BA23 fan noise

Warner Losh imp at
Mon Feb 1 10:22:21 CST 2016

In general with fans, there's two things that make them loud. 1 is the
size. All you can do about that is to get a smaller fan that can turn more
slowly. 2nd is some kind of lube problem. Sometimes you can fix these with
proper lubrication. Others, you have to replace the fan.

You really want to move the same amount of air through the system. Smaller
fans have to spin faster to move the same volume of air through the system,
and will be much louder. Larger fans can spin more slowly, while still
supplying the right amount of air.

With the BA23 cabinet, your options may be limited as to what you can do
w/o modifications to sheet metal to accommodate larger fans.

Less air flow is risky business for this old gear that has fewer heat sinks
on the parts, relying on the air flow to carry the heat away.


On Sun, Jan 31, 2016 at 8:27 PM, Jon Elson <elson at> wrote:

> On 01/31/2016 08:42 PM, Mark G. Thomas wrote:
>> Does anyone have any suggestions for figuring out how much airflow I
>> actually need, and achieving it with either stock fans at further reduced
>> voltage, or some kind of replacements? I don't need an accurate solution,
>> or something with complicated compensation for varying temperature,
>> just something quieter, moving less air, but still enough air.
>> I may have cooked some peripheral boards in my homebrew uVAX cabinet.
> The KA630 seems pretty robust, it ran for 21 years continuously under these
> conditions.  I got an EBM motorized impeller and made up my own plenum.
> The AC motor ran it WAY too fast, so I cobbled an 8" floppy brushless motor
> onto the original impeller, and I could adjust the speed.  My main test was
> to let it run an hour and see if the air coming out seemed too warm.  This
> was pretty unscientific.  The only boards that croaked were Dilog and such
> 3rd party boards.  I did have a thermal safety system that would cut power
> if the cooling failed (which it never did).  I later got a tangential
> blower for the expansion backplane, and it was a good deal quieter, but
> maybe didn't move enough air.
> Jon

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