Hi, i have a 12" alpine type-r in a box tuned at 42hz. Im deciding what to set my amps low pass at. Will having my amp set at 42hz increase spl? or will that have nothing to do with it? thanks

 

for competition you want your lpf basically off if playing tones...
but for daily, you want to have it around 50-80 hz depending on your music and the filter slope in the amp or deck

dont set your filter at 42 if your box is tuned at 42... the cross of ever point of your filter is the 3db down point
if u set it at 42hz and you have a 500 watt amp... you will only get 250 out of your amplifier
now depending on the slope( 6/12/18 or 24 db/oct) you will want to set it higher according to what the system can handle and the music you listen too
you might also want to use a subsonic if you're tuned that high

 

The low pass filter doesn't affect SPL directly unless you have it set so low that the amp isn't outputting any frequencies... But in that case, there would be no output period. Subwoofers are designed to handle anywhere from 20-120 Hz. As MTA mentioned, 50-80 Hz is the norm, but again, it depends on your type of music.

 

better wording might get your point across... but LPF has a huge effect on your SPL... so does subsonic.

 

soo very tru.. i have learned that the hard way a few time. Peter knows lol

 

MTA & Menace: Ya, you guys are probably right. I tried to keep my response likened to foreplay.... Just dipping my toes in before going for the big dive LOL As you both know, there are a lot of variables in play with SPL, or even just trying to get a relatively flat response. Considering it's a single Type R 12, I don't think SPL is the same language for you guys and the OP.

 

huh what does a 12" sub look like. who is alpine. just joking man. i hear they are good bang for the buck with out getting into the hardcore . the warranty are really good too.

 

Yeah, not too bad. I was impressed at a show in Kingston Jeff had put on. A couple people had thrown 2 R 12" in a prefab box, slapped an Alpine MRP-M2000 (1500wrms if memory serves me correct) on them and a single run of 1/0awg from the batt hitting just a bit north of 145

 

that's kinda soft to be honest.

 

in a mock up on winisd, i modelled your sub in a 1.5 cube box tuned to 42hz with 500 watts. The max spl difference between lp on at 42 hz @12db/oct and off is 5dB centered around 45-50 hz...thar's a lot! Start you lp at 100hz and adjust down until you find a good balance between loud and sq.