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Bass Enabler
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Discussion Starter · #1 ·
Hey guys. I finally got around to modding the fans in my cv5000. Bought some Noctua fans and wired them in series for 24v on the amp. They seem great but I hear this scratching sound. It's intermittent. Definitely nothing rubbing or touching the fans. The sound is audible when power is applied to the amp. As soon as I turn off the amp the scratching sound disappears even though the fans are still moving. I can't figure it out. I'd like to fix. The fans are nearly silent but the scratching is audible enough to be annoying. I've uploaded a video. Please help. Thanks.

 

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Bass Enabler
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21,719 Posts
Discussion Starter · #4 · (Edited)
EDIT: Well it's definitely the fans. I turned on the amp and then put my thumbs on the center of each to stop them. Sound went away. I can't think of how to fix this. These fans are new and got them a month or two ago. It would be quicker to order a couple more but they were expensive. Plus... both are making the sound. What are the chances of that? Ugh. I don't know what to do.


It sounds like both do it. Hard to really tell but the noise stops the moment I turn off the amp even with the fans still spinning.

Can't say I'd hear it for sure. The amp is not fully closed up yet. I did stand back a few feet and I could hear it still. If not I'd just put up with it. There is a possibility that I won't hear it when I close up all the sides of the rack. But if I can fix it then I'd like to do that before I button up the whole lot.
 

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Remove both fans.

Apply power while holding each fan.

Hold each fan in various positions to see if the scratching is present when vertical vs. horizontal.

End result to any troubleshooting appears to be replacing the fans anyway.

If the scratching is inaudible at the MLP and the bearings are fluid dynamic then I wouldn't worry about it. If the bearings are anything else, the scratching will only get worse over time.
 

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Pull the fans out and connect them to a DC wallwart and see if they still make the sound (power supply vs fan motor).
Hopefully it's not the CV fan supply.
 

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The most common reason for the fan tick is because of fan orientation. Some fans are not meant to be vertical or horizontal. Contact the manufacturer to find out if yours falls into this category.
 

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True ^ but with quality fans this becomes less of an issue. Noctua fans are premium fans that do great vertically or horizontally.
 
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