Denon AVR-X3600 Heat and Eco Mode Observations

[Timbo2]

Given the recent focus on the various Denon AVRs I figured I'd post my research and observations. As I had no need of 8K video and preferred not to be bitten by the multi-channel bug Amir found in the 3700 I recently picked up a 3600.

The thing is about 3/4 of an inch taller than my last AVR and the Denons are noted for running hot. I was already tight on space so cooling is a concern. I'd read elsewhere that when running on "Auto" for Eco mode that there is essentially a hard transition to "Eco Off" at about 45 on the volume scale. This seemed odd to me as I would have thought it was dependent on the source volume, but it does indeed to be the case. So on anything except a silent source with the volume above 45 you will hear a relay click and the receiver kick out of Eco. From my observation there would seem to be no downside to "Auto" as for anything but the softest listening it won't be used. It really does seem as if if was designed only to satisfy regulatory requirements for idle power draw.

While the unit does have two fans they never activate in normal use despite the unit getting quite warm to the touch. Amir isn't the only one who has noted this. Fortunately for me I reached into my large store of PC parts and had a spare Noctua 140mm fan. Noctua makes great stuff with a focus on durability and low noise. Problem was until recently you had to deal with tan and brown fans!

This particular fan starts and runs fine on 5V and I used a DVM to measure a maximum current draw of about 390mA. So I grabbed an old USB cable and wired the two together. I initially plugged it into the Denon AVR's front USB slot, but the bad news here is that the USB is powered when the unit is in standby. I thought I was stuck until I remembered my TV has 3 USB ports and the 1A one is switched with the TV. Problem solved! So when my TV is on I have the fan gently blowing across the top of the unit. The unit now only gets warm to the touch and I can't hear the fan at any seating position in the room. When you shut down the TV and AVR so does the fan!

For folks without the PC parts basket and the extra USB cable a variable speed USB fan is usually under $20US.

 

[rxp]

Laptop cooling pads or things like this are also very easy to do and useful: https://www.amazon.co.uk/gp/product/B071CL82G9/. I like that gadget because it has the variable fan control built in and it's cheap as buying the fans yourself and rigging it up.

I've actually gone into using Eco mode full time since trying it out in a heatwave the last couple weeks. I listen at reference volume (0 on AVR), calibrated with 85dbA (A in small rooms is better IMO) on a UMIK-1 at my listening position. When a loud scene came on in a movie or TV show I'd quickly toggle the eco mode off and on and I couldn't discern any difference. That's on my KEF R300 setup, I sit 1.8m away from the center channel.

Now the amp runs nice and cool with no fans needed.

It is frustrating that D+M won't have a better algorithm for controlling eco. Since Audyssey Dynamic Volume looks ahead one frame or half frame (forget which) there's scope within the processing to know what's coming. So it could dynamically adjust the Eco mode based on a look ahead algorithm.

 

[rccarguy]

What's the point of fans in the avr if they never kick in? Why don't they allow you to customise fan profile? Ie lowest rpm whenever in standby and 10 mins after switch off

 

[bobopich]

What's the point of fans in the avr if they never kick in? Why don't they allow you to customise fan profile? Ie lowest rpm whenever in standby and 10 mins after switch off

Probably because Denon guys put them in to kick only in extreme situation and the temps although seemingly high are actually quite normal. I have the 3600 and checked in a few times, it is not hotter than my previous Arcam 390 nor hotter than my 4 channel AB Nad amp for atmos channels.

 

[Timbo2]

What's the point of fans in the avr if they never kick in? Why don't they allow you to customise fan profile? Ie lowest rpm whenever in standby and 10 mins after switch off

I’m a bit sympathetic to Denon here. I’ve been building PCs for decades and fan failures are a common issue. Bearing technology is a trade off between quiet and durability. So in a data center application they use ballbearings which are noisy. There are companies like Noctua that have custom bearing designs that are quiet and long life but at a cost. So on something like this where every penny counts Denon has to choose noisy ball bearing or short life sleeve bearings. No idea which they chose here, but neither is conducive to continuous use in a home environment.

My guess is they are ball bearing and because of noise only come in the worst case. Both a fan controller and fan that will work well with a controller add cost.

 

[rccarguy]

I would still like user control of that, plus I can always replace them when they die, or upgrade them to delta crossflow 200cfm

 

[Lattiboy]

I’m using my 3600H as a pre amp for my mains and subs and having it only power the center channel. I also disconnected the front amps with the 11.1 channel setting.

I have been super impressed with heat management! I’m coming from a Marantz SR6012 which was doing the same work and it is night and day. The 6012 would be HOT AS HELL after about thirty minutes of pre amp work. Before that I had a 3500H and it too got very hot. I should’ve taken proper thermal measurements, but just by touching the top the 3600H gets just slightly warm, even after multi hour listening. This is the case even if I’m using the center channel for movie viewing.

Very happy with my purchase and wanted to let people know that disconnect feature is real and makes this one of the coolest running non-class D amps I’ve ever owned.