Discrete 7.1 Surround USB DAC

The Qudelix-T71 is a USB DAC (Digital-to-Analog Converter) that is designed to receive and process multi-channel audio from a host source device. Unlike most conventional USB DACs that only receive two-channel stereo audio, the T71 can receive up to 8 channels of digital audio.

The T71 is equipped with a high-performance Digital Signal Processor (DSP) that utilizes a proprietary algorithm to process the incoming multi-channel surround audio. It mixes the audio channels into the appropriate speaker format based on the connected speakers or headphones.

One of the features of the T71 is its ability to automatically detect the incoming audio channel format. The device's screen displays real-time channel information of the incoming audio. This information shows the format, such as 5.1 Rear, 5.1 Side, 7.1, or 2.0 channels, indicating what the T71 USB DAC is currently receiving from the host source device.

Based on the input format detected, the T71's DSP switches its processing mode accordingly. This ensures that the audio is processed and mixed in the most appropriate way for the given input format, providing an optimal listening experience.

 

Why T71 Discrete 7.1 Surround?

Relative Dynamics

One of the primary disadvantages of down-mixing surround audio, such as 7.1 or 5.1, into a 2-channel stereo format is that it can lose relative dynamics in the audio signal.

In a surround sound system, different audio channels are used to deliver specific sounds to different speakers, creating a sense of immersion and spatial positioning. Each channel carries specific audio information, such as dialogue, background noise, music, or sound effects.

When down-mixing to stereo, the audio information from multiple channels must be combined into two channels. This process involves reducing the number of channels and redistributing the audio content across the stereo field. As a result, certain audio elements, such as spatial cues and specific channel separation, can be lost or compromised.

Additionally, the audio signal's dynamic range may be affected during down-mixing. Dynamic range refers to the difference between the quietest and loudest parts of the audio. With a larger number of audio channels, each channel can have its own dynamic range. However, when down-mixing to stereo, the dynamic range of the entire audio signal needs to fit within the limitations of two channels. This can lead to compression or scaling down of the audio within the given dynamic range, potentially reducing the overall impact and fidelity of the audio.

Therefore, while down-mixing allows compatibility with stereo systems, it does come with the disadvantage of potentially sacrificing the relative dynamics and spatial qualities of the original surround sound audio.

Dynamic Range Enhancement

The Qudelix-T71 is designed to process multi-channel audio while preserving the relative dynamics of the original audio source. This means that the device aims to maintain the balance and level relationships between different audio channels as intended by the content creator.

When the T71 receives multi-channel audio, its built-in Digital Signal Processor (DSP) processes the audio signal using a proprietary algorithm. The goal of this processing is to ensure that the relative dynamics, including the volume and loudness relationships between the different audio channels, are retained as much as possible.

By preserving the relative dynamics, the T71 aims to provide an accurate representation of the original audio source. This is important for maintaining the intended balance and spatial positioning of different audio elements within a multi-channel audio mix. It helps to create an immersive and realistic sound experience, especially when listening to surround sound content.

By processing the multi-channel audio with care and attention to the relative dynamics, the Qudelix-T71 aims to deliver a high-quality and faithful reproduction of the original audio source, ensuring an enjoyable and accurate listening experience.

Per-Channel Signal Processing

T71 provides per-channel digital signal processing for all surround channels, allowing users to adjust and fine-tune various parameters such as gain, crossfeed level, EQ, 3D, FIR, and more.

We will update the DSP features based on user feedback and preferences to enhance the audio experience and cater to individual preferences.

By providing per-channel EQ processing, users can have more control over the audio characteristics of each channel in their surround sound system. This allows them to customize the audio output according to their specific preferences, room acoustics, and speaker setup. Adjusting gain, EQ, crossfeed level, and other parameters for each channel can help optimize sound reproduction and achieve a more balanced and immersive audio experience.

Compatibility with conventional stereo Earphones & Headphones

T71 USB DAC is compatible with traditional stereo earphones and headphones. Despite being designed for surround sound, the T71 still provides an enhanced audio experience when used with conventional stereo headphones.

While stereo headphones are typically designed to reproduce audio in a left-right channel configuration, the T71 can leverage its advanced DSP features to enhance the audio quality and provide a surround sound-like experience. This is achieved through virtualization techniques that simulate the spatial characteristics of surround sound, even when using a stereo output.

The T71's DSP processing can add depth, spaciousness, and localization cues to the audio, making it feel more immersive and expansive. By leveraging techniques such as crossfeed, EQ adjustments, 3D processing, and FIR (Finite Impulse Response) filters, the T71 can enhance the stereo audio output and create a sense of soundstage beyond the typical left-right presentation.

While the T71 can enhance the stereo experience, it doesn't replace the full surround sound experience that dedicated surround sound systems or headphones can provide. The virtualization techniques employed by the T71 aim to simulate surround sound but may not fully replicate the precise positioning and channel separation offered by true surround sound systems.

Nonetheless, the compatibility of the T71 with conventional stereo headphones allows users to enjoy an improved audio experience with enhanced spatial characteristics and immersion, elevating their listening enjoyment beyond standard stereo reproduction.

 

ES9219 DAC + INA1620 OPAMP

The T71's design with four ES9219 DACs (Digital-to-Analog Converters) and two INA1620 OPAMPs (Operational Amplifiers) suggests a high-quality audio circuitry to deliver powerful and optimal sound to any headphones and earphones.

By employing a full-balanced circuit design and combining multiple DACs and OPAMPs, the T71 aims to provide a robust and high-quality audio experience. This design choice demonstrates a focus on delivering powerful and optimal sound reproduction, ensuring that the audio output is clean, detailed, and faithful to the original source.

Max. Output Voltage: UNBAL 4VRMS / BAL 8VRMS
Max. Output Power: TBD
2Ch Mode: 384KHz x 32bit (High-Resolution Stereo Audio)
8Ch Mode: 96KHz x 32Bit (Gaming, OTT, Movie)
1000mA Battery (for mobile use case)