which x-over to use?

Stryker · Post by **Stryker** » Tue May 26, 2009 3:03 pm

OK here's the setup for those of you who do not know. I use a 215ix(2) and RSD amps,2-1200.1's and 500.4. so I'm wondering how to set up the x-overs properly. do I leave the Rsd's xovers in bypass and only use the eq"s or use the amps x overs and leave the eq set at 30Hz? I would like to use the EQ because of the 24 dB octave slope and not the amps.... just wanting some clarification on this. The headunit is basic so does not have x-over built in.

thx

jwilson273 · Post by **jwilson273** » Tue May 26, 2009 3:14 pm

Do you still have that AX 204 for sale?

Stryker · Post by **Stryker** » Tue May 26, 2009 3:59 pm

gone kg1961 has it for sale.

Post by **Francious70** » Tue May 26, 2009 4:11 pm

If you like the x-over on the EQ, then use it and set all the amps to "bypass" or "full-range".

Keep in mind, any x-overs you have running simultaniously will ADD the two values together.

Example: you have the x-over set at 70Hz on the EQ AND the amp. If the EQ is 24db/oct. and the amp is 12dB/oct. then what you'll end up with is an x-over @ 70Hz for 36dB/oct.

dBincognito · Post by **dBincognito** » Tue May 26, 2009 4:15 pm

The RSD 1200.1's can't do that IIRC....you can't bypass the x-over....or am I wrong....don't own one...so not sure

Example: you have the x-over set at 70Hz on the EQ AND the amp. If the EQ is 24db/oct. and the amp is 12dB/oct. then what you'll end up with is an x-over @ 70Hz for 36dB/oct.

I understand mixing signals to be a bad thing.

knightrider358 · Post by **knightrider358** » Tue May 26, 2009 4:23 pm

francious70 so when that oct slope happens what does that exactly do and when getting an eq which is better a 12db/oct or 24db/oct slope or neither

dBincognito · Post by **dBincognito** » Tue May 26, 2009 4:27 pm

Slope is how sharp the cutoff is.......my personal opinion is the higher the slope the better....it allows for tighter tuning.

Anything that is 24dB per octave or higher is what I look for.....I won't run anything less than 24...the cutoff isn't clean enough for me

knightrider358 · Post by **knightrider358** » Tue May 26, 2009 4:28 pm

thanx dB

dBincognito · Post by **dBincognito** » Tue May 26, 2009 4:31 pm

knightrider358 wrote:thanx dB

You can imagine it as a parabola on a graph....I think that's right......where the x-over point is ( cutoff )....it would drop very sharply at that point....almost straight down......where as a 12db would " roll off " and the line would gradually decrease into another set of frequencies

Stryker · Post by **Stryker** » Tue May 26, 2009 5:43 pm

there is a bypass on the 500.4, no bypass on the 1200.1's. so more or less use all the xover's I can and try to set them the same...ie eq matching the amp. this is how I've always done it, but wasn't sure if the signals were getting muddyied up, if you know what I'm saying.

Post by **Francious70** » Tue May 26, 2009 5:48 pm

Hopefully this will help you understand a little better.

dBincognito · Post by **dBincognito** » Tue May 26, 2009 5:50 pm

This only works if the x-over settings are the same correct ?

Post by **Francious70** » Tue May 26, 2009 5:58 pm

Stryker wrote:there is a bypass on the 500.4, no bypass on the 1200.1's. so more or less use all the xover's I can and try to set them the same...ie eq matching the amp. this is how I've always done it, but wasn't sure if the signals were getting muddyied up, if you know what I'm saying.

No, you don't want to do this unless you are specifically going for that.

First if you've never seen this, please read this.

http://www.bcae1.com/xovrslop.htm

The best way I can explain crossovers are that they will filter out the undesired signal starting at a specified point at a certain rate.

Your EQ will filter high, low or bandpass if I'm not mistaken. If you set an EQ for 80Hz highpass that means everything about 80Hz will "pass" thru. Below 80Hz the frequencies will be cut at a rate of 24dB/oct. What that means is that if there is an 80Hz & 40Hz tone playing simultaniously the 40Hz tone will be 24dB quieter. In power terms that means it would put out 1/16 the power for 40Hz.

Now imagine adding another filter on top of that. You in essence would be creating almost a brick wall filter.

knightrider358 · Post by **knightrider358** » Tue May 26, 2009 6:04 pm

thanx for that info francious i totally get the octave slope way better now wow I cant wait ti get my 3-xover and begin my new re-install its gonna be freakin awsome thanx again

Post by **Francious70** » Tue May 26, 2009 6:10 pm

1 Octave is a doubling of the frequency. 20Hz to 40Hz is an octave, 40Hz to 80Hz is an octave, 80Hz to 160Hz is an octave, ect....

With crossovers we can filter signals accurately and at a fixed rate. You don't want your subs playing 140Hz tones, so we normally set our crossovers at 70Hz. So that means the sub WILL be playing that 140Hz tone, but it will be reduced at whatever fixed amount we want or have, 6dB/oct., 12dB/oct., 18dB/oct., 24db/oct., oct...

But the filtering comes at a price. A crossover will make the signal get out of phase at a rate of 90*/6dB/oct. So that means if you run multiple slope filters, say a 12dB/oct. highpass for your fronts and a 24dB/oct. lowpass for your sub the signals will be out of phase by 180* and you would either need to invert your sub, or the signal to it.

Gawd. Try saying that five times fast.

Stryker · Post by **Stryker** » Tue May 26, 2009 6:12 pm

ok I'll set it up tommorow using both eq and amp x over's. my 500.4 has low, high, and bypass(which is a full range signal) should I use this or the high pass setting? Or try both and use whichever sounds best I guess. Is there a wrong way really?

Post by **Francious70** » Tue May 26, 2009 6:15 pm

dBincognito wrote:
knightrider358 wrote:thanx dB

You can imagine it as a parabola on a graph....I think that's right......where the x-over point is ( cutoff )....it would drop very sharply at that point....almost straight down......where as a 12db would " roll off " and the line would gradually decrease into another set of frequencies

That's correct dood. The higher the slope, the less of the unwanted frequencies you'll get... but remember blending is a good thing.

You do want the get some of those frequencies thru so it doesn't sound like you've just got a front stage and a sub in the trunk.

Post by **Francious70** » Tue May 26, 2009 6:17 pm

Stryker wrote:ok I'll set it up tommorow using both eq and amp x over's. my 500.4 has low, high, and bypass(which is a full range signal) should I use this or the high pass setting? Or try both and use whichever sounds best I guess. Is there a wrong way really?

What all is going in this build man and what are you going for? SQ I'm assuming.

Post by **Francious70** » Tue May 26, 2009 6:20 pm

knightrider358 wrote:thanx for that info francious i totally get the octave slope way better now wow I cant wait ti get my 3-xover and begin my new re-install its gonna be freakin awsome thanx again

Not a problem my man.

jwilson273 · Post by **jwilson273** » Tue May 26, 2009 7:05 pm

Keep in mind, any x-overs you have running simultaniously will ADD the two values together.

Example: you have the x-over set at 70Hz on the EQ AND the amp. If the EQ is 24db/oct. and the amp is 12dB/oct. then what you'll end up with is an x-over @ 70Hz for 36dB/oct.[/quote]

If your head unit has a selection for sub db level, would that add to the whole mess of shit too? is it better to use a dead headunit?

dBincognito · Post by **dBincognito** » Tue May 26, 2009 7:44 pm

Francious70

but remember blending is a good thing.

I like 12 on the sub...to mix in with the mids

and 24 or higher between the mids and tweets....so I can get precise

Post by **Francious70** » Wed May 27, 2009 5:19 am

jwilson273 wrote:
Francious70 wrote:Keep in mind, any x-overs you have running simultaniously will ADD the two values together.

Example: you have the x-over set at 70Hz on the EQ AND the amp. If the EQ is 24db/oct. and the amp is 12dB/oct. then what you'll end up with is an x-over @ 70Hz for 36dB/oct.
If your head unit has a selection for sub db level, would that add to the whole mess of shit too? is it better to use a dead headunit?

If it's talking about level as far as gains go, then no, that won't create any problems. But if we're talking a lopass filter, then yes. I know my HU has the lowpass turned ON by default for the sub outputs but I turn them OFF so I can control the x-over point and slope elsewhere.

dBincognito wrote:Francious70
but remember blending is a good thing.
I like 12 on the sub...to mix in with the mids

and 24 or higher between the mids and tweets....so I can get precise

Word word. That sounds pretty good. I have mine the exact opposite way, 24 between the sub and the mids and 12 between the mids and tweets

which x-over to use?

which x-over to use?

AX 204X or A