# Speaker Cross-Over Network and Power Design

I have some speakers I want to drive from a single output: a 4Ohm 300W Subwoofer, a 6.44 Ohm 60W Midrange, and 2 8Ohm 3W Tweeters. All ratings are RMS.

I know that if I were to wire all of these in parallel, the equivalent resistance would be 1.52 Ohms, but there is different power at different frequencies, so calculating the max output amp voltage isn't trivial. If my cutoff frequencies would be something like 120Hz and 2kHz and assuming my music follows a pink noise spectral power distribution, my subwoofer is taking something like 40ish times more power than my tweeters. However, this is not reflected if one treats the whole network as an equvilant resistor.

How should I approach this? I would assume that using 1.52 Ohms as the equivalent resistance and using the limiting part of the network in terms of power, the tweeters, to designate the highest voltage would be faulty. Should I instead use the pink-noise sound approximation to design my crossover with appropriate crossover frequencies and power distributions to each speaker, then just use the equivalent network resistance to calculate the max voltage the network can take? How exactly do I quantify the amount of voltage each speaker will see after all of the filtering?

• What have you found so far? Any examples of circuits? Feb 6, 2018 at 9:08
• Music doesn't have the same power density as pink noise. I suggest reading this question and my answer: electronics.stackexchange.com/questions/353988/… I also suggest to look up some guides on designing speaker crossover filters to learn how it is done. At the moment you are seeing issues that are really not an issue. For example: there will not be 1.52 ohms, the crossover filter will make sure a certain frequency goes to a certain driver (speaker) so at that frequency the amplifier will see about 8 ohms. Feb 6, 2018 at 9:43
• @Bimpelrekkie With todays kids' listening to so called EDM and dubstep, this has shifted, but try playing say 1000 songs from various categories such as jazz and classical at the same time, it becomes much closer to pink. I did extensive simulation about this when I designed PA amplifiers for a living in MATLAB. Unlikley candidate for tipping of your amplifier energy hold-up design or just straight out bad amplifier design killer was Enya :-) Feb 6, 2018 at 9:57
• @Andyaka Another <--- This guy get's it! :-) Feb 6, 2018 at 10:21
• @winny aha a fellow studier of music spectrums LOL Feb 6, 2018 at 10:26