guitar speaker / was Re: Tube challenge!

Martin Czech martin.czech at intermetall.de
Thu Nov 25 13:56:44 CET 1999


:::While it's well known that an *open* output can cause some damage on a tube
:::power amplifier, I nver heard of a constant load resistor instead of a
:::speaker
:::would cause any problems. Is this really true ? And if so, why ?

I think the transformer without load makes a resonator (winding
inductance and capacitance). Thus the isolation of the windings
can be dammaged due to very high voltages. A resistive load
will damp this completely.

AFAIK it is only dangerous to run without any resistive load,
or too high resistance value. The order of magnitude is important,
there is no exact value of resistance.

I once killed an old mono record player (Dual) with this,
the output transformer made nice sparks without the load,
then ... holy smoke ...


m.c.




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