Denon avr-x3900h preamp measurements

[Dougey_Jones]

Don't these affect the frequency and phase response somewhat? I usually address HDMI ground loop hum by simply using fully isolated optical HDMI cables since it will have no effect on the sound output while eliminating the hum.

Interesting. Which specific HDMI cable are you using? Most active optical HDMI cables still have copper conductors for DDC/CEC/eARC, so I didn't think they completely eliminated ground loops. If they're affordable I'd be happy to give it a shot because it would eliminate the need for my Rolls line filter.

 

[jonfitch]

Interesting. Which specific HDMI cable are you using? Most active optical HDMI cables still have copper conductors for DDC/CEC/eARC, so I didn't think they completely eliminated ground loops. If they're affordable I'd be happy to give it a shot because it would eliminate the need for my Rolls line filter.

Get one with external USB power. It's fully electrically isolated.

Amazon.com

 

[Dougey_Jones]

Get one with external USB power. It's fully electrically isolated.

Amazon.com

Oooohhhh weeeeeee, $133 for an HDMI.

I’ll give it a try

 

[jonfitch]

Oooohhhh weeeeeee, $133 for an HDMI.

I’ll give it a try

You don't have to buy them new. They get sold used on third party markets like ebay for cheap often. I have like 5-6 pairs of these I snagged for around $30-40 each.

 

[Platypus]

Anyone sent in a X3900H for testing?

 

[Power Pop 23]

Anyone sent in a X3900H for testing?

Yes, another member has confirmed this AVR is in the queue.

 

[Kichoi]

Denon AVR-X3900H does have noise through preamp outputs in preamp mode. All channels had hissing and also faint 60hz noise audible from about 3' away from all speakers. I've given up and wanted to return but missed the return window from Amazon. Decided to use is as HT only and playing through its internal amps. Although I have set it for full range front L&R and rest as small with 80Hz crossover. In 9.1 setup with two powered subs, it is good enough to play sound during NFL games and Blu-Ray concert videos. It is nice to be able to switch 4 HDMI sources but had to limit eARC HDMI cable to 4M long max to avoid 4K video issues. After about three hour use with its 9 channels of its amps running it got toasty when touched on top.

 

[Ruediger]

Denon AVR-X3900H does have noise through preamp outputs in preamp mode. All channels had hissing and also faint 60hz noise audible from about 3' away from all speakers.

Sounds like a ground loop to me.

If you trigger the external amp, try removing the trigger cable to test. Also make sure you use a mono cable.

 

[Toni71]

I have a 3900H with a Rotel 1582 MKII power amp connected. There is no hiss from my speakers. In my experience with the heat, that can sometimes be an issue with AV receivers. I’ve had around 25 receivers over the years (I’m getting old and have two setups), most of them top models from various brands, mostly used as processor with external amplifiers. Even then, I always put a fan on top of every receiver to extract the heat (Noctua now a days, silent). Even with an AV10 processor.

 

[Kichoi]

Sounds like a ground loop to me.

If you trigger the external amp, try removing the trigger cable to test. Also make sure you use a mono cable.

Thanks for your comment. Unfortunately the noise is present even with no analog/digital inputs nor HDMI inputs and using just two front channels' preamp outputs idling. I am getting used to using the receivers internal amps and they are not too bad driving a pair of Genesis Maestros for front, another Genesis center channel, two Genesis P7 petites for side surrounds, Paradigm Monitor 3s for back surrounds and NHT Ones for Front Heights.

 

[Kichoi]

I have a 3900H with a Rotel 1582 MKII power amp connected. There is no hiss from my speakers. In my experience with the heat, that can sometimes be an issue with AV receivers. I’ve had around 25 receivers over the years (I’m getting old and have two setups), most of them top models from various brands, mostly used as processor with external amplifiers. Even then, I always put a fan on top of every receiver to extract the heat (Noctua now a days, silent). Even with an AV10 processor.

Interesting to know you are not getting any noise using external amps with X3900H. Have you tried to put your ear close to the speaker and try to listen for noise?

 

[Ruediger]

Thanks for your comment. Unfortunately the noise is present even with no analog/digital inputs nor HDMI inputs and using just two front channels' preamp outputs idling.

If it's a ground loop with poweramps, then it's there all the time regardless of inputs.

The reason I'm mentioning it is that I have seen this exact behaviour from a X3800H.

 

[Toni71]

Dear Kichoi,

Of course. Completely silent on my Kef Reference 5 Meta. After I've read your post, I checked this. But if the noise was present, I would have noticed that for sure. I am critical.

 

[peng]

Dear Kichoi,

Of course. Completely silent on my Kef Reference 5 Meta. After I've read your post, I checked this. But if the noise was present, I would have noticed that for sure. I am critical.

I am not surprise to know yours is silent. I don't own an AVR-3900H but did own several Denon from the 1000 to 4000 series (including two that have very similar preamp/dac signal path parts/circuitry) before, as well as two Marantz AV preamp processors, and have never had audible hiss with any of the Denon avrs unless my ears are actually touching the case but even then it would only be audible if the room was in its quietest state, fridge, HVAC all off, and volume up near 0. The Marantz AV8801 did give me audible noise during very quiet passages and the room quiet but the volume would have to be cranked up pass -10 to -15 so for normal listening still not an issue.

It is hard to image given the specs and parts used in the preamp/dac signal path of the X3900H would do worse so I would suggest @Kichoi to continue his efforts in isolating the root cause(s). It is more like a higher pitch hiss than hum, it may not be due to ground loop, but other sort of interference picked up that could be reduced/eliminated by experimenting with wiring layout. I might have mentioned that possibility before but thought it might be worth repeating.