Originally Posted by tsloms
What would be the best type of resistor to use for this? They will need to dissipate quite a bit of wattage to attenuate that much.
Before you go and spend the time and money to build this high power attenuator, why don't you try a quick experiment to see if 20 dB is enough to reduce the hiss to an acceptable level.
Try adding a 1/4 Watt, 144 Ohm resistor in series with your tweeter (150 Ohms is close enough) but don't play any music with it hooked up, just listen for an acceptable reduction of hiss.
If your tweeter actually presents a 16 Ohm load then you should get about 20dB of attenuation with that value resistor and easily determine whether 20dB is enough or not.
And finally, for a really radical idea, why don't you think about using a 10:1 transformer to attenuate your tweeter by 20dB instead of using an L-Pad?
A transformer doesn't have any of the power dissipation issues that L-Pads have, and I've never heard of any complaints about the "sound" of transformers from the dedicated tube amplifier lovers.
(Transformers can be quite linear for the frequency range you're interested in, if you get a decent one)
Maybe others can suggest a good source for a high quality transformer.