Need help with subsonic filters...

 

Bronze Member
Username: Invain

Michigan United States

Post Number: 67
Registered: Aug-04
Ok, here's the deal. I have a 12" dual 4 ohm voice coil sub, that has a freq. resp. of 20hz - 500hz, that will be going into a slot ported box tuned to 38.2hz. The amp pushing the sub is a MTX 311D, with a frequency response of 20 - 85hz, Low-Pass Crossover Frequency 85Hz, Low-Pass Slope 18dB. I know the crossover is only pretecting the sub against higher frequency's, I think, but what I know I need is a sub sonic filter, since the sub is in a ported enclosure. So what exactly do I need?
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 70
Registered: Aug-04
anybody?
 

Silver Member
Username: Insearchofbass

Post Number: 282
Registered: Jun-04
those subsonics are only 18 db per octave too so it wont be any better than your crossover you have if its 18 db per octave just adjust the frequency on the amp
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1373
Registered: May-04
Harrison Labs FMods, the one closest to your tuning will be the 30 hz one.
 

Silver Member
Username: Insearchofbass

Post Number: 286
Registered: Jun-04
jon arent they just 18 db per octave so wont help any better than his factory crossover correct?
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1378
Registered: May-04
His factory crossover is a low pass filter, and he needs a subsonic filter, which is a HPF, so that he doesn't damage the sub below tuning.
 

Silver Member
Username: Insearchofbass

Post Number: 289
Registered: Jun-04
ok ty
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 72
Registered: Aug-04
Is this what I need then? http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=14931&item=3076531712&rd= 1&ssPageName=WD1V
 

Silver Member
Username: Insearchofbass

Post Number: 344
Registered: Jun-04
30 hp yes according to jon
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1401
Registered: May-04
That's the one.
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 73
Registered: Aug-04
thanks guys!
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 74
Registered: Aug-04
By the way, since the fmods come as pairs, 1 high pass and 1 low pass, what should I order the low pass set at? I have to specify what I want for the low and high pass frequency's.
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 75
Registered: Aug-04
anybody?
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 78
Registered: Aug-04
?
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 79
Registered: Aug-04
?
 

Silver Member
Username: Insearchofbass

Post Number: 349
Registered: Jun-04
high pass ....thats what i meant by hp
 

Silver Member
Username: Insearchofbass

Post Number: 350
Registered: Jun-04
sorry thoght you were confused about my earlier suggestion disreguard that one
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 80
Registered: Aug-04
No, I meant the fmods come in pairs, 1 hp, and one low pass, I know that I need a 30 hp now, (thanks by the way) but I need to know what I should order the lp to be set at.
 

Silver Member
Username: Caraudiofng

Houston, TX

Post Number: 203
Registered: Aug-04
You don't need a low pass....the amp has that built in.
 

Bronze Member
Username: Invain

Michigan United States

Post Number: 83
Registered: Aug-04
OK, you don't get it. I am ordering Harrison Labs Fmods, a pair, one low pass and one high pass filter. When I order them, I have to specify what i want them to be set at. I am running my sub in a slot ported box, so I need to get a hp filter. I am going to order the hp to be a 30hz, but what should I get the lp set at? I meen, I have to get the lp also, they come in a pair. And I know my amp has a lp built in. But what should I get the lp fmod set at?
 

Gold Member
Username: Jonathan_f

GA USA

Post Number: 1432
Registered: May-04
Both of them should be high pass 30 hz, you'll need one per channel. That picture is just for showing the difference in color rings.
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