How to PROPERLY set subsonic filter with ported enclosure

[mikemihai 0]

I've been told the Subsonic filter is NOT always accurate, with some parts on amps made in bulk somewhere in china trying to cut costs, they can turn out to be less accurate with a subsonic filter resulting in a 20% variance.

I guess what im asking is besides looking at the Hz marking alongside the subsonic filter knob, how else can a person figure out what Hz the filter is really set up to.

I don't want to set up my filter based on the knob markings thinking its filtering everything below 31 hz when it really is set up to filter below 28 hz.

So is there another way to set up the subsonic filter without assuming the standard markings on the knob are accurate.

Thx 4 reading

[Adrian_D 520]

Nick (NDMStang) posted one option, I can't remember the details, sorry

One idea I used is to play a tone of the frequency you need, measure the amp output voltage and turn up the SSF frequency (you start with it set all the way down) until you notice a drop in the output voltage.

[mikemihai 0]

Nick (NDMStang) posted one option, I can't remember the details, sorry

One idea I used is to play a tone of the frequency you need, measure the amp output voltage and turn up the SSF frequency (you start with it set all the way down) until you notice a drop in the output voltage.

yeah i was thinking its going to be something between those lines with testing out based on constant tone on a loop, i want to set it up right tho, hopefully avoid what happened in the past to my sub.

p.s.

N-am mai fost pe forum de mult timp dar ti-am trimes mesaj inapoi la ce mi-ai scris ultima data acum vre-o luna

[Adrian_D 520]

Nick (NDMStang) posted one option, I can't remember the details, sorry

One idea I used is to play a tone of the frequency you need, measure the amp output voltage and turn up the SSF frequency (you start with it set all the way down) until you notice a drop in the output voltage.

yeah i was thinking its going to be something between those lines with testing out based on constant tone on a loop, i want to set it up right tho, hopefully avoid what happened in the past to my sub.

p.s.

N-am mai fost pe forum de mult timp dar ti-am trimes mesaj inapoi la ce mi-ai scris ultima data acum vre-o luna

The method should work good. I'll test it better when I practice for bass-race.

Cool, raspund imediat

[ssh 924]

Let's use 30hz as an example...

disconnect speakers

turn ssf counter-clockwise until it's considered "off"

play 30hz tone at volume 10.

Measure the voltage output

Let y = voltage output * 0.707

turn ssf clockwise until voltage output now matches "y"

Now your ssf is set.

[NDMstang65 403]

Well...That takes into account that you are assuming by using the .707 caluation that your voltage is "this" ..but your amp may never reach that voltage which causes people to set their gains up wrong all the time...so that might not work so well when you put a load back on the amplifier for it to drive..I'll have to test that..

Turn your subsonic filter all the way down, put a tone CD on. Put a track where you 'think' tuning is and ease the volume up. If the speaker is moving a LOT then you are playing below tuning, bump up a track. When the speaker is moving the least amount that is where the port is doing all of the work and is where it is tuned to.

Once you take note of this, click the cd player down 3 tracks. Then adjust your subsonic filter up (to the right) until the speaker stops freaking out. This is how you set it 2-4Hz below your port tuning frequency.

[mikemihai 0]

Well...That takes into account that you are assuming by using the .707 caluation that your voltage is "this" ..but your amp may never reach that voltage which causes people to set their gains up wrong all the time...so that might not work so well when you put a load back on the amplifier for it to drive..I'll have to test that..

Turn your subsonic filter all the way down, put a tone CD on. Put a track where you 'think' tuning is and ease the volume up. If the speaker is moving a LOT then you are playing below tuning, bump up a track. When the speaker is moving the least amount that is where the port is doing all of the work and is where it is tuned to.

Once you take note of this, click the cd player down 3 tracks. Then adjust your subsonic filter up (to the right) until the speaker stops freaking out. This is how you set it 2-4Hz below your port tuning frequency.

I will do that, if i have any trouble with it i'll be back on here =), I need to see if theres a way to tune my stock side speakers too they are wired stock to an aftermarket HU, but i dunno much about those other than they kinda suck at higher vol and cant tell if the wrattling that comes out of them is b/c of the plasticky interior(most likely) of my car or if those are clipping from higher vol. I hope its not the sony xplod HU (JOKE OF A HEADUNIT). But once i get a job at school or something I will have to upgrade those too, only prob is they are BOLTED on to a factory mold and theres gonna be a lotta work to get the midranges out and replaced.

Anyways, im gonna go try to set it up how you said. Btw since im a noob lol, I didnt understand what u meant by cliking down 3 tracks on the cd, do i like need a full tone test cd with all the frequency tracks like one from rockford fosgate tuning i seen ppl use on youtube videos? I think that one is free to download, im going to go look for it.

Thx

Edited July 30, 2010 by mikemihai