HDMI bug: Denon and Marantz solve problems with HDMI adapters


Sound United was the first manufacturer to announce a solution to the HDMI compatibility problem with its Denon and Marantz branded AV receivers.

At the end of October 2020, c’t reported on the breakdown of the chip manufacturer Panasonic Solutions (now taken over by Nuvoton Technology). This ensures that all HDMI 2.1 compatible receivers (also called “8K models”) from Denon, Marantz and Yamaha are not able to record videos in 4K resolution at 120 frames per second (4K120 for short) with a higher contrast range (High Dynamic Range) from Microsoft’s Xbox Series X console to a suitable television.

Specifically, the problem lies in a faulty implementation of the FRL (“Fixed Rate Link”) transmission method introduced with HDMI 2.1 in the AV receiver’s HDMI chip. The devices work flawlessly with Sony’s Playstation 5, as it uses the same method for HDMI 2.1 transmission as the XSX, but sends the video bits (to put it simply) in a different pattern over the lines.

Sound United now wants to solve the compatibility problem with its branded AV receivers Denon and Marantz provide a new “HDMI adapter” SPK618, which will be delivered in Europe from the end of May. Affected customers in Germany, Austria and the Netherlands will receive the low-profile box for connection to the AV receiver at home free of charge during the warranty period. The processing takes place on a special website from Denon and Marantz, which will go online in mid-May.

There isn’t much to see here: the adapter only has an HDMI input and output and a USB power connection.

(Bild: Sound United)

The adapter receives the input signal from the XSX at its HDMI input, decodes it and re-encodes it in a pattern that the AV receiver can understand before it in turn outputs it to the AV receiver via HDMI. According to Sound United, this process takes 50 to 80 microseconds, so there is no audible latency. Also with the now usable 4K / 120Hz and 8K signal no loss of quality is to be feared.

The HDMI adapter comes between the Xbox Series X and the AV receiver.

(Bild: Sound United)

According to Sound United, the Denon and Marantz branded AV receivers have been produced with a revised and therefore error-free HDMI chip since April. An exchange is not necessary here. Whether buyers have acquired one of the affected devices is therefore checked on the addressed websites.

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When asked by c’t, Sound United confirmed that after the warranty period of the affected receiver had expired, no further delivery of the HDMI adapter was planned. However, the warranty period for the AVC-X6700H is a full five years – and even after that, the board in the receiver would have to be exchanged for one with a fault-free HDMI chip (which may then be chargeable for the customer).

Yamaha’s already available entry-level models RX-A2A, RX-V4A and RX-V6A are also affected by the bug. The only reason the error does not currently occur with the devices is that HDMI 2.1 has not yet been activated by an update on them. So far, Yamaha has not commented on how to solve the problem with these models.


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