Lyricman

I have an Audison SRX4, Infinity Kappa 60.5 component fronts and Infinity Kappa 6x9's on a custom rear shelf. I thought I would try a sub in place of the 6x9's to see if you guys know what you are talking about. I have quickly come to the conclusion that you do because the addition of the sub has certainly done everything you experts say that it will. I was loaned a Kenwood 10" KFC-W2505 to try and have the 12" to try as well. I would like some advice on setting of the filters on the amp and the head unit - Pioneer 6300 with sub output.
If the Sub freq. range is 25 - 800 hz and the front components are 45 - 20khz what is the optimal filter settings.
I have set the high pass for the fronts at 50hz and low pass for the sub at 220hz. Should I allow higher frequencies to go to the sub and increase the minimum frequency to the fronts to say 125hz.

WagonRich

It's really going to vary from system to system, but I would normally set the LPF on a sub somewhere in the 80-120Hz region depending on how good the fronts are. 50Hz is almost certainly too low for the fronts, and 220Hz is definatly too high for the sub.

Rich

chiark

My fronts are high passed at 50Hz, as I can hear a bit of response at that level. The sub is 80Hz. I wouldn't want it much higher than that, with 120Hz the absolute max.

Lyricman

Thanks for the reply. I had experimented and with the Pioneer HU I can set the LPF for the sub at 50, 80 or 125HZ and the HPF at 50 80 and 125Hz. From what you have said you have your sub and Fronts both output the 50 - 80 Hz range. My logic was that where the sub stopped the fronts would take over so would it not be right to set both the LPF and HPF to the same e.g. 80 Hz or am I wrong in my thinking. I have left the amp filters set to 50hz HPF for the front and 200Hz for the sub as I assume the Pioneer has the control.

chiark

Lyricman,
Good call on the filters on the amp. I'd be tempted to wind the 200Hz down a little bit, just to ensure that you were getting the best effect.

Big of background:
Filters have different levels of effect, or steepness of their response curves, which is measured in decibels (dB) per octave. Standard filters are either 6, 12 or 18 dB/octave. A note that is an octave apart higher than another has twice the frequency... dB is a logarithmic scale, too.

If you can match your h/u to your amp, you will effectively be creating a steeper filter for the frequency you've chosen. If you don't, then a little bit of sound will be getting through that would otherwise be stopped but if you can't notice that sound intruding (and I didn't in previous installs) then don't worry about it. I normally don't.

Just thought people might be interested in how filters work. They're not an absolute "anything under 80Hz gets through, everything over 80Hz gets blocked", unless you've got some seriously seriously serious digital stuff.
Cheers,
Nick.

Lyricman

Chiark

Thanks for that, a great help. The filters on the Audison are 12db/Oct. I tried the Kenwood 12" today and was not that impressed. Decided to try my sons JL Audio 12W3v2 D2 WOW what a difference, now this is a sub with great tight, fast deep bass. I guess I now know what to buy, the only problem is the output of the Amp is 190watts rms and the JL's are rated at 250 rms and I am concerned it might be under powered, although is was pretty damn loud at normal volume levels.
Do people use test tones to actually set the filters

chiark

Never used test tones myself - just listen to the music and have a fiddle. make sure you're playing music that you know fairly well...

You don't need to match speaker rating and amp output, but if you're using a smaller amp be sure that you don't drive the speaker into clipping, as this can knacker a voice coil quite rapidly (although some people dispute this...)

A good set-up CD if you are bothered is Sound test, by someone who's name escapes me. I'll dig it out...

Lyricman

Thanks for the advice Chiark