The development history of switches
In October 2016, as the distributor of Opera's headphone amplifier, CelAudio was officially established and started to conduct business in the HiFi industry. In 2017, as a company with a boss who has more than 20 year's experience in IT industry, CelAudio began to provide free Raspberry Pi images for headphone amplifier customers to play HQPlayer streamed music. It's sound quality of USB output was significantly better than some very expensive USB interfaces. Then, CelAudio discover the impact of the network devices. We tried to improve sound quality by adding linear power supply to the switch/router, isolating network noise with fiber etc. Sharing the experience with customers become the daily work of CelAudio.
Around 2018 - 2021, modifying ordinary switches to HiFi switches became popular. Lots of 'HiFi' Switches were launched during those years. However, CelAudio,which had the ability to design switches, launched the first fully linear power supply HiFi switch in China - NW100. Unlike the 'HiFi' switches modified from ordinary ones, the NW100 uses LT3045 as a voltage regulator to directly supply 3.3V and 1.1V voltages to the switch chip.
In 2021, the NW200 was launched, featuring an SFP port and powered by 220/110V AC-- similar to the HiFi switches we commonly use today.
In early 2023, the NW300 was introduced. NW300 is a HiFi switch that elevates sound quality to next level. Prior to the NW300, the mainstream view held that HiFi switches were used to isolate the noise of the home network. Based on this concept, the best solution should be to disconnect the digital player from the network during playback to eliminate all home network noise. Howerver, the NW300 broke this. With the NW300 connected, the sound quality is better than when it is disconnected. The HiFi switch is no longer only for isolating home network noise, and it has become a key device to improve sound quality. The HiFi network looks more and more like another "power system" of the streamer HiFi system—similar to how power cable and power regenerators enhance the sound quality. The network cable, network devices now contribute to better audio performance.
The Core Technical Points In The Design Of HiFi Switch
Low Noise
Higher noise will lead to the loss of sound details, a decline in imaging accuracy, and more noisy. The low noise here includes two aspects, one is the noise generated by the HiFi switch itself, and the other is the noise coming from the home network. HiFi switch must isolate the noise from home network, and provide low working noise itself.
High-precision Clock
The clock accuracy has a significant impact on the resolution and density of the sound. Generally, the higher the clock accuracy, the stronger the resolution and density. However, blindly improving the resolution may cause problems for mid-to-low-end systems, because if the sound has too much detail retrieval but less envelopment, the musicality of the sound will be significantly reduced. For a high-end system, the clock accuracy can be unrestrictedly improved. However, we should balanced the detail retrieval and envelopment in low-mid-end systems, therefore, products with different positioning may have different clock accuracy requirements.
Multi-switch Architecture
For HiFi switches, the multi-switch architecture is the core design point. When the RJ45 is used to connect the home network, network noise can be transmitted through the copper wire, and it is difficult to completely eliminate with single switch. When fiber is used, the SFP optical transceiver itself will generate a certain amount of noise when working, which is one of the reasons why the optical module impact the sound so much. Therefore, the design of processing home network noise through multiple HiFi switch is reasonable. However, although HiFi switches can remove noise, they cannot completely remove the sound characteristics of devices and cables in the home network, and the sound will still be affected by home network. As well as, HiFi switches not only affect streaming playback, but also impact the sound when the digital player plays music saved on the local disk.
NW330
The NW330 HiFi switch internally has three switches. Different switches provide different sound characteristics, and different topologies have different acoustic impressions.
High-precision Clock Design
NW330 uses a high-precision reference OCXOand achieves global clock synchronization by using the CelCLK II PLL system.Learn more about CelCLK II...
Noise Control
The NW330 internally has three switches. The lower-layer has two switches and the upper -layer has one switch. The network transformers between the low-layer switches ,and the SFP between lower-layer switches and the upper -layer switch, are used for isolating noise.
Topology And Sound
The upper -layer and lower- layer switches have different sound characteristics. The lower -layer switch uses audio class capacitor, delivering more reverberation, a lush and fatigue-free sound. The upper switch has more resolution, a bigger soundstage and stronger macrodynamics. So, when NW330 uses uppler SFP port to connect the streamer, the sound will have more upper layer switch's sound characteristics.Similarly, using lower layer to connect streamer, it will have more lower layer switch's sound characteristics.
NWX
All Independent Ports And Noise Control
NWX internally has two same switches. By using the industrial and operator grade switch chipset, NWX is designed as a fully independent port switch.
For each RJ45 port uses an independent PHY chip, which has an independent clock and fully independent power supply based on LT3045.Additionally, each SFP port also uses an independnt linear power supply based on LT3045. Due to the independent power supply for each port, NWX has excellent noise suppression and isolation capabilities. Especially, the crosstalk between ports is also minimized. Thus, it can effectively eliminate the noise from home network and minimize the noise generated by NWX itself.
High-precision Clock
The clock module of the NWX uses a -120dB@1Hz and 8e-13@1s 10MHz OCXO as the reference clock and a -85dB@1Hz and 1e-11@1s 50MHz OCXO as the VCO separately. The VCO clock and the 10MHz reference clock play a role of 1 + 1 > 2, making the entire machine achieve extremely high clock accuracy whether it is supplying the 10MHz clock signal externally and 25MHz clock signal internally.
For each RJ45 port uses an independent PHY chip, which uses an independent clock from CelCLK II PLL system. That means when the data enters RJ45 port, it is reclocked at the port level. Then the sound quality is benefited by the high-precision clock.
Thermal Noise
OCXOs typically work at 85℃, and the linear power system , SFP2fiber or SFP2RJ45 module also generate a lot of heat.Therefore, the thermal noise must be taken care. NWX is designed with industrial and carrier-grade switching/PHY chips, and Low Temperature Coefficient of Resistance resistor etc., which have extremely wide-temperature stability. Ensure that the sound is consistent under any temperature conditions during normal operation.