Question I would like to know more details regarding the EQ of the Spark Booster. Answer Frequency ranges: (low cut, high roll off) 20Hz-20khz 
  • Centre: 500Hz (means the middle value that you can then either go up or down from when moving the pots) 
  • Bass boost/cut 125Hz 
  • Treble boost/cut: 2kHz
The tone corrections work this way. The center point is "neutral" position. When you turn counter clockwise, either cut the frequency and when you turn clockwise, you boost the frequency. The Spark Booster filter reacts like a shelf filter with high and low pass filter for limiting frequencies outside the audible band. The center frequencies refers to frequency where the amplitude has dropped by -3dB. I attached a curve that makes you well understand. To sum up, the two tone knobs act like shelf with the fixed frequencies of 125Hz and 2kHz plus you have a high pass filter set at 20 Hz and a low pass filter set at 20kHz. The Clean' setting means no equalization, just clean gain. The Fat' setting fattens up your signal much like a 'Loudness' button on a stereo works. The Mid-boost section provides a bump in the mids to make guitar solos stand out. Unfortunately at the moment, I do not have the information about the gain of the filters but I think it should be +/- 15dB or 18dB, which is a standard. Here are the Spark Booster features :
  • 26 dB of clean boost. 
  • Level knob - drive amps even harder. 
  • Place after existing distortion/overdrive to enhance drive sounds. 
  • Place before existing distortion/overdrive will increase the amount of distortion and sustain. 
  • Add grit, life and compression to your tone. 
  • Add body, punch and warmth to pickups. 
  • Mid-boost - cut through any mix. 
  • Active EQ - extended low and high end. 
  • True bypass - optimal signal integrity.
The product page can be found here. EQ diagram: Spark_Booster_Filters.jpg