![]() There are a few threads on here about Bass restorers.Some one took a few different brands apart and found they were all copies of the Epicenter.Even the circuit boards were identical. The newer epicenters do have the PFM but the old ones dont.Īlso AC recommends not using a low pass filter on the signal going into the unit.If you have to use low pass make it as high as you can,at least 120hz.I have had decent results using it at 200hz but if its to low(60hz) all that comes out is a sloppy rumble. Price 219. When running a ported box there should always be an active high pass crossover set at or just below the tuning frequency of the box.This is mostly to keep the sub from over excursion because it is not loaded below the tuning frequency.So a properly designed system should already have this.Īctive crossovers do have phase shifts just like passive ones.They are the same,90 degrees for 6 db/oct.180 degree for 12 db/oct etc.They also have the same phase characteristics as the type of crossover,such as Butterworth,Bessel,Linkwitz-Riley etc. Concert Series Digital Bass Maximizer and Restoration Processor with PFM Subsonic Filter (Black) Item 19817 / Condition: Brand New 14 Reviews 149.00 Free Shipping in US 48 Save 70.00 Reg. The upshot is you get a lot more precision and a 24dB/octave slope (except the 2XS, which is 18db). Both crossovers work with modules and both have a PFM (AudioControls name for subsonic) module in them. This is different than most other active crossovers that use a frequency adjustment knob accessible on the outside. You can also make modules with individual resistors, but it's a bit more tedious. For a smaller sub with less power, you could play louder if the cutoff was set higher. For my 6XS, I set the subsonic filter at 20Hz with a 360kOhm resistor module since I was running a 12" Polk sub in a sealed enclosure driven by 800 watts. You can order them from Mouser or Digikey for pennies- just search for resistors/resistor networks/isolated circuit type, etc.ħ200/frequency= the kOhm of the resistance. ![]() You can purchase modules from AudioControl dealers, but you'll spend about 20x what they are worth. The frequency is set by a resistor network that fits on a DIP socket on the main board accessible only by opening up the chassis- not exactly intuitive or convenient. What sucks about it being 33Hz, is if you have a system that can nicely produce 25Hz notes, they will get a 12db reduction (24db/octave)- cut in half 4 times, so basically inaudible. PFM Subsonic Filter: On: removes frequencies below 20 Hz Off: filter is bypassed, generally a bad idea, particularly with ported sub enclosures Output Voltage: set the maximum output voltage to match downstream processor/amp(s) 5 volts, 7. The subsonic filter (high pass crossover) on AudioControl components is 33Hz only because that just happens to be the factory default. The EQS has a subsonic filter set at 33hz also. It's the passive crossovers that are guilty of this. ![]() An active pre-amp crossover should not have any effect on phase. Click to expand.Just because a ported enclosure is tuned to a certain frequency does not prevent wasted energy reproducing frequencies outside the desired range.
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