[BigD5213]

I have a Dayton SUB-100, which, according to the specs list is rated to go down as low as 30hz.


Would it make any sense to pick up something like this from Parts Express?:

http://www.partsexpress.com/pe/showd...number=266-248


Just to limit frequencies going to the sub that it is unable to reproduce. Am I correct in my logic, or am I way off-base here? Experts, let me know. Thanks.

 

[sivadselim]



Quote:
Originally Posted by BigD5213 /forum/post/12973280


Would it make any sense to pick up something like this from Parts Express?

No. There is a good chance that the subwoofer already has a subsonic filter in it. Many do. But even if it doesn't, it's not necessary.

 

[BigD5213]

Why isn't it necessary? I'm not questioning your answer, I just like to know all the technical details.

Thanks.

 

[TheEAR]

Why you do not need these...


Simply because any powered sub MUST have a high pass filter(that will varry depending on tuning/driver amp capabilities). As you can bottom any driver and clip any amp pushing them too far.


You Dayton sub has a high pass(amp plate).I do not know of any powered commercial sub with no high pass.This would be murderous as you have people whu pop in a movie withe xtreme LF and pump it up. No high pass would equal to bottoming/clipping.


To test how well the high pass is implemented play a 20Hz test tone. If the drivers moves very little ...you filter works great.

If you bottom the driver or hear rasping noises...call them and ask "What the ...where you thinking ?".




I am sure the high pass is in place.

 

[BigD5213]

Well, I can tell you it's not a variable high pass filter, as there is no setting or knob for it.

 

[Mr. Audio]

I think those high pass filters are a terrible idea. Just because sub says it's rated frequency response is 30hz doesn't necessarily mean that the subwoofer doesn't produce bass lower than that, it's just not as loud as 30Hz. I think if you cut it of at 30Hz you will ruin your subs low frequency extension and overall shaking ability.

 

[mailiang]



Quote:
Originally Posted by BigD5213 /forum/post/12974380


Well, I can tell you it's not a variable high pass filter, as there is no setting or knob for it.

The infrasonic high pass filter is not like a crossover control. It's an integrated circuit in your amp. Filters vary from sub to sub and can increase the slope below the tuning point anywhere from 6 to 24db. Some subs also have high pass filters that are fixed above 80hz or so to improve linearity and reduce noise at higher output levels. However many economy subs do not have these filters, so check with Parts Express. You shouldn't have a problem over driving the sub if you have it calibrated properly.



Ian

 

[sivadselim]



Quote:
Originally Posted by BigD5213 /forum/post/12974380


Well, I can tell you it's not a variable high pass filter, as there is no setting or knob for it.

In this instance he is calling the "subsonic" filter a high-pass filter. For example, your sub may have a fixed 30Hz high-pass filter on its input. It will "pass" anything above 30Hz that is input to it.


He is not talking about a fixed high-pass filter that subs often have that is applied to the sub's speaker outputs. In that instance, that fixedhigh-pass filter is applied to the sub's speaker-level output.

 

[sivadselim]



Quote:
Originally Posted by Mr. Audio /forum/post/12974694


I think those high pass filters are a terrible idea. Just because sub says it's rated frequency response is 30hz doesn't necessarily mean that the subwoofer doesn't produce bass lower than that, it's just not as loud as 30Hz. I think if you cut it of at 30Hz you will ruin your subs low frequency extension and overall shaking ability.

As EAR pointed out they are necessary. Almost any commercial sub will have one. They are designed to cutoff the low frequencies at a very specific frequency that the subwoofer is not physically capable of reasonably reproducing. It's not the filter that limits the subwoofer's reasonably usable low-end capability. That is dictated by everything else; enclosure size, driver size, driver excursion, port size, etc., etc.. The filter prevents the subwoofer from exceeding those parameters in the design that, yes, can be exceeded, but when exceeded, cause the sub to operate beyond the limits of some other parameter(s) that cannot be exceeded in order for the subwoofer to perform properly.


Sometimes DIY builders will not include the filter because their sub's design has none of the limiting parameters within any range that the sub will be normally and reasonably used.

 

[Mr. Audio]



Quote:
Originally Posted by sivadselim /forum/post/12975366

As EAR pointed out they are necessary. Almost any commercial sub will have one. They are designed to cutoff the low frequencies at a very specific frequency that the subwoofer is not physically capable of reasonably reproducing. It's not the filter that limits the subwoofer's reasonably usable low-end capability. That is dictated by everything else; enclosure size, driver size, driver excursion, port size, etc., etc.. The filter prevents the subwoofer from exceeding those parameters in the design that, yes, can be exceeded, but when exceeded, cause the sub to operate beyond the limits of some other parameter(s) that cannot be exceeded in order for the subwoofer to perform properly.


Sometimes DIY builders will not include the filter because their sub's design has none of the limiting parameters within any range that the sub will be normally and reasonably used.

Ok, go ahead BigD, blow 25 bucks on the filters.

 

[BigD5213]

Okay. Worst-case scenario, I don't notice any difference at all, and I pay the $2.50 to ship it back to them.

 

[sivadselim]



Quote:
Originally Posted by Mr. Audio /forum/post/12983253


Ok, go ahead BigD, blow 25 bucks on the filters.

Quote:
Originally Posted by BigD5213 /forum/post/12984234


Okay. Worst-case scenario, I don't notice any difference at all, and I pay the $2.50 to ship it back to them.

We told you both that the sub already has one built-in. WTF?

 

[TheEAR]



There was a great man who once said ...nevermind.


ALL commercial subs HAVE subsonic filters or HIGH PASS filter.depending on the design the slope will be more or less agressive. All have them.


Even all half competent DIY subs ...must use them. Unless the owner loves to waste amp power and driver displacement.Only device not in need of a subsonic filter is the FAN sub. As it is designed to operate at extreme LF(20Hz and below).


The Dayton is very far from a FAN sub and will not move several cubic feet of air.

 

[sivadselim]



Quote:
Originally Posted by TheEAR /forum/post/12985812


The Dayton is very far from a FAN sub and will not move several cubic feet of air.

Over its lifetime it will!

 

[mailiang]



Quote:
ALL commercial subs HAVE subsonic filters or HIGH PASS filter.depending on the design the slope will be more or less agressive. All have them.

Correct.


Not all powered subs have infrasonic high pass filters.

Quote:
Infrasonic (Subsonic) Filter: A filter designed to remove extremely low frequency (25Hz or lower) noise from the audio signal. Useful for Ported box designs.

ACI



Ian

 

[sivadselim]



Quote:
Originally Posted by mailiang /forum/post/12986163


Not all powered subs have infrasonic high pass filters.

They almost all do. I'm sure there are some exceptions. But this is something built into the subwoofer and it's designed to filter the input. It is by definition a high-pass filter. It allows frequencies above a certain frequency to pass.


The high-pass filter on sub's speaker level outputs filters the output. That's not what the OP or any of us are talking about.

 

[mailiang]



Quote:
Originally Posted by sivadselim /forum/post/12986225


They almost all do. I'm sure there are some exceptions. But this is something built into the subwoofer and it's designed to filter the input. It is by definition a high-pass filter. It allows frequencies above a certain frequency to pass.

I am familiar with subsonic filters. They are also used on car audio subwoofer amps. (I've sold quite a few.) However, there are cheap powered subs that don't have them since their tuning points are so high and the roll off below that is so steep, that it's rarely an issue.


Ian

 

[Geoff L]

Just a interesting fact, the first generation powered SVS sono subwoofers used "NO" high pass filter.!

But as mentioned already, 99% plus of comercial powered sub offerings use some type of high pass filter. It's nearly always built into the amp with no external user control over it's location or slope.

 

[TheEAR]



Quote:
Originally Posted by Geoff L /forum/post/12997934


Just a interesting fact, the first generation powered SVS sono subwoofers used "NO" high pass filter.!

But as mentioned already, 99% plus of comercial powered sub offerings use some type of high pass filter. It's nearly always built into the amp with no external user control over it's location or slope.

And this explains why some users who pushed these SVS could BOTTOM them out. You can set limiters on amps,with no subsonic filter...well 5Hz...CLAK!

Looks impressive to some to see a driver's cone move like it wants to lave the basket,not practical .

 

[Geoff L]

Didn't take long for them to incorperate SS-fiters in their NEW amps.


As to those very first gen subs:

They soon offered upgraded longer throw higher power handle drivers to those that purchased these subs. In hind site, almost like it was planned.

Tho I certainly don't belive that this was intentionaly done by any means.!


But many did buy the upgraded drivers for their subs which helped ,but did not cure the driver bottoming or clipping problem with those first gen subs when pushed to their limits.


They have a very good grip on things now, so SS-filters are common place in SVS on board amps now and have been for quite sometime..