RadioBanter - View Single Post

January 9th 06, 12:28 AM posted to rec.radio.shortwave

wrote:
Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

--------------------------
It might be safer or better to say that transformerless
amplifiers(OTL), either
stereo or mono power amplifiers can almost always operate safely
without a load.
I remember a Kakimichi ~50W unit that tended to go into ultrasonic
oscillation
unless it was operated with something close to 8 ohms.

However transformer output amps will more freqeuntly then not self
destruct
with any significant power. Tubes survive slighlty longer then
transisitors.
Transistors will very frequcnly "pop" on the first load sound impulse
where
tubes may survive the high voltage spike only to have the output
tranformer
arc through in short order. I have made nice money repairing older
Macintosh,
audio not PC, amplifiers that people had neglected to operate under
load.

And I made a nice bundle repairing a high power Marshall guitar amp
that
a doper guitarist fried by operating with the speakers disconnected.
this
unit operated with about 1400V DC on the plate. Most of us will not see

consumer power audio, and damn little pro, gear that has output
transformers.

I no longer do much work on tubed gear because in a +12V world I fear I
might
have becmoe a bit lax in my safety habbits.

Touching, while also touching ground, a 1400 plate line will KILL you!
A good tech I new screwed up back in 1985, he got just a little
careless
on a Marshal amplifier "head" and got bit but good.

Terry