Been messing with car audio since 1999 but only with sealed boxes. I just bought my 1st ported box for 2 kicker solobarics 15's L7's. The box is tuned at 38HZ to go in my 95 Impala SS. Heard you gotta use the subsonic filter with ported box? What do I put the subsonic, LPF, and bass boost set at?
Set the subsonic filter at about Fs or about 15% below the port tuning frequency (FO) whichever is higher.
Set the LPF at 60-80 Hz. Most amplifiers have a 12 dB crossover slope on the LPF, so if you set the LPF higher, you will get punchy bass and it will hit very hard, but if you keep it at 60-80 Hz you will get smoother lower more pleasant bass. Besides if you go above 80 you will drown out the mid-bass from your mids and highs (if you have any).
I do not recommend using the bass boost. Keep in mind that if you use the bass boost or EQ or bump up the bass level on your HU, you will give up power to the rest of the frequencies. Every 3 dB is twice/half the power. So if you bump up the bass boost 3 dB at say 60 Hz you will lose half power to the rest of the other frequencies. Your amp has only so much power. When you boost up, you take away from the others.
Using bass boost, EQ, and/or bass levels above 0 will increase the chance of clipping, distortion, and damage.
Also, the loudness button is intended only at low volume applications.
What is Fs and FO? So if port is tuned at 38Hz 15% below 38Hz would be 32.3 basically 32Hz. Subsonic filters are 20Hz minimum and 50Hz Max right? so 1/4 is 27.5Hz 1/2 is 35Hz. So it should be at 1/2 between the 1/4 and 1/2 which would make it at 31.25Hz
My recommendations are not comcrete numbers. I just gave an idea where one might consider doing. It doesnt have to be 15%.
I am just saying that you cut it off just below the port tuning fequency. That way you do not force your subs out of control.
When subs are aked to play below their limits, they start to sound as if they are producing air instead of sound. This is when they travel long linaer ways and may even damage the sub. Thats what a subsonic filter is for, to filter out stuff below what the sub can naturally do.
Fs is the frequency that driver has a peak in its impedence. It is usually the point at which the driver is able to hit its lowest note in free air.
FO is the frequency output. Otherwise known as F3. Basically 3 dB below par level. The point where your driver starts to tapper off from its normal outlevel because of natural limitations, not crossover knees.