I would not recommend using a 200 watt light bulb, and in general I would not recommend other light bulbs rated to operate at 120 volts.
Their resistance will vary extremely widely depending on how much voltage is applied to them. For example, a 120 volt bulb whose power consumption under normal operating conditions is 200 watts will have a resistance following its very brief initial warmup of about 72 ohms. However, extrapolating from resistance measurements I’ve performed in the past on various other light bulbs its resistance when cold will be in the rough vicinity of only 5 ohms. So depending on how much signal is applied to it by a power amp its resistance may be at any point in between, and its effectiveness may vary unpredictably.
More significantly, if you happen to be using a tube amp resistances in the higher end of that range may be too high to be safe. As you may be aware, tube amps which have output transformers should not be operated unloaded, at least when they are processing a signal, and 40 or 50 ohms or more may be high enough to be an inadequate load, that may result in serious damage.
And of course the 200 watt bulb would be totally unsuitable and quite possibly harmful if used as a load for a DAC or preamp, which would not be able to supply enough current or voltage to raise its resistance above the vicinity of 5 ohms or so. For that matter, operating DACs or preamps into a 100 ohm resistor for a considerable amount of time could conceivably not be healthy in some cases either, in addition to being extremely non-optimal sonically if the system is listened to while the resistor is in place.
Regards,
-- Al
Their resistance will vary extremely widely depending on how much voltage is applied to them. For example, a 120 volt bulb whose power consumption under normal operating conditions is 200 watts will have a resistance following its very brief initial warmup of about 72 ohms. However, extrapolating from resistance measurements I’ve performed in the past on various other light bulbs its resistance when cold will be in the rough vicinity of only 5 ohms. So depending on how much signal is applied to it by a power amp its resistance may be at any point in between, and its effectiveness may vary unpredictably.
More significantly, if you happen to be using a tube amp resistances in the higher end of that range may be too high to be safe. As you may be aware, tube amps which have output transformers should not be operated unloaded, at least when they are processing a signal, and 40 or 50 ohms or more may be high enough to be an inadequate load, that may result in serious damage.
And of course the 200 watt bulb would be totally unsuitable and quite possibly harmful if used as a load for a DAC or preamp, which would not be able to supply enough current or voltage to raise its resistance above the vicinity of 5 ohms or so. For that matter, operating DACs or preamps into a 100 ohm resistor for a considerable amount of time could conceivably not be healthy in some cases either, in addition to being extremely non-optimal sonically if the system is listened to while the resistor is in place.
Regards,
-- Al