Yamaha's 2020 HDMI 2.1 receivers' bandwidth capped at just 24Gbps

Mike Wheatley

Yamaha’s first generation HDMI 2.1 receivers are causing yet more upset, as it has been revealed the devices are capped to just 24Gbps bandwidth, even if the faulty HDMI board has been replaced.


The cap is a hugely significant limitation for anyone planning to use the receivers with the Microsoft Xbox Series X or Nvidia and AMD GPUs, FlatPanelsHD reported.

Yamaha’s first batch of HDMI 2.1 receivers were impacted by a nasty hardware bug that meant they were unable to deliver the full 4K 120Hz experience when paired with a Microsoft Xbox Series X or Series S console.

The issue was discovered by the German language website Heise last October. It found that fault was due to a problematic HDMI 2.1 microchip supplied by Panasonic Solutions that powers the devices. The faulty chip, it was discovered, is incompatible with HDMI 2.1. So it meant that anyone who tried to pass a 4K signal at 120 frames per second from their Xbox through the receiver would only see a black screen.

In May, Yamaha announced it would replace the HDMI boards in the faulty RX-A2A, RX-V4A and RX-V6A receivers in order to remedy the bug. It promised that the free update program would kick off in the autumn.

HDMI 2.1 allows for a maximum bandwidth of 48Gbps, but it has emerged, via a thread in AVDForum, the replacement boards Yamaha is providing are capped at just 24Gbps. As anyone with technical knowledge will understand, that is too low to carry uncompressed 4K120Hz, 10-bit RGB from the Xbox Series X and Nvidia’s and AMD’s HDMI 2.1 graphics cards. The bandwidth is also too low for uncompressed 8K signals. So users will still see a black screen unless they downgrade the signal.

FlatPanelsHD reached out to Yamaha to understand its reasoning behind the limitation, and the company explained its intention was to “avoid inconvenience of HDMI path through on gaming use.”

“Key features for gaming, such as 120Hz flaming rate and VRR / ALLM / QFT, can work on 24 Gbps bandwidth,” Yamaha said in its statement to FlatPanelsHD. “So, we chose this spec for these models. (Of course, these models have limitation on 8K60 uncompressed and 4K120 4:2:0 chroma sampling).”

The company explains that it has made the limitation clear on its website, saying it is showing “8K60B” and “4K120AB”, which is a reference to the fact that the models are limited to 24Gbps as per the HDMI Org regulations.

“However, we've found that it might lack politeness,” the company continued, acknowledging that perhaps not everyone will understand this. “Now, we're under considering to show an additional information on our website."

Yamaha said it has no plans to offer customers the chance to upgrade to a 40Gbps board. However, the company’s second-generation HDMI 2.1 receivers announced in May do support up to 40Gbps bandwidth.

The company stated that it has no current plans to offer customers of its first-generation HDMI 2.1 receivers, RX-A2A, RX-V4A and RX-V6A, an option to upgrade to a 40 Gbps HDMI 2.1 board.

Yamaha's second-generation HDMI 2.1 receivers, RX-A4A, RX-A6A and RX-A8A, and are equipped with an HDMI 2.1 board that supports up to 40Gbps bandwidth.