Source of heat while at "idle"?

[KEW]

I left my Marantz SR6001 on for a couple hours while not using it (the CD player was off). When I noticed it was on, I felt it and was amazed at how warm it was - given it wasn't doing anything (at least nothing obvious).
It wasn't too hot, but it was probably around 110°F.
Can someone explain why it is getting so warm?

Thanks!

 

[PENG]

I left my Marantz SR6001 on for a couple hours while not using it (the CD player was off). When I noticed it was on, I felt it and was amazed at how warm it was - given it wasn't doing anything (at least nothing obvious).
It wasn't too hot, but it was probably around 110°F.
Can someone explain why it is getting so warm?

Thanks!

Leaving it on means everything (prepro and amps) remains on just not pushing current to the speakers. I would guess that under no load condition the 6001 would consume around 80 to 120W. That can certainly produce a lot of heat.

Whether the AVR is making sound for you or not (idling) the temperature would not differ by much. As we all know for normal home use the average power draw by the speakers is very low.

 

[highfigh]

I left my Marantz SR6001 on for a couple hours while not using it (the CD player was off). When I noticed it was on, I felt it and was amazed at how warm it was - given it wasn't doing anything (at least nothing obvious).
It wasn't too hot, but it was probably around 110°F.
Can someone explain why it is getting so warm?

Thanks!

The power supply is still on, the output transistors are still receiving bias voltage and current, the transistors will still need to dissipate heat and since it's Class AB, it will generate some heat at idle.

 

[KEW]

Since this is a full-blown HT receiver and I only use it for 2 (or 2.1) channel audio, are there any video features or options I can turn off to reduce heat/power consumption? Or does it work that way?
Thanks,
Kurt

 

[PENG]

Since this is a full-blown HT receiver and I only use it for 2 (or 2.1) channel audio, are there any video features or options I can turn off to reduce heat/power consumption? Or does it work that way?
Thanks,
Kurt

You can try turning off any video conversion/upscaling but I don't think it would help much. Let's face it, in additon to what highfigh talked about the bias current for the preamp/amp section transistors, there are also processing chips in it that generate heat. I have an older Toshiba laptop that has a full blown Pentium 4 CPU (one that was used in desktops) in it and that makes the laptop just as hot or hotter than my Denon 4308.

If you are concern about reduced life due to the heat, you can do what I have done, go and buy a 12V CPU cooling fan that uses ball bearings with noise level <20 dB you will be all set.

 

[highfigh]

You can try turning off any video conversion/upscaling but I don't think it would help much. Let's face it, in additon to what highfigh talked about the bias current for the preamp/amp section transistors, there are also processing chips in it that generate heat. I have an older Toshiba laptop that has a full blown Pentium 4 CPU (one that was used in desktops) in it and that makes the laptop just as hot or hotter than my Denon 4308.

If you are concern about reduced life due to the heat, you can do what I have done, go and buy a 12V CPU cooling fan that uses ball bearings with noise level <20 dB you will be all set.

If it's not overheating, the fan isn't helping anything. As long as it never shuts off, it's fine. Nothing that's not on a heat sink is in danger of overheating unless the ventilation slits are blocked.

Nothing puts out more than it uses, so the difference is BTUs instead of output wattage.

 

[PENG]

If it's not overheating, the fan isn't helping anything. As long as it never shuts off, it's fine. Nothing that's not on a heat sink is in danger of overheating unless the ventilation slits are blocked.

Nothing puts out more than it uses, so the difference is BTUs instead of output wattage.

Actually if it is really hot (to the touch) at the outside of the box, it should still help in terms of longivity if you cool it even though it may not be "over" heating as such. That being said I agree most people won't do what I do.

 

[KEW]

It is not overheating, but on my old amp, things didn't seem to heat up too much until you really worked it. Probably a simple matter of having room for more heat sink.
It doesn't get that hot, but I'd be a little reluctant to stack components on top of it, which is something I'm used to being able to get away with.

Thanks for the info and I'll look into the video upscaling/conversion.

 

[highfigh]

But your receiver is 5 channels vs 2, right? If it's high power, that contributes, too. Plus, it undoubtedly has different output transistors and your old one may not have been discreet outputs.

 

[TLS Guy]

It is not overheating, but on my old amp, things didn't seem to heat up too much until you really worked it. Probably a simple matter of having room for more heat sink.
It doesn't get that hot, but I'd be a little reluctant to stack components on top of it, which is something I'm used to being able to get away with.

Thanks for the info and I'll look into the video upscaling/conversion.

There is a trade off between heat at idle and quality. A pure class A biased amp, uses as much power at idle as running full power. A pure class B amp uses little at idle. Most amps are class AB, however the more the amp is biased towards class A the less crossover distortion the amp will have, and in many ways will be a better sounding amp.

The only way "to go green" is to embrace class D amps, where the greater portion of the power consumed goes to the speakers.

 

[PENG]

It is not overheating, but on my old amp, things didn't seem to heat up too much until you really worked it. Probably a simple matter of having room for more heat sink.

I am not sure if your old one is Marantz made as well but I can comment on my newer Denon 4308 versus my older 3805. If I go by feeling on the top vent of the box, there is no question the 4308 is hot while the 3805 is just warm, idling or not does not make much difference. This is expected as explained by both TLS and highfigh. It only gets noticeably hotter if I listen to multichannel material at closer to reference level. I am guessing the following may be among the reasons why the newer one feels warmer.

1. More (by quantity or processing power or both) processing devices/chips in the newer one that will produce heat even when not in use.

2. Different heat sink design that may disspate the heat more towards the top. May be the 3805 is just as warm if I feel it at the bottom chassis instead of the top vent.

Just for information I will take some measurements (top and bottom) and report back my findings. May be you can do the same, so we can quantity how hot/warm we are really talking about.

 

[highfigh]

Actually if it is really hot (to the touch) at the outside of the box, it should still help in terms of longivity if you cool it even though it may not be "over" heating as such. That being said I agree most people won't do what I do.

If it's too hot to touch when idling for a long time, it may have a problem. Onkyo is the only brand I frequently hear about when heat is mentioned, although when it's cranking along, just about any brand can run hot. I don't recommend stacking anything directly on top of an amp or receiver. Without knowing how hot it's supposed to run, it's hard to say if it's actually "too hot".

 

[highfigh]

I am not sure if your old one is Marantz made as well but I can comment on my newer Denon 4308 versus my older 3805. If I go by feeling on the top vent of the box, there is no question the 4308 is hot while the 3805 is just warm, idling or not does not make much difference. This is expected as explained by both TLS and highfigh. It only gets noticeably hotter if I listen to multichannel material at closer to reference level. I am guessing the following may be among the reasons why the newer one feels warmer.

1. More (by quantity or processing power or both) processing devices/chips in the newer one that will produce heat even when not in use.

2. Different heat sink design that may disspate the heat more towards the top. May be the 3805 is just as warm if I feel it at the bottom chassis instead of the top vent.

Just for information I will take some measurements (top and bottom) and report back my findings. May be you can do the same, so we can quantity how hot/warm we are really talking about.

1. The processors don't generate much heat- if they did, they would be mounted on a heat sink.

2. The heat usually has no choice but to go to the top- it uses conduction (outputs to heat sink) and convection (heat sink warms the air, which rises and is replaced by cooler air from below) to cool the amp and this is exactly why nothing should be set on the amp or receiver. If the bottom is hot, it's from radiated heat and isn't a very efficient way to remove heat. Taller feet would help, IMO.

If you have an infrared thermometer, that would be best.

 

[PENG]

1. The processors don't generate much heat- if they did, they would be mounted on a heat sink.

Some processors do generate quite a bit of heat and yes in those cases their should be mounted on heat sinks. Those not mounted on heat sinks still generate some heat, and everything adds up to more heat being dissipated to the top by convection as you said and/or by conduction to other parts of the enclosure, including the bottom plate/chassis.

2. The heat usually has no choice but to go to the top- it uses conduction (outputs to heat sink) and convection (heat sink warms the air, which rises and is replaced by cooler air from below) to cool the amp and this is exactly why nothing should be set on the amp or receiver. If the bottom is hot, it's from radiated heat and isn't a very efficient way to remove heat. Taller feet would help, IMO.

If the bottom is hot, it can be due to both radiated heat and heat conducted from the hot components. Efficient or not, it is possible that some designs utilize part of the enclosure/chassis (such as the bottom part) as heat sink to help dissipate heat. My PS3 gets quite warm at the bottom and I do use taller feet as you suggested.

If you have an infrared thermometer, that would be best.

I don't have an infrared one on hand so I could only measure the temperature outside of the enclosure. I will be posting the readings shortly.

 

[PENG]

Here are the temperature readings in Celsius:

From the vented part of the top of the 4308's enclosure:

Idling -----------------------------------------------------------------------------------------------------------------38 to 40

Playing Bourne Supremacy with volume at -15 dB and SPL=65 to 75 dB from 12' away ------------------------- 40 to 42

Playing Chris Botti live in Boston with volume at -13.5 dB and SPL at about 72 dB average --------------------- 42 to 45

The hottest part of the bottom part --------------------------------------------------------------------------------- 38

The components inside should be at a higher temperature but hopefully well below 70 deg.C., the typical rated operating temperature of electronic components in general.

 

[KEW]

I am not sure if your old one is Marantz made as well ....
I am guessing the following may be among the reasons why the newer one feels warmer.

1. More (by quantity or processing power or both) processing devices/chips in the newer one that will produce heat even when not in use.

2. Different heat sink design that may disspate the heat more towards the top. May be the 3805 is just as warm if I feel it at the bottom chassis instead of the top vent.

My old one is a circa 1980 Sansui AU-717 integrated stereo amp. I would expect that the number of processing devices/chips is zero.
I don't know about the A-B class category. I think that was not the common technology of the time (I bought another amp 5 years later that has "Class A" lit up on the front).
The Sansui is an 85Watt amp and stays cool because I never push it that hard (at least that was my concept of the relation between heat and sound output). The new Marantz is 100W, so you can see why I was a little perplexed.
I'll see if I can dig out my infrared and get a reading. It almost seems like it gets hotter from not playing music. I would guess it is generally in the saame range as your data. Definitely warm, but not so much as to believe it is malfunctioning.

 

[highfigh]

My old one is a circa 1980 Sansui AU-717 integrated stereo amp. I would expect that the number of processing devices/chips is zero.
I don't know about the A-B class category. I think that was not the common technology of the time (I bought another amp 5 years later that has "Class A" lit up on the front).
The Sansui is an 85Watt amp and stays cool because I never push it that hard (at least that was my concept of the relation between heat and sound output). The new Marantz is 100W, so you can see why I was a little perplexed.
I'll see if I can dig out my infrared and get a reading. It almost seems like it gets hotter from not playing music.

I think part of it may be in the number of channels. Even if each channel loses out the same amount of heat, the Marantz will be losing 2.5 times more than the Sansui. The design has a huge amount to do with this. I had a Sony VFet integrated amp that was rated at 30W/ch and I could have fried eggs on it. The next Sony integrated amp ran cooler but when it was pushed, it threw off a pretty good amount, too. The one I have now is even cooler.

 

[PENG]

My old one is a circa 1980 Sansui AU-717 integrated stereo amp. I would expect that the number of processing devices/chips is zero.
I don't know about the A-B class category. I think that was not the common technology of the time (I bought another amp 5 years later that has "Class A" lit up on the front).
The Sansui is an 85Watt amp and stays cool because I never push it that hard (at least that was my concept of the relation between heat and sound output). The new Marantz is 100W, so you can see why I was a little perplexed.
I'll see if I can dig out my infrared and get a reading. It almost seems like it gets hotter from not playing music. I would guess it is generally in the saame range as your data. Definitely warm, but not so much as to believe it is malfunctioning.

I see at least the following reasons for the Sansui to run cooler:

1. It is one of the best Sansui made and it probably has higher grade, more efficient components, e.g. power supplies in it. As you must know, Sansui made much better amps in the 70's and then deteriorated from there.

2. The heat sinks in that thing is absolutely huge, and as highfigh said it has only 2 amps in it so the heat generated by the transistors and transformer can be dissipated more evenly throughout the enclosure. The AU-717 weighs 6.5 lbs more than the SR-6001, with much more room to breathe for sure.

3. Zero processing chips, though not a significant factor as the SR-6001 doesn't do much video processing anyway, it is not like something that has the reportedly hot Reon chip in it, still one less heat source.

The Sansui is definitely not class A but I am not sure if it is a higher bias A/B (closer to A) or one that is closer to class B. My guess is that it is class A/B, and likely of the higher bias design too. Even then, with only 2 channels it would still generate less heat and with much more heat sink area, it would feel cooler to the touch for sure. By the way, I hope you are getting it fixed, it is too nice an amp not to.

 

[KEW]

No luck finding my IR thermometer, but basically after 2 hours at idle the top center of the receiver is warm but still very comfortable to set and keep my hand on. I would say 110° is about right. The threshold for feeling out-right pain is 140°F.
I believe this is completely normal, but I would not want to trap the heat by putting a CD player on top.

I'll keep my Sansui going forever unless it really gets fried somehow. It has been in the shop once (earlier this year) in 30 years! I will take it back before long, just to go ahead and recap it (the visit earlier was a repair and I should have gone ahead and recapped it then).

 

[highfigh]

I see at least the following reasons for the Sansui to run cooler:

1. It is one of the best Sansui made and it probably has higher grade, more efficient components, e.g. power supplies in it. As you must know, Sansui made much better amps in the 70's and then deteriorated from there.

2. The heat sinks in that thing is absolutely huge, and as highfigh said it has only 2 amps in it so the heat generated by the transistors and transformer can be dissipated more evenly throughout the enclosure. The AU-717 weighs 6.5 lbs more than the SR-6001, with much more room to breathe for sure.

3. Zero processing chips, though not a significant factor as the SR-6001 doesn't do much video processing anyway, it is not like something that has the reportedly hot Reon chip in it, still one less heat source.

The Sansui is definitely not class A but I am not sure if it is a higher bias A/B (closer to A) or one that is closer to class B. My guess is that it is class A/B, and likely of the higher bias design too. Even then, with only 2 channels it would still generate less heat and with much more heat sink area, it would feel cooler to the touch for sure. By the way, I hope you are getting it fixed, it is too nice an amp not to.

I seriously doubt the outputs are more efficient- electronics is nothing if not always trying to get more from less. The output devices need different bias voltage and current. The normal operating temperature is determined by the device, how much power is developed for output and how much is wasted and dissipated as heat. If it was Class A, you'd know it. 110 degrees would be when it's heating up or cooling down, but definitely not when it was cranking along. A Class A amp runs a lot hotter than this one. I can't think of a single purely Class B amp, either.