Help with changing the fan on a Behringer EP1500

[Dotay]

I purchased a Behringer EP1500 to power an Avalanche 15" sub. I had planned on swapping out the fan for a quieter upon receiving it. I purchased a quiet case fan for a computer but the computer fan has a three wire plug whereas the fan on the amp is a two wire plug. Here is a pic of the inside of the amp.



High resolution version

The fan also has a small dab of glue on it holding to the circuit board.

So what are my options here? Do they make an adapter that switches from three wire to two wire? I'd like to avoid cutting any of the stock wiring if possible but if that's what it's going to take I guess that's what I'll have to do.

[Dennis H]

The amp uses a 24V fan so, if you bought a 12V computer fan, you're SOL. Here's a digest of several postings on the subject. These are about QSC amps but the Behringer is a clone.

Quiet fans for the QSC DCA amps.

Papst TYP 8414 L
Delta AFB 0824 L

All the fans are roughly the same noise level, though they all make a different pitch sound that is perceived differently, or louder. The fans are in order of what I think the quietest ones are, with the first being the quietest:

FAN / Model

Delta AUB0824L
Delta AFB0824L
Panaflo (Panasonic) FBA08A24L
Papst TYP8414L
SanyoDenki 109RO824H402

I think the QSC wants a 24V fan whereas PC fans are 12V. digikey has a fan P/N 381-1050-ND, which I think is the right size and is rated at 29 dBA. It's made by EBM industries.

But most of the quiet fans, while they may have some improved aerodynamics, get most of their noise reduction by turning slower and moving less air. The cheapest mod is to measure the DC resistance of the fan. Buy a 5 watt resistor somewhere near that value. Clip one of the fan wires and solder in the resistor. Voila, way less fan noise. Still too loud, try a resistor of twice the fan's resistance.

Or, cheaper and easier yet, just unplug the fan (gasp). Play some dynamic material and feel the amp case to see if it gets hot. If it doesn't get above warm to the touch, you're good to go in total silence. Remember the amp has thermal protection circuits so it will shut itself down before it does any heat damage.

[Dotay]

Hmmm...very interesting. I definitely like the idea of total silence. I might try that first and see where it gets me. I'd like to avoid chopping up the wire incase I ever need to make a warranty claim on the amp, although I'm sure manufacutrer would frown upon complete disabling of the fan as well. Thanks for the info.

[Dennis H]

Let us know how it goes. I've unplugged the fans in QSC amps without problems but I've never used a Behringer.

[JoshK]

I think undervolting the fan would work well if shutting it off didn't. Here is another idea. The fan is there somewhat in part because it is for pro-audio, and there is a good chance it will be in a rack with no side, top or bottom airflow or venting. I intend to buy one of these amps too (for my AV15) and was thinking I would cut a hole in the top of the case the size of the heatsinks and use hex-mesh steel grating in the hole. This will allow the heatsinks to convect upwards. It might help, it might not.

If that doesn't work, undervolt the clock. Try apexjr.com for 24v fans. They might have some on the cheap.

[Dotay]

That's an idea as well although the top of the case rests on the top of the heatsinks. The top of the case actually has 4 screws on it that screw into the top of the heatsink. If you look at the pic you can see the holes in the top of the heatsink.

[Dennis H]

The case acts as part of the heatsink if you provide ventilation around the case. Cutting holes in the case would be counterproductive. Most pro guys have them stacked in racks, amp touching amp, so they need the fans. Not to mention how much harder they drive their amps. If it turns out to be a problem, and you have the room to do it, you can stand the amp on end so you get convective flow through the fan's channel.