[sdiy] Quietest 60mm fan?

[Colin f]

> Eventually ive got around to opening up my Akai S6000 to find 
> the source of 
> the racket inside...
> 
> The culprit is a matsushita 12v dc SF60 fan...

Check.
 
> Im looking at various replacement fans, using the old 
> favourite, ebay, and 
> comparing noise and airflow data, and wondering -
> 
> Generally, if something has, to use easy figures, 50CFM 
> airflow at 50DBA, if 
> i lower the fan voltage to, say, 10v, am i likely to see a linear 
> relationship between noise and airflow, or can i expect optimums?

Some designs are better than others, but as a general rule, small diameter
fans cant give decent airflow with low noise.

I took some tin snips to my S6000, and opened the hole up for an 80mm
Panaflo fan with a speed reducing resistor.
It's now less audible than the humming transformers in some more vintage
equipment.

> In this example, the s6k is, i believe, little more than a 
> custom board with 
> an intel 386 dumped on it.  This machine has no internal hard 
> disk either, 
> so im wondering how much cooling i really need anyway.

The S6000 has an auto-speed function - it will speed up the fan when the
temperature gets 'too high'.
You could test whether your unit reaches that temperature by sitting the fan
outside the unit.
Leave it running for a good while, and if the fan speed doesn't increase,
then it isn't getting too hot.
If it isn't getting too hot with the fan outside the enclosure not doing
anything, then it's safe to say you don't need the fan at all.

Cheers,
Colin f