LPF Filter

[wolfman1966 10+ year member]

Just wondering, can changing the LPF freq change how loud your subs sound? I moved mine up a bit earlier today, and it seems like they got louder. I used to turn the volume up all the way, and then when I really wanted them to hit, turn up the bass on the radio...NOW I can't turn up the volume more than 3/4 or then it sounds like it did before at full volume with the bass up, and IF I turn the Bass up all the way too, then the amp cuts out

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[diminishedpower 10+ year member]

what frequency did change toe LPF from and then to what freq?

 

[wolfman1966 10+ year member]

forgot to mention, this is still with the gain set barely above minimum

kinda hard to tell on the amp I have, but best guess would be going from 100 up to about 140

 

[diminishedpower 10+ year member]

higher frequencies just sound louder, and im going to guess with those 8's the higher frequencies are much more noticeable. But personally i never turn LPF higher that 80's

 

[wolfman1966 10+ year member]

maybe, but I am still playing BASS songs, ie Bass Mekanik....and it actually sounds like the same songs I played before are just louder, and hit harder.

 

[diminishedpower 10+ year member]

if it sounds like the exact same frequency and not an overtone then could you have been mistaken on what it was set at, cause i mean if you had it set at 50, it would still play 50 hertz just a lot quieter and if you turned up all of a sudden the 50-80 hertz range would be quite a bit louder

 

[diminishedpower 10+ year member]

like to note i dont know everything and anyone else input would be koo, maybe i learn something.

 

[wolfman1966 10+ year member]

what someone on another forum said

http://www.splbassx.com/forums/index.php?showtopic=10104&pid=115893&st=0entry115893

 

[diminishedpower 10+ year member]

i would like that explained because thats doesnt make sense, you play a 45 hertz signal changing the lpf isnt going to change how loud that hertz is. I just dont understand

 

[dragnix 5,000+ posts]

what that guy on splbassx tells u is right. However, u should be careful as how high u cross it over at and make sure ur subs can play those frequencies. Also, ur sub is to play low notes, and when u get to 100hz they're pretty much mids, so i would advise u not to run the LPF that high. Just invest in a good front stage and you should be good. My $0.02

 

[dragnix 5,000+ posts]

i would like that explained because thats doesnt make sense, you play a 45 hertz signal changing the lpf isnt going to change how loud that hertz is. I just dont understand

I don't think he means 45hz will be louder, but the sub will hit the higher notes, which sounds louder than lower notes. Or at least that's the way it should be.

 

[luvinthebass 5,000+ posts]

good rule of thumb is to set your LPF at 80 hz and let your fronts or mids play 80 hz and up, that's what i do

 

[diminishedpower 10+ year member]

I don't think he means 45hz will be louder, but the sub will hit the higher notes, which sounds louder than lower notes. Or at least that's the way it should be.

Well thats what I was basically saying, but the guy through that link doesnt make it sound that way he leaves it at a very broad statement.

And i agree 80 hertz and below sub i sometimes do 70 -75 and below on sub depend on how strong midbass is on the comps.

 

[helotaxi 5,000+ posts]

Lots of variables here and you guys have covered (partially) one of them.

First you have to understand what the frequency of the filter means. The "cutoff" freq of the filter and the number that you are setting is the "half power" point or the frequency at which the filter has reduced the level of the signal by 3dB.

Second, for the signal to be down 3dB at the filter freq, then the filter must be affecting the lower freqs as well. Most filters (depends on the order and type of the filter) will begin attenuating the signal an octave away from the nominal filter freq. This means that you 100hz filter is affecting the signal as low as 50hz. Changing the slope of the filter to a higher order can minimize this.

Example:

The 4 plots here are all the same sub in the same box and will help explain the effects of the different filter freqs and slopes. The white curve is the sub with no filter. The red curve is same sub with a 50hz 12dB/oct. filter applied. The blue curve is a 50hz 24dB/oct filter. The yellow curve is a 100hz 12dB/oct filter.

Notice that the red curve is 1dB below the unfiltered response at its peak and it peak is below the LPF freq. Notice how the steeper filter at the same freq is .5dB louder than the first and its peak freq has shifted closer to the filter freq. Finally note how the higher freq allows the sub to reach its potential in the region below 70hz. Neither of the other filters did this. The 40-70 hz region is where most rock and hip-hop bass is centered. Setting your LPF too low will limit the ability of the sub to get loud in this region. Steepening the slope will allow a lower filter freq with minimized effects below the filter freq.

 

[wolfman1966 10+ year member]

OK, thats kinda technical, but what your saying is that by setting my LPF filter higher, it lets the sub reach its potential at the same region as where most of the bass on the songs I listen to is centered.righ?