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Thanks to Doug Goldberg, I now have all the information on the boost in these amplifiers, and no time to get it on the webpage at the moment, so I guess I'll just post it here. The standard Apex Senior or Stryke AMP350 has a 6dB boost centered at 30Hz. As you can see in the graph below the boost begins to effect things way up at about 65Hz, and by 15Hz the level is about 10dB down. I believe the graphs are done with the LP filter set to 50Hz:
http://www.stryke.com/pics/amp-350-stock.gif
Modifying the boost is very simple. R26 on the crossover board has a stock value of 18k ohm. Changing this to 100k ohm removes the boost and gives the amplifier an F3 point of 12.5Hz:
http://www.stryke.com/pics/amp350-noboost.gif
The second mod that can be done is to change the low pass filter from 12dB to 18dB. The stock value on C16 is .12uF. Changing this to .22uF will increase the order on the crossover to 18dB and the slope will now look like this:
http://www.stryke.com/pics/amp350-noboost-18db.gif
The 18dB slope will often work much better for integrating your subwoofer with your system. Other values for R26 can also be picked to get different values of boost if desired. I plan to get the exact resistor values to center the boost at 20Hz or 25Hz, and also the amount of boost given at these frequencies.
John
http://www.stryke.com/pics/amp-350-stock.gif
Modifying the boost is very simple. R26 on the crossover board has a stock value of 18k ohm. Changing this to 100k ohm removes the boost and gives the amplifier an F3 point of 12.5Hz:
http://www.stryke.com/pics/amp350-noboost.gif
The second mod that can be done is to change the low pass filter from 12dB to 18dB. The stock value on C16 is .12uF. Changing this to .22uF will increase the order on the crossover to 18dB and the slope will now look like this:
http://www.stryke.com/pics/amp350-noboost-18db.gif
The 18dB slope will often work much better for integrating your subwoofer with your system. Other values for R26 can also be picked to get different values of boost if desired. I plan to get the exact resistor values to center the boost at 20Hz or 25Hz, and also the amount of boost given at these frequencies.
John