Does attaching a fan to your solid state amp decrease sound output

Connor G

Ear conditioned
Subscriber
Im going to apologize in advance for this post but I have a question for all of you transistor gurus out there. I have a Marantz model 2215 receiver I got for free. I restored it and after a while I decided to attach a 12v computer fan onto the amplifier over the transistor heat sinc. The receiver was working great for the first week until I attached the fan to the top. Now one channel is quieter than the other. A few minutes after I take the fan off of the top of it, it sounds fine. ( no difference in volume between the 2 channels) All I'm wondering is if having a fan over the output transistors can make them perform at sub-par levels. Do transistors have to get to a certain operating temperature for them to work at peak performance? Thank you :)
(It could be because I'm either deaf in one ear or I'm just going crazy) any info is appreciated.
 
So, why did you find the need to use a fan? And where exactly did you mount the fan?

If the heatsink with the output devices for both channels is getting hot, this is a Red Flag. It should not.

Cheers,

David
 
:scratch2: If the unit needed a fan. Don't you think it would already have a fan installed ? I think I'd be checking your bias setting on both amplifier circuits.
 
So, why did you find the need to use a fan? And where exactly did you mount the fan?

If the heatsink with the output devices for both channels is getting hot, this is a Red Flag. It should not.

Cheers,

David

Doesn't get hot. Barely even gets warm when on for a few hours. Very nice unit in great condition. I just like to keep a fan on my units. I put it on top of the cover above the heat sink
 
:scratch2: If the unit needed a fan. Don't you think it would already have a fan installed ? I think I'd be checking your bias setting on both amplifier circuits.
Output transistors don't get hot at all. Barely warm at all but I just like to keep a fan on my units. It's an OCD thing I guess ;)
Thanks for the reply
 
You may want to check DC offset with and without the fan.

Sent from my SM-N900V using Tapatalk
 
DC offset issue unlikely. Cold solder connection maybe.
 
IF the amplifier uses a transistor to monitor the heatsink temperature and compensate the bias (as many do), the fan cooling it may be the cause. BUT if so, it indicates a fault in the bias compensation circuit which should be attended to.
Faulty bias circuitry can blow up output transistors and loudspeakers with very little warning.
 
Mounted this small computer grade cpu fan at 12vdc off a 6.5v wallrat.. on my onkyo tx-82 just to blow the air around inside. (convection ovens) have another tx and a rare jvc with stk's that both suffered from over heating inside. fried many resistors just over heating over time.. probably stuck in one of those glass coffins. At 90F this puppy runs cool. without it? bout 100+ inside coming out of the top vents. Others chimed in when posted was mount on top like you but also ran the wall rat with a pair of fans on top like up to 5". Half the v and the fans run quiet yet enough to get the convection air moving. Listening to it right now on the screened in porch.

http://www.audiokarma.org/forums/picture.php?albumid=3372&pictureid=22503
 
The 2215 dies not want a fan on it and when you put that one on it, it decided to show you how it felt and just stop working right. Remove the fan since you said the unit works fine without it.

Other than dropping one channel to a lower output, the fan decreases the signal to noise ratio by being a noise in the system. Some gear does not need a fan. If this unit does not get hot then using a fan keeps the system from reaching normal operating temperatures where it was designed to operate.
 
why I used that small fan and rat on the switched output. just move the air around.. my transistors are running normal. It was the heat generated by the transformer and unvented circuitry by 'flat layout design'.. obviously vertically mounted power boards venting from underneath solves this problem. I'm not directly cooling my transistors the fan just induces better convection. If I put my hand over the heatsink that is the only area that is warm

500ma wall rat is nothing off a ps a/c switched outlet. Many like the OP run computer fans on top.. just suggesting quiet fans vrs a/c or higher dc fans.. the computer fans can push a hell of a lot of air like the 2.5" cpu fan I'm running. better long term reliability, too.
 
500ma wall rat is nothing off a ps a/c switched outlet. Many like the OP run computer fans on top.. just suggesting quiet fans vrs a/c or higher dc fans.. the computer fans can push a hell of a lot of air like the 2.5" cpu fan I'm running. better long term reliability, too.

I run cooling fans on many of my amps that give off some heat. Only one amp really needs it due to a poorly designed heatsink. I consider the fans a cheap insurance policy to allow my amps to last much longer - heat is the enemy.

I did try installing a fan and wall wart inside the case of one integrated amp - connected to the switched outlet leads. That was a huge fail because the wall wart caused noise and hum - especially in the phono section. Shielding is necessary.
 
If the fan is running off the voltage rail to one of the amps, I can see where the current drain would decrease its output.

I have the fan connected to a 12v Power supply plugged into a wall socket.
Thanks for the reply :)
 
IF the amplifier uses a transistor to monitor the heatsink temperature and compensate the bias (as many do), the fan cooling it may be the cause. BUT if so, it indicates a fault in the bias compensation circuit which should be attended to.
Faulty bias circuitry can blow up output transistors and loudspeakers with very little warning.

Thanks for the information :) I will be bringing this to a tech in the near future to have him do a full check on it
 
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