Cheap crossover

I am adding a sub, and I want to filter out the bass from the stock speakers (so they don't bottom out when turned up), and let the sub handle all the bass.

About building the crossover, where can I get cheap inductors? Anywhere from 10 to 12 mH would work, but I can't find ones that I like. The PE ones are 300w and too expensive,:mad: and others that I found are only good for ~0.25 amps.:bawling:
 
What I want to do is to use a HP filter on the stock speakers, so they don't get any bass, and use a matching slope active LP filter for the sub. I really like my stock headunit, and I don't want to rip it apart to insert an active HP filter before the amps, and I don't want to build/buy an amp to drive the stock speakers just so I can use active filters. So my only option is to use passive HP filters.
 
Don't bother with trying to remove the bass from your interior speakers. Just add the sub and amp. Use the crossover on the sub amp. I have had people make me use extra passives on their interior speakers and they do little to nothing. You may not want to spend the money but adding a small four channel amp, even with your stock h/u and speakers, will make a huge difference in sound.
 
Don't bother with trying to remove the bass from your interior speakers. Just add the sub and amp.

That's the way I have it right now, and I don't really like it. What I want is a SQ setup, and the filters should do what I want. It would be just like a HT setup, where the speakers play down to 80 hz, and the sub takes over from there.

You may not want to spend the money but adding a small four channel amp, even with your stock h/u and speakers, will make a huge difference in sound.

My car is an 02 Honda Accord, and I think that the stock headunit sounds really good. All I want to do is improve the bass.
 
If you want an SQ setup then you are going to have to do a lot more then add a sub. Don't worrie about getting the bass out of the speakers. If anything upgrade your front speakers. In an SQ setup you want your front stage to play as low as possible. This way you can cross your sub over lower so you can't localize it. I have my front stage playing from 50hz and up and my sub 40hz and down with a 12db slope. I still need to do more tweeking but it's pretty close.

I don't think I can emphasize how much of a difference between the 15w amp in your hu and even a cheap 50w amp would make on your front stage.

While you are at it I recomend you disconnect your rear speakers or at least fade your speakers to the front. If you have a sub using line level adaptors your only option is going to be to disconnect.
 
honestly you are worrieing about something that you don't need to worrie about. If your sub is in phase with your speakers you will get a bit more midbass if it is out of phase you will get less midbass. I have work as a pro installer for a year and a half. You will not be getting close to a flat 20-20k unless you are using external amps and processing. In a car though flat isn't ideal due to all the reflections.
 
Hey xplod, if you want a passive HP filter you need a capacitor, not an inductor. You can get something like this: http://www.crutchfield.com/S-Ap4HRTmEfu3/cgi-bin/ProdView.asp?g=761&I=127BB150A2&search=bass+blocker -- "bass blockers." They only go down to 150Hz but that's pretty good. If you really want to go lower you can buy 496.88uF capacitors and wire them in series, but that's all the bass blockers are, plus shielding. You said you already tried the sub without crossing over the factory speakers -- what frequency is the low-pass filter on the sub? If it's 6db/oct at 80Hz the 150Hz bass blockers should match nicely, the frequency overlap will be at lower decibels and therefore end up closer to flat response.
 
No, that filter was a 12db/oct type which uses an inductor and capacitor. My 2p is that adding a passive filter at those kinds of frequencies is a recipe for disaster sound wise as you will be right in the middle of the resonance of the drive unit so the response will be all over the place.

The way forward in this instance is to use a cheap amp with active high-pass filter built in. That will probably cost about the same as passive crossovers but offer much better performance.
 
GhettoSQ said:
You said you already tried the sub without crossing over the factory speakers -- what frequency is the low-pass filter on the sub? If it's 6db/oct at 80Hz the 150Hz bass blockers should match nicely, the frequency overlap will be at lower decibels and therefore end up closer to flat response.

I'm not sure exacly, but I'm guessing it's 80 hz at leat 12dB/oct. (there is only an on/off switch)

The way I have it set up right now is the bass on the HU is turned down all the way to prevent the speakers from bottoming out. Even at this setting, when turned up ~3/4, the speakers still have to play a lot of bass. The bass adjustment affects frequencies from ~20-160, maybe even higher. So with the sub only playing up to 80 hz, I'm missing the 80-160 hz range. The reason why I want to cross them over is I want to be able to use the bass adjustment on the HU without worrying about the stock speakers bottoming out from trying to reproduce the really low bass.
 
xplod1236 said:


I'm not sure exacly, but I'm guessing it's 80 hz at leat 12dB/oct. (there is only an on/off switch)


The first thing you want to do is find out for sure -- it might be as high as 300 or 500 Hz, our ears might not know the difference. What kind is it? Does it come with a manual?

Now that I think of it, it might even be rolling off the top frequencies naturally. You could always experiment with inductors on that end, take charge of the situation :)

richie is right about that frequency...you'd be better off at least using a higher cutoff. What is your speaker config? if it's only the front speakers, you coud cut them off higher and let the rears fill in a bit...
 
"richie is right about that frequency...you'd be better off at least using a higher cutoff. What is your speaker config? if it's only the front speakers, you coud cut them off higher and let the rears fill in a bit..."

This is compleately untrue if he is trying to build an SQ setup. Rear speakers may amke it so your rear passangers can hear the music but they do nothing but wreck the phase of the front speakers in an SQ system.
 
With the large amount of cabin gain in a car I am sure you arn't missing as much as you think you are.

Actually, I am. The sub amp isnt that great. I have the gain turned up all the way, and had to turn up the bass boost quite a bit to get decent output from the amp. The bass boost is centered around 30 hz, so that screwes up the flatness of the response curve. Attached is the FR curve that I measured once. It shows where the bass boost is, and the cutoff of the LP filter.

How did you set the gain level on the sub amp?

Trial and error. I went with what sounded good to me.

Have you currently bottomed out your interior speakers?

I can't really say. When I turn up the HU with the bass turned up, I get distortion, which, as you said, could be the amp clipping.

The first thing you want to do is find out for sure -- it might be as high as 300 or 500 Hz, our ears might not know the difference. What kind is it? Does it come with a manual?

I will be building a new LP filter to go with the rest of the system, and possibly a new amp too, so the cutoff will be whatever I will need.
 

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DJNUBZ, from a lot of peoples' perspectives, it wouldn't be a true SQ system unless he ripped out the carpet and spent $800 on a head unit, either. The point is, right now he wants a better system without major hassle and expense, and he's coming here for advice rather than having some SPL dudes tell him to get a 2000 watt amp and 3 12" subs.

I've been through what he's doing, and made a nice sounding system without big bucks. You are entirely right about the rear speakers; the best thing would be to upgrade the fronts, ditch the rears, and match the slopes of the crossovers (if he doesn't want an amp and new HU). It had just struck me that if he's worried about missing some sounds, it's possible that his rears could handle them without bottoming out. Certainly worth a try.
 
xplod1236 said:

I will be building a new LP filter to go with the rest of the system, and possibly a new amp too, so the cutoff will be whatever I will need.

Hmmm, in that case I would go a bit higher than 80Hz since that does seem to be your Fs on the sub driver. Maybe try 300Hz for the HP, 150Hz for the LP? then you can have fun with zobel circuits.

I agree with DJNUBZ about the clipping; upgrading your factory speakers at some point should help with that, yah?