805 and 875 overheating

NewHTguy

I've been considering upgrading from my Onkyo 605 to either the 805 or 875. Some of the reviews on Amazon claim that these AVRs get too hot and, in a few instances, have actually started to smoke! I'm wondering how often this has happened and whether this was due to keeping the AVRs in an unventilated cabinet. Anyone have the same bad experience? Are these isolated incidents?

billbillw

All of the Onkyos make a lot of heat. They will not work in an enclosed cabinet. Some people fail to follow the guidelines for proper ventilation and have problems. If you can give the 805/875 room to breath, you shouldn't have any problems.

kuntasensei

The 705, 805, 875, etc. have dual thermal-controlled cooling fans beneath the heatsinks which should keep things quite cool. In fact, my 705 is in an open area and I've never heard them come on. If you're putting ANY receiver in an enclosed cabinet, you need to work out ventilation.

I think the 805 overheating problems are fairly isolated. The vast majority are working fine.

demaples

My 805 gets warm but has never been a problem. I bought a pair of fans with a thermostatic switch off of ebay for about $40 for my Rotel but it never even gets warm so I placed them on the 805 for back up. They come on occassionally since it is partially enclosed on a shelf.

BIZILL

my 805 gets pretty dang hot. i added a cooling for for a pc to the top of mine and it's helped keep her cool. many have done this to their 805.

p.s. my 805 is out in the complete wide open.

sagasa

I use small clip on oscillating fan, I clip it on the back and turn it on when needed.
It works fine the 805 stays cool..

NewHTguy

Thanks for your feedback. Can't help but get a little worried when electronics start smoking... Seems that the 875 runs hotter than the 805. Can anyone out there comment on the 875?

Serendipity

My Onkyo TX-SR702 gets very warm at times, even with nothing on top of the unit. In fact it sits in the open on top of a small table and still gets very hot.

I would recommend having plenty of space around the unit and making sure that it is well ventillated.

WilliamM2

NewHTguy wrote: »

Thanks for your feedback. Can't help but get a little worried when electronics start smoking... Seems that the 875 runs hotter than the 805. Can anyone out there comment on the 875?

The 875 probably does run warmer, due to the REON chip. I have the PR-SC885, which is a pre-amp, no amps inside. It ran very warm, especially over the REON chip, which will burn you if you touch it! It also runs very warm on the opposite side over some large heatsinks with two transistors attached. I have attached a picture of the 9.8, which is identical to my unit.

What I did was put a heatsink on the REON chip, and I have a small 12v 60mm fan (running off 6v, so it's silent), directly behind the heatsinks pulling hot air out of my closed cabinet. It's cool as can be now.

JDOGG

If anyone feels theirs is running too warm and is looking for ideas to help cool it, here is something to look into. http://coolerguys.com/comcool.html
If mine runs too hot, I am gonna pick that up.

LushMojo

Ours got very hot. Sent it back and got a Denon 3808. Sounds much better and the video processing looks better than the Reon (to my eye, anyway).

NewHTguy

WilliamM2, That's cool but I think doing something like that is out of my league. Also, alterations of that sort may invalidate the warranty. Is that right?

Lush, Does the Denon 3808 upscale the signal from, say, a cable box over hdmi?

WilliamM2

NewHTguy wrote: »

WilliamM2, That's cool but I think doing something like that is out of my league. Also, alterations of that sort may invalidate the warranty. Is that right?

Lush, Does the Denon 3808 upscale the signal from, say, a cable box over hdmi?

The heatsink is just a self adhesive type from my collection of computer parts, it can be removed if need be. The fan is not mounted to the 885, but to the back of my equipment cabinet, no alteration there.

JDOGG

JDOGG wrote: »

If anyone feels theirs is running too warm and is looking for ideas to help cool it, here is something to look into. http://coolerguys.com/comcool.html
If mine runs too hot, I am gonna pick that up.

Well the back right corner gets really hot, so I am gonna grab one of those up and hopefully that will cool it down a bit.

jon s

the onkyo 875/905s do get extremely hot... and it is definitely from the reon processor. if you select pure audio mode which disables the video circuitry, the onkyo runs cool. i have a denon 3930ci with the realta video processor (an upgraded reon) and it really cooks too.

NewHTguy

Thanks Jon. That's useful info.

Btw, how is the video upscaling with the 3930?

avguytx

I sell/own Onkyo/Integra stuff and anymore these days, it's the video processing circuitry that gets the most warm anymore....even at idle. With ANY receiver this can happen, too. I use fans on my stuff that's in an enclosed entertainment center from this company...www.coolcomponents.com. They have a huge variety of cooling options and we have a lot of the custom A/V installers in the DFW area (plus the rest of the territory we cover) that uses them. Very economical. Just my $.02 and YYMV.

NewHTguy

If I find a good deal on an 875 or 905, I'll definitely add a fan.

kuntasensei

I say if you're not doing much in the way of scaling, screw the 805/875. Grab a 705 instead and look for a cheap external amp if you feel you need more power. As a pre-pro, the two are basically the same.

NewHTguy

kuntasensei, that may be a way to go. Basically I would be paying for pre-outs... Is the 705's audio better than the 605? I must admit that I would like something that helped with the crappy sd cable signal.

kuntasensei

No pre-outs on the 605. Plus, the 605 only has Audyssey 2EQ whereas the 705 has MultEQ XT (so the 605 doesn't EQ your sub at all). The 605 also doesn't have the DSP power to apply 5.1 to 7.1 processing on lossless 5.1 tracks if that matters to you.

As far as 705 vs. 805 on the audio side, the decoding is the same. The 805 has better DACs, but the difference is essentially inaudible.

xandra

say if you're not doing much in the way of scaling, screw the 805/875. Grab a 705 instead and look for a cheap external amp if you feel you need more power

ABOUT HEAT: I own a 705 which is in a cabinet with 4" above, 1 1/2" on sides The cab's back is open and I leave the front door open while running. In this enviorment the thing remains VERY cool. So I wouldn't regard this model as hot.
My sense from asst'd formuns is that the 805 (which doesn't have the reon but does have 30 watts more amplification) runs hotter. And I assume the 875 hotter still.

As to Onk 705 vs 805
The 805 has some minor but fairly useful upgrades to the 705 (in addition to power) Including: burr-brown DACs, one extra AV input (vital for those like me who've Maxed out available inputs), a flip down front (pretty useful dustguard), an extra Zone. The 805 has a great speaker terminal layout, and a 7 band equalizer, 12 pre-outs (vs 10). And, According to an Onk techie the amplification (or some aspect affecting sonic quality other than the DACs) is quite different between the models. (note THD diff .05 vs .08)

But oddly the thing that appeals to me the most is the front panel "Audio Select" button which allows you to toggle thru available inputs for the selected device. for example you can hook up a device to both optical dig and analog and in one touch switch between them depending on what you're listening to... (you can achieve same with 705 -- but only within submenus)

Lastly the 30 watts of additional power can make the difference of only needing to Amp fronts vs amping all channels. Admittedly, none of this is major, but now that sales are on for 805.. it seems worthy of consideration.

sorry for the length... have been pondering this myself alot lately.

NewHTguy

Xandra, you make some good points. And, the key is that the price differential between a new 705 and new 805 is only about $100. I'm not too worried about the 806's heat. However, I do worry about the 875. I think a fan is a must when you're not using the pure audio mode.

xandra

And, the key is that the price differential between a new 705 and new 805 is only about $100

Yes, that's the point. Back when difference was about $300, it was harder to justify going with the 805. Don't get me wrong - I have the 705 and still think it's an amazing receiver for the price - but if I were choosing right now, I'd go with the 805. And yes, the heat with the 875 is big-league intimidating.