Digital Audio Signal Processing

Even high end speakers together with acoustically treated rooms are still in, most cases, the weakest links when reproducing a high quality audio recording. Room acoustics treatment is often needed, at least to some extent, to be able to reproduce the experience similar to the live music in a studio. However, in this section we focus on the speakers. High end speakers are extremely expensive often resulting in severe compromised due to budget limitations. Our solution is based on programmable crossovers, digital filters and adaptive delays to improve passive speaker performance. This means that our audio DSP digital filters and delays are calibrated together with the speaker in use by using a dedicated calibration setup. In the end, what matters is to create soundwaves in the listening room that as close as possible reproduce the recorded audio in the studio.

The DAC and Volume Control

The DAC running at 192kHz sampling frequency uses a state of the art output digital filter with short delay and slow roll off. This avoids any unnatural pre-ringing at impulse response. It also minimize post ringing. This type of filter is often chosen as it is said to reproduce original sound best with minimal echo.

There are many discussions regarding how to design the best volume control. We have chosen an analog motorized volume control. A good designed analog volume control is hard to beat in terms of performance. Our design is inspired by the excellent G Word volume controller by Bruno Putzeys.

Bruno Putzeys G Word

Power Amplifier

We integrate state of the art class D power amplifiers into our designs. Low output impedance (<5mOhm) and low distortion (<0.005% THD) are essential parameters.