20/20 Fan Noise: What a Nuisance!

[PlanarBeing]

I just bought a Boogie 20/20 power amp and the tiny 5v/1w fan inside is driving me crazy.

It resonates inside the box: when the top of the metal case is taken off, it's several decibels quieter; when I take the fan out and hold it in the air it just makes a soft whirring sound. But as soon as I put it in, and put the lid back on . . . it's too much.

I must find a way to either slow that fan, or get one which will run slower when wired in place of the little monster that's in there now. Can I manipulate speed by changing to a different wattage, or voltage? Or what? Can I wire some kind of variable resistor in there, so that I can adjust the speed to where it makes as little sound as possible?

It seems to me that the fan doesn't need to be running that fast or even moving that much air.

Any advice appreciated. Thanks.

 

[Old BF Shred]

Sounds like a bearing/bushing starting to go. Or could there be dirt on or damage to one of the blades? Perhaps it could be cleaned/repaired.......
Either will cause it to go out of balance and make noise when it contacts a hard surface (like mounting into the amp).

If the cover is the main source of noise you might try using a tightly closed density (almost like neoprene) weather stripping along edges of the chassis that contact the cover to help dampen it. Avoid putting it too close to any tubes or other high heat sources. 8)

The root cause, however is likely the fan. I have a 50/50 and the fan is virtually inaudible.

So should yours......

Good luck with that!

 

[PlanarBeing]

50/50's a different design. Twice the rack space, outside fan. Nothing to do with 20/20.
This fan needs a rheostat wired into the circuit. It just runs too fast for the dimensions. Overkill.

 

[Old BF Shred]

OK...so have you called Mesa to ask if this is normal? :?:

Then ask why they don't put a "rheostat wired into the circuit" as a stock feature....?

Maybe you just need a new fan? 8)

 

[marantz1300]

I disconnected my 50/5os fan.Haven't had any problems.

 

[PlanarBeing]

I disconnected my 50/5os fan.Haven't had any problems.

Why don't Mesa-Boogie build off/on switches into their fans, or speed controls?
Because there are lots of things they don't do, as they're not required by most users.

 

[masque]

i've had a 20/20 for about 9-10 years and from day one that fan sounds like a small plane taking off!!!!!!! LOL. i've gotten used to it and it does not cause any problems anywhere but in the studio but i have learned to deal with it.

 

[PlanarBeing]

Good to get verification from someone who's actually lived with, and used, one of these. If you just take the top of the amp off, you'll notice how the fan sounds quite different. I removed the 4 screws that hold it in place and verified that it's actually almost silent when held in the hand.

If the box were, say, twice as big, the fan noise wouldn't be resonating like it does. It's a bit like a kazoo, a very 'nasal' sound.

The fan speed has to be slowed and tuned to a quiet RPM rate, or the space inside the 'box' has to be increased.

Shooting for the one rack-space, design-wise, has some pitfalls. It reminds me of the noise from the fans on the old Mac Plus and SE, only much worse, because it's even smaller than the fans in those machines.

 

[sir riff a lot]

I was concerned that my 20/20 fan wasnt good enough , so I installed another fan
just behind the tubes in my 20/20 to push the heat out of the back of my rack.

now that is some loud fan noise :lol:

it is fine for live use, but in the studio I only use the 20/20 fan.

 

[PlanarBeing]

Now, that is really weird, isn't it -- the position of the standard fan in the 20/20? It's in the center of the 'box.' The tubes, located outside, at the back, get virtually no draught from that fan. So what's the 20/20 fan supposed to be cooling?

I can see the sense in having a fan outside, as with fan functionality on the 50/50.