[sdiy] (OT) help with DEC branded relays

[Harry Bissell Jr]

--- The Peasant <ecircuit at telus.net> wrote:

> You have to be careful here, as high current relays
> usually don't do well with 
> the smaller signals that make up most of the audio
> signal. A special audio type 
> or wide current-range relay would be best. As 280W @
> 2ohm is a peak value not 
> normally sustained, you can use a significantly
> smaller contact rating than 12A 
> as well.

I agree with *most* of Mssr. le Peasant's assessment.

A wide current range relay should be unnecessary as
the
current will 'sometimes' be quite high and this will
maintain the relay contacts.  (so - disagree here ;^)

Most relays are specified for switching current, not
carry current.  This relay is not required to switch
while the signal is applied.  We can also look at the
duty cycle of those high current peaks.  If they were
10% of the time, you could multiply the actual current
by the square root of the actual duty cycle and get
the rating you require. The relay contact could be
rated at 
roughly .316 of the applied current (a one amp relay
could carry 3 amps at 10% duty).  Real crest factors
are MUCH less...

...unless they were mastered for maximum loudness :^P

H^) harry