Denon AVR-4700 Preamp Mode Question

[kevin1969]

This is probably been addressed somewhere on the forum but I can't seem to find it. Are the Tone Controls and Audessy correction still available if the AVR is in pre-amp only mode?

 

[Golfx]

This is probably been addressed somewhere on the forum but I can't seem to find it. Are the Tone Controls and Audessy correction still available if the AVR is in pre-amp only mode?

 

[Golfx]

Yes. Those are functions of the preamp purpose.

 

[batfunk]

An other question about preamp mode and i want a definitive answer:
If i assign the 4700 on 11.1 setup, connect a 3 channels power amp to it(with fronts left, right, centre speakers on it), Will the centre give sound ?
If it's yes, which amp powers it, internal denon one or power amp one or both (?). Will sound quality suffer from it, worse than if powered by 4700 internal amp only ?


Me and a friend are in a disagreement...

 

[batfunk]

Strange, i read everywhere that on 11.1 assignement, with power amp connected on the back and fronts assign to preouts, it automatically deactivate Denon front left and right internal amps...

"Next, use the Center "Pre-out" RCA to the external power amp and then Fronts and Center will be powered off the external amp"

You mean that before i connect the center preout rca, L and R are powered by External amp ? After that, L C and R Will be powered by Denon amp ? Sorry, my english is poor...

If i resume, with 11.1 assignement and whatever power amp(3 channels or 5 or 7) behind, speakers connected to power amp Will be powered by the power amp and others by Denon but Will not benefit from the cleanliness of the preamp only mode ? Right ?

 

[Golfx]

PreAMP amp assign mode shuts off ALL internal amps.

 

[Dj7675]

PreAMP amp assign mode shuts off ALL internal amps.

To reduce confusion... instead of shuts off, better to use the term disconnect.

 

[batfunk]

I understood that. My question was simple:

On 11.1 assignement, Can i connect a center speaker on a power amp and benefit from it as with Front Left and right channels ?

 

[Golfx]

Agreed but didn’t know sender’s mastery of English words.

 

[Golfx]

Only Denon 8500 or a110 can selectively shutoff (disconnect) individual channels beyond the LR feature. So even though your LR channel internal amps are disconnected your center channel internal amp would not be disconnected. But would gleefully use any external amp.

 

[batfunk]

Thanks. I assume it's the same with this case:
-11.1 assignement with fronts assigned to preout
-5 channels power amp
-5.1.4 speakers.

5 speakers Will benefit from the watts of the power amp, but only L er R from the cleanliness (better Sinad, less distortion).
The others speakers are powered by the Denon. Right ?

That Will be my Last question

 

[peng]

Thanks. I assume it's the same with this case:
-11.1 assignement with fronts assigned to preout
-5 channels power amp
-5.1.4 speakers.

5 speakers Will benefit from the watts of the power amp, but only L er R from the cleanliness (better Sinad, less distortion).
The others speakers are powered by the Denon. Right ?

That Will be my Last question

That is correct, but keep in mind in practice, even the 3 channels not assigned to pre out because you can't, will still have the same SINAD as the front left and front right that are assigned to pre out at output voltage level up 1.4 V or a little more. At higher output level SINAD would degrade gradually as the internal power amps starting to clip and would be at about 75 dB at about 2 V.

At pre out voltage of 1.4 V, a power amp that has the same 29 dB gain as the internal amps, would output almost 200 W into 8 ohms or 400 W into 4 Ohms.

So for those who don't listen near reference level, sitting not too far (say 10-12 feet) and have speakers that have sensitivity not too low, say 87 to 90 dB, preamp mode, amp assign or neither, SINAD will not really degrade, but of course preamp mode has other benefits even if SINAD is not the issue.

 

[peng]

As far as selecting the Front Pre-out configuration in 11.1 you are correct the power rail is disconnected from the internal amp in this configuration but all other internal amps are live.

That would be nice, but the fact is, the internal amps will still be connected to the power rail. It is the power amp inputs that get disconnected from the corresponding preamp outputs. This is the same for both amp assigned set to preamp, or in full preamp mode. The difference is, using the amp assign feature, only the front left and front right channels can be assigned to pre out.

 

[batfunk]

Hi again ! Finally another question

With another setup,:
5.1.4 speakers
11.1 assignement
2 power amps, one for left and right, one for centre(purifie mono Block) .

I know that Denon centre preout Will clip at 1.4 vrms(internal amplifier still connected). My centre power amp has a 2.25 vrms input.
Can i compensate voltage difference by increasing output gain in denon setup?How?Is it worth it ? Will i still lose watts to power central speaker compared to internal amplifier capacity ?

Thanks again !

 

[peng]

Hi again ! Finally another question

With another setup,:
5.1.4 speakers
11.1 assignement
2 power amps, one for left and right, one for centre(purifie mono Block) .

I know that Denon centre preout Will clip at 1.4 vrms(internal amplifier still connected). My centre power amp has a 2.25 vrms input.
Can i compensate voltage difference by increasing output gain in denon setup?How?Is it worth it ? Will i still lose watts to power central speaker compared to internal amplifier capacity ?

Thanks again !

Again, the pre out doesn't clip at 1.4 Vrms (the internal power amp will be clipping at that point). Take a look of the center channel of the X3600H, that obviously has the internal power connected:

That's almost as good as the AV7705 (a so called "separate" preamp processor.
Note that the dash board of the AV7705 measurements show about 4 V but that's XLR, had Amir used RCA for that measurement, it would have been 2 V and SINAD would have been about the same, again, as the AVR-X3600H that is an AVR, therefore internal amps would be "clipping" and degrading the SINAD at pre out.

So I really wouldn't worry about your center channel, unless you will be pusing the Purifi amp to output almost 400 W average (800 W peak) into 8 Ohms and you can hear the difference between 75 dB and 95 dB SINAD (I know I can't..).

 

[batfunk]

Again, the pre out doesn't clip at 1.4 Vrms (the internal power amp will be clipping at that point). Take a look of the center channel of the X3600H, that obviously has the internal power connected:

That's almost as good as the AV7705 (a so called "separate" preamp processor.
Note that the dash board of the AV7705 measurements show about 4 V but that's XLR, had Amir used RCA for that measurement, it would have been 2 V and SINAD would have been about the same, again, as the AVR-X3600H that is an AVR, therefore internal amps would be "clipping" and degrading the SINAD at pre out.

So I really wouldn't worry about your center channel, unless you will be pusing the Purifi amp to output almost 400 W average (800 W peak) into 8 Ohms and you can hear the difference between 75 dB and 95 dB SINAD (I know I can't..).

View attachment 128503

View attachment 128504

Hmmm, if i understand, only denon internal amps Will clip if i push beyond 1.4 vrms output. Denon preouts will still power to the max my purifi moblock(2.25 vrms input, 257 watts 4 ohms 2 channels driven) at the expanse of Sinad.

So why this Amirm's recommandation ? :

"As you see, peak performance with the amplifiers off is around 1.1 volts with SINAD of 101 dB which is excellent for an AVR. With the amps on, you are OK up to 1.4 volt output before it nose dives. So when selecting an external amplifier for channels beyond fronts, make sure it can output its maximum power at or below 1.4 volts (usually specified as "sensitivity")."

Was He talking about Sinad only and not power ?

 

[peng]

Hmmm, if i understand, only denon internal amps Will clip if i push beyond 1.4 vrms output. Denon preouts will still power to the max my purifi moblock(2.25 vrms input, 257 watts 4 ohms 2 channels driven) at the expanse of Sinad.

As someone mentioned, it depends on how we define "clip". Someone suggested 0.1% THD, others may say 1%, or 0.05%, so again, it depends..
If I remember right, Amir seems to consider the "clippping" point where THD starts to rise sharply, that means SINAD would start to fall sharply. So if you look at that graph, you can see for the X4700H, it would be 1.4 V. However, if you base it on say 0.05%, that is 66 dB SINAD, then the pre out with the internal amp remain connected does not clip even at 2 V or higher. At that level, if sustained (that would be rare for real word contents) the amp may shutdown, depending on the protection system's design. In my opinion, Amir is not wrong but I don't agree with using the term "clip" until SINAD falls to say less than 80 dB, that is THD+N = 0.01% and Amir would go with that, from the same graph, pre out would be at about 1.6 Vrms. That would still be generous, because it would mean the Marantz AVP "clips" at about the same point as a Denon AVR. I am sure no owners of any Marantz AVRs/AVPs would agree with that. This is just my own opinion and I won't argue with anyone who don't agree with me.

So why this Amirm's recommandation ? :

"As you see, peak performance with the amplifiers off is around 1.1 volts with SINAD of 101 dB which is excellent for an AVR. With the amps on, you are OK up to 1.4 volt output before it nose dives. So when selecting an external amplifier for channels beyond fronts, make sure it can output its maximum power at or below 1.4 volts (usually specified as "sensitivity")."

I think by now, you should know Amir sets his bar at different height than some other reviewers lol!! Again, think about this, so it nose dive from 1.4 V at peak performance, to 74-75 dB SINAD at 2 V? Nose dive or gradual fall, or whatever you'll be the judge on how it compares with the SINAD of some of the AVPs that don't even have internal power amps!!

Was He talking about Sinad only and not power ?

I think the part you quoted was from the X3700H review, and yes he's talking about SINAD of the pre out.

 

[bigguyca]

Hi again ! Finally another question

With another setup,:
5.1.4 speakers
11.1 assignement
2 power amps, one for left and right, one for centre(purifie mono Block) .

I know that Denon centre preout Will clip at 1.4 vrms(internal amplifier still connected). My centre power amp has a 2.25 vrms input.
Can i compensate voltage difference by increasing output gain in denon setup?How?Is it worth it ? Will i still lose watts to power central speaker compared to internal amplifier capacity ?

Thanks again !

V not v for volt. You might as well learn to use the correct units.

If your power amplifier requires 2.25Vrms for full output, and the input to the power amplifier is 1.4Vrms, then you will lose about 4.1dB of output from the full output of your power amplifier by driving your power amplifier with 1.4Vrms.

 

[batfunk]

Noted for Volt unit. As you noticed I'm a noob. Thanks again !

 

[bigguyca]

Again, the pre out doesn't clip at 1.4 Vrms (the internal power amp will be clipping at that point). Take a look of the center channel of the X3600H, that obviously has the internal power connected:

That's almost as good as the AV7705 (a so called "separate" preamp processor.
Note that the dash board of the AV7705 measurements show about 4 V but that's XLR, had Amir used RCA for that measurement, it would have been 2 V and SINAD would have been about the same, again, as the AVR-X3600H that is an AVR, therefore internal amps would be "clipping" and degrading the SINAD at pre out.

So I really wouldn't worry about your center channel, unless you will be pusing the Purifi amp to output almost 400 W average (800 W peak) into 8 Ohms and you can hear the difference between 75 dB and 95 dB SINAD (I know I can't..).

- Omitted -

Denon/Marantz Preamp output limits and Gain Structure

I'm becoming less convinced over time that the 1.4V preamp limit is based on the associated power amplifier channel clipping. There may be a lot we don't understand about the Denon/Marantz AVR's/AVP's. This is a good subject for some future thread. Some items to consider concerning the 1.4V level and also the D/M gain structure.

(1) 1.4V into an amp with a 28.2x gain gives 39.5V or a rail voltage of 55.4V plus some extra for drops in the power stage. 39.5V into 8 ohms is about 200W.

With five channels driven the power output per channel may drop to 100W. This requires an output of 28.3Vrms with 39.6V as the rail voltage. At a gain of 28.2x the input from the preamp would be about 1V. Does this really mean that the preamp channels now essentially clip at 1V output since the associated undriven power amplifier stage will now clip at 28.3V output due to the drop in the rail voltage due to the load on the other channels?

This drop in preamp clean output suggests that the distortion performance of the preamp outputs will be modulated by the output of the power amplifier channel. This seems a mess and unacceptable. The 1.4Vrms value is such a common value in D/M gear that I wonder if it is set by gear and not determined by the clipping level.

(2) Based on my measurements of the AV7705, a 0dbFS input with 1.4V XLR output results in about -96dB THD and about -95dB THD+N. -6dBFS input with 1.4V XLR output with the volume control increased by +6dB results in about -104dB THD and -99 THD+N. Does Denon/Marantz make use of this relationship in the actual operation of the AVR's/AVP's? Output levels in the 1V to 2V range produce similar relationships in output performance.

Products like RME DAC's switch resistors to change gain to a take advantage of this sort of relationship. D/M could reduce the digital output in the DAC IC by 6dB and increase the volume control setting (internally, not seen by the user) by 6dB to get the better measurements noted above. The relatively low preamp output levels reported by many for D/M gear used in home theaters of -10dB to -25dB would allow a lot of room for adjusting gain to maximize performance.