For the Yamaha RX-A2A, RX-V4A and RX-V6A AV receivers, which are the first generation of 8K receivers, the manufacturer’s website indicates compliance with 8K60B, 4K120AB. The “B” in the 8K60B means it is an 8K 60Hz signal compressed using DSC (not to be confused with uncompressed “A”). Which is disappointing, since 8K60B is not supported by most video cards and new-generation consoles, and they are the main sources of 8K video today.
Yamaha said, “Key gaming features such as 120Hz bit rate and VRR / ALLM / QFT can operate at 24 Gbps. Therefore, we have chosen this specification for these models. ”
The story of malfunctioning HDMI modules in AV receivers began last year. In May 2021, Yamaha launched a program to replace HDMI 2.1 modules in the RX-A2A, RX-V4A and RX-V6A models, but alas, even with the updated board, the transmitted signal resolution did not exceed the same 24 Gbps.
For the sake of fairness, we note that the HDMI 2.1 standard provides for a bandwidth of up to 48 Gb / s – that is, it may be less, and manufacturers are free to choose the value of this parameter from the options of 24 Gb / s or 40 Gb / s. That is, formally, even with a maximum resolution of 24 Gbps, the device complies with the HDMI 2.1 standard. However, the weak link is the AV receiver transmitting this signal.
At the same time, the second generation Yamaha HDMI 2.1 receivers – the RX-A4A, RX-A6A and RX-A8A models – support bandwidth up to 40 Gbps.