You don't really need a hpf on the sub, let it roll off and no you would not be hurting it. For the lpf I would use the steepest slope. I lpf my sub at 50hz on a 36db/oct slope. If you're crossing the sub and mids at 80hz, put the sub on the steepest slope that yoour hu gives and chances are you'll find your midbass much clearer. 12/18 db slopes at 80hz means your sub is playing well into the 200hz+ zone.

 

You are not that right on this, is best to have HPF on your sub...... To safeguard your amp and sub... What you can't hear does not means it does not exist... The sub will still moving if you see it properly....

 

I'm running active using my headunit DRZ9255 which only has a slope od 18db max.
So why is there a HPF filter for my sub on the headunit ??

 

I've run the DRZ and 18db is all your gonna get. Use either 63 or 80hz. I see you're running Studio 100 amps so there is no onboard crossover. If you were running an amp with built in crossovers I would have suggested to see if it had a steeper slope.

 

Hey, just a question.
I have my crossover slope on my sub set at 12db on both ends.
I have my LPF set to 80hz and HPF set to 25hz.

(Btw,the spec sheet says my 8" kicker sub plays down to 29hz)
Will I damage the sub with the HPF set to 25hz ?

The spec sheet probably reports the +/-3dB or +/-4.5dB frequency response. This means that below 29Hz the output will be dropping. You can play deeper bass content but be careful about not exceeding driver's excursion limits.

For high-pass (subsonic filter). I would recommend the steepest slope you can select with with cut frequency at around 20Hz unless the subwoofer just can't do it. Stuff in 20-25Hz can be barely heard. However, it can be felt.

For subwoofer low pass slope, I prefer the same as for the mids, 18dB. Definitely aim at making the sub inaudible above 100Hz. Most mids should have no problems playing down to 100Hz well.

 

Absolutely use a HPF (12 dB/oct) to protect the sub from infrasonics.
For the LPF, that will take some tweaking, slope between 12-24 dB/oct.
It really depends on the natural roll-off of the driver. Generally, I prefer 18 dB or 24 dB.

 

Really

 

The way I see it, there is no evidence that having speakers reproduce the frequencies below 20Hz will add anything to audible music. So I personally would go ahead and set HPF at 20Hz. Actually my amplifier has a subsonic filter than can't be defeated.. At the same time, it is probably not terribly wrong not to have subsonic filter. After all, many amplifiers do not have it, specially with sealed box subs.

When I was breaking in my sub I let it run for a while playing a 20Hz 0dB tone. There was something like 1 inch excursion peak to peak. No one could hear it.

 

Well, some people that self claim that they are audiophile claims that they are able to hear it, be it 20Hz or the "life" after 20kHz.... Which are completely dumb....
Setting the HPF at 20Hz are good, but I would go higher, depending on the sub's paper specs.... But then, I won't do so as I may lost something later on, so subsonic filter(better if the value adjustable) will be the best bet....

 

Setting up my new sub stage this week, two diyma's in a 1.5 sealed arrangement. I guarantee I'll be using a hp....

 

But what 'music' has content that low? All I can think of would be pipe organ, some bass specific stuff, and test tones. Is't that about it?
I'm not going to listen to test tones, bass tracks, and prob not pipe organ... So in the interest of protecting my subs, I think having a hp filter is warranted. No?

 

Beat me to it.

 

Lol not a bad thing having different people say the same thing, in different ways, helps others to understand better.... Maybe. Lol

 

Does your sub need a hpf? No

Will not having an hpf on your sub hurt your amp? No as long as you're not clipping the amp

Can you hear a 20hz note? Yes but you can feel it more than you hear it.

Do you need a grasp over basic English to communicate on this forum?

 

Guys, yes I have an 8" ported sub (see pic) that can play down to 29hz max, as per spec sheet ! I have set the HPF to 25hz @ 18db and call it a day

http://carphotos.cardomain.com/ride_images/3/2046/3009/30114004125_large.jpg
http://carphotos.cardomain.com/ride_images/3/2046/3009/30114004123_large.jpg

To me, technically it makes sense to have a HPF on your sub to keep your amp from stressing to play low frequencies.

thanks for your input guys