Denon AVR-X4800H AVR Review

[soerenssen]

Super informative and helpful as always, much appreciated @peng!
I contacted KEF and asked for the impedance and phase angle curves, in order to make the right amp choice.

 

[soerenssen]

a clasAB or class D power amp that is rated for 300 8 ohms, 600 W 4 ohms.

How important is the 2ohm performance in this case? The 1ET7040SA, at least with the MA power supply, is rated 950W at 2ohm but less power at 8ohm than the NCx500, while the NCx500 is rated at 700W (with dedicated PSU) at 2 and 4 ohm too. I'm just curious, by looking at the impedance curves, how do you decide which fits the speakers's impedance profile better?

 

[soerenssen]

If I bi-amp the fronts following Denon's instructions, can I send more current to the KEFs?
Would it change the impedance requirements?
Is it a good idea with the Denon (at least as long as I don't have an external amp) or would it damage the AVR?
I don't instructions for the center - is it possible to bi-amp that too (in a 5.1 speaker setup)?

The goal would be to make use of the internal amps as much as possible.

 

[peng]

How important is the 2ohm performance in this case? The 1ET7040SA, at least with the MA power supply, is rated 950W at 2ohm but less power at 8ohm than the NCx500, while the NCx500 is rated at 700W (with dedicated PSU) at 2 and 4 ohm too. I'm just curious, by looking at the impedance curves, how do you decide which fits the speakers's impedance profile better?

For the reference speakers rated 4 ohms by KEF, don't worry about the amp's 8 ohm output, focus on the power output into 4 ohms and 2 ohms, make sense?

 

[soerenssen]

For the reference speakers rated 4 ohms by KEF, don't worry about the amp's 8 ohm output, focus on the power output into 4 ohms and 2 ohms, make sense?

Both the NcoreX and the Purifi (with dedicated PSU for each amp) seem to be more than adequate, so the cheaper / more available should be the one I guess.

 

[peng]

If I bi-amp the fronts following Denon's instructions, can I send more current to the KEFs?
Would it change the impedance requirements?
Is it a good idea with the Denon (at least as long as I don't have an external amp) or would it damage the AVR?
I don't instructions for the center - is it possible to bi-amp that too (in a 5.1 speaker setup)?

The goal would be to make use of the internal amps as much as possible.

It will help the amps in terms of heat dissipation, but the effect will be very marginal, virtually no effects.

Active cooling is the way to go. I use a near silent fan for may preamp processor, because the build in fan is audible from a few feet and I prefer to keep it off regardless.

 

[peng]

Both the NcoreX and the Purifi (with dedicated PSU for each amp) seem to be more than adequate, so the cheaper / more available should be the one I guess.

Sounds logical.

 

[soerenssen]

It will help the amps in terms of heat dissipation, but the effect will be very marginal, virtually no effects.

Active cooling is the way to go. I use a near silent fan for may preamp processor, because the build in fan is audible from a few feet and I prefer to keep it off regardless.

What pre/pro and amp are you using if I may ask? And what speakers are they driving?

 

[peng]

What pre/pro and amp are you using if I may ask? And what speakers are they driving?

I am using a lower end Anthem avp (AVM70), and 3 power amps, MM8003 for surround, M2200 for the center, and MCA20 for FL/FR.

Speakers: Energy Veritas 2.3i

 

[anarchist]

This is interesting. I cannot compare mine to other receivers on the same set of speakers but I can still send it back if I find a better alternative. In my case, I noticed the weak bass when I used the internal amps of the Denon, but I use an external amp for LR and no problems. The Pioneer for twice as much would probably struggle too. My plan is to have a dedicated second system in parallel, used only for stereo, so the Denon won't heat up my apartment while listening to background music. It gets ridiculously hot..

I recorded a short comparison video of Yamaha A3080 vs Denon 4800H.
Frankly after calibrating SPL levels of both receivers to ~60 dB, they sound more similar than not, yet Yamaha being slightly brighter/edgy (clear?) to my ears - the reason could be better DAC in Yamaha, and/or extended HF response comparing to Denon, just speculating.

 

[peng]

I recorded a short comparison video of Yamaha A3080 vs Denon 4800H.
Frankly after calibrating SPL levels of both receivers to ~60 dB, they sound more similar than not, yet Yamaha being slightly brighter/edgy (clear?) to my ears - the reason could be better DAC in Yamaha, and/or extended HF response comparing to Denon, just speculating.

Very decent bass extension from the organ, towers only or with sub(s)?

 

[pogo]

No idea why you respond to the post

That was already intended for you and referred to your complete post
If you don't follow the manufacturer's guidelines, you shouldn't be surprised if the amplifier sections or the tweeters are pre-damaged and fail sooner or later.
...we couldn't convince him otherwise...is totally out of context and you can hear that even before!

 

[anarchist]

Very decent bass extension from the organ, towers only or with sub(s)?

Towers only, double 8" woofers.

 

[peng]

For the reference speakers rated 4 ohms by KEF, don't worry about the amp's 8 ohm output, focus on the power output into 4 ohms and 2 ohms, make sense?

Since you mention 2 ohms, I suspect you may still be thinking about the so called 1.8 ohms EPDR shown in Erin's measurements. Let me try to clarify that a little more:
EPDR is Equivalent Peak Dissipation Resistance. You cannot use that value to calculate current draw by the speaker. Current, still has to follow Ohm's law, current = Voltage/Resistance, or for impedance, current, I = V/(|Z|), |Z| is the absolute value of impedance. The low value of EPDR vs just impedance does not change the calculated current, it just changes the calculated heat dissipation by the amplifier.

For example, if impedance is 3 ohms, EPDR is 2 ohms, at a given voltage, say 30 V, the current flow is still going to be I = V/|Z| = 30/3 = 10 A, not 15A (A is ampere), but the heat dissipation will be expected to be equivalent to that resulted from a load with impedance = 2 ohms. I hope this does not confuse you.

To see how EPDR is calculated, read jackocleebrown's post:

Stereophile has started calculating EPDR.

https://www.stereophile.com/content/goldenear-brx-bookshelf-reference-x-loudspeaker-measurements And he is going back to previous reviews and adding this in. EPDR (Equivalent Peak Dissipation Resistance) takes the impedance and phase data and computes a new impedance that shows what equivalent...

www.audiosciencereview.com

 

[peng]

That was already intended for you and referred to your complete post
If you don't follow the manufacturer's guidelines, you shouldn't be surprised if the amplifier sections or the tweeters are pre-damaged and fail sooner or later.
...we couldn't convince him otherwise...is totally out of context and you can hear that even before!

I would say there is no need to convince him any more, if you mean @soerenssen, he already knows what the 4-ohm setting is for, after being linked the Audioholics article. Our discussions has been about using that setting, and/or take precautions to not crank the volume above 50-60. For Denon, you probably know that using 82 as reference (based on ASR measurements), even at 60, it would be 22 dB below reference, so the amp output voltage would be quite low, mostly likely below (don't want to say 100% sure just in case) the rail voltage limit for the 4-ohm setting. Anyway, I think he is convinced to look for a power amp such as those based on the NCx, with appropriate SMPS. Until then, I trust he would use the 4-ohm setting. He seems like someone who is very careful about the whole thing, it is very unlikely he would damage the tweeter or the Denon.

 

[pogo]

it just changes the calculated heat dissipation by the amplifier.

This is not correct. Perform a reactive load test and you will immediately recognize the problem of conventional AVRs. The voltage drop is still the least evil.

 

[soerenssen]

I would say there is no need to convince him any more, if you mean @soerenssen, he already knows what the 4-ohm setting is for, after being linked the Audioholics article. Our discussions has been about using that setting, and/or take precautions to not crank the volume above 50-60. For Denon, you probably know that using 82 as reference (based on ASR measurements), even at 60, it would be 22 dB below reference, so the amp output voltage would be quite low, mostly likely below (don't want to say 100% sure just in case) the rail voltage limit for the 4-ohm setting. Anyway, I think he is convinced to look for a power amp such as those based on the NCx, with appropriate SMPS. Until then, I trust he would use the 4-ohm setting. He seems like someone who is very careful about the whole thing, it is very unlikely he would damage the tweeter or the Denon.

Correct. As long as I don't get a new power amp, I'll use the 4 ohm setting. Stereo at max. 60dB. I am watching Mad Max Fury Road and I had to increase the master volume to 65dB because at 4ohm setting I don't understand speech coming from the R6 Meta center. Either 8ohm setting at lower master volume level (and the top of the AVR getting hot quickly) or 4ohm at around 5dB higher (and the top of the AVR staying a bit cooler that will be easily addressable using active cooling. I'm hearing more details / better clarity at higher volume levels. So instead of DAC improvements, more power seems to be the way to go. The difference is easily noticeable when listening to speech from the center.
It is really time to do a new Dirac calibration too (along with REW) so I expect things get better soon!

 

[ban25]

Correct. As long as I don't get a new power amp, I'll use the 4 ohm setting. Stereo at max. 60dB. I am watching Mad Max Fury Road and I had to increase the master volume to 65dB because at 4ohm setting I don't understand speech coming from the R6 Meta center. Either 8ohm setting at lower master volume level (and the top of the AVR getting hot quickly) or 4ohm at around 5dB higher (and the top of the AVR staying a bit cooler that will be easily addressable using active cooling. I'm hearing more details / better clarity at higher volume levels. So instead of DAC improvements, more power seems to be the way to go. The difference is easily noticeable when listening to speech from the center.
It is really time to do a new Dirac calibration too (along with REW) so I expect things get better soon!

My advice remains:

1. Apply a house curve with Dirac
2. Confirm results with REW
3. Buy a subwoofer

Any differences between amps, once properly level-matched, will be impossible to discern in a blind A/B test. The KEFs, with their small 6.5" woofers, are unable to compete with a good 8-12" subwoofer. Consider KEF's specifications for the KF92: -3 dB at 11 Hz compared to those of the Reference 3 Metas: -6 dB at 28 Hz.

As far as the heat is concerned. The majority of it is from the AVR's HDMI board and internal processing, and that will be active no matter what speakers are driven. I ran my full 5.1 setup on a Denon X3700H for a year -- no external amplification -- and had no issues with heat or clipping.

 

[peng]

Correct. As long as I don't get a new power amp, I'll use the 4 ohm setting. Stereo at max. 60dB. I am watching Mad Max Fury Road and I had to increase the master volume to 65dB because at 4ohm setting I don't understand speech coming from the R6 Meta center. Either 8ohm setting at lower master volume level (and the top of the AVR getting hot quickly) or 4ohm at around 5dB higher (and the top of the AVR staying a bit cooler that will be easily addressable using active cooling. I'm hearing more details / better clarity at higher volume levels. So instead of DAC improvements, more power seems to be the way to go. The difference is easily noticeable when listening to speech from the center.
It is really time to do a new Dirac calibration too (along with REW) so I expect things get better soon!

Volume at 65 is still safe, but please do use an ext. fan. As explained before, the artificially lowered EPDR value is used to account for the much higher heat dissipation, it is a thermal issue so you can mitigate the effects by using active cooling.

I think I have done the calculations, before but maybe appropriate to repeat it at this point:

Based on Amir's measurements, the X4800H's pre out is about 2 V, with volume at 82, and input HDMI at 0 dBFS (see pic of the dashboard below).

With Pre out voltage at 2 V, the Power output at 8 ohms will be about 400 W, or 800 W into 4 ohms, based on the Denon's gain of 29 dB.

So at 62 dB volume, that is a drop of 20 dB, power output will drop by 100X, that is 8 W into 4 ohms.

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At 65 dB volume, power output will double to 16 W into 4 ohms.
Now, if you assume the EPDR is 2 ohms overall, the heat dissipation in the Denon amp will then be double again, that is 32 W into 4 ohms.

I think we can all agree that 32 W into 4 ohms is still within the Denon's power limit even with impedance setting set to 4-ohms. Reminder: This is "equivalent" based on heat dissipation. In reality, at volume 65, your spl calculation is still going to be based on 16 W into 4 ohms. If you want to know the spl you can achieve under such conditions, use the online calculator, or give me the distance and I can do it for you.

There is still some room to go higher, but to be on the conservative side, and being at the 4-ohm impedance setting, volume 65, that is -15, is probably the limit you should adhere to and not exceed it. At this level, you can still stay clear from the Denon's clipping point.

Note: Calculations based on volume setting above assume direct mode, if Audyssey is in use, check the level trim settings and if they are not at 0, then adjustment to the volume limit of 65 need to done (up or down) accordingly. Audyssey may also apply boost to the bass, though I wouldn't worry too much if you are using subwoofers and set crossover to 80 Hz.

The above calculations are based on Amir's actual bench test measurements, as shown below:

 

[peng]

This is not correct. Perform a reactive load test and you will immediately recognize the problem of conventional AVRs. The voltage drop is still the least evil.

Do you read the posts before responding?
Again, no idea why you keep saying things not related to the topics being discussed.

Who said anything about volrage drop?

If there is anything incorrect, it is your generalized, blanket statement about avrs being a problem driving reactive loads.