Denon AVR-X6700H AVR Review (Updated)

[Bello]

Isn't SINAD a character from Disney cartoons ?.

MAAAAAAAN you kiddin... I thought Joe Biden was a character from Disney too

 

[Obiden]

MAAAAAAAN you kiddin... I thought Joe Biden was a character from Disney too

"Come on Maaan "

 

[Fillius]

I have received my X6700 back. The box has taken a bit of a beating (thanks UPS), but the unit seems unharmed as far as I can tell.

The statement of work included said they replaced the 'DAC PCB':

Looking back at the original and updated measurements, this seems appropriate since the HDMI measurements improved, but the analogue didn't (if you exclude the grounding improvements).

I expect there will also be an improvement on the analogue performance when not used in pure-direct mode. If the input is digitised, it then presumably needs to go through the DAC board the same as any other signal.

I will wire it up tonight and have a listen, I'm looking forward to getting the 'weighty' sound back, I've been using my old Onkyo for a week now and it sounds bright/harsh/hollow in comparison. Although this could just be down to the room correction differences and the fact I had Audessey only correcting up to 300Hz on the Denon (not configurable on the Onkyo).

 

[peng]

Peng- I appreciate your time / attempt to answer my question. I'm certain, if I personally attempt all what you recommended. I'd be left with a far off estimate given all factors, and unknowns. At the end, I think I'll stick with my personal estimate right / left channels (ears) as my power meter SINAD, lol

When I receive my newly, correctly spec'd 6700H. I'll see if I hear a pre-amp difference or not. And later rely on Amirm's random re-test reassurance of a correctly spec'd system.

Thank you!

You are very welcome!

Long story short, the biggest unknown (yes there are more, such as the level trim settings..) that makes it practically impossible to calculate pre-out voltage and power amp output watts based on volume position only, is the signal level of the media content. If you are watching a Star War movie, during the very quite scenes, you can turn the volume to 95, your pre-out voltage and power amplifier output would still be near 0 V and 0 Watt, while in a loud explosion scene, even with volume at 75, your pre-out voltage could be over 1 V and power amplifier output may peak to over 100 W.

If you use a constant signal level such as the AVR generated test tone, then you can do some meaningful calculations.

I suggest you try the calculator I linked, and you may find that you actually don't need more than a few watts on average, with peaks to may be 100 watts, or much less. It depends a lot of how far you sit and how loud you listen.

 

[peng]

I have received my X6700 back. The box has taken a bit of a beating (thanks UPS), but the unit seems unharmed as far as I can tell.

The statement of work included said they replaced the 'DAC PCB':
View attachment 81188
View attachment 81189
Looking back at the original and updated measurements, this seems appropriate since the HDMI measurements improved, but the analogue didn't (if you exclude the grounding improvements).

I expect there will also be an improvement on the analogue performance when not used in pure-direct mode. If the input is digitised, it then presumably needs to go through the DAC board the same as any other signal.

I will wire it up tonight and have a listen, I'm looking forward to getting the 'weighty' sound back, I've been using my old Onkyo for a week now and it sounds bright/harsh/hollow in comparison. Although this could just be down to the room correction differences and the fact I had Audessey only correcting up to 300Hz on the Denon (not configurable on the Onkyo).

If you can hear a difference from the better cap's effects, then I would say you have excellent "hearing".., or Placebo works well on you..

 

[bigguyca]

I think it will be quite pointless hunting cap porn.. There is little chance an electrolytic would lead to so much worse SINAD. If so, it must be such a bad alternative part, that it would be beyond stupid.

As for the "monoblock" amps.. That's one part marketing, and another part flexibility in thermal setup. In the end the design and layout of the individual amps is more important than it having a single or multiple PCBs. In any case, it is clear that they don't really spend a lot of money and design skills on these amps: they are just dua(or is it even single layer?)l layer PCB's with conventional components, and riddled with wire bridges. Due to thermal issues, they even need to standoff a lot of the components (see raised resistors and caps), which adds inductance everywhere. That alone would add significant noise and distortion. Why they would choose the cheapest PCB tech is also beyond me.. A 4 layer design would easily be far superior, and not much more expensive. And a SMD board would save a shitload of money on assembly, and would yield a much smaller amplifier, leaving much more room for better cooling. And while they are at it.. why not switch (pun intended ) to Class D amps. It would actually give the opportunity to really give a shitload of more power output for the higher tier amps.

The Effect of Electrolytic Capacitors on Denon DAC Performance

The AKM DAC iC's used in the Denon products are voltage output DAC's. An electrolytic capacitor and resistor are used to implement a 1st order R/C lowpass filter for the DC reference voltages supplied to the DAC IC's. The "quality" of the reference voltage has a direct effect on the noise characteristics of the output.

The AK4458 8-channel DAC used in the X6700H has 4 of these filters per IC. This is one filter for each of the reference voltage supplies. There is one supply for each two channels. The AK4490 2-channel DAC used in the X8500H has a reference voltage supply for each channel with one filter for each supply. The minimum value for the electrolytic capacitors seen in current products is 220uF, with values up to 470uF seen in some units. The value of the capacitors used by D/M has increased over the years.

The higher the value of the filter capacitor the better the filter. A defective capacitor in the filter location would have very negative effects on performance. Here is a graph showing the effect of the value of properly functioning capacitors on the noise performance of the AK4490 DAC as used in the AK4490 Evaluation Board. The graph is from Version 1 (deleted in Version 2) of the AK4490 Evaluation Board Manual. The overall effect of capacitor value on AK4458 DAC noise performance is likely similar.

The important concept is that the filter capacitor can have significant effect on noise performance. The actual values of noise would vary depending on other aspects of the design in the actual product. A lower noise power supply, and careful board layout and cable routing would result in the lower noise DC voltage supply, with less noise to be removed.

 

[voodooless]

The Effect of Electrolytic Capacitors on Denon DAC Performance

The AKM DAC iC's used in the Denon products are voltage output DAC's. An electrolytic capacitor and resistor are used to implement a 1st order R/C lowpass filter for the DC reference voltages supplied to the DAC IC's. The "quality" of the reference voltage has a direct effect on the noise characteristics of the output.

The AK4458 8-channel DAC used in the X6700H has 4 of these filters per IC. This is one filter for each of the reference voltage supplies. There is one supply for each two channels. The AK4490 2-channel DAC used in the X8500H has a reference voltage supply for each channel with one filter for each supply. The minimum value for the electrolytic capacitors seen in current products is 220uF, with values up to 470uF seen in some units. The value of the capacitors used by D/M has increased over the years.

The higher the value of the filter capacitor the better the filter. A defective capacitor in the filter location would have very negative effects on performance. Here is a graph showing the effect of the value of properly functioning capacitors on the noise performance of the AK4490 DAC as used in the AK4490 Evaluation Board. The graph is from Version 1 (deleted in Version 2) of the AK4490 Evaluation Board Manual. The overall effect of capacitor value on AK4458 DAC noise performance is likely similar.

The important concept is that the filter capacitor can have significant effect on noise performance. The actual values of noise would vary depending on other aspects of the design in the actual product. A lower noise power supply, and careful board layout and cable routing would result in the lower noise DC voltage supply, with less noise to be removed.


View attachment 81212

Like I said.. " it must be such a bad alternative part, that it would be beyond stupid."

 

[bigguyca]

I have already done an numerical example for you in my post#213 so I am only going to be repeating part of it that is applicable here.

On the bench, Amir was getting 2 V, volume 82.5. The power amplifier output would be almost 400 W based on gain = 29 dB. For calculations see post#213.

For volume 72.5, that's a drop of 82.5-72.5 = 10 dB.

To calculate the pre-out voltage:
Vpre-out=2X10^(E5/20) = 2X10^(10/20) = 2X0.31623 = 0.6325 V.

To calculate the power amp output voltage:
https://emotiva.com/products/xpa-2-gen3

From the Emotiva website linked above, we know that the gain is 29 dB, that is, same as the X6700H

Power amp output voltage = Input voltage (that is the X6700H) pre-out voltage X 10^(29/20) = 0.6325 X 28.1838 = 18.826 V
Power amp output =(V^2)/8 = 18.826 X 18.826/8 = 39.72 W

That's of course base on Amir's bench tests that use digital input of 0 dBFS as bigguyca mentioned before.

I took a look of Spotify's website and if I understood right, they use "loudness normalization" and the normalized level is -14 dB LUFS.
https://artists.spotify.com/faq/mas...-is-loudness-normalization-and-why-is-it-used

LUFS is not the same as dBFS, so you really don't know what the pre-out voltage would be if you are streaming from them and have volume at 72.5. From what I can gather though, the pre-out voltage would likely be less than the 0.6325 V that I calculated as shown above, based on Amir's measurements using digital signal at 0 dBFS.

For ball park estimate, I would say use pre-out voltage 0.6325 V and Power amp output 39.72 W and that would be on the high side or reality.

Also, all my calculations were based on trim level settings of "0 dB". What did Audysssey set the level trims to?

For more accurate numbers, you are going to have to take some measurements and make a bunch of assumptions. Even then, you really can only calculate/estimate sort on a worst case scenario basis. That is because the pre-out voltage and power amp output "watts" at volume 72.5 or whatever depends on the input signal level to the AVR, and that various moment by moment with the music. Music is not a test tone at a constant level. So yes, that would be beating a dead horse in a sense.

If you wish to play with more calculations yourself, there are some online calculators. I developed my own in Excel because there aren't any online one that can do everything I want. The one linked below is one of the best site for such calculators.

http://www.sengpielaudio.com/calculator-FactorRatioLevelDecibel.htm

The easiest way to estimate your power need is probably to do it in reverse, that is, find out the spl you listen to with a reliable spl meter such as Radio Shack's 33-2055, use "C" weighting slow, and an online spl calculator such as the one linked below:

https://myhometheater.homestead.com/splcalculator.html

LUFS

The following link provides a excellent explanation of LUFS and the associated standard, EBU R 128. It would be best to read the link before proceeding with the remainder of this post unless you are already familiar with the subject. A search of the Internet will provide more information.

https://en.wikipedia.org/wiki/EBU_R....&text=It was first issued by,in the ITU-R BS.

For purposes of looking at maximum output requirements, maximum digital output under the EBU R 128 is still based on 0dBFS. (but read the link) Material with a higher LUFS value will sound louder, but the LUFS value doesn't define the maximum value for that material. Maximum output should still be based on 0dBFS.

LUFS values for audio material are evidently based on complex computer programs that are in turn based on research into perceived loudness. The LUFS value of a piece of audio material can also be set/adjusted by computer programs. This allows the material to be used on sites that have specified requirements for LUFS values.

The link above provides a bit of interesting information concerning the loudness levels of streaming platforms that use LUFS. See the chart in the lower left corner, above the references. It appears that Tidal will sound louder than Apple Music. Apple Music will sound louder than Facebook.

The above is from a bit of reading. There are no doubt those here who are much more familiar with LUFS technically, and in actual use, who could add a lot more insight.

 

[Obiden]

I ordered my X6700

 

[SILLENT HILL]

Great review and a big surprise from the update, I wait in anticipation on a Marantz 8015 review as they are very close in most areas.

 

[Bello]

I ordered my X6700

I hope you had them checked s/n's before they ship it.

 

[Obiden]

I hope you had them checked s/n's before they ship it.

I was assured that these are their latest coming from Denon.

 

[Bello]

I was assured that these are their latest coming from Denon.

As mentioned many times over, trust but verify.

 

[Obiden]

As mentioned many times over, trust but verify.

The great Reagan said that once.

 

[Obiden]

Sorry if I triggered some of you guys

 

[crawfordiii]

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.

View attachment 79205

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:

View attachment 79206

This catapults the 6700H into the coveted green category of DACs from formerly red status:
View attachment 79207

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:

View attachment 79209

IMD test shows the improved distortion:

View attachment 79210

Linearity improved as well:

View attachment 79211

As did filtering:

View attachment 79212

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

View attachment 79213

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

View attachment 79214

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

View attachment 79215

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:

View attachment 79216

View attachment 79218

But signal to noise ratio improved good bit:

View attachment 79219

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:

View attachment 79221

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.

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

US is nearly one of its most important elections in decades. The panthers have been watching the election news with me and are demanding that I campaign for them to get the right to vote!!! I tell them this is not going to happen but they don't listen. They want me to make signs for them and go stand on street corners to protest. I figured it is easier to do that than to argue with them but I don't have the money for signs. Would you be kind enough to donate what you can to make them happy using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

If people are worried about whether Denon provided a "golden" one, we can always have Amir test another one from the latest production run provided by a user.

 

[Mikechw]

I was comparing different AV receivers and found this Yamaha receiver pre-amp.

https://www.audioholics.com/av-preamp-processor-reviews/yamaha-cx-a5200-mx-a5200/conclusion

I see the measurement result is around 101db (1k hz tone @ 1Vrms)..
So how do I compare it with the results of Amirm's measurements of Denons ?

Thanks..

 

[peng]

I was comparing different AV receivers and found this Yamaha receiver pre-amp.

https://www.audioholics.com/av-preamp-processor-reviews/yamaha-cx-a5200-mx-a5200/conclusion

I see the measurement result is around 101db (1k hz tone @ 1Vrms)..
So how do I compare it with the results of Amirm's measurements of Denons ?

Thanks..

Are you referring the their SNR/DR measurements, as Gene commented that:

The Yamaha CX-A5200 exhibited a very low noise floor for almost every mode of operation. In Pure Direct with an HDMI input signal of -10dBFs, the measured SNR was > 101dB (a-wt) at 1Vrms output which is excellent.

compared that to Denon AVR-4700H's:

The Denon has much better number but that's measured with output at 2V RCA. If Audioholics measured the CX-A5200 at 4 V XLR, it would have much higher number than 101 dB, probably a little better than Denon's but won't be by much, that's my educated guess.

https://www.ap.com/technical-library/signal-to-noise-ratio-snr-dynamic-range-and-noise/
https://www.ap.com/technical-library/more-about-signal-to-noise-ratio-and-dynamic-range/

 

[Mikechw]

Thanks for the info..
I am looking for a pre only AV receiver.

 

[sp123]

Is the 6700 similar to 6300 (few years old)?