Re: Loudspeaker to Line Level Pad
When I am looking at the output of a "modern" amplifier, (who knows what the black terminal is hooked to?) I like to stick a transformer between the output of the amp and the measuring device-for isolation reasons.
Yes at the extremes there may be some "drooping", but much better than possibly damaging the amp.
Since the measuring device should be high impedance, there will be minimal load on the transformer.
I guess it all depends on what sort of measurement you are trying to look at.
Regarding the resistors and "power" it depends on what the input (output voltage of the amp) voltage is to the circuit. We would assume that the measuring device is a high impedance, so your circuit is a 600 ohm load.
At 40V output ( 400 watts@4 ohms) the wattage (continuous sine wave) across the 30 ohm resistor would be around 0.13watt. Across the 570 ohm resistor it would be around 2.53 watts.
At 90 volts (2000watt@4ohms) the wattage across the 30 ohm resistor would be 0.675 watts. THe 570 ohm resistor would be around 12.8 watts.
