6/17/2017
XKITZ XAMP-M2
7
Customizing Your Active Crossover Frequency
The crossover (XO) frequency is determined by the value of the ten resistors mounted to a 20-pin socketed
component carrier called the ‘XO Module’. All 10 resistors are set to the same value.
Xkitz offers a wide range of standard XO Module frequencies at this location:
https://www.xkitz.com/collections/active-crossovers-and-bi-amplifiers-1/products/xo-module-for-use-with-
xover-2-and-xamps
Or you can select your own custom XO frequency resistor values with our filter calculator tool at:
http://www.xkitzconnect.com/files/Linkwitz-Riley-2Way-Calculator.htm
Just enter your desired crossover frequency. Then hit the ‘Calc’ button. It will give you the suggested resistor
value for your crossover, and it will show a schematic diagram of the crossover. You may have to round the
suggested values to standard available resistor values. High precision (1% or better) resistors are recommended
to minimize distortion.
Selecting Your Ideal Crossover Frequency
Consult the specifications of your loudspeakers to select your ideal XO frequency. Every loudspeaker has its
own ideal operating frequency range. Woofers, of course, work well in the low frequency range, but as frequency
increases their performance deteriorates. Same for tweeters; they operate well at upper frequency ranges and
deteriorate as the frequency comes down. Your crossover frequency should be somewhere near the mid-point
between points where both the woofer and the tweeter are still solidly within their ideal operating frequency
range.
Baffle Step Compensation
The Baffle Step Compensation circuit, or BSC, if you choose to use it, allows you to apply a low pass filter
function to the audio signal to compensate for a phenomenon where sounds above a certain frequency
(determined by the size of the baffle, or the front of your speaker box) are actually reflected by the front of the
speaker enclosure. Sounds that fall below that frequency do not get reflected, but instead wrap around the back
of the speaker enclosure. This has the effect of reducing the magnitude of the lower frequencies. Your ear hears
the primary waves plus the reflected waves on the highs, but only the primary waves of the lows. The BSC
circuit, by applying a low pass filter, will roll off some of the highs to restore the overall sound to a more natural,
linear state. Check the web for more detailed description of BSC.
The VR3 precision 20-turn trim-pot allows the BSC magnitude to be adjusted. Turning the pot 20 full
revolutions counter-clockwise reduces the BSC magnitude to the point of being entirely disabled. Turning it
clockwise increases the BSC magnitude to a maximum of 6dB. In other words, it increases the amount of
attenuation of the higher frequencies to 6dB below the lower frequencies. This compensates for the theoretical
6dB attenuation of the low frequencies due to the baffle step.
Table 3.
Baffle Step Compensation – Recommended C42 Value
Baffle Width (in Inches)
Baffle Step Freq.
C42 Value
Less than 10"
507Hz
0.022uF
10" - 16"
351Hz
0.033uF
Greater than 16"
240Hz
0.047uF