"Ron(UK)" wrote:

Maybe someone with experience in 'designing' power amplifiers
could comment?

I have done !

There's something worth adding though.

To optmise air flow you need a high 'static pressure'. There's a huge variation
in this characteristic. The best examples I've found are NMB (formerly Boxer) and
Panasonic's Panaflow fans. Be careful to order the high pressure version. They
make versions with various motors speeds. In the case of NMB, the 'best' ones
used to have 'B50' as part of the part number. I forget Panasonic's method of
marking.

DO NOT use cheap 'off brand' fans for applications like this.

I see Farnell have NMB but only as a special US import. You didn't say what size
it is but the popular 80mm size would be for example ....
http://uk.farnell.com/8235414/electr...kl-05w-b50-e00

Read the data sheet here
http://www.eminebea.com/content/pdf/...3/I/3112kl.pdf

to see just how radically. the airflow varies with the Bxx model number.

Graham