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.[..]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.
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.
But hey Amir slow down now!
we are waiting for the Marantz 6014 review!
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.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.
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.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.
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.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.
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.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.
"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.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.
As I just explained, I am definitely not sending it all 8 channels of the same data.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.
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.
If you must, but try not to slobber too much.Thank you sire. May I kiss your ring now?
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.
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.
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.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 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 betterI 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.
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.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.
"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.