LPF crossover for RE 3x 12" w/2way components

 

unregistered
Unregistered guest
Whats a good Lowpass crossover point for a RE xxx 12" in a 2.1cu ft ported to 28hz.. when being used with a front fill 2 way component setup?

80hz and lower to sub? 100? 125? 150? 200? 250?
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 539
Registered: Dec-04
Why don't you try all of them. It's a matter of preference and we don't know what you like
 

unregistered
Unregistered guest
well i am going to buy a harrision in line crossover.. and they are $25 a piece so trying all of them really isnt a luxary.. in general.. whats peoples ideas for such a setup? (my box is already ported to sql specs..so whats a good crossover point to match)
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9115
Registered: Dec-03
good starting point?
60Hz, 18dB slope for subs
100Hz/12dB slope for mids

less than an octave of separation, so the roll off will cover any gaps.
that keeps the subs low and tight, and lets the mids handle the midbass.
 

unregistered
Unregistered guest
imsorry glass i need a more down to earth explanation of what you just described.

so 60hz and lower for the sub and 100hz and higher for my components? (is that what your saying)

Are we leaving out 61-99hz on purpose or am i missing something?

less than an octave of seperation? roller off will cover any gaps? (i dont understand those statements)

thank you for your first response but can you please clarify.
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 543
Registered: Dec-04
The cutoff for the mids is 12db so it should play audibly loud to about 80hz and the subs will play to about 70hz before it becomes inaudible.
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 544
Registered: Dec-04
The first answer covered rolloff
Didn't see the other questions my bad. An octave is an interval between two sounds whose fundamental frequencies differ by a ratio of 2 to 1. 440 Hz. is one octave above 220 Hz.
 

unregistered
Unregistered guest
so do i get a LPF 60hz crossover and put it inline with the sub amp and get 100 HPF and put it inline with the mid/highs? or do i get a 60hz LPF for sub and 60hz HPF for the mid/highs?

please can the answer be in those terms of what to do.. instead of the science behind it because im still not understanding..

thank you very much

 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 550
Registered: Dec-04
Ok, you need a 60hz lpf with an 18db cutoff slope and a 100hz hpf with a 12db cutoff slope.
This is how you would wire it. The crossover should be have this on it anyway.

+ - + -
input output
from to
amp speaker.
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 553
Registered: Dec-04
That didn't turn out right, but you get the concept right?
 

unregistered
Unregistered guest
ok this is the closest i found to what your saying.. its a 70hz not 60hz lpf with 12db slope, not 18 (http://www.thezeb.com/p-Harrison-Labs-FMOD-900061-101686.htm) and the 100hz HPF filter with 12db i found exactly ( http://www.thezeb.com/p-Harrison-Labs-FMOD-900076-101695.htm )

are those going to work for me?
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 555
Registered: Dec-04
They'll work if you have seperate amplifiers for your subs and components. Those crossovers are designed to fit between the rca cables and the amp.
 

unregistered
Unregistered guest
yeah i got sep. sub amp and mid/high.. is there going to be a difference on the not being 18db and only being 12?

and ice one last question maybe you already answered it in some way but just for my curiosity again, why do we do the HPF at 100hz if were cutting off LP at 60.. leaving out 61-99hz (vs getting a HPF of 70hz)...
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 556
Registered: Dec-04
The frequencies 61-99 aren't cut out completely, they are still there. A crossover slope looks like this-Upload the point where the 2 lines cross is the crossover point. So, where the subwoofer ends at the midbass picks up where it left off at. I know I'm not the best at describing things, but if you don't understand I'll try to clear it up some more.
 

Silver Member
Username: Tbolt

Collipark, GA United State...

Post Number: 557
Registered: Dec-04
Maybe this website can explain it a little better http://www.bcae1.com/elecxovr.htm
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9124
Registered: Dec-03
unreg'ed, the easiest way to understand slope and XO points is to read www.bcae1.com
see the sections on "slope" and "crossovers"
they have everything very well explained there.

basically it's like this:
you cut off the subs at 60Hz.
the slope, or Q, will be 18dB. that means every octave you go up from 80Hz (each octave is double the prior frequency), the subs will get 18dB quieter. (-6 to -10dB is considered half the audible volume, and -3dB is half the actual power)
(crossovers aren't brick walls. after teh XO frequency you set, the signal gets quieter from there on, at the rate of the Q or slope. the steeper the "slope", the quicker teh speakers get quieter above ro below the XO point.)

the midranges, as you also said correctly, will be cut off starting at 100Hz or 120Hz.
you'll use a more shallow slope for these, of 12dB per octave.
The gap to see between 120 and 60Hz is exactly 1 octave, and this will actually be covered by both the subs and midranges overlapping smoothly.. since both will be playing this range, but both will be gradually getting quieter as each moves in frequency toward the other speaker's range of operation. This makes for a smooth transition without creating a "warm spot" by crossing both speakers at the same frequency and having both playing the same frequencies making the volume louder just at the range where they overlap.
 

Silver Member
Username: Basshead86

Ocala, FL USA

Post Number: 120
Registered: Aug-05
is that on any set up or just his?
b/c my lpf on my sub is set at 80hz with a 18db slope and my mids are set at 100hz with a 12db slope. should i change mine to 60hz?(single 10")
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9128
Registered: Dec-03
with a 10" I'd leave it at 80

 

Silver Member
Username: Basshead86

Ocala, FL USA

Post Number: 121
Registered: Aug-05
ok good, thats what the installer said, but i just read all that and got thinking...
the next thing that popped into my head was "don't fix it if it ain't broke"
but i figured i'd make sure
 

Gold Member
Username: Ffxdevilarms

Dubuque, Iowa United States

Post Number: 1124
Registered: Jul-04
I got mine set pretty low. The lower it is the better sound my subs seem to get. Although i did have to go up a little bit and it got a bit better, but after that it got worse.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9138
Registered: Dec-03
it's always best to go by ear to get what sounds good to you. I'm just suggesting starting points..
generally the larger the surface area of teh driver's cone, the lower you want the LPF set.. otherwise the large cone area tends to resonate or ripple at higher frequencies, which causes that muddy effect that makes a sub sound "sloppy."
setting the LPF just right, with a fairly steep slope can avoid that problem most of teh time, and with that 10" sub, he can go higher than he could with say, a 15" before the sub rolls off naturally, or you run into issues with the cone staying rigid at higher frequencies.
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