Denon AVR-X8500H 13.2CH IMAX Enhanced AV Receiver Review

[AcuDefTechGuy]

Do you think i am better off with a proper av processor rather than using a denon x8500?
I like the denon as it is future proof but i understand audyssey is not great.
If yes which one do you suggest arcam, anthem, onkyo etc...
I couldn't pass on the rotel 1585 as it was real bargain( its a beast )and weight a 40 kg.

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I think if you’re going to spend that much money, might as well get a Separates pre-pro from Yamaha, Anthem, Arcam, or Marantz.

 

[lovinthehd]

Future proof? LOL, sure. As far as getting a dedicated pre-pro since you have the amp....maybe.

 

[Verdinut]

That's only true if the volume level isn't high enough to clip the internal power amps.This is a problem I'm finding in most AV receivers including Denon and Marantz without a poweramp disconnect mode.

What would cause the internal power amps to clip when they are not connected to any load?

 

[gene]

Do you think this has always been the case with avrs or a fairly new development? How far back are you finding this?

It's probably always been this way and I've seen it in FFT distortion tests but never understood why until recently that I realized the power amp sections were clipping causing it.

 

[PENG]

What would cause the internal power amps to clip when they are not connected to any load?

Here's why:

P = (V^2/Z)*P.F. (P: Power in Watt, V: Voltage in Volt, Z: Impedance in ohm, P.F.: power factor = Cosine (phase angle)

Vo = Vi*((10^(Vg/20))) (Vo: Output voltage, Vi: Input voltage, Vg: voltage gain

At an input voltage Vi of 1.3 V, and Voltage gain of 29 dB (Denon/Marantz/Yamaha AVRs/AVP/Cs),

Vo (Output voltage) = 36.64 V, and Power output = 167.8 W if connected to an 8 ohm load.

At that point, a little AVR like the AVR-X3600H, SR6013/4 would be well into clipping already.

You are correct that when there are no speakers connected power output will be 0, but that's only because there is no load connected, the voltage is still there, at 36.64 V, that is, well past the clipping point. So the lower the AVR's rated power output, the earlier the power amp output voltage will clip.

 

[Verdinut]

Here's why:

P = (V^2/Z)*P.F. (P: Power in Watt, V: Voltage in Volt, Z: Impedance in ohm, P.F.: power factor = Cosine (phase angle)

Vo = Vi*((10^(Vg/20))) (Vo: Output voltage, Vi: Input voltage, Vg: voltage gain

At an input voltage Vi of 1.3 V, and Voltage gain of 29 dB (Denon/Marantz/Yamaha AVRs/AVP/Cs),

Vo (Output voltage) = 36.64 V, and Power output = 167.8 W if connected to an 8 ohm load.

At that point, a little AVR like the AVR-X3600H, SR6013/4 would be well into clipping already.

You are correct that when there are no speakers connected power output will be 0, but that's only because there is no load connected, the voltage is still there, at 36.64 V, that is, well past the clipping point. So the lower the AVR's rated power output, the earlier the power amp output voltage will clip.

1. Am I right in assuming that the pre-out voltage which feeds an external is split between the input to the external amp and the input to the internal amp?

2. Then if that assumption is exact, the pre-out voltage would need to be quite high ie > 2 volts to get the internal amp to clip.

3. Would that internal amp clipping affect the SQ out of the external amp the point that it would be audible to a certain extent? Were some serious practical tests done to prove an impairment in the SQ in such circumstance?

 

[PENG]

1. Am I right in assuming that the pre-out voltage which feeds an external is split between the input to the external amp and the input to the internal amp?

2. Then if that assumption is exact, the pre-out voltage would need to be quite high ie > 2 volts to get the internal amp to clip.

3. Would that internal amp clipping affect the SQ out of the external amp the point that it would be audible to a certain extent? Were some serious practical tests done to prove an impairment in the SQ in such circumstance?

1. I'm not sure what you meant by "split"? Yes, the pre-out voltage is applied to both the internal amp and the external amp and it should be the same as long as the combined impedance of the internal and external amps are within the current capability of the preamp.

Remember the formula for calculating equivalent resistance/impedance of a parallel circuit?

From Wiki:

For example, if your Marantz's internal amp's input impedance is 15,000 ohms and your external DCA1622's input impedance is 10,000 ohms, then the combined equivalent impedance of the two amps running in parallel, that is, both being fed by the same preamp, will be:

R (consider it resistance for simpliciy) eq. = 10000X15000/(10000+15000) = 6000 ohms

That means for the same pre-out voltage, say 1.3 V the same value I used in my post #45, the pre-amp will have to deliver more current than if it is only feeding the internal amp. Based on this example, the pre-amp IC alone without help by a buffer stage (OPA, HDAM etc..) should still be able to close to 4 V (depending on the IC and the buffer/if any) so for real world movie/music use I don't see any problem.

2. I don't know what you mean here. In my post #45, Vo is the pre-amp output, i.e. pre-out voltage; and is therefore the Vi, i.e. input voltage to the power amp. So in the numerical example I used, when the pre-out voltage reaches approx. 1.3 V (by cranking the volume up), the power amp output voltage will reach approx. 36.6 Vrms, that's a whopping 57.75 V!! If you connect an 8 ohm resistor to the output of the power amp, at that voltage the power into the resistor will be 36.6*36.6/8 = 397 W average, or 794 W peak!! Since something like a Denon AVR-X3000 series or Marantz SR5000 series would likely be starting to clip when their rated output (100-110 W) by 50%, I thought I could make an educated guess that the power amp's output voltage would start to clip at around 37 Vrms, 58 V peak because that would be voltage required to deliver 167 W into 8 ohm. Again, I could be wrong but I doubt I would be too far off.

3. Assuming Gene is right about the internal power amp clipping (again, that is the power amp output voltage clipping) affecting the pre-out negatively, i.e. higher distortions, then yes it will affect the external amp because it is the same pre-amp that is driving both internal and external amp.

 

[anthonyrizzo84]

So to resume, is there any gain using an power amp into the denon x8500 ?
My rotel is almost as expansive as the denon so i would hope so

 

[everettT]

So to resume, is there any gain using an power amp into the denon x8500 ?
My rotel is almost as expansive as the denon so i would hope so

So to resume, it depends. If you're clipping your speakers without it, yes. If not, maybe.

 

[anthonyrizzo84]

So to resume, it depends. If you're clipping your speakers without it, yes. If not, maybe.

Is there anyway to shut the internal amp of the denon for the front, center and surround and use the power amp for those rather than having all internal amp off ?

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[everettT]

Is there anyway to shut the internal amp of the denon for the front, center and surround and use the power amp for those rather than having all internal amp off ?

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I know there was talk of that being possible on the newest, but I haven't heard of conformation. I use a 3500 for a preamp in my two channel setup and have not had any issues with the preout not driving my amp.

 

[AcuDefTechGuy]

The key, again and again and again, is the VOLUME.

For most people with normal hearing acuity in most typical rooms no larger than 20’ x 20’, listening to normal non-deafening volume, you have nothing to worry about.

But you do need to add about 2 fans to that AVR to keep it cool.

 

[PENG]

Is there anyway to shut the internal amp of the denon for the front, center and surround and use the power amp for those rather than having all internal amp off ?

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I was waiting for @gene or @TheoN to give you a definitive answer but no show so far so I am going to simply quote jdsmoothie:

The *OFFICIAL* Denon AVR-X8500H 13.2ch Flagship AVR Thread

www.avsforum.com

"X8500H also has a "Custom" amp assign setting which allows you to map virtually any speaker binding post to any channel of output. For example, if you're using a 5ch amp to power LCR+Surrounds in the main zone, you can repurpose the unused FL/FR and SL/SR amps in the AVR to power Zone 2/3 speakers (the X6400H only has predefined templates for amp assign)."

If you go to post #2 and scroll down, there is a table, that I believe might have been copied from the Owner's manual.

So yes, you can do it by using the custom amp assign feature instead of the "pre-amp mode" that would disconnect the internal amps via switches NJU72750.

The AVR-X8500H is the only AVR in the D+M line up that allows such disconnection between the pre-amp and power amp sections using the custom assign feature. The lower models such as the AVR-X3600H, through X4X00H, and SR6012 through SR7013 only allows you to do the same with the FL and FR channels.

By the way, even "pre-amp mode" will not turn off the internal amps off (this, is according to Gene iirc),it simply isolate the pre-amp from the power amp, so the power amps rail will still be "live". From the pre-amp stand point, it will still behave like the prepro AV8805, just no HDAM..and no balanced output.

Edit: I edited AVR-X3X00H to AVR-X3600H, because anything older than the 3600 in the 3000 series are capable of 7.1 only, therefore the FL/FR internal amps are not asssignable because it would be of no purpose anyway.

Also, the amp assign trick/cheat likely won't work on the AVR-X6400/6500H because they have 11 channel amps and 11.1 processing but don't have the flexible "custom assign" feature that the AVR-X8500 offers.

 

[PENG]

Verdinut, below is a good reference for you. For the internal amp and external amp both connected to the pre-amp (that is, pre-out, in the case of using your AVR) scenario, just imagine the same diagram but with a second Amplifier connected in parallel to the one shown in the sengpielaudio.com digram. You can easily see that the pre-out voltage, that is, input voltage at the power amplifier(s) input is the same as is in the case of only one power amplifier is connected, as long as the much reduced impedance due to the two parallel load effect is still more than high enough for the pre-amplifier output stage.

Measuring input impedance and calculating output impedance calculation calculate audio amplifier op-amp how to measure impedance voltage gain total loudspeaker speaker microphone resistance resistor bridging matching test load loudspeaker source resistance - Why input impedance is in parallel and output impedance is in series? - sengpielaudio Sengpiel Berlin

Calculate input impedance and measure output impedance calculation total audio amplifierr op-amp how to measure impedance voltage gain total loudspeaker speaker microphone resistance resistor bridging matching test load source resistance - Eberhard Sengpiel sengpielaudio

www.sengpielaudio.com

 

[Verdinut]

Assuming Gene is right about the internal power amp clipping (again, that is the power amp output voltage clipping) affecting the pre-out negatively, i.e. higher distortions, then yes it will affect the external amp because it is the same pre-amp that is driving both internal and external amp.

@PENG,
So, on any AVR without disconnection of internal amps, when an internal amplifier starts clipping, since it would also affect the performance of the preamp section driving that power amp, doesn't that impairment of the preamp circuit performance add to the power amp's THD and stability? But I've never heard of a reference to that preamp effect. I guess that it would be almost impossible to measure it?

 

[anthonyrizzo84]

I was waiting for @gene or @TheoN to give you a definitive answer but no show so far so I am going to simply quote jdsmoothie:

The *OFFICIAL* Denon AVR-X8500H 13.2ch Flagship AVR Thread

www.avsforum.com

"X8500H also has a "Custom" amp assign setting which allows you to map virtually any speaker binding post to any channel of output. For example, if you're using a 5ch amp to power LCR+Surrounds in the main zone, you can repurpose the unused FL/FR and SL/SR amps in the AVR to power Zone 2/3 speakers (the X6400H only has predefined templates for amp assign)."

If you go to post #2 and scroll down, there is a table, that I believe might have been copied from the Owner's manual.

So yes, you can do it by using the custom amp assign feature instead of the "pre-amp mode" that would disconnect the internal amps via switches NJU72750.

The AVR-X8500H is the only AVR in the D+M line up that allows such disconnection between the pre-amp and power amp sections using the custom assign feature. The lower models such as the AVR-X3600H, through X6X00H, and SR6012 through SR7013 only allows you to do the same with the FL and FR channels.

By the way, even "pre-amp mode" will not turn off the internal amps off (this, is according to Gene iirc),it simply isolate the pre-amp from the power amp, so the power amps rail will still be "live". From the pre-amp stand point, it will still behave like the prepro AV8805, just no HDAM..and no balanced output.

Edit: I edited AVR-X3X00H to AVR-X3600H, because anything older than the 3600 in the 3000 series are capable of 7.1 only, therefore the FL/FR internal amps are not asssignable because it would be of no purpose anyway.

This is amazing, what a beast
This amp has everything, i am glad i pull the plug on this no regret.

 

[RRRR]

Anyone know what will happen in HDMI 2.1?
Cost of upgrading kit?

 

[anthonyrizzo84]

Hi Guys, any tips on how to set up audyssey properly on this amp, i have the app as well.

Thanks for your help

 

[lovinthehd]

Hi Guys, any tips on how to set up audyssey properly on this amp, i have the app as well.

Thanks for your help

Lots of good setup guides out there if you do a search, including a decent one in the manual. Basically place mic at ear height, use all 8 positions with the first being your MLP-main listening position and group the other positions around that (I use about a 2ft radius from MLP using a mic boom). I'd recommend turning off Dynamic Volume if enabled at the end but would suggest you do experiment with using DynamicEQ and Reference Level Offset for various content. It may also set some speakers to full range rather than use a crossover, but that's Denon rather than Audyssey's recommendation when using subs.

 

[anthonyrizzo84]

Hi there, got this amp as well and love it.
I have the audyssey app as well and i am not to sure how to set it up like you explain in your review.
Could you help?