subsonic setting as easy as it seems?

[budget76 10+ year member]

so, building a new ported box wed., and want to make sure I don't screw up my sub. The box plans say "25HZ subsonic filter at 24db/Octave". Now, i've got a knob that goes from 15hz to 55hz, and it's as easy as turning that knob to where I think 25hz would be, correct?

There's also a bass bass boost, low pass, and lever settings. These don't need to be touched, correct? I'll be the first to admit I don't know wtf i'm doing here.

thanks

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[DejaWiz 5,000+ posts]

bass boost: no, leave it at 0 dB.

Low pass: Set to 70-80ish Hz.

SSF: Set to 25 Hz.

 

[thch 10+ year member]

pretty much. I'd play some test tones around 20-30hz and just drop the SSF until I was comfortable with the excursion.

(bass boost and excessive gains can effectively lower the SSF)

gain = level setting. There are many guides to this. in short - it adjust the amount of amplification. because not all HU's put out the same signal strength, it is made to accomodate most/all of them. unfortunantly, this means 100% turn may not be 100% volume! In many cases full gain settings would give too much gain, and the amplifier would be forced to distort. This can cause equipment failure in severe cases, though mild clipping is not normally concerning.

If you have friends with car stereos, you might have seen the "its soooo loud at volume setting 5/30." This is because the gain is high enough to give near full power at such a low level input signal. as they turn the volume up, the sound gets more and more distorted without getting much louder, usually reaching a "this sounds unsafe" level well before reaching 30/30 on the HU!

lowpass is used to remove vocals from the subs. highpass filters remove bass from the other speakers.

 

[budget76 10+ year member]

thanks guys. appreciate the quick reply.

as for the level (typed lever by mistake), this is where I would use the gain setting tutorial that's on here, correct?

I do know the whole don't pass 75% on gains and stuff. Off to download some test tones. Excursion, as in the excursion of the sub, making sure it doesn't try to move in and out too much and 'kapow'?

thanks again

 

[DejaWiz 5,000+ posts]

thanks guys. appreciate the quick reply.

1. as for the level (typed lever by mistake), this is where I would use the gain setting tutorial that's on here, correct?

2. I do know the whole don't pass 75% on gains and stuff. Off to download some test tones. Excursion, as in the excursion of the sub, making sure it doesn't try to move in and out too much and 'kapow'?

thanks again

1. Correct.

2. You don't want to exceed whatever gain setting matches the voltage output of the HU's RCA's. Could be 5%, could be 25%, could be 75%... It's a good idea to never exceed 75% of max HU volume anytime (general rule of thumb), especially when setting gains.