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Review and Measurements of Denon AVR-4306

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Okay, here's the effect of a 470 ohm in-line resistance on the signal fed to a pair of Sennheiser HD 535 headphones. They are headphones with neither the most variable, nor the most even of impedances across the audible frequency range. This graph ought to be more satisfactory. It's generated by RightMark Audio Analyser 6.4.5. It's pretty much the same as the white noise graph I showed above. As Restorer-John says above, it's wise to choose headphones with a flat impedance since they'll be immune to frequency balance variations caused by the voltage splitting differently at different frequencies. But impedance graphs for headphones aren't routinely published, so it would be preferable if electronics didn't allow their output voltage to be much affected by headphone impedance. That is, it would be best if they would keep their internal impedance low.

Sennheiser HD 535 via 470 ohm load.png
 

cjfrbw

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As I recall, all of the Yamaha prepros of recent memory have had chip opamps for headphone that they rate at [email protected] I looked up the chip op amp on one of the high end Yamaha units (3000 model I believe) and it was an op amp that can be bought in bulk for 50 cents apiece. Not what I would call a high end solution, but I thought the headphone outputs of my various Yamaha receivers sounded pretty good nontheless.
 
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As I recall, all of the Yamaha prepros of recent memory have had chip opamps for headphone that they rate at [email protected] I looked up the chip op amp on one of the high end Yamaha units (3000 model I believe) and it was an op amp that can be bought in bulk for 50 cents apiece. Not what I would call a high end solution, but I thought the headphone outputs of my various Yamaha receivers sounded pretty good nontheless.
Ah, yes. Yamaha does seem to do it differently to the others. RMS open circuit headphone output voltage on a Marantz NR1609 is 27 volts, on a Pioneer VSX-LX303 is 15.5 volts, on a NAD T 758 v3 is 28.5 volts, on a Denon AVR-X3500H is 42 volts (!).

But on a Yamaha Aventage RX-A3080, it's only 3.2 volts. It seems that the others are just sticking some resistors in line with their speaker amp outputs, while Yamaha is using a specific amp (albeit one that still apparently needs 100 ohms in line).
 

cjfrbw

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The nice thing about the Yamaha headphone output is that all of the surround modes are mixed down to two channels, and you can use them with headphone listening. It is quite effective.
 

March Audio

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Biggest issue I've had with receivers using say 470 ohm or 220 ohm resistors to tap amp output is noise. I think that is because the amps in those often don't have great dynamic range or SNR at mid levels. With some headphones you sometimes get a little low level noise added to everything which I find sounds poor.
This is my experience with amps. A dedicated headphone section is a must imo, attenuated from the main output is not a good solution.
 

RayDunzl

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One issue I identified involves the calibration microphone connected using the headphone output. If nothing is done, the microphone could potentially be damaged when plugged in while a large level signal is at the headphone jack.
Does it come with a dynamic or condenser microphone?
 

Sal1950

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Curious how my Marantz AV7703 Pre/Pro generates it's headphone out. Has a nice 1/4" plug on front panel which I like over the flimsy 1/8" ones. Drives my Senn HD-650 to an unsafe level at 0 db and would still go up to +18 db so there's plenty of power. Did some searching on the net to find a spec or measurement but I guess no one pays much attention to the headphone stuff on 11 channel processor. LOL. Don't use it much myself in any case, when I want to listen to a source that drives my Emotiva DC-1 DAC, I plug into that, which Amir did measure with a excellent 0.9 ohm output impedance.
 

Sal1950

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But does not that comment go to the heart of the entire audio debate, i.e. once you get to a point where you cannot discern any further sound quality improvement then why spend any more?
I know, I quote Peter Aczel way too often.
"Amplifiers have been quite excellent for more than a few decades, offering few opportunities for engineering breakthroughs. There are significant differences in topology, measured specifications, physical design, and cosmetics, not to mention price, but the sound of all properly designed units is basically the same. The biggest diversity is in power supplies, ranging from barely adequate to ridiculously overdesigned. That may or may not affect the sound quality, depending on the impedance characteristics and efficiency of the loudspeaker. The point is that, unless the amplifier has serious design errors or is totally mismatched to a particular speaker, the sound you will hear is the sound of the speaker, not the amplifier. As for the future, I think it belongs to highly refined class D amplifiers, such as Bang & Olufsen’s ICEpower modules and Bruno Putzeys’s modular Hypex designs, compact and efficient enough to be incorporated in powered loudspeakers. The free-standing power amplifier will slowly become history, except perhaps as an audiophile affectation. What about vacuum-tube designs? If you like second-harmonic distortion, output transformers, and low damping factors, be my guest. (Can you imagine a four-way powered loudspeaker driven by vacuum-tube modules?)"

From,
Peter Aczel My Audio Legacy
 

restorer-john

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Ah, yes. Yamaha does seem to do it differently to the others. RMS open circuit headphone output voltage on a Marantz NR1609 is 27 volts, on a Pioneer VSX-LX303 is 15.5 volts, on a NAD T 758 v3 is 28.5 volts, on a Denon AVR-X3500H is 42 volts (!).

But on a Yamaha Aventage RX-A3080, it's only 3.2 volts. It seems that the others are just sticking some resistors in line with their speaker amp outputs, while Yamaha is using a specific amp (albeit one that still apparently needs 100 ohms in line).
Bear in mind, some manufacturers will also employ a resistive voltage divider to prevent excess voltage appearing over the headphone socket. Your 'unloaded' voltage test will be misleading in that case.

Example:

1549658615866.png


If you want to measure maximum available voltage swing at the headphone jack, use a fixed value resistor as your reference and measure the voltage drop over it. That will account for both series only resistive implementations, dividers, and dedicated headphone amps.

:)
 

JJB70

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I know, I quote Peter Aczel way too often.
"Amplifiers have been quite excellent for more than a few decades, offering few opportunities for engineering breakthroughs. There are significant differences in topology, measured specifications, physical design, and cosmetics, not to mention price, but the sound of all properly designed units is basically the same. The biggest diversity is in power supplies, ranging from barely adequate to ridiculously overdesigned. That may or may not affect the sound quality, depending on the impedance characteristics and efficiency of the loudspeaker. The point is that, unless the amplifier has serious design errors or is totally mismatched to a particular speaker, the sound you will hear is the sound of the speaker, not the amplifier. As for the future, I think it belongs to highly refined class D amplifiers, such as Bang & Olufsen’s ICEpower modules and Bruno Putzeys’s modular Hypex designs, compact and efficient enough to be incorporated in powered loudspeakers. The free-standing power amplifier will slowly become history, except perhaps as an audiophile affectation. What about vacuum-tube designs? If you like second-harmonic distortion, output transformers, and low damping factors, be my guest. (Can you imagine a four-way powered loudspeaker driven by vacuum-tube modules?)"

From,
Peter Aczel My Audio Legacy
I honestly think that the words Peter Aczel wrote as his audio legacy are a perfect summation of the state of audio and that he said pretty much all that you need to know in that one short article. A remarkable writer on matters audio, I could honestly read his words all day long.
 

maty

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In my second system I have an AV Marantz SR4500 tweaked and modified by me (it sounds much better than original, much better). The question is that I have an iFi micro iCAN (class A headphones amp), tweaked too.

Before my Marantz mods, the iCAN offered better sound to my open dynamic headphones (cheap Chinese Takstar ts-671 102dB, 120 Ohms, tweaked, modded and star quad recabled -much better sound now). But after my mods the Marantz has better sound! Of course, they need a HPF about 200 Hz (Q=0.7) to compensate for the bass excess caused by impedance mismatch.

Updated with the iZotope RX 7 De-Hum VSTplugin x64 in JRMC 24 x64. HPF at 220 Hz, Q=0.7

iZotope-RX-7-De-Hum-220-takstar-ts671-JRMC.png


Marantz SR4500

https://www.soundandvision.com/content/marantz-sr4500-av-receiver-ht-labs-measures

AV-Marantz-SR4500-headphone-scheme.png


iCAN

Especificaciones:

• Ganancia: 0dB, 10dB and 20dB user-selectable
• Ratio señal-ruido: >117dB(A)
• Total Harmonic Distortion(THD): <0.003%(400mV/150R)
• Frequencia de respuesta: 0.5Hz a 500KHz(-3dB)
• Potencia de salida: >400mW(32Ω)
• Voltaje de salida: >5V (>600Ω)
• Voltaje de entrada: AC 100 – 240V, 50/60Hz
• Uso de energia: < 4W reposo, 10W max.
• Dimensiones: 158(l)x68(w)x28(h)mm
• Peso: 216g

Class A, much better specs but worse sound!
 
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graz_lag

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Does it come with a dynamic or condenser microphone?
It is the typical mic supplied with the AVR for the digital room correction :

HK990 microphone.jpeg
 

restorer-john

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It is the typical mic supplied with the AVR for the digital room correction
They are pretty much always a 10 cent electret capsule and fed with DC bias from the AVR for the internal FET.
 
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Sal1950

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They are pretty much always a 10 cent electret capsule and fed with DC bias from the AVR for the internal FET.
That would make it unwise to plug any other mic into it then, no?
 

restorer-john

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hat would make it unwise to plug any other mic into it then, no?
Pretty much. Any electret would likely work, but the corrected response (eg audessy) would be potentially all over the shop as the compensation 'curve' could be quite different.

I like to think that they all use a quality Panasonic insert and crosscheck them all for adherance to a target curve, but I think that is optimistic. The inserts are most likely the 10c ones from China.

I have a few Yamaha ones here with the nice tripod mount on the bottom- I could test them just for fun to see how similar they are to one another.
 

Blumlein 88

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I know, I quote Peter Aczel way too often.
Is that a real thing?
What about vacuum-tube designs? If you like second-harmonic distortion, output transformers, and low damping factors, be my guest. (Can you imagine a four-way powered loudspeaker driven by vacuum-tube modules?)"

From,
Peter Aczel My Audio Legacy
Yes, yes I can. I want it to be electrostat multi-panels with DSP and David Berning switch-mode tube amps. Preferably the 211 based one's he makes.

Why tubes? Cause tubes give you street cred no matter what you are doing with them.

Triodes just make it more triodelicious!
 

Sal1950

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[QUOTE="Blumlein 88, post: 148613, member: ]

Triodes just make it more triodelicious![/QUOTE]
I starting to worry about you D.
 
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Bear in mind, some manufacturers will also employ a resistive voltage divider to prevent excess voltage appearing over the headphone socket. Your 'unloaded' voltage test will be misleading in that case.

Example:

View attachment 21569

If you want to measure maximum available voltage swing at the headphone jack, use a fixed value resistor as your reference and measure the voltage drop over it. That will account for both series only resistive implementations, dividers, and dedicated headphone amps.

:)
I use a little load box I made. I measure into open circuit, 47.1kOhm, 295 ohms and 15.9 ohms @ 100Hz, 1kHz and 10kHz. I advance the volume to the highest level it will go without visible clipping at 15.9 ohms and use that level for all the measurements. I calculate the resistance using both the 295 ohms vs open circuit, and 15.9 ohms vs open circuit measurements. So far all six results have been fairly close together. With these high resistance outputs the standard deviation is less than 2.5%. I have yet to get a different voltage measure between open circuit and 47.1kOhms.
 

sonci

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I wonder what a Denon PMA 2500 or 1600Ne would measure..
They are very interesting like an all in one box, Dac + Amplifier..
 

maty

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To finish with respect to the iFi iCAN micro, I suspect that its bottleneck is the small SMPS.

My problem is that I prefer to listen to music through the speakers (KEF Q100, tweaked and modded to) and I hardly use the headphones, so I have not looked for an alternative to the power. Well, I researched but decided it was not worth the expense. The cheap headphones sound very good but I do not like to have anything in my head. That is why I decided to try something cheap before buying more expensive ones, but after my improvements the sound is very satisfactory, very good (I listen to very good recordings with high/very high dynamic range).
 

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