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Denon AVR-X6700H AVR Review (Updated)

amirm

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#1
This is an updated review of the Denon AVR-X6700H. I tested an early production 6700H a few weeks ago and found lower than expected performance. Denon Engineering traced this to a faulty capacitor( or capacitors) used in the initial run of this AVR. I requested an updated unit which the company was kind enough to send me.

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Updated Review.jpg


I have re-tested the DAC portion almost completely but for the amplifier I am just showing some of the highlights as the problem was not there.

EDIT: this is the serial number of the tested unit: DBCY032000007

Updated AVR DAC Measurements
The original AVR-X6700H returned a SINAD of just 87 dB which was well short of what the lower end models had achieved. I am pleased to report that this second unit nicely remedies that defect:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Audio Measurements.png


This catapults the 6700H into the coveted green category of DACs from formerly red status:
Best AVR DAC Reviewed 2020.png


Initially I had some problem with dynamic range in one channel. I traced that to noise due to grounding. Upon unifying the Audio Precision chassis with that of the AVR that problem was remedied and performance is as good as before now:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Dynamic Range Audio Measurements.png


IMD test shows the improved distortion:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver IMD Audio Measurements.png


Linearity improved as well:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Linearity Audio Measurements.png


As did filtering:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Dac Filter Audio Measurements.png


Distortion in lower frequencies in multitone are the same as before but at mid to higher frequencies, it is much better:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Multitone Audio Measurements.png


As expected, this showed up in THD+N versus frequency:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver THD+N vs Frequency Audio Measur...png


And here is our favorite new graph with THD+N versus output level:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver THD+N vs Output Level Audio Mea...png


Per requests, I turned up the volume so that we could go beyond 4 volts to see the response there for external amplifiers that are much less sensitive (green).

AVR Amplifier Updated Measurements
The amplifier did not change but improved grounding did make some things better. In Dashboard we are dominated by distortion so this remains the same:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Amplifier Audio Measurements.png


Best home theater avr amplifier review.png


But signal to noise ratio improved good bit:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Amplifier SNR Audio Measurements.png


Note that this is NOT due to the capacitor fix but rather better grounding of the AVR and measurement system.

And here is a power sweep showing that the one channel that was misbehaving before, no longer is:

AVR-X6700H AVR Surround HDMI Dolby Atmos Home Theater Receiver Amplifier Power into 4 ohm Audi...png


Conclusions
Engineers struggle to improve system performance by 3 dB. Here, the proper capacitor resulted in whopping 12 dB increase in SINAD. That is a lot of performance to have left on the table. The AVR-X6700H goes from "hmmm? to "now this is nice!" with this component change.

Given the new performance, I am happy to recommend the Denon AVR-X6700H. The company has a great platform here relative to its competitors and now you go up and down the models and not given up on the core value of it.

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As always, questions, comments, recommendations, etc. are welcome.

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amirm

amirm

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Thread Starter #2
One note on temperatures. I had the unit in pre-amp mode for the DAC test and I was pleasantly surprised that it hardly rose above room temperature. So to the extent you use external amplification for all the channels, these AVRs will run cool and comfortable as processors.
 

BillH

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#5
It's great to see the improved results.
It's also great to see a major audio manufacturer pay attention to ASR (again).
Congratulations Amir!
 

BsdKurt

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#9
@amirm Nice updated review! It is good to know that Denon can and probably normally does (outside of a global pandemic) deliver on their products objectively.

The one thing I‘m still curious about is which capacitor(s) caused the initial problem? I know this is not something you can answer since you can’t open the unit and compare it to the initial unit. It would be great if Denon would be more transparent about how to determine if a given unit has the Covid capacitor Issue. So far messaging from Denon has been variable and not transparent. I think eventually the community will identify the changes if Denon doesn‘t tell us.

So the question for Denon is why not just come clean and tell us the serial numbers affected as eventually it will come out? Certainly being upfront and transparent about it develops trust in their brand while letting the community figure it out does not.
 

restorer-john

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#14
The one thing I‘m still curious about is which capacitor(s) caused the initial problem? I know this is not something you can answer since you can’t open the unit and compare it to the initial unit. It would be great if Denon would be more transparent about how to determine if a given unit has the Covid capacitor Issue. So far messaging from Denon has been variable and not transparent. I think eventually the community will identify the changes if Denon doesn‘t tell us.
I agree with this. It's all very well to present another sample with better performance and attribute the problem to a "capacitor".

As discussed in the last thread, let's identify the specific, actual component/s that are at fault or out of spec and document this properly. Over the decades, I've seen any and all forms of dodgy practices inside gear of all pedigrees and prices in the interests of saving a few dollars down the track.

The previous tested model is apparently owned by a member local to @amirm . Half an hour looking at them both with the covers off would easily identify any and all changes/substitutes of components.
 

Tks

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#15
Yo boss man, from time to time I see you talk about "tried playing with grounding", or "perhaps you'll get better results with messing with grounding" and today: "Initially I had some problem with dynamic range in one channel. I traced that to noise due to grounding. Upon unifying the Audio Precision chassis with that of the AVR that problem was remedied and performance is as good as before now"

What exactly are you doing? Like how does one "play with grounding" anyway, and what was wrong with yours? And why not keep things consistent in the future, or test these configurations, or tell us what they are so we may know what to do ourselves perhaps if we have issues?
 
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#16
Whatever is the veracity of the "faulty capacitor" excuse the upgrade of the measurements shows that without changing the fundamental design the manufacturer is able to improve the performances.
It is the result of the pressure from the customers (thank you ASR) and may be less marging for Denon ( the capacitor may cost 50 more cents!).
 
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#17
Hardly inspires confidence in a company that ships out a production run with shiiittyy capacitors

like we have to be a beta tester for denon? Couldn’t they divert money from sound United shareholders to pay someone to test their products ?

i will steer clear from this company
 
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amirm

amirm

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Thread Starter #18
Yo boss man, from time to time I see you talk about "tried playing with grounding", or "perhaps you'll get better results with messing with grounding" and today: "Initially I had some problem with dynamic range in one channel. I traced that to noise due to grounding. Upon unifying the Audio Precision chassis with that of the AVR that problem was remedied and performance is as good as before now"

What exactly are you doing? Like how does one "play with grounding" anyway, and what was wrong with yours? And why not keep things consistent in the future, or test these configurations, or tell us what they are so we may know what to do ourselves perhaps if we have issues?
Normally when you hook up two Audio products with RCA cables, you cause ground currents to run between them and potentially create Hum. The Hum may not be loud enough to be heard but is likely to be there.

The Audio Precision unbalanced inputs are actually floating and not connected to its chassis ground. Most of the time this presents a better situation than actual use, allowing me to measure the gear without ground loops interfering. On occasion though, it doesn't work this way and grounding the analyzer to the audio device improves things. I have many options here, grounding the output but not input, input but not output, or both. This is what I mean when I say "playing" with grounding.

For your situation it is best to use balanced connections when you can as to obviate this issue. If you are using RCA, then you are condemned :)
 

Vasr

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#19
Whatever is the veracity of the "faulty capacitor" excuse the upgrade of the measurements shows that without changing the fundamental design the manufacturer is able to improve the performances.
It is the result of the pressure from the customers (thank you ASR) and may be less marging for Denon ( the capacitor may cost 50 more cents!).
Not sure what "fundamental design" means. They didn't "improve the performance" beyond what the "fundamental design" was intended to deliver. They apparently fixed a problem that was affecting the performance negatively and was below what the design should have delivered. Now, it is performing as the design was supposed to do, hence in theory no need to change the design.

However, we don't really know what changed. They could very well have replaced one of the boards entirely - the DSP board or the input board or whatever was the root cause of the problem and the problem could be anything from a "faulty" capacitor to faulty board manufacturing to a faulty circuit layout, or even circuit design, etc.

Anyone who knows the story behind a voluntary auto recalls know that the public statement (to avoid liability) is very often never the truth of what was actually wrong.

I have no reason to believe Denon is lying about the "faulty" capacitor but I have no reason to believe that they would be telling the whole story either. This is standard practice in most manufacturing industries for PR or liability reasons.
 

Vasr

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#20
Normally when you hook up two Audio products with RCA cables, you cause ground currents to run between them and potentially create Hum.
Typically, when this happens, it affects all channels equally as their shields are connected to the same ground on the unit. Don't understand what happened here that affects only one channel.
 
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