Denon AVR-X4700 AVR Review (Updated)

[ezra_s]

This tells much about the brand. My next AVR will certainly be a Denon if things keep like this.

PS: Just hope they remove the old connections already

 

[LTig]

[..]The original review measurements showed significant degradation of AVR's performance when measured using HDMI input as opposed to Toslink input. This was surprising to me as I had not seen much discrepancy in the past reviews (sans jitter and such). This resulted in some harsh comments from me regarding the unit and vote of non-confidence.

In my view your comments weren't too harsh, but there were quite a few comments from other members about Denon which certainly were not correct. And I've seen this with other bad reviews as well (e.g. Kali 6 where the review was correct but the speaker was broken). This is not good and shows ASR in a bad light. We don't like it when @amirm is attacked because a unit measures bad - we say fight the measurements not the person. As a consequence we as well should not fight the producer if a unit measures bad, especially if it has not been ensured that the unit is not broken.

I think everyone here at ASR should calm down a bit and refrain from bad and aggressive comments about the producer or the unit until the latter had the chance to discuss (and hopefully fix) the problem discovered in the review.

 

[gvl]

Hallelujah! If anything it proves that it is best to stick with plain old 2ch setup for stereo, there are just too many variables with AVRs.

 

[bigguyca]

No need to worry. As far as I understand this issue - and I'm not an expert in multichannel audio or HDMI, so take whatever I write now with a bucket of salt - your configuration (send 8 channels with 6 of them having zero signal, to an AVR in 2 channel speaker configuration) is perfectly valid. I use my AVP just like this, and customers use a BD player or a PC and not an AP to feed their AVR.

I would expect that an AVR or AVP mixes those 8 channels down to 2, but I would not expect it to do so with clipping the output channels. I would rather expect the output level being lowered by a factor of 4 (12 dB) max since 6 of 8 channels contain a zero signal (assuming a very simple averaging mixdown algorithm which is certainly wrong). So in my view the AVR-X4700H has a problem with this configuration and it should be fixed in a firmware upgrade (which I think should be possible).

It also shows that an AVR or AVP needs to be measured in many configurations if one wants to be sure to find all hidden flaws. Surely those tens of thousands of tests Denon says to do (which I do not dispute) did not cover this configuration - and I'm very sure that Denon will add this configuration to their future test suite (if not already done).

EDIT: @Vasr just beat me with a much better explanation.

To build on the above, in at least some conditions (multi-channel in, all conditions, this isn't clear) if SW = none, in the configuration of the unit then the L & R channels for digital inputs are reduced by 9.5 dB in the digital domain, as noted above, this to prevent digital overflows from adding in the bass output from other channels. The level of the L and R channels is then raised by 9.5 dB in the analog domain using the analog volume control. Looking at the level diagrams for D/M equipment its not clear if this is an effect in all cases when L and R only are used or just in some cases. It is hard to believe it would be in all cases.

The subwoofer receives similar treatment to above if it is present. If the SW is present, the L and R inputs are not modified. See further below.

In the specifications for the volume control, performance of the volume control when used to produce net positive gain does not appear to be shown. The specifications seem to address attenuation only. Gain in the volume control will result in resistance in the feedback path around an internal opamp from the output to the negative input for the channel. This may increase the noise level since the noise from the resistor (Johnson noise) is fed back to the input. Gain over 0dB will also likely affect the linearity of the circuit since any gain used as "real gain" is not available for feedback.

In conceptual terms, at higher frequencies this may mean that +6dB of gain for example will increase distortion by a similar amount. The gains implemented using the volume control are not visible to the user. The actual gain setting could be plus or minus depending on the how the user has set the gain. For example, with a -14dB user setting and 9.5dB "hidden" gain, the gain will still be negative. If the unit already being tested with the volume control set a 0dB, which is 82.5 as Amir tests the unit, then it would seem these bass adjustments by the unit would result in positive gain from the volume control.

If a SW is present and receives the above negative digital, and then positive analog gain, there is much less an effect on the subwoofer output. The volume control is very linear at low frequencies and most added noise isn't reproduced by a SW.

Note that the SW gain is lowered by about 18dB under the process above with that being made up with a +6.5dB gain in the analog filter circuitry after the DAC IC and +11.5dB in the volume control. Again, the gains implemented using the volume control are not visible to the user.

 

[peng]

But hey Amir slow down now!

we are waiting for the Marantz 6014 review!

Yes, let the man get some sleep first..

 

[Vasr]

This is correct. And why this took so long to troubleshoot. It was only when I tested this on another AVR without this issue that I realized there is a problem here.

Sorry to be insistent because it is important. Are you confirming here that your PC sent out signals only on two channels and nothing on the remaining 6? Is it possible to or has been positively confirmed? This would be good to document as the test condition for your measurements in the future.

A normal mixer would apply a gain to every channel, perform the sum and handle potential overflow. If higher than input resolution is used for intermediate sum (which one hopes is the case), then dither is involved as is gain management in the AVR. Both or each may be responsible for the clipping and increase in noise floor.

Here is where it makes a difference. If you were sending zero bits in other channels, applying gain on those channels should have no effect. Mixing them and creating noise indicates a more serious problem (or a different problem) than if your PC was sending the same signal in all 8 channels at 0db.

The reason I am not losing sleep over this is because almost everyone using these AVRs uses it with more than a stereo pair of speakers.

People who listen in stereo in Zone 2 all the time might lose sleep over it if they had placed an order and come to know of this.

It is also a curious statement for a site that nitpicks differences in inaudible performance on a functional glitch. But then different people lose sleep over different things.

 

[Baff]

Not sure why Amir needs to be egged for finding this issue.
If anything it will make the product better if it can be addressed.

Amir should not be egged for finding this issue. His first review will likely lead to an improvement in future Denons, and hopefully even in the current Denons. At the very least, it will be a known issue that people can be told how to avoid.

On the other hand, he could certainly be egged for his trash talking of Denon for things that they did not actually do wrong. He did note how gracious Denon was for overlooking his comments. This new review seems a little over-glowing in its praise in order to make up for the undeserved harshness of the original review.

So, while his review certainly caused some people to cancel their orders, I expect most of those orders to be put back in soon (some people will have already bought something else, or they just won't hear about the change in the review). In the long term, Amir will have cost Denon a few sales, but he has also found a flaw to be fixed, which could lead to the reduction of frustration for some current/future owners.

I won't heap praise upon Amir for the way this played out, but neither will I heap blame upon him. Hopefully he has learned from this and will also do better in the future. The same goes for some of the crazy things that were said in response to his review (both about Amir and Denon). None of us are without flaw, certainly not I.

 

[amirm]

Sorry to be insistent because it is important. Are you confirming here that your PC sent out signals only on two channels and nothing on the remaining 6? Is it possible to or has been positively confirmed? This would be good to document as the test condition for your measurements in the future.

"Sent out" is something I can't confirm. I don't have an HDMI analyzer at home (have one at work but not close). So I can't tell you with 100% confidence what went on HDMI bus itself. I can tell you that I can turn on the other channels one by one and watch left and right levels rise proportionally. So mixing is definitely occurring. Since the levels go down to expected value when the other channels are turned off, I am assuming nothing is output on HDMI for the extra channels.

In addition, I can delete the extra channels in AP software so only two are exposed and then everything works as good as what I reported here.

Best way to troubleshoot this is for Denon to instrument inside the AVR. I am pretty sure it won't take them long to figure out what is going on.

 

[amirm]

Here is where it makes a difference. If you were sending zero bits in other channels, applying gain on those channels should have no effect. Mixing them and creating noise indicates a more serious problem (or a different problem) than if your PC was sending the same signal in all 8 channels at 0db.

As I just explained, I am definitely not sending it all 8 channels of the same data.

Here is the UI and results I shared with Denon when I discovered the problem:

As you see in the UI on the right, channels from 3 to 8 are in white meaning they are not selected to be output.

So by every measure, I am telling the system to just send two channels over HDMI out of 8. Once I hear back from Denon, we will know what it is seeing and whether there is an issue with AP software. But I doubt it.

 

[bigguyca]

Amir should not be egged for finding this issue. His first review will likely lead to an improvement in future Denons, and hopefully even in the current Denons. At the very least, it will be a known issue that people can be told how to avoid.

On the other hand, he could certainly be egged for his trash talking of Denon for things that they did not actually do wrong. He did note how gracious Denon was for overlooking his comments. This new review seems a little over-glowing in its praise in order to make up for the undeserved harshness of the original review.

So, while his review certainly caused some people to cancel their orders, I expect most of those orders to be put back in soon (some people will have already bought something else, or they just won't hear about the change in the review). In the long term, Amir will have cost Denon a few sales, but he has also found a flaw to be fixed, which could lead to the reduction of frustration for some current/future owners.

I won't heap praise upon Amir for the way this played out, but neither will I heap blame upon him. Hopefully he has learned from this and will also do better in the future. The same goes for some of the crazy things that were said in response to his review (both about Amir and Denon). None of us are without flaw, certainly not I.

Thank you sire. May I kiss your ring now?

 

[Baff]

Thank you sire. May I kiss your ring now?

If you must, but try not to slobber too much.

 

[RichB]

As I just explained, I am definitely not sending it all 8 channels of the same data.

Here is the UI and results I shared with Denon when I discovered the problem:

View attachment 71676

View attachment 71677

As you see in the UI on the right, channels from 3 to 8 are in white meaning they are not selected to be output.

So by every measure, I am telling the system to just send two channels over HDMI out of 8. Once I hear back from Denon, we will know what it is seeing and whether there is an issue with AP software. But I doubt it.

Internally, it may be mix-down logic but obviously mix-down is not necessary.
If the AVR is configured without the center, just two channel and the sub, will the "mix-down" issue occur?
If that is the case, then 2-channel users should wait for a fix.

- Rich

 

[RichB]

I won't heap praise upon Amir for the way this played out, but neither will I heap blame upon him. Hopefully he has learned from this and will also do better in the future. The same goes for some of the crazy things that were said in response to his review (both about Amir and Denon). None of us are without flaw, certainly not I.

Momma told me never to heap, I tell my kids, never to tweet

It sounds like this AVR has a flaw when used in 2 channel-mode HDMI.
Since that is allowed configuration, it is an issue.

- Rich

 

[Promit]

On the off chance they're reading: thank you Denon. I look forward to buying many more Denon receivers in the years to come. It's proof that not only are the 3600 and 4700 excellent products, but that the company really does care about producing good respectable performance in their products and does take engineering and measurements seriously.

 

[JohnBooty]

Hallelujah! If anything it proves that it is best to stick with plain old 2ch setup for stereo, there are just too many variables with AVRs.

I agree, but it's also good to note that this Denon would work just fine for a two-channel setup if using TOSLINK inputs, analog inputs, etc. I don't think too many people do 2-channel audio over HDMI.

In general though, yeah, this made me think very lovingly about the simple two-channel amps in my life.

 

[RichB]

I agree, but it's also good to note that this Denon would work just fine for a two-channel setup if using TOSLINK inputs, analog inputs, etc. I don't think too many people do 2-channel audio over HDMI.

In general though, yeah, this made me think very lovingly about the simple two-channel amps in my life.

I used a Yamaha AVR in my game room to drive the Revel M20s. I never liked it an replaced it with an HDFury HDMI switch, Oppo UDP-205, and Benchmark amp and it sounds much better (IMO). I have subsequently upgraded to Revel 126Bes and it sounded even better

@amirm's multi-tone test was different from the Denon test so the issue made it into the field.
That's a shame, but it seems likely that there will be a firmware fix.

It is not hard to imagine a customer hearing the issue, reporting it, and being mocked by the community. Measurements make it real...

- Rich

 

[BsdKurt]

This is correct. And why this took so long to troubleshoot. It was only when I tested this on another AVR without this issue that I realized there is a problem here.

As I noted in the review, Denon engineering is investigating why this is occuring:


A normal mixer would apply a gain to every channel, perform the sum and handle potential overflow. If higher than input resolution is used for intermediate sum (which one hopes is the case), then dither is involved as is gain management in the AVR. Both or each may be responsible for the clipping and increase in noise floor.

The reason I am not losing sleep over this is because almost everyone using these AVRs uses it with more than a stereo pair of speakers. But yes, I hope a firmware fix is provided once it is confirmed to be the down mixing algorithm.

Could you clarify if you would expect an issue with a 3.1 speaker setup? This is my current bedroom setup using the x3600h and I wonder if x4700h would be tripping the down mixing issue with my minimal speaker setup.

 

[tparm]

So for us non-sciency folk, if you own an X4700 operating in full pre-amp mode and have nine speakers connected to external amplifiers and two powered subs, use analog input for two channel listening and HDMI for multi-channel only, don’t care about gaming or 8K TV, you’re good. Do I understand this correctly?

 

[kokishin]

@amirm

Congrats man!

Just got home from the dentist and read the updated review on the 4700H.

It's always a great experience to work with a company such as a Denon to solve issues with such esprit de cours. (One of my best summer's was working with Toshiba-Ome, in my case on a new laptop design).

After this was all said and done, both you and Denon shined for the professional way you all handled this!

I own a Denon 6200 and when I have the urge to upgrade, Denon will definitely be on my preferred list again.

Glad I'm a member of ASR!

 

[Vasr]

"Sent out" is something I can't confirm. I don't have an HDMI analyzer at home (have one at work but not close). So I can't tell you with 100% confidence what went on HDMI bus itself. I can tell you that I can turn on the other channels one by one and watch left and right levels rise proportionally. So mixing is definitely occurring. Since the levels go down to expected value when the other channels are turned off, I am assuming nothing is output on HDMI for the extra channels.

In addition, I can delete the extra channels in AP software so only two are exposed and then everything works as good as what I reported here.

Yes, that would seem to confirm that there is a "zero" signal in other channels when AP software sees 8 channels available. Which means there is a significant bug in the logic of the AVR when it tries do a down-mix even when trying to mix-in empty signals!

But the last statement kind of suggests that perhaps the HDMI protocol (of which I know nothing) differentiates in the format between a two channel audio being sent (no issues here) and a multi-channel audio being sent with only 2 channels carrying signal and the problem is being triggered by the AVR logic when a multi-channel stream (albeit with only two channels having non-zero signal) is received. In my opinion, this can be categorized as broken (without making any judgment on the severity).

For everybody trying to minimize this use case, please note. There are a lot of scenarios in which this can happen.

1. Listening with down-mixed in Stereo in Zone 2 is very common. Don't know if Zone 2 avoids this problem when audio is down-mixed and sent to Zone 2. Note that some of the AVRs including at least some previous generation Denons, down-mix even the main zone to Stereo for multi-channel content if also listening to the same content in Zone 2. This could very well be the source of the bug in handling-logic problem.

2. A lot of the video content only has 2.0 audio. But the source may be sending it as 5.1 or 7.1 over HDMI with other channels zeroed out, depending on what the source is configured for. Some players may have a default to up or down mix everything to 5.1 or 7.1 or users may have configured it that way (especially in computer based media players like Kodi to avoid some other issue).

I am not trying to diss Denon. Also, I wouldn't dismiss the earlier test as measurement (input) error, just a mis-identification/mis-attribution of the problem at most.

But clearly Denon needs to come up with an explanation (and a fix), something more than simply dismissing off the result as test error when they make a public statement. So best to wait for that.