Do Pre-pros & AVRs have lower output when too cold?

[AcuDefTechGuy]

You have a real mystery on your hands.

Have you ever watched a movie without warming up the preamp/amp for 30 minute first?

If so, have you ever had to turn down the volume a little bit after watching a movie for 30 - 60 minute?

 

[lovinthehd]

Have you never watched a movie without warming up the preamp/amp for 30 minute first?

If so, have you ever had to turn down the volume a little bit after watching a movie for 30 - 60 minute?

For myself, I've never had to do anything like this.

 

[Irvrobinson]

Have you never watched a movie without warming up the preamp/amp for 30 minute first?

If so, have you ever had to turn down the volume a little bit after watching a movie for 30 - 60 minute?

I never warm up any of my equipment. The one exception is my Benchmark DAC2-HDR. It doesn't have a power switch, so, annoyingly, it sits there and cooks unless I unplug it. And it does cook; the DAC2 runs quite warm, which can't be good for the capacitors (though Benchmark claims they're good for at least 20 years, when I called them about it).

 

[M Code]

If the system's output volume level varies by up to 5dB when cool and hot, there is a major internal problem.. Some crucial internal component is changing value, not a good sign most likely soon the changing component will fail..

Just my $0.02..

 

[Swerd]

Like the others, I've never encountered anything like this. I never warm up my AVR, amp, or BR player before use. On weekends, I do leave the AVR in standby mode instead of switching it off.

The only thing I can say about ATDG's problem, is that the solution is easy. Stop using those fans and put them away .

You have an AV gear closet with it's own separate HVAC? Really? Do you set the thermostat to 45° F ?

I do remember way back in college, a room mate came back after Christmas break with a stereo he inherited from his older brother. It was a cold day in January, and he drove several hours with it in the trunk of his car. It sounded terrible, soon after he arrived, when we first played it. The next day, after it warmed up to room temperature, it was much improved.

 

[Irvrobinson]

I do remember way back in college, a room mate came back after Christmas break with a stereo he inherited from his older brother. It was a cold day in January, and he drove several hours with it in the trunk of his car. It sounded terrible, soon after he arrived, when we first played it. The next day, after it warmed up to room temperature, it was much improved.

Your roommate is lucky that the stereo didn't short out. Bringing cold equipment into a warm room can cause condensation, which in a bad case (the warm room is humid) could cause a short. He should have let it warm up for at least a full day. I can't explain why it sounded terrible. ;-)

 

[lovinthehd]

In the past I think I've always powered up the Pre-Pro/Amps to warm up about 30 min before watching anything and I've never placed the fans atop the Denon AVP.

The reason I checked the test tones was because when I watched some movies, I had to turn up the master volume way up to around -5.0. The master volume is usually about -20.0. So it didn't make any sense why I had to turn the volume up that high.

And I noticed this happened after I placed the fans atop the Denon AVP.

So now without the fans, the volume is back to -20.0.

It does seem very strange.

I still wouldn't leave my Denon/ATI powered on 24/7.

But I sure will power up my system and let it warm up at least 30 min before watching anything from now on.

While I can understand some differences/variations in volumes between various discs to an extent, that does seem too large a difference (unless maybe it's another movie source like streaming, tv, etc, then who knows). However, hope you're not testing movies but actual test tones and still curious if the test tones would measure differently internal vs external....

I can't imagine needing to "warm up" my solid state audio gear in any case.

 

[AcuDefTechGuy]

Well, (fingers crossed) hopefully nothing is wrong with my $7,500 Denon AVP-A1HDCI, which I bought brand new a few years ago.

 

[Swerd]

Well, (fingers crossed) hopefully nothing is wrong with my $7,500 Denon AVP-A1HDCI, which I bought brand new a few years ago.

You probably voided the warranty with all that fan-forced room temperature air going through it .

 

[PENG]

Well, (fingers crossed) hopefully nothing is wrong with my $7,500 Denon AVP-A1HDCI, which I bought brand new a few years ago.

I highly doubt there is anything wrong as such. My best guess is that your aggressive forced air cooling is affecting the temperature compensating circuit where the sensing part may not be subjected to the same cooling that the transistors are subjected to. In heavy industry, we have all kinds of instrumentation and control systems that are affected by temperature so there are naturally all kinds of temperature compensation systems in place, and one important point is to make sure if any sensing circuits/devices are involved, they have to be subject to the same ambient temperature as the device/system that they are designed to temperature compensate.

The AVP-A1HDC1 packs tons of components in one box, as such, if subjected to forced air cool, especially a sucking one, it is possible that the sensing/control parts and the parts being temperature compensated are no longer operating per design. The key is to limit the air flow, slower flow should result in more even cooling of all the components inside the box.

I have my laptop running REW monitoring my AV8801 all day, and so far I have seen a maximum variation of about 2 to 2.5 dB when I played around to create extreme conditions, no noticeable difference most of the time. There was one observation though, when I first turned on the system, it was stone cold, yet the output was about 5 dB higher than any other time. That was a weird one as I could not make it happen again, even after running two fans full blast with the unit on standby, until the temperature gets down to room temperature, a little higher because of the standby power. So the lowest temperature recorded on top of the case was 27 deg. C and the highest was 43 deg C. No noticeable change in output so far. I am still monitor it in case something weird may happen again, but no luck so far.

Edit: I found out why I momentary drop 5 dB at one point. For some reason, all of a sudden, REW change the default output from both channel to just left channel, could be just operator (me) error.

 

[Alex2507]

I never warm up my equipment.

That's not what I heard.

 

[agarwalro]

But the AVP-A1HDCI, AVR-5308CI, X7000, X6000, X5000, and maybe X4000 series don't seem to get that hot. So I think adding cooling fans here probably doesn't add any benefits.

My X4000 (sitting on a well ventilated open rack) goes into thermal protection in the summer. One fan completely solved the heat buildup and shut down issue.

 

[Verdinut]

I highly doubt there is anything wrong as such. My best guess is that your aggressive forced air cooling is affecting the temperature compensating circuit where the sensing part may not be subjected to the same cooling that the transistors are subjected to. In heavy industry, we have all kinds of instrumentation and control systems that are affected by temperature so there are naturally all kinds of temperature compensation systems in place, and one important point is to make sure if any sensing circuits/devices are involved, they have to be subject to the same ambient temperature as the device/system that they are designed to temperature compensate.

The AVP-A1HDC1 packs tons of components in one box, as such, if subjected to forced air cool, especially a sucking one, it is possible that the sensing/control parts and the parts being temperature compensated are no longer operating per design. The key is to limit the air flow, slower flow should result in more even cooling of all the components inside the box.

I have my laptop running REW monitoring my AV8801 all day, and so far I have seen a maximum variation of about 2 to 2.5 dB when I played around to create extreme conditions, no noticeable difference most of the time. There was one observation though, when I first turned on the system, it was stone cold, yet the output was about 5 dB higher than any other time. That was a weird one as I could not make it happen again, even after running two fans full blast with the unit on standby, until the temperature gets down to room temperature, a little higher because of the standby power. So the lowest temperature recorded on top of the case was 27 deg. C and the highest was 43 deg C. No noticeable change in output so far. I am still monitor it in case something weird may happen again, but no luck so far.

Edit: I found out why I momentary drop 5 dB at one point. For some reason, all of a sudden, REW change the default output from both channel to just left channel, could be just operator (me) error.

I like your thought about the situation which might be caused by a too aggressive forced air cooling.

I am using three 120mm AC Infinity fans on top of my Marantz SR5010 and the temperature so far has varied between 42°C without fan cooling and around 30°C with the fans operating on the "Smart" mode at various speeds depending on the sensed temperature and on the demand as required by the settings. What I like is the variable speed function which also, apart from avoiding an aggressive forced air movement, also keeps the fans from producing annoying noise. An excellent product indeed.

 

[Johnny2Bad]

With such a large variation in output, and without an examination of the schematic diagram, you can't rule out the possibility that this is a characteristic of the protection circuit(s). Also for the EEs here, what do you think of the bias trimpots (or fixed resistors) heating / cooling and changing value?

 

[PENG]

With such a large variation in output, and without an examination of the schematic diagram, you can't rule out the possibility that this is a characteristic of the protection circuit(s). Also for the EEs here, what do you think of the bias trimpots (or fixed resistors) heating / cooling and changing value?

I believe that too, could be part of the potential issue here. Denon must know how to design and implement adequate compensation for the temperature effects on gain, as well as the bias control circuitry, but they would not have assumed, or guessed the less predictable effects of forced air cooling as that depends on the kind of cooling applied by different users. So the build in temperature compensation circuitry and components could be operating out of wack, due to the high air flow rate and flow pattern.

As an example, let's say those fans caused the air flow pattern to be such that it cools the temperature sensing part much more than the bias resistors/pots etc., and/or the transistors, then the circuitry would have been under compensating; and obviously if the reverse is true, then the system would have been over compensating. Again, this is just my guess, albeit an educated guess.

ADTG: Just back off the flow, using variable speed ones that Verdinut is talking may be a good idea. If possible, I would blow air from the back just to take the local ambient heat away so the unit's build in passive cooling design can work efficiently. Affecting the gain structure is one thing, that you can compensate for with the volume setting, affecting the bias as J2B mentioned would be worse, obviously.

 

[AcuDefTechGuy]

My X4000 (sitting on a well ventilated open rack) goes into thermal protection in the summer. One fan completely solved the heat buildup and shut down issue.

Balance is the key.

One 120mm fan is probably all it takes.

Last night at 10PM I placed two 120mm fans atop my AVP-A1 and kept the power on all night!

This morning I measured the top rear of the chassis, which is the hottest part of the chassis, and the temp was 27C/81F degrees.

Without any fans, the hottest temp was 50C/122F last night before I placed the 2 fans atop the Denon.

Amazing how effective these 120mm fans are!

Again, unfortunately for me, the volume output dropped 3dB for the FL/FR and 6dB for the Center.

I'll try just one fan today and see.

 

[Pogre]

Anyone else measured the SPL at both "Cold" and "Hot" temperatures of the Pre-pro/Amps/AVRs?

I was going to do that this morning but forgot to get a "cold" reading. Everything is warmed up now. If I shut it down later today I'll try to remember.

*Edit: What did you use for test tones?

 

[AcuDefTechGuy]

I was going to do that this morning but forgot to get a "cold" reading. Everything is warmed up now. If I shut it down later today I'll try to remember.

*Edit: What did you use for test tones?

I used the Denon's Speaker Channel Level test tones in the manual setup.