sub LPF (crossover) point...

[ayjay]

i got a question for ya guys... actually simm commented on this in another thread but i just figured i'd post it up and get some more feedback if possible...

what's a good cross-over point for the sub? like if i'm runnin a 63hz high pass on my components up front, how much overlap should i have? i was gonna set the LPF for the sub at 150hz, cause i don't want it to fall short on the higher bass frequencies... this too high or too low? i've heard mixed oppinions, i guess it's all based on preference and the type of setup you run...

[Rex]

Good Crossover info.

Are you actually talking about using LPF (Low Pass Filters) or electronic crossovers?Do you have any rear-fill mids?Are you talking about using 150hz crossover on your 15" sub ?What's the slope of the crossover you're referring to above?Have you ever used an Autotek amp?

Hi, my name is Rex, I'm a question asker.

[ayjay]

hello "Rex", sorry if i was unclear as to how to i phrased my question/concern. I was going to be using a built in LPF from the amp (24db Linkwitz-Riley). I don't like ruining my front sound stage with rear fills and yes the 15" is what i was thinkin of running up to 150hz. Hope this gives you a better idea...

now give me an answer ****er :pface

[Rex]

Wow, maybe I'm too old school, but we never took a sub that big up that high . I'd say with a slope that steep you might could go to 120hz, but even I think you're pushing the upper limits of what that speaker (in the box you've built) would be bad for the sub long term.

I got no facts to back up my opinion

[ayjay]

hmm well that's cool... ya i was wonderin how my sub might feel playin those frequencies... i got a Focal Test cd and there are some tracks that i felt the sub should be playin over 100hz... but i guess 150 is pretty damn high... i should probably back it off a bit..

[AustinSilvia]

just curious, why would it be bad for the sub to just let it play all frequencies the amp will accept? only curious because you said you have nothing to back it up and i've never heard that before. i mean then again i have never had 15's, so just curious. i mean i've never heard a sub get hurt by high frequency... it's usually the low that make it bottom out (obviously) but also with breaking the voice coil. well it only happens when the sub hits low you know?. again i'm not trying to say you're wrong i just have never heard that it's bad to just let a mono amp stay in non filter mode... trying to expand my knowledge i suppose.

[AustinSilvia]

i suppose it kind of depends on where you have the speakers all mounted. i have seen your setup, and the sub is in the cabin with you cause you have a fastback. well it may sound different if it were in a trunk. also the way you have your speakers mounted in the front will change the way it all sounds. imaging isn't going to be the same cause those mids and highs are right in your face. to be honest i dont know how i would overlap it. it's a much different setup than mine. i would just play around and see what sounds good. i mean to me that's the best way to really learn your system and what it is capable of... sorry i couldn't be of more help. it's just easier to sit down and play with it and try things than it is to describe how i might go about it if i were in your situation.

[ayjay]

hey man thanks for the advice... ya i think i just gotta mess around with the settings and see what works best with my setup... i got crazy midrange in my setup but lacking a little in midbass, so i might wanna look into capin off my sub frequencies a little higher than a typical setup to balance it out a little... i'll just have to test out my theory and see how it goes...

[Rex]

My "point" that the higher frequencies could/would hurt the sub is based on the concept that sub's have a freq range they're designed for and when you ask that sub to produce a higher freq you're potentialy asking it to move alot faster than the motor or surround were designed to move. That faster (attempted) movement will create heat and subs loose efficiency ast the voice coil/magnet get warm, then even more when hot.

As with most things heat is bad and a sub trying/creating higher frequencies would create heat.

[AustinSilvia]

I see your point, but mono amps have frequency ranges too. Personally I wouldn't be hooking a sub up to an amp with no mono output, or if I did of course I would tune it down. I don't *think* it would really damage the sub to let a mono amp play all its frequencies, but I could be wrong (depending on the setup i suppose). For instance my JL 500/1 amp... it's frequency response is 5Hz to 500Hz. None of those freq. will be damaging or cause overheating in my subs. I see what you're saying though.

[Rex]

I see your point, but mono amps have frequency ranges too. Personally I wouldn't be hooking a sub up to an amp with no mono output, or if I did of course I would tune it down. I don't *think* it would really damage the sub to let a mono amp play all its frequencies, but I could be wrong (depending on the setup i suppose). For instance my JL 500/1 amp... it's frequency response is 5Hz to 500Hz. None of those freq. will be damaging or cause overheating in my subs. I see what you're saying though.

Unless I misunderstood (and I do often), he was asking about passive crossovers on the speaker side of the amp, thus the crossover frequnecy and slope of an amps (mono or otherwise) wouldn't apply.

[AustinSilvia]

oh that might be. i dont know.

[QX4MIkey]

150Hz LP??..wow, and I thought my Xovers were kinda high @ 65Hz... The best way is really to play around with it and see what Xover point "Blends" in better with your component set.

My CDTs comp set are perfectly happy with a High Pass @ 60Hz axover point so I have my sub @ 60Hz LP. The reason it is quite low is because I HATE "Hearing" the subs...I want to "FEEL" them and when voices come out of my subs, I know the xover point is toooo high.

A good rule of thumb is 80/80..80HP (Mids/highs) and 80LP(Subs)..but depending on your car's characteristics and your subwoofer enclosure.

I hope this helps.

Mikey

[NY94J30]

Another factor to consider is staging. The higher the frequencies you send through your sub in the rear of your car, the more likely you are to lose the adirectional quality that lower frequencies provide, and which allow you to put the sub in the trunk w/o ruining the soundstage effect.

[AustinSilvia]

i think all this is pretty good advice ESPECIALLY cause you have a hatch...

[k-mart]

Ideally, for the best imaging/staging, you want to cross the sub over as low as possible while retainting a relatively flat frequency response. This is because sub-bass frequencies (i.e. 80hz and down) are omni-directional and, as you go up in the frequency range, sound waves become more directional. Basically, if you run your sub up to 150hz, you're going to know exactly where the bass is coming from and its gonna sound like poo. I'd say stick between 60-80hz.

[diamondj30]

240's seam to peak sound at80-120 hz.you may be able to run a gap from 50-60 hz/.startr nlow work up.24 db slope will give you sharper response.less wasted energy.you dont want your sub so high that it cancelles out midbass from your components.you basically want one freq.from one speaker.crossovers dont cut out freqs,they roll them down,so there still there jnust real low. you may be able to run a gap and still have overlapping freqs,hopefully i made this understandable.if you got an e.q. try bumping up 160 hz,that should ad some high end pop to the bass in you mids.when using kick speakers,240s have a 80 and 120 hz peek.most cars do really.midbass is one thing many peeps have problems with.how do you pair up a 6" mid with a 15 inch sub..somethings got to give.maybe a pair of fat 5's behind the dash would give you what you want.being behind the dash,really helps the stage too.a freind did this in his camary,very nice sound..dedicated midbass speakers are pretty cool.i cross my subs at 33hz for comps and 40 for street,but i run 8"in my front doors in boxes.hope this helps,if not oh well.

[MECPInstaller]

I set my low pass for my 2 12's around 115-130 and subsonic filter to 25hz. I really never mess with the amp to much since I put the pioneer deck in. It gives me the option of switchign around bass boost from 50hz, 80hz and 125hz with settings of up -6 to +6. It works great since i'm always switching out rap to rock to techno just afew pushes of a button and my subs sound pretty decent for any music i can throw at it.