In article . com,
wrote:
The "HT" rail is quite likely to be in excess of 12V, especially if
the power output is reasonable (i.e. much in excess of 10W
rms/channel).

No - the usual way in a car radio is via bridged output amps if more
than approx 6 watts. Some earlier designs improved on this with an
output transformer.

Normal transformerless outputs from 14 volts into 4 ohms are actually
less than 6 watts, though, regardless of ad speak. Bridging those can
give approx 3 times the power output still into 4 ohms.

Higher power amps use a switch mode voltage booster to supply the
bridged output amps.

Indeed - but not likely on a motorbike?

--
*If a pig loses its voice, is it disgruntled?

Dave Plowman London SW
To e-mail, change noise into sound.