From: jreiser@scott.skidmore.edu (Jason Reiser... Asleep)
Subject: Passive X-Over Chart Repost...
Organization: Skidmore College, Saratoga Springs NY
Date: Tue, 17 Nov 1992 06:46:27 GMT

	Since there has been more talk recently on building passive
crossovers, I figured I would re-post these charts.  Sources for all
of this are Car Stereo Review, March/April 1991 and the Orion
Newsletter, July/August 1991.

 
	6 db per octave high and low pass filters
-------------------------------------------------------------------
   Frequency |           S p e a k e r   I m p e d a n c e        |
     (Hz)    |        4   O h m s       |        8   O h m s      |
             |-----------------------------------------------------
             |     L1     |     C1      |     L2     |     C2     |
-------------------------------------------------------------------
     80      |   8.2 mH   |   500 uF    |   16 mH    |   250 uF   |
    100      |   6.2 mH   |   400 uF    |   12 mH    |   200 uF   |
    130      |   4.7 mH   |   300 uF    |   10 mH    |   150 uF   |
    200      |   3.3 mH   |   200 uF    |  6.8 mH    |   100 uF   |
    260      |   2.4 mH   |   150 uF    |  4.7 mH    |    75 uF   |
    400      |   1.6 mH   |   100 uF    |  3.3 mH    |    50 uF   |
    600      |   1.0 mH   |    68 uF    |  2.0 mH    |    33 uF   |
    800      |  0.82 mH   |    50 uF    |  1.6 mH    |    25 uF   |
   1000      |  0.62 mH   |    39 uF    |  1.2 mH    |    20 uF   |
   1200      |  0.51 mH   |    33 uF    |  1.0 mH    |    16 uF   |
   1800      |  0.33 mH   |    22 uF    | 0.68 mH    |    10 uF   |
   4000      |  0.16 mH   |    10 uF    | 0.33 mH    |     5 uF   |
   6000      |  0.10 mH   |   6.8 uF    | 0.20 mH    |   3.3 uF   |
   9000      |    68 uH   |   4.7 uF    | 0.15 mH    |   2.2 uF   |
  12000      |    51 uH   |   3.3 uF    |  100 uH    |   1.6 uF   |
-------------------------------------------------------------------
 
 L = inductor          uF = microfarad        uH = microhenries
 C = capacitor         mH = millihenries
 
-------------------------------------------------------------------
 
-- High pass... use the capacitor in series to the speaker.
-- Low pass.... use the inductor in series to the speaker.
-- Band pass... use an inductor and capacitor in series to the speaker
                with the capacitor closer to the speaker.
                (this can be reversed) 

-- Note that these can be done in other ways, ie. use a cap. in
parallel to a woofer for low pass, but these represent the usual methods.
 


        12 db per octave high and low pass filters
------------------------------------------------------------------
   Frequency |          S p e a k e r   I m p e d a n c e        |
     (Hz)    |       4   O h m s       |        8   O h m s      |
             |----------------------------------------------------
             |     L1    |     C1      |     L2     |     C2     |
------------------------------------------------------------------
      80     |    11 mH  |     330 uF  |     22 mH  |    180 uF  |
     100     |   9.1 mH  |     270 uF  |     18 mH  |    150 uF  |
     130     |   6.8 mH  |     200 uF  |     15 mH  |    100 uF  |
     200     |   4.7 mH  |     150 uF  |    9.1 mH  |     75 uF  |
     260     |   3.6 mH  |     100 uF  |    6.8 mH  |     50 uF  |
     400     |   2.2 mH  |      68 uF  |    4.7 mH  |     33 uF  |
     600     |   1.5 mH  |      47 uF  |    3.0 mH  |     27 uF  |
     800     |   1.0 mH  |      33 uF  |    2.0 mH  |     15 uF  |
    1000     |  0.91 mH  |      27 uF  |    1.8 mH  |     13 uF  |
    1200     |  0.75 mH  |      22 uF  |    1.5 mH  |     11 uF  |
    1800     |  0.50 mH  |      15 uF  |    1.0 mH  |    6.8 uF  |
    4000     |  0.22 mH  |     6.8 uF  |   0.47 mH  |    3.3 uF  |
    6000     |  0.15 mH  |     4.7 uF  |   0.33 mH  |    2.2 uF  |
    9000     |  0.10 mH  |     3.3 uF  |   0.20 mH  |    1.5 uF  |
   12000     |    75 uH  |     2.2 uF  |   0.15 mH  |    1.0 uF  |
------------------------------------------------------------------
 
 L = inductor           uF = microfarad       uH = microhenries
 C = capacitor          mH = millihenries
------------------------------------------------------------------
 
NOTE--
12db/octave crossovers are set up as following...
  -- high pass - capacitor in series followed by inductor in parallel
		   (inductor is closer to speaker.)
  -- low pass  - inductor in series followed by capacitor in parallel
               - (capacitor is closer to speaker).
  -- band pass - inductor in series followed by capacitor in parallel
                 followed by capacitor in series followed by inductor
                 in parallel (closest to speaker).
		 (basically, a high and low pass in series to each other) 

Sorry if this is becoming confusing, but to attempt to draw this on
the system would be extremely difficult.  Check out the CSR issue
for diagrams and talk.  
 
I have not included the 18db/octave charts due to the complexity of
those charts, but if someone would like to know some specific points
just drop me some mail.
I have the 18db/octave information only for the same crossover points
(in Hz.) as listed above.  

AND, if anyone has information on building crossovers at other
frequencies, please post.


				- Jason



-- 
---------------------------------------------------------------
\ Jason A. Reiser  \ Send E-Mail to jreiser@scott.skidmore.edu \
 \ Skidmore College \ Saratoga Springs, NY 12866 \ 518-581-6580 \  
  \ It's a new Ice Age!  Hooray!!  Sled City!  - Calvin & Hobbes \
Xref: sparky rec.audio.car:5025 alt.locksmithing:2090 alt.tasteless:12898