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EBS HD350 fan too noisy. Replacement?

gimmeagig

gimmeagig

Feb 25, 2004
2,891
1,197
Coeur D'Alene,Idaho
#1
Hi,
I like my old HD350 but even at it's slowest speed the fan still seems noisy in comparison to some other amps I have used.
I know that for desktop computers there are quieter fans available with blades that are shaped to be more efficient and the speed can be reduced to make the fan quieter as well.
Is there a way to modify the EBS to be quieter? Does the fan really have to be on all the time?
When I play in my music room I don't play very loud and the fan is annoyingly loud even though the amp is barely working.
Do any of you have experience with this sort of thing? What are my options?
 
#3
Usually quieter fan options are available. These fans tend to cost more.

Your first step is to look at the label on the the fan and note the make and model number. Look up the specs, these include AC or DC, the size and depth, the air flow rate, the noise spec, etc. Then find a substitute with the same air flow, etc. specs but with lower noise ratings. I like ebm-papst fans for their low noise. Other companies make ultra-quiet fans. There are good products out there. They are available from electronic distributors such as mouser, digi-key, and newark.

Some fans require a power cable that plugs into the fan. That would have to be ordered as well. Other fans have built in power wires. Some fans use molex or similar connectors that plug into the circuit board. These would have to be ordered as well. These aren’t big problems but you have to sweat the little details.
 
#5
gimmeagig said:
Great, thanks for the advice. I'll open up the amp a little later to see what's in there. As long as I don't have to solder anything to a circuit board I'll be able to do it...
Click to expand...

It there is a lot of dust inside the chassis, this can insulate the temperature sensor circuit and make the fan run faster. It tricks the circuit into thinking that the amp is hotter than it is. Also if the fan blades are covered, this can make the fan louder. Sometimes a good cleaning with a vacuum can help. Best not to use air to blow dust out unless you know what you are doing. Dust driven into the wrong area can increase the electronic noise level.
 
#6
So what I got in the EBS is a "NONOIse" Oriental electronics fan
F8025M24D4
DC24V 0.080A three wires with a plug going to the circuit board.
It doesn't tell me about noise or cfm

I did a search and I could not find a match for that number only this
https://www.amazon.com/Evercool-25mm-3-15-0-98-Bearing/dp/B005GSF1EG

impossible for me to tell if that is an upgrade or not
 
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#7
Is there a chance that the part number is incorrect? The company doesn’t have a listing for that part number.

Invalid Link Removed

Their fans are used in TV sets made in Korea. Perhaps you are right that it may not be the original fan. I’m wondering if EBS can confirm the original part number and recommend a replacement. Their contact is [email protected]

Link Removed
 
#9
I just got a message from EBS and that fan is indeed the original one. They told me that this fan is temperature controlled but that I can replace it with any other 80mm 24V fan. So it seems that control is not on the circuit board but on the fan itself. Now I'm not sure if I can make that amp quieter if I bought a silent fan which might operate on higher RPMs than the low stage of the EBS fan. Maybe I just keep the amp the way it is...It doesn't seem like a simple thing
 
#10
It would be nice if they could send you the data sheet with the specs for the fan since you can’t locate it. If you wanted to try a substitute you’d need that to start with. It is usually best to stay around the original air flow specs. Too high a flow rate can make it louder.

It is true that the temperature control circuit can be built into the fan itself. Some fans have that feature built in, it helps when the fan is mounted remotely. Cleaning the fan might help, especially if the blades or sensor are covered with dust.
 
#12
gimmeagig said:
I'll clean it and see what happens. Where on the fan would be the sensor?
Click to expand...

Often in the airflow pathway on one of the arms that holds the motor. The sensor can take different forms depending on the design. It could look like a small capacitor, a transustor, or even a metal plate glued onto a mount. Sometimes it isn’t obvious.

This one is more obvious than most. The tiny green component is a thermistor, the resistance varies with temperature.
E601D7B5-7AC7-47B1-B56B-054D904F11C0.jpeg


Here is another example. If the leads are shorted, the fan runs full speed.
D011FF9E-5031-4A48-8A78-BEFB22D69777.jpeg
 
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#13
Note that temperature sensing fans only sense the air temperature around the fan and not the temperature of the devices or structures they are actually cooling. This means that there will always be a long time constant between the two, resulting an a large error. One way to handle this is to increase the minimum speed (which increases the noise level), but reduces the error span. This is why this kind of fan is rarely used in audio products.
 
#15
gimmeagig said:
I just got a message from EBS and that fan is indeed the original one. They told me that this fan is temperature controlled but that I can replace it with any other 80mm 24V fan. So it seems that control is not on the circuit board but on the fan itself.
Click to expand...

If any 24 volt fan can be used, to me that implies just the opposite, that the temp control must be elsewhere than on the fan, since many fans do not have built in temp control.
Yel_wink.gif
 
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#17
beans-on-toast said:
Sometimes these type of fans are mounted on or close to a heatsink where the temperature is highest. It is true that this type is not the norm in amps.
Click to expand...
Certainly on the amps being discussed. When mounted directly to a heatsink, with a long thermal time constant, and with the fan spinning at a slow base speed it's a fine solution.
 
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