Subsonic filter

[johnny40]

Hi guys new to forums hope im posting in right section. I have a ported box not sure on what its tuned to. I have 2 alpine type r SWR 1242D subs. Using a alpine pdx m12 which has subsonic setting of off 15 or 30. The shop that did the work set it on 30 but other people are telling me to put it on 15. Any help much app ty

[MotorCityFats13]

Hi guys new to forums hope im posting in right section. I have a ported box not sure on what its tuned to. I have 2 alpine type r SWR 1242D subs. Using a alpine pdx m12 which has subsonic setting of off 15 or 30. The shop that did the work set it on 30 but other people are telling me to put it on 15. Any help much app ty

if its a prefab box they are often tuned on the high side hence why the shop choose 30hz... the box is probably tuned in the low 40's.... if you play below tuning your subs will lose control "unload" and bad things start to happen .... now if the box was tuned in the low 30's you might get away with 15hz but it would be better if it had more options like a sweeping potentiometer and you could choose closer to 25-28hz

I built my box to 32hz and set the subsonic around 25hz.... anything lower than 20 is almost pointless since humans cant hear below 20hz... I say almost because you can still feel the air moving but cant tell shit is going bad until you smell coil burning

[johnny40]

its not a prefab box the shop custom made it for the car and to suit the subs is about all i know atm. it was sealed before but i wanted it louder so they made the ported box but it nearly sounds like the sealed one sq wise. until i play some songs with the lower notes then you can def tell difference

[MotorCityFats13]

so they know what its tuned at and they feel 30hz is the best choice.... if you move the switch you run the risk on voiding any warranty claims if the shop wants to be ass holes.... and it does not shut down everything under 30hz it just starts to filter out at 30hz so it probably still plays down to mid 20's... to know for sure you would need to know what slope it is using

[Smoove]

Proper name is infrasonic

[MotorCityFats13]

Proper name is infrasonic

I know right... someone should tell amp makers to start putting that on the amps

by putting sub sonic on the amps it makes me think it slows the amp down below 768 mph

[Smoove]

Proper name is infrasonic

I know right... someone should tell amp makers to start putting that on the amps

by putting sub sonic on the amps it makes me think it slows the amp down below 768 mph

Exactly why I thow this out there. I wish I could find Tony D's post.

[Karkov]

Rockford uses Infrasonic.......

EDIT: Is it still a rule of thumb to set "it" a half octave below tuning? Does it still depend on slope? Even with DD1+ how do I change slope?! Isn't it built into the amplifier and thus unchangeable? Am I thinking of something different or am I just super noob? Does "ohm rise" affect slope in any way?

I think I need to go refresh myself on slopes........

[MotorCityFats13]

my amps paperwork says if you set it to 25hz it will not play 25hz and lower but I really think they had the wrong person write the instructions manual because every amp Ive ever seen has a slope and you cant adjust it but this is the point it starts to cut off.... but I dont know maybe class D amps work differently on their crossovers... the OP's amp has a 3 position switch and I have never seen that

[poorfish88]

Rockford uses Infrasonic.......

EDIT: Is it still a rule of thumb to set "it" a half octave below tuning? Does it still depend on slope? Even with DD1+ how do I change slope?! Isn't it built into the amplifier and thus unchangeable? Am I thinking of something different or am I just super noob? Does "ohm rise" affect slope in any way?

I think I need to go refresh myself on slopes........

Older RF amps use the wrong term subsonic filter as well.