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Review and Measurements of Denon AVR-4306

maty

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2 / I own a Yamaha RX-V683, which includes a "limited" DAC at 24bits / 192khz. Am I mistaken in saying that one way to upgrade stereo sound quality would be to use an external DAC with 32 bits/384Khz, like the topping D50?
[Polish] https://audio.com.pl/testy/kino-domowe/amplitunery-av/2824-yamaha-rx-v683

to English with Google: https://translate.google.com/translate?sl=pl&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=https://audio.com.pl/testy/kino-domowe/amplitunery-av/2824-yamaha-rx-v683&edit-text=&act=url

[Hungarian] https://www.av-online.hu/hazimozi/yamaha-rx-v683-hazimozi-erosito-teszt_2346

to English with Google: https://translate.google.com/translate?sl=hu&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=https://www.av-online.hu/hazimozi/yamaha-rx-v683-hazimozi-erosito-teszt_2346&edit-text=&act=url

[Manual, PDF] https://usa.yamaha.com/files/downlo...web_YJ202A0_EN_RX-V683_om_UCRABGLFH_En_B0.pdf

To listen good recordings try with Direct but, FIRST, try different Input trim values (by default is 0 dB). The sound will not only increase or decrease in volume. Page 93. The test is free.
 
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andreasmaaan

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@Jean-Philippe, @amirm is of course spot on with his advice.

24/192 is already way beyond the limits of human hearing, so there will be no inherent advantage in using a DAC with higher bit depth/sample rate.

But on the other hand, if you enjoy your current speakers, stick with them :)

A better way to approach this then would be to ask, what don’t you like about how your system sounds (if anything)?
 

amirm

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Hi, I’m interested in HD-AMP1, how soon do you expect to publish results?
Hi. I still have a few urgent ones to get out of the way and then I can review the Marantz.
 

trl

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It would be interesting to see sines and squares (dual spot scope, to compare both IN and OUT) at 10KHz and 20KHz. In A/B tests I was able to perceive differences if phase delay is really visible or if square starts to get rounded corners. I was only using headphones to test this; on speakers I doubt I'll feel any difference.
 
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I don't imagine that you measured the headphone output on the Denon receiver, or I suppose you would have reported it. I've been measuring the output impedances on some mid to high level home theatre receivers lately, and in recent models I'm getting 98 ohms (Yamaha), 327 ohms (Pioneer), 460 ohms (NAD) and 470/480 ohms (Marantz and Denon). They are of course insanely high numbers and obviously impact on the performance of many headphones. I was wondering whether the older Denon might be similar.
 

restorer-john

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...They are of course insanely high numbers and obviously impact on the performance of many headphones...
These are deliberate and very sensible design choices. Since Adam was a boy, headphones outputs are fed via resistors.

The headphone outputs are of course tied to the main power amplifier stage and without dropper resistors, your headphones would be vaporized with a tiny turn of the volume control and probably deafen you at the same time.

Here's the AVR-4306 implementation:

1549594011537.png
 
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True, that's certainly a way of protecting both headphones and amplifier. Another way would be to put in a separate headphone amp with suitable output protection. The result of these high impedance outputs is wide (and unpredictable) frequency response variations in many headphone models, and lousy bass damping.

Meanwhile, the output resistance of a diminutive $AU12 iPhone DAC/headphone amp is just 1.5 ohms. (But they aren't really suitable for high impedance headphones, due to the <1VRMS max output).
 
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Incidentally, after I wrote that post I remembered I had a 13 year old Yamaha receiver here, so I measured it and it comes in at 100 ohms output. My ancient NAD 1010 preamp doesn't have a power amplifier (for speakers) at all, of course, but it still applies 235-ish ohm output resistance.
 

restorer-john

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...Another way would be to put in a separate headphone amp with suitable output protection...
Plenty of manufacturers are doing this now. Since the recent (<10 years) explosion in headphone listening popularity and the re-emergence of proper headphones, people are demanding a little more than the token implementation.
 
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bigx5murf

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I don't imagine that you measured the headphone output on the Denon receiver, or I suppose you would have reported it. I've been measuring the output impedances on some mid to high level home theatre receivers lately, and in recent models I'm getting 98 ohms (Yamaha), 327 ohms (Pioneer), 460 ohms (NAD) and 470/480 ohms (Marantz and Denon). They are of course insanely high numbers and obviously impact on the performance of many headphones. I was wondering whether the older Denon might be similar.
My Yamaha actually lists 100ohm in the manual specs. Looks like they at least rated conservatively.
 

restorer-john

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Which is why I'm pointing out areas of the industry and models which don't. It seems that big brand home theatre receivers don't.
By definition, big home theatre receivers are not designed for headphone listening, it's rare people are going to sit in their big-ass home theatre room with their monster AVR listening on headphones.

It's not a priority in the HT world, never has been. I would say 99.9% of HT receivers have never had headphones plugged into them.

Seriously, headphone listeners take themselves way too seriously. I have many hundreds of HiFi components in my collection and there wouldn't be one with a dedicated ultra low output impedance headphone amplifier. Many have source impedances around 100ohms on digital sources, often driven by ubiquitous opamps from +/-15V rails. They need dropper resistors or serious hearing damage could occur.

If I want a zero output impedance source because I'm obsessed about minor FR variations in my attached cans, I have plenty of preamplifiers with output impedances of a few ohms that are way quieter than some of the dedicated HP amps being peddled these days. With high rails and robust line driver stages, they can run headphones directly. Damping in the bottom end with headphones is a fallacy. They have no moving mass, don't generate any back EMF of significance and their impedance plots are benign.
 
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By definition, big home theatre receivers are not designed for playing network audio, but they do it. Since they do it, it's worth reporting on this aspect of performance. Since they offer headphone outputs, it's worth reporting on this as well. Which until recently is something I've neglected to do. I've seen no survey of headphone usage, but I would note that the receiver makers consider it a selling point to include something like 'Silent Cinema' headphone mode (Yamaha), which attempts to replicate surround sound through headphones. Likewise Denon lets one use 'Virtual' with headphones.

It's not my job to tell people whether they are too obsessed with some aspect of performance. It's my job to tell people about as much as possible and let them weigh up which is important to them. If they don't use headphones, they can ignore that. And if I don't report on this aspect -- and nobody else does -- it will never change. If over time it becomes an 'issue', then the manufacturers will change it.

There are quite a few headphone amp reviews here at Audio Science Review. Because people who like headphone listening need to buy a separate headphone amp because the ones built into general purpose equipment are inadequate.

Finally, I note that many of the frequency response graphs here of things like DACs resolve down to +/-0.1dB. Here's the voltage of a signal being received by a pair of Sennheiser HD 535 headphones which the signal is delivered through a 470 ohm load (voltage expressed as dB). Perhaps that's a 'minor' response variation. Perhaps not:
Sennheiser HD535 on 470 ohm load.png
:
 

restorer-john

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Perhaps that's a 'minor' response variation. Perhaps not:
Yes, minor. But with that plot, you'd be hard pressed to extract anything useful out of it, other than the resonant impedance peak being around 80-90Hz, where the impedance reaches about 500 ohms on that model, as compared to 320 ohms or so at 1KHz. Clearly there's a ton of uncertainty with a >6dB fuzz at the top end and >4dB at the low end. Basically, I'd chuck it out and start again. Too many sampling points, way too much non-linearity in the A/D or whatever software you are using, and it ultimately proves nothing useful does it?

A swept sine will be a lot more useful.

Headphones are a benign load and easy to drive with a reasonable voltage swing.

https://www.audiosciencereview.com/...dphone-amplifier-drive.2327/page-2#post-76501
 
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Of course there's a lot of uncertainty. I did those measurements a few weeks ago and I was doing third best because the RMAA software I normally use is flaky, and wouldn't work any more on any of my computers. I've just re-installed the OS on this desktop and got RMAA going again, so I plan to repeat. But what you see is good enough for proof of concept. It doesn't take much to see a 4dB swing between the high and the low. That's a 4dB swing in the signal being delivered to the headphones.

Here's the same test repeated on a set of magnetic planer headphones which are said to have a flat impedance across the audio spectrum. Note, same fuzz (since it's just ten seconds of white noise). But easy enough to see that there's no bias towards any particular frequency:
Blue Ella Passive.png
 

Blumlein 88

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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.
 

restorer-john

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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 very true. And also, if you were to remove the resistors, to get a closer to zero output impedance, you'd be hearing even more residual noise. That said, I am a firm believer in either running a dedicated headphone stage or picking cans that are relatively immune due to their inherent flat impedance and can be driven happily via a higher impedance source.

I have a few integrated amplifiers of good pedigree where there is essentially no noise to speak of on the headphone jacks, regardless of the sensitivity of the attached cans.
 

graz_lag

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My Yamaha DSP-Z7 is rated @ 150mV / 100 Ohms ...

Interestingly, because these AVR amplifiers offer the acoustic optimization via the microphone, a potential issue associated to the headphone stage is described in the review of my Harman Kardon HK990 by Mr. David A. Rich of hometheaterhifi.com : (the HK990 is not an AVR but it offers a 2.2-channel EQ room optimization)

HK 990 Headphone Stage
The high performance Texas Instrument TP6120 obviates DC coupling or blocking capacitors in this stage. The TP6120 has very low distortion and noise. It has a current feedback topology and 1300V/us slew rate. I have no idea why it is designed with a slew rate 100 times larger than what is required. Without circuit details, I cannot conclude if Otala would approve, but with a THD under full load approaching 0.0002% at 1 kHz, I doubt this design has low return-loop gain.
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. The headphone amps are disconnected when the HK 990 is put in calibration mode, but it is unclear if they are disconnected automatically when the microphone is inserted and the unit is not set to calibrate. I suspect all HK units with room calibration have the same issue but they use a small IC to drive high efficiency headphones. The TP6120 can deliver much more current and only a 20 ohm resistor is between it output and the headphone jack. The instruction book does not caution about these circumstances.
 
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