Buying Denon X4000 or Onkyo 929 need help

[PENG]

In another thread someone posted to run the 4ohm speakers using the 8ohm setting in the receiver. That was followed up with 3 others saying to do the same thing and then a link was posted why.

how do you al feel about that

I would definitely leave it on the 8 ohm position regardless. If the user is an idiot he/she may cause damage no matter what setting.

 

[jomark911]

In another thread someone posted to run the 4ohm speakers using the 8ohm setting in the receiver. That was followed up with 3 others saying to do the same thing and then a link was posted why.

how do you al feel about that

I and they don"t recomend that, because the amperage draw will superseede the psu"s power ability.
The switch in the back for 8 or 4 ohms load selects a different winding from the transformer with lower voltage. So the psu doesn"t really get stressed out that match. By leaving the switch to 8 ohms and use 8 ohms speakers mixed with 4 ohms, you just do what the amp must avoid to do. Stress the psu.
And then the dangers are multiple for the amp and the speakers.
The correct solution for that kind of use is a seperate power amp. Specially one with 4 ohms power capability.

 

[PENG]

I and they don"t recomend that, because the amperage draw will superseede the psu"s power ability.
The switch in the back for 8 or 4 ohms load selects a different winding from the transformer with lower voltage. So the psu doesn"t really get stressed out that match. By leaving the switch to 8 ohms and use 8 ohms speakers mixed with 4 ohms, you just do what the amp must avoid to do. Stress the psu.
And then the dangers are multiple for the amp and the speakers.
The correct solution for that kind of use is a seperate power amp. Specially one with 4 ohms power capability.

You and "they" are correct if people use the AVR at near to (say 50%) their rated capacity. Or as extreme examples, play highly compressed music loud and long, using it as a welder, or to power light bulbs. Music contents are complexed and the speakers will be seen by the amp as a variable load that has a lot of peaks and valleys. So if you are not using the amp near its capacity, like most people do, using the 4 ohm setting that typically result in a lower rail voltage, you limit the amp's headroom for no good reasons. Some manfacturers provide that selector probably for liability reasons but for instance in Denon's FAQ, they told you all their AVR (most of their line do not have the 4 ohm setting) can handle 4 ohm speakers. Basically if you read between the lines, you will be fine as long as you don't go crazy with the volume control, but then that is true regardless of where you set your selector to.

 

[RichB]

I completely agree with PENG.
I do not use the 4 Ohmn setting because it seems to degrade the sound quality even at a moderate level driving two speakers.
I recommend paying some attention to the sound coming out of your speakers and the heat of your components.
If you don't, there will be problems.

I had to put a fan on the Marantz AV8801 preamp which is sitting on a open shelf because it reacted 126 degress F.
It became a problem because the Parasound A51 below it raised the ambient tempurature to the low 90 degree range.
The AV8801 trigger 1 faled and it was repaired. The fan seems to have sufficiently lowered the tempurature.
My next processor will have a better thermal design.

- Rich

 

[jomark911]

If you relocate the marantz , you won"t have to use fan.
What is the fan's airflow? inwards or outwards?
If outwards, ie, sucking hot air , you are fine. If inwards, ie pushing air in , it will get full of dust in no time. No good.
Try relocate marantz , not on top of a power amp , so you won"t have problems with it"s thermal design.

 

[RichB]

If you relocate the marantz , you won"t have to use fan.
What is the fan's airflow? inwards or outwards?
If outwards, ie, sucking hot air , you are fine. If inwards, ie pushing air in , it will get full of dust in no time. No good.
Try relocate marantz , not on top of a power amp , so you won"t have problems with it"s thermal design.

There are WAF issues
I can't find components that would not have the same problem.
The shelves are glass so the amp must be below something.

I am using a GELID Solutions Slim 12 UV BLUE 120mm Case Fan.
I made a USB to fan connector that is connected to the 1 amp USB port of the Marantz.
It is tricky, but if you setup the Marantz AV8801 and turn off the network hub when powered off and select the USB rear port as active, the fan is powered with the unit. The Gelid fan runs well at 5 volts and is essentially silent.

View attachment 12321

It is a good idea to make sure components are not overheating.
You would think that a Processor would not get hot, after all there are no amps.
But some of the video processing chips get hot.

- Rich

 

[jomark911]

You have a point,(regarding waf) .
What i have done , and would recomend, is place the fan or two, directly on top of the marantz, and slow it down a bit , so it gently sucks hot air from inside , so it slightly increasing the natural air circulation.Way more effective solution.
As for the heat that preamps are puting out , sometimes its more than what power amps do. Surely video chips get hot enough to require their own fan,eg(denon avp a1hd), and some other times some less complex but quite good components like SANSUI C2301, produce so much heat (because of class A operation) that one might think thei are ready to catch fire.But that is their natural operation.Geting hot .

 

[PENG]

You would think that a Processor would not get hot, after all there are no amps.
But some of the video processing chips get hot.

- Rich

I am not surprised that they could get hot and in many cases such as mine, hotter than the power amps. My power amps for HT on average probably output no more than 10 to 20W all channels combined and the heat dissipated would be in the range of 40 to 60W. That likely would be less than what the 8801 would have dissipate.

 

[RichB]

I am not surprised that they could get hot and in many cases such as mine, hotter than the power amps. My power amps for HT on average probably output no more than 10 to 20W all channels combined and the heat dissipated would be in the range of 40 to 60W. That likely would be less than what the 8801 would have dissipate.

I think it is less about dissipation and more about thermal design.
My Parasound A51 idles at 150 watts but when idling is only warm to the touch.
Tha AV8801 draws a fairly constant 60 watts but without the fan hits over 120 degrees in the center back.
The 8801 does not seem to use the chassis for cooling so the heat builds up.

- Rich

 

[PENG]

I think it is less about dissipation and more about thermal design.
My Parasound A51 idles at 150 watts but when idling is only warm to the touch.
Tha AV8801 draws a fairly constant 60 watts but without the fan hits over 120 degrees in the center back.
The 8801 does not seem to use the chassis for cooling so the heat builds up.
- Rich

The power consumption specs is 90W and I bet most of that has to be dissipated as heat. Comparing the perforated tops of the 8801 and the 7005 I know for sure the 8801 cannot get rid of the heat as efficiently as the 7005 can. So if by thermal design you meant heat sinking/ventilating/removal then we may be saying similar things differently. My rack has one divider that separates the 8801 and the 105 that is on the top shelf. If I adjust the divider one notch higher, the 105 will end up with about 1 inch clearance on top leaving no room for a fan. As it is now, the 105 has lots of clearance to vent naturally but the 8801 below it ends up with just under 2" of clearance from the divider, enough for a 100 mm fan on top sucking but due to the lack of headroom I have to add another one at the back blowing horizontally just like yours. There was no problem when I had the 7005 and 95 because the 95 is not as tall, has a built-in fan and the 7005 has a much better ventilated enclosure so one fan on top was enough to keep it cool.

 

[RichB]

The power consumption specs is 90W and I bet most of that has to be dissipated as heat. Comparing the perforated tops of the 8801 and the 7005 I know for sure the 8801 cannot get rid of the heat as efficiently as the 7005 can. So if by thermal design you meant heat sinking/ventilating/removal then we may be saying similar things differently. My rack has one divider that separates the 8801 and the 105 that is on the top shelf. If I adjust the divider one notch higher, the 105 will end up with about 1 inch clearance on top leaving no room for a fan. As it is now, the 105 has lots of clearance to vent naturally but the 8801 below it ends up with just under 2" of clearance from the divider, enough for a 100 mm fan on top sucking but due to the lack of headroom I have to add another one at the back blowing horizontally just like yours. There was no problem when I had the 7005 and 95 because the 95 is not as tall, has a built-in fan and the 7005 has a much better ventilated enclosure so one fan on top was enough to keep it cool.

I wonder why it is rated at 90W maybe it uses more when you power more channels...

We are saying the same thing. The A51 is pulling more the wall but does not get hot because it has a ton of heat sink area.

The fact that the 7005 has more perforated top suggests that Marantz could have done better with the 8801. I called tech support and they said it should not reach 126 degrees even if the shelf with in the low 90's. However, when I sent the 8801 in for a failed trigger, nothing else was fixed.

My 105 has lots of clearance so it does not get too hot.

I am not sure what this means for the longevity of the AV8801. I imagine some of them are tucked in pretty tight quarters. United Radio should be pleased

- Rich</SPAN>

 

[PENG]

I am not sure what this means for the longevity of the AV8801. I imagine some of them are tucked in pretty tight quarters. United Radio should be pleased

- Rich

With one fan blowing from the back and one sucking from the top I am able to keep the thing below 39 deg C so I hope it will last forever or at least 10 years. Seriously I am 100% please with it's sound quality and feature set that I can't imagine any need to upgrade for a long time. That's one good thing about the likes of the X4000, the much lower cost should make it easier to upgrade every 2 to 3 years.

 

[RichB]

With one fan blowing from the back and one sucking from the top I am able to keep the thing below 39 deg C so I hope it will last forever or at least 10 years. Seriously I am 100% please with it's sound quality and feature set that I can't imagine any need to upgrade for a long time. That's one good thing about the likes of the X4000, the much lower cost should make it easier to upgrade every 2 to 3 years.

That should do the trick

- Rich