First post here at ASR. I’ve been enjoying several reviews & discussions here, including this interesting one for DRA-800H. amirm tested the DRA-800H using the Zone 2 Pre-Out, which is downstream of the 7-in/3-out matrix switch. This switch can be seen in the analog and digital block diagram attached to post #117
@amirm : I'm absolutely not sure you measured the main AKM DAC at ZONE2 output. There are 2pcs PCM5102 TI stereo DACs on the board (right up next to AKM) for ZONE2 and Subwoofer outputs. These are responsible for driving the above 2 outputs, even when the main zone and zone2 plays the same music...
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Inputs into that 7-in/3-out matrix switch include the analog outputs from the following dacs: 1) Main zone dac AKM4458, 2) the “Network / Zone 2” DAC PCM5100A, and 3) “Downmix” DAC PCM5100A.
The label “Zone 2 Pre-out” on the outside case is suggestive but not proof that this pre-out is receiving the analog output from the “Network /Zone 2” DAC PCM5100A. The presence of the switch raises the possibility that this pre-out can be fed from any of the 3 DACS depending on the configuration. amirm stated in post #1 that he set the DRA-800H such that Zone 2 would “mirror the main zone output”.
https://www.audiosciencereview.com/.../denon-dra-800h-review-stereo-receiver.26743/
Perhaps amirm can state what he set on the DRA-800H (ie All Zone Stereo? Another setting?) and based on this setting choice members can comment on which of these DACs was likely feeding the Zone 2 Pre-out in his testing procedure. My guess is that it was probably the Network / Zone 2 DAC PCM5100A, but this is just the simplest explanation based on the probable settings and “Zone 2 Pre-out” label.
This discussion also raised an issue that I’ve been wondering about, which is the purpose of the “non-zone” DACs in many AV receivers. Consider the AVR-X6400H, similar to many receivers reviewed at ASR. In addition to a Main Zone AKM4458 DAC, the AVR-X6400H has a dedicated PCM5100 DAC for Zone 2, and another dedicated PCM5100 DAC for Zone 3. That each zone has a corresponding and dedicated DAC stack (I write “DAC stack” because the main zone actually consists of two AKM4458 chips).
For the AVR-X6400H, any three of these DACs can receive a digital input such as from optical or coax, but also from the Network module. The signal pathway from the Network Module can be observed in the AVR-X6400H service manual going to the respective DAC stacks for the Main Zone (p162), Zone 2 (p165, attached here), and Zone 3 (p.167). That the Network Module can send digital signal to the Main Zone DAC is consistent with statements from Denon posted elsewhere at ASR and also the nearly identical SINAD for AVR-X4700H using a 1khz zone via Heos (network) or coaxial input.
This is a second review of the Denon AVR-X4700 AVR. It was kindly purchased by a member and drop shipped to me. It costs US $1,700 from Amazon including free shipping. I will explain the reason for the revision in a bit. For now, I will cut and paste some of the information from the first...
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So the Network Module can send digital signal to any one of the 3 DACs serving Zones: Main, 2, and 3. Yet, many AV receivers, including the AVR-X6400H and the DRA-800H have an additional ‘network DAC’. So what is the purpose of this specific ‘network DAC’?
The DRA-800H also has a “downmix DAC PCM5100A” and what is the purpose of this? I’m not sure what the “downmix” could be because the DRA-800H HDMI input accepts only 2ch PCM (p 175 user manual), and not the usual (in AV receivers) 5.1 or 7.1 ch, and not DSD, Dolby True HD or DTS Master Audio.
The AVR-X6400H has 3 zones, each with its corresponding dedicated DAC-stack, yet there is an additional (4th) ‘network dac’. Likewise, the DRA-800H has just 2 zones and three DAC stacks. For ‘n’ zones, there seems to be n + 1 DAC stacks. There must be a reason for this, but it is unknown to me.
In summary, questions I’ve posed here:
1. Which of the three DACs in the DRA-800H was feeding the Zone 2 pre-out for Amir’s testing procedure, the Main Zone AK4458, the Network /Zone 2 PCM5100A, or the “Downmix PCM5100A” ?
2. What is the purpose of having a separate “Network dac” in many AV receivers including the DRA-800H, given that there is a dedicated DAC for each Zone which can process digital signal of network source? Further, why is there an additional ‘downmix dac’ for the DRA-800H? The answer may or may not be related to the observation that for n zones there are n+1 DAC stacks in these receivers.
3. Does anyone have any evidence, such as from a Service Manual or other source including physical testing, of whether for the DRA-800H the network digital signal (HEOS) is sent to the Main Zone AKM4458 DAC, just as it does for the mainline Denon receivers such as AVR-X6400H and AVR-X4700H?
Hope this generates further discussion. Thanks!