Head Unit Low Pass Filter

[Basshead808 10+ year member]

Okay my Headunit Sub LPF is set to 50HZ. It was originally set to 125hz I don't like the sound of the high frequencys I can hear singing comming from my subwoofer lol I don't want my sub to act like a giant speaker so it is set to 50HZ but my amp LPF is set to 35HZ so what is the final H the sub is set to? I hope 35HZ..

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[wilzyx 5,000+ posts]

im guessing it would be at 35hz because the signal goes through the amp last before it gets to the sub.

 

[Basshead808 10+ year member]

lol okie thanks.

 

[PhatTonyDeMarco 5,000+ posts]

35Hz is rather low.... You are missing a lot of subsonic frequencies...

 

[Prowler573 5,000+ posts]

Why do you have the LPF on the amp set so low? That is going to leave a pretty big gap between your midrange and the substage, IMO....what's reproducing say from 35Hz up to around 50 or 60 or wherever your mids pickup?

 

[Basshead808 10+ year member]

I am trying to set my LPF on my amp according to the box which is supposed to be tuned to 35HZ. Is that what the LPF is supposed to be for on the amp to tune the amp to the recommended box frequency? Dang I must've did something wrong then //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[squeak9798 5,000+ posts]

I am trying to set my LPF on my amp according to the box which is supposed to be tuned to 35HZ. Is that what the LPF is supposed to be for on the amp to tune the amp to the recommended box frequency?

No

Dang I must've did something wrong then //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Yes, yes you did.

The LPF doesn't need to be set to the enclosure tuning frequency. Set it where ever sounds best (much like you did with your HU LPF...just set it where ever it sounds best).

What you may have been thinking of that needs set to (or close to) the tuning frequency of the enclosure is the SSF, or subsonic filter. The SSF is there to protect the subwoofer, and should be set to ~1/2 octave below the tuning frequency.

As to your original question;

I don't want my sub to act like a giant speaker so it is set to 50HZ but my amp LPF is set to 35HZ so what is the final H the sub is set to?

The simple answer here is; Both.

Crossovers aren't brick walls, they attenuate the frequencies above or below the crossover point at a given rate, or slope, which is expressed as decibels per octave, or db/oct. Lowpass filters (LPF) attenuate the frequencies above the crossover point. Most slopes on HU's and amps are 12db/oct to 24db/oct, meaning above the crossover point (for a LPF) they attenuate the frequencies by 12 decibels per octave or 24 decibels per octave (depending on the slope of your actual crossovers).

So, what happens when you set two crossovers on the same speaker like you currently have? Well, the two crossovers basically work together. From 35hz (the "first" crossover point) to 50hz (the "second" crossover point) the slope will be, for simplicity sake, approximately the same as the slope of the first crossover. Past 50hz, the slope will become much steeper because now both crossovers are actively attenuating the frequencies.

 

[JimJ 5,000+ posts]

35Hz is rather low.... You are missing a lot of subsonic frequencies...

You mean you're missing a lot of audible frequencies //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

35Hz for a LP is way too low, unless you're running Extremis's or XXX midbasses with assloads of power to your front stage. I've heard 25Hz lowpassed mids before, and while it's impressive, definitely not something you do without a lot of prep work, or it'll sound like ass //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Bring the sub's LP higher up, around 75-80Hz to start with. Go lower only if you know your front stage can handle the stress.

 

[Basshead808 10+ year member]

Alrighty //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif thanks guys!. I think it's going to sound much better after lol.