[Mike D]

Can anyone please tell me what capacitor and resitor values I will need to build in-line, balanced, high pass filters with a slope of 18db and a crossover frequency of 60 hz?  

Thank you in advance.

Mike

[Occam]

What is the input impedance of the load/leg?
What sort of 3rd order high pass filter, Chebychev, Butterworth, Frick 'n Frack, Punch&Judy?

These a questions you must answer before any solutions can be computed.

[Mike D]

The input impedance of the amplifier is 200K Ohms.  It is Rogue M150 monos.  The specs are at the Rogue Audio site.

http://www.rogueaudio.com/Products_m150.htm

The speakers are Magnepan IIIA which are 4 ohm speakers with Butterworth third order 18 db low pass crossover from bass to mid.

I am new to crossover design.  Thank you very much for showing interest is helping me design a couple high pass filters.  The maggies have no business trying to punch out deep bass at high volumes when I have an excellent sub from Legacy Audio that mates very well with the Maggies.

[Occam]

Mike,

This reference is for a line level 12db (2nd order) highpass -
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html

please note that it is for a single ended signal.
For conversion of filters into balanced versions -
http://www.filter-solutions.com/passive.html#balance
and please note that these conversions are for constant total load impedance. This is why I specifically asked you the input impedance per leg, whether that nominal 100k input impedance represents 50kohms/phase or 100kohms/phase. Is the single ended input impedance 50 or 100k ohms. If you really want to make a balanced highpass, you must resolve these questions by getting specific answers from Rouge Audio. If you resolve those questions, Bob's yer uncle.

It might be that the scarcity of 18db (3rd order) passive, line level highpass filters, is that they will show a rather large attenuation, making it difficult to match the level adjustment range of a powered subwoofer with its own built in lowpass. Then again, maybe not. Nevertheless, the only 3rd order passive line level highpass I recall was the HDLLP published in a 'who knows when' issue of Speaker Builder that mated to a similarly attenuating lowpass.
FWIW

EDIT - I've not checked the 'Q' (shape) of the falloff from the filters in the first URL. It should be between 1 and .5 with .707 being 'ideal' for mystical reasons. Iff'n you're interested, do a google on 'q' and '2nd order filter', and the solution is left as an exercise....