I'd be willing to bet 25hz will be fine for you, but you probably wouldn't miss much setting it to 30hz either, which would be even safer. Using Tones you can see the correct filter by watching cone movement. My 10W6's are going to be celebrating their 9th birthday in 2004, they've been in a very large 32hz ported environment for most of their life now, and I've never had the need for a subsonic filter. "need" is such a strong word ) for a subsonic filter. Rather than nearly twice the pressure forces inside the box compared to a sealed box, you end up with literally none, if you go too far, and it's really easy to bottom out a sub essentially free-air like that. However, as you travel away from the tuning frequency in either direction, they become less and less "in phase", eventually you'll get to the point where the sub again might as well not even be in an enclosure.Īt low frequencies, this is bad, because the sub literally behaves like it's not in a box at all. In reality, it's never going to be a perfect phase alignment, but your "tuning frequency" is the frequency where, if played, the cone and energy escaping out the port are going to be as close to "in phase" with each other as they can get, so they combine constructively rather than cancel out. it's just about in time for the cone to move out again and compress the air in front of the cone again. so that by the time a pulse of compressed air travels out of it, say. Now, the reason why you need a subsonic filter on a ported box is because once the sub starts playing frequencies too far below the tuning frequency of the box, you run the risk of 'unloading' the sub (laymens terms the box loses control over the subs movement), which could and generally will result in mechanical damage to the subwoofer. but they are delayed by that static amount of time. so the pressure fluctuations inside the enclosure can travel through this port. The port is a tube with a known air mass and resistance. it simply contains and destroys that rear wave energy, so it can't escape to cancel out the front wave energy. Hence the need for a box.Ī sealed box is like a garbage disposal. If it weren't for your enclosure, the pressure would bleed into the vacuum, and you'd get almost no sound.
and decompresses the air behind the cone. The cone moves out, and compresses the air in front of the cone. When a sub moves in and out, the signal generated off the front of the cone are 180 degrees out of phase with the signal off the rear of the cone. None of it matters in the scope of "just be careful, and listen for your sub's limits, and set the subsonic based on those." :cool:īear in mind, the port is simply a delay device, essentially. 10hz below is probably a better rule of thumb, but there are some influencing factors. For fitting this data you need to include the LPF in the curve fitting.You don't need to set it right at the tuning frequency. For the receiver I set the mains to small and the crossover at 80Hz then just hooked REW to stereo inputs and measured the sub line output. If the polarity is wrong the lights on the EP2500 will light up.
SUBSONIC FILTER SERIES
Maybe try it out with a 10k resistor in series first. You must use unbridged mode and also the ground (black) output from the amp must go the ground of your sound card. Even though they may only contribute less than 1dB in this range, there are several so they add up and should be considered.įor the EP2500, I just was careful with the gain setting before looping it back to my sound card. This provides the greatest accuracy in the range that you are interested in: 10-20Hz. We didn't have subs at that time but a bad turntable could really work the woofers hard, stealing power in the process. I'm a computer programmer in Melbourne Australia. Subsonic filters used to be built into any receiver or integrated amp way back when. Try Elliott Sound Products for more projects. Both DSE and Jaycar Electronics would have kits of Rob Evan's Subwoofer Processor (which only has a 6dB/oct subsonic filter if memory serves me well). I limited the fitting range from about the -6dB point up to about 2-3 octaves above the cutoff frequency. Making a subsonic filter is very easy, especially if you go the kit route. You just have to decide what part of the data is important for the fitting. I then used the solver to fit the filter cutoff frequency and order to the data. I saved that data to text and opened it up in excel. I used REW and a sweeps up to 200Hz to find those cutoffs. I would guess that they would be within 10% of my measurements because of combined tolerances of electrical components. Click to expand.They will vary primarily because of component tolerances.
0 kommentar(er)
