How do I build a subwoofer cross-over ???

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stuparumihairadu

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Joined 2011
#1
hello.

I got my hands on a car amp.doesen`t have any bass bost, lpf etc.
only rca-input know from 400mv to 4 V
and a dyn gain knob max-min.

so i thought that I could get some tips on how to do a sub cross-over.
better still if I can make it with lest say 3 various levels...(ex. 400 hz- 600hz - 1000 hz something like this.)
It`s a 2 channel amplifier with bridged option.
I`m thinking that if I get tips one how to build one i`ll build 2 of them (for each channel).


I am sorry if I post in the wrong section.

Thank you and lets hope i`ll get this sorted out.
 
#3
A 6dB per octave crossover would just use a coil of the appropiate value, as linked by carshateme above. However, bass frequencies are much lower than 400Hz-thats midbass territory, you want to be looking at freqs of 100Hz and down. Also coils aren't used commonly for sub crossovers in car audio(power handling and cost/lack of adjustability)-you may be better off using an active crossover, most stereos over £100 will have HPF and LPF filters built into them now days.
 
#6
thnx a lot.


Got all the info I needed.Run once in the past with the same type of problem.forgot the websites doh....any how...

thx a lot for posting! once again this forum (for wich i am a newcommer) gave me up to date and speedy answers.

cheers to all of you and diyaudi...nr 1
 
#8
stuparumihairadu said:
thnx a lot.


Got all the info I needed.Run once in the past with the same type of problem.forgot the websites doh....any how...

thx a lot for posting! once again this forum (for wich i am a newcommer) gave me up to date and speedy answers.

cheers to all of you and diyaudi...nr 1
Click to expand...

Its what the forums is for. Feel free to ask any other questions. A lot of experienced peopld on these forums. I'm just an entry.
 
#9
i`m thinking on something like this .And here is where i am asking if its posible?
In theory is the same as using a single coil for sub freq.
I wanna use a switching device to select freq. between lest say 100-200-300. (or someting like that).

could it work or should I use only 1 ?

The frec on whom the switch is switched to is in contact.and the others are off basically.
 

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#12
ODougbo said:
It's next to impossible to use a 6db passive crossover for a 100hz subwoofer. I guess you would get some results, although the inductor would be huge.

What impedance is the woofer?
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They're not terribly huge, I've got a few sets of passive sub crossovers, my largest ones are 80hz lpf @12db/4ohm and the coil plus the caps are glued to a piece of wood that measures 5 inches by 6 inches or so, the coil itself is about an inch thick and maybe 5 inches long.

Air cores might be huge (and expensive) but the steel laminate most folks use aren't that big, see here:

ERSE - Super Q
 
#13
inductor for a 4 ohm woofer

yes a inductor for a 4 ohm woofer wouldn't be bad e.g. 3.5mh - 6.5mh.

The roll off will be so gradual with a 6db slope, it will drive you crazy when trying to set it up. I'd at least go for a 12db, or if the expensive parts are free, go 24db.
 
#14
ODougbo said:
yes a inductor for a 4 ohm woofer wouldn't be bad e.g. 3.5mh - 6.5mh.

The roll off will be so gradual with a 6db slope, it will drive you crazy when trying to set it up. I'd at least go for a 12db, or if the expensive parts are free, go 24db.
Click to expand...

Yes I looked it up.one coil for 6 db, and for exp 2 caps and a coil for 18 db.
I looked it up and saw it.


hmmm...by parts your refering to The simple coils and no other parts (like capacitors or resistences) no?

I thought if I just put a single coil on the + wire before the speaker it would have solved it.(at least thats what I saw from the schematics on the net..simple coil gives you freq of lets say 100 hz)

If I am mistaken please let me know.

A basic paint drawing if you got time would be helpfull .
 
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#15
stuparumihairadu said:
hmmm...by parts your refering to The simple coils and no other parts (like capacitors or resistences) no?

I thought if I just put a single coil on the + wire before the speaker it would have solved it.(at least thats what I saw from the schematics on the net..simple coil gives you freq of lets say 100 hz)

If I am mistaken please let me know.

A basic paint drawing if you got time would be helpfull .
Click to expand...

It does, but it only gives you a 6db electrical slope, which would mean you'd still hear muffled vocals and stuff coming out of your sub.

Adding the parallel cap(s) to make it 12db electrical would be a great idea. It'll clean up the sound of the sub and will only be a few additional dollars depending on what grade of cap you choose. I've always used relatively inexpensive electrolytics in my sub crossovers and haven't had any trouble with them yet.
 
#16
DrDyna said:
It does, but it only gives you a 6db electrical slope, which would mean you'd still hear muffled vocals and stuff coming out of your sub.

Adding the parallel cap(s) to make it 12db electrical would be a great idea. It'll clean up the sound of the sub and will only be a few additional dollars depending on what grade of cap you choose. I've always used relatively inexpensive electrolytics in my sub crossovers and haven't had any trouble with them yet.
Click to expand...


Yes I see....i`ll study up some models on the net and see what I can do.
Parts wi`ll be bought in the weekend days.thats the electric supply days .
I think i`ll go allong with the 12 db ones.If I can find the necessary parts i wi`ll try a minimum of 2 switches or a maximum of 3 deppending on the stuff found and bought.

If not I`ll stick with a single freq.

p.s.

the parts are bought at arround 0.35 cents the piece...capacitor, coils, etc.
lets hope I find the right ones.

Keep in touch and i`ll keep you posted with the construction.
 
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