[mike s]

On Tuesday, May 31, 2011 6:46:12 AM UTC+1, Paul D. Spiegel wrote:
What do RATS use as a "rule of thumb" to select a fuse for a power amp?
In the past I've doubled the idle current, but honestly, that was just a
guess. How do you choose?

How do I choose? For a power supply use common ratings 1A, 2A, etc. So I'd generally use 1A for a typical amp. My experience is that 1A fuse won't blow if the amp is working fine, but will for most faults.

On the HT side I like to put a fuse between the centre tap and chassis. 500mA will again protect expensive components against typical failures.

Any amp requiring more than 500mA of HT (that's about 150W) will clearly need a bigger fuse, but probably needs other considerations too.