subsonic filter??

[DMarsh525 10+ year member]

i noticed some amps have this subsonic filter and some dont. what it do and do i really need one?

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[kuijo 10+ year member]

its the highpass filter for bass. If you're going in a sealed box you don't really need one.

 

[noob with an RS 10+ year member]

you dont need one if u have a sealed box. if u have a ported enclosure it can help some.

 

[Polecat 5,000+ posts]

with high power, ported, much desired...as mentioned, sealed, nevermind... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Raven 10+ year member]

My Orion has a SSF with variable frequency AND variable Q. That Q adjust is a freaking Godsend. I can make my system peak in the high 20s for competition. A really high number is great, but a moderately high number at 29hz is worthy of mentioning anywhere. =)

I only mention this because everything that can be said has been already, so what can I add?

 

[RandyJ 10+ year member]

My Orion has a SSF with variable frequency AND variable Q. That Q adjust is a freaking Godsend. I can make my system peak in the high 20s for competition. A really high number is great, but a moderately high number at 29hz is worthy of mentioning anywhere. =)
I only mention this because everything that can be said has been already, so what can I add?

When you say the Q can be controlled, do you mean the total Q as in Qts? If so, how does the amplifier control Qes or Qms, because it has to control one of them in order to change the Qts.

 

[JamesG 10+ year member]

I came here tonight to ask this exact same question.

Now, my KX1200.1 has a subsonic filter. The manual lists it as 12dB at 25hz. Does this mean it will filter out any notes below 25hz? Since I'll be using a ported enclosure, do I need to use it on my amp?

 

[RandyJ 10+ year member]

I came here tonight to ask this exact same question.
Now, my KX1200.1 has a subsonic filter. The manual lists it as 12dB at 25hz. Does this mean it will filter out any notes below 25hz? Since I'll be using a ported enclosure, do I need to use it on my amp?

For every octave below 25hz, the output will be reduced by 12dB. So as soon as the notes start to dip below 25Hz they will be attenuated. I imagine the SSF on that kicker is adjustable, a set SSF @ 25hz is pretty **** low and not at all on the safe side for those who are ported to around 35Hz.

What will your enclosure be tuned to? This has a lot to do with it. if you are going to tune to a low frequency, usually a SSF is not needed. Most music does not dip into the 20's anyway.

 

[JamesG 10+ year member]

Nooblet,

I'm not sure what frequency I'll have my box tuned at. I've been asking for recommendations in another thread. What do you recommend? I have 2 Diamond Audio D612D4 12" subs.

The SSF on my KX1200.1 is actually fixed at 12dB @ 25 hz. I can turn it off, but it's not adjustable.

 

[RandyJ 10+ year member]

What type of musci do you listen to? I had my Ti tuned to 25Hz in a 4.3^3ft enclosure with 750wrms and I loved the responsewith nearly all music, many prefer higher though.

 

[JamesG 10+ year member]

I listen mostly to hard rock and classic rock, but also some rap. I like hard hitting punch bass the best, but I don't want to miss out on all the booming bass.

 

[thch 10+ year member]

When you say the Q can be controlled, do you mean the total Q as in Qts? If so, how does the amplifier control Qes or Qms, because it has to control one of them in order to change the Qts.

no, not quite. Q is best visualized in bandpass or bandstop filters (such as a typical parametric EQ). basically, Setting tuned frequency shows you where in the spectrum the effect is, and Q shows how frequencies near the tuned frequency are affected.

This is actually very similar. for the highpass filter, we know that above 30hz, bass is unaffected -- 0db/oct. and at some point below 30hz, bass is attenuated at 24dB/oct. Q determines HOW the transition from 0dB/oct to 24dB/oct occurs.

basically in this sense, how frequencies NEAR the tuned freqeuncy are affected. the overall slope shows how freuqencies BELOW the tuned frequency are affected.

A high Q leads to a mild resonance, and thus a gain. Slope then shots down sharply at maybe 30dB/oct and the at lower frequencies settles at 24dB/oct. low Q is opposite, the slope slowly transitions from 0dB/ort to -24dB/oct.

as for changing Qts electrically -- look into Linkwitz Transform. note that it gives high gains at low frequencies.

as for amplifiers changing Qes -- look into damping factor and multiple feedback (voltage and current feedback). you can raise Qes by increasing the output impedance of the amp.