Setting X-over frequency and sub sonic filters

[Wigzter]

Bet you guys are sick of me already huh?

Well thanks to every one who has been helping me out so far, I'm learning a lot and I appreciate all your time you guys have taken to help me.

Now my installer has already set my X-over frequency and sub sonic filter and so I can only assume it's correct. But like I stated in previous posts. I really want to learn the in's and out's of car audio for myself.

So basically this post is to gain more knowledge on X-over frequencies and sub sonic filters. I will continue to do my own research, but like before if someone is able to break it down Crayola-style for me that would be awesome!

For those who don't know my setup I have an 08 Honda Accord Sedan with a stock receiver that use a really nice 6 speaker set. 2 tweeters up front, 2 6.5"s in the front doors and 2 6.5"s on the rear deck panel. It sounds really great and my girlfriend loves the stock look so I had my installer add a Line Out Converter so I can add the Ti21300.1 and (2) Ti212D4's at a 1 ohm load.

So is there anyone out there with a similar setup to mine or maybe is there a preferred set of settings that you like to run for the X-over and sub sonic? Or is every single setup completely different? Maybe someone could suggest a good starting point for these two? I will go check to see what my current settings are and let you know.

Once again, thanks in advanced for taking your time to help a noob.

[ttocs]

this has a lot to do with the equipment, but imo its more about the listener and what he listens too and wants out of it. Do you understand what they do to be able to make the adjustments needed to make the best sound for you?

[Wigzter]

Yeah from what I've been reading is that it's kind if like a cutoff for certain frequencies to go through your subs right? That's kind of why I was curious as to what people use. In the manual for the Ti21300.1 it says the default it's 80hz for X-over and 30Hz for the subsonic. But then when you check the click settings there isn't an actually turn dial click for 80Hz or 30Hz lol. It's like 88hz and 34hz or something I think.

And I don't really know what I'm listening for either

[ttocs]

yes exactly a cross over is a device that will allow some freqs to pass, and stop others. A low-pass cross over lets the low freqs go through, a high-pass lets the high freqs go through.

A subsonic filter is a high-pass cross over that is set to a very low frequency so that it will take out the extremely low bass that we have problems hearing, that uses a lot of power and can cause problems with some subs that just can't play that low. So if you listen to a lot of techno/rap it might take out some of the bass that they use intentionally, but on rock for instance will just take out a lot of the notes you can't hear. Some speakers can play the low notes better then others and do not need it as much and again your music and sound tastes are really the final judge.

Now the subwoofer cross over is a low-pass to take out the high freqs that the sub can't play. again depending on what music you listen too you might like it higher, again let your ears be the judge.

I know this isn't what you want to hear as you want me to tell you 75 hz +2db bla bla bla but its just not that easy. The vehicle, what the mid/high speakers are and how they fill in/blend with the sub and general music tastes make it hard to give you the numbers you want. Get a cd or two that you know well and put them in and close your eyes and listen for a few mins. Make some adjustments and see if it sound better, if not do it again. Its never a bad idea to take a pic/notes of what the settings are at before you start as if your not happy in the end you can just put them back. You will be a more educated listener this way and be happier.

[Wigzter]

Yeah I'm actually having a tough time figuring out the notches because sometimes I feel like I can feel a notch, but maybe a half notch so I don't know if that counts as one or not.....

So when I do 25 notches for 88Hz, it's not always in the same spots so I'm not exactly sure which one is right lol.

If that makes any sense...

[Wigzter]

"48dB Subsonic and 24dB Low Pass Crossovers" per the Ti2 Amp Manual.

What is the 48db and 24db per octave mean?

[vwdude]

That has to do with the roll off at the frequency that the crossover is cut off at. Think of it as a slope to an angled line on a graph.

IIRC, 24 is a steep slope and 48 is gradual. That means that if you set your lowpass to 80hz, it doesn't just cut off at 80. It's not like anything 81 and above won't play through it, it just gets less and less power as the frequency increases, and the 24 or 48 has to do with how fast it rolls off.

I hope that helps. Again play with it and set it for how you like it. I think subs are usually cut off at 24db because you don't really want a sub playing too far outside of its rates range. The subwoofer serves a very specific purpose (as opposed to a Midbass which covers a much large frequency range).

[dwnrodeo]

48db/octave is steeper than 24db/octave. It literally means that the sound is 48 decibels lower over one octave as opposed to 24 decibels.

[ttocs]

in simple terms if you were to look at the frequency graph starting at 20 and going to 20k, is the slope of the line on the graph of the frequencies the cross over is blocking. So a higher DB/octave # will have a higher slope and will block the frequencies after the cross over point faster. These are important to how the different speakers blend with one another and can make a difference in the sound