Low/High Pass question

[Waterwookiee]

So, I got rid of that crappy Sony head unit and replaced it with a Pioneer which I REALLY like. It's got all the features I wan't with a good price to boot. But I have a question.

The headunit has adjustable low and high pass filters. Before now, I have been using the low/high pass filters built into my amp.

The amps filters have always been on, throughout my experimenting.

When I put the high pass filter on (in the headunit) it makes a much larger cut, than i am used to hearing from the amp's filter alone (both at 80).

Is this because I am filtering it twice, thus twice the decible roll off?

Which filter is better to use, the amp, headunit, or both?

If I only use the filter in the headunit, I'm a little afraid of turning it off while playing with EQs and whatnot, thus rushing my mains with bass. (granted, I am only sending 45w RMS to speakers rated for 70W RMS so it may be a moot point)

The amp is under my seat, and that little switch isn't likely to get accidentaly moved so I feel more secure with that.

Of course I want a good sound, and I can adjust the headunit, unlike the amp's crossover.

Here's what I have.

Pioneer 4800 headunit
JL XR650-CSI comps in doors
Alpine MRP-240 amp (2x 45w to the front and 1x 100W to the sub)
Crappy old sub to be replaced

blah blah blah..... (you get the idea)

Thanks!

[88 LE]

Since your using the passive crossovers that come with the components. You don't need to cross them over again with the headunit or amp.

For the crossover on the amp. If you can't turn it off, set it to full range, but only for the components.



Sub needs a lowpass. You can use the crossover in the headunit or amp for this. Use either one, not both.

The headunit might have a dedicated set of rca outputs just for the sub + lowpass crossover for the sub out. If so, you can run this to the amp.

Or turn off all crossover functions on the headunit and use the one built into the amp. Only use the crossover for the sub though.



You may need to rewire some stuff, depending on how you go about this.

[Waterwookiee]

I do have a rca running from the headunit to the sub, via a sub out that I can fade and switch on and off from the headunit.

And a second set of RCAs running from the "front" rca outs in the headunit to the amp for the mains.

I always thought you should use a high pass filter when using a sub (with a low pass), so you don't double up on the bass notes, and protect the smaller speakers from all that bass???? Why have both the mains and the sub playing the same low frequencies? Isn't that what will happen if I wire as above, with "full range" going to the mains and "low pass" going to the sub?

[88 LE]

Originally Posted by Waterwookiee

I do have a rca running from the headunit to the sub, via a sub out that I can fade and switch on and off from the headunit.

Does the sub out have a crossover on it that you can adjust? I imagine that it would.

I always thought you should use a high pass filter when using a sub (with a low pass), so you don't double up on the bass notes, and protect the smaller speakers from all that bass????

In your case your already using the passive crossovers supplied with the components. Those crossovers take care of crossing over the components.

So you don't need to use another crossover on them (ie: the amp and/or headunit).

Why have both the mains and the sub playing the same low frequencies? Isn't that what will happen if I wire as above, with "full range" going to the mains and "low pass" going to the sub?

No....

Once again, your using the passive crossovers supplied with the components. Those crossovers take care of crossing over the components.

Lets say you were to use a highpass on the mains (the components) in combination with the passive crossovers supplied with the components. The components would only be getting higher frequencies and this definitely is not what you want.


So what you want is a full range signal to those passive crossovers. The passive crossovers will then split up that full range signal and send the proper frequencies to the mid and tweet.

[Waterwookiee]

Dude, I totally don't mean to be difficult but....

The passive crossovers for the JL speakers are "two way" as far as I know.

So they split the signal into two paths 1) "the tweeters" and 2) everything below (including down below 80hz)

If the sub is taking care of 80hz and below, why do I want my mids getting 80 and below as well?

If I use the high pass (on my amp or headunit) (at 80 hz) would it work out like this.

Sub 80hz and down

Mid 80hz up (due to the "high pass at 80hz) to where the JL crossover splits to the tweeters

Tweeters on the top end.

If I use a low pass to isolate the sub and the stock crossovers to isolate the highs for the tweeters wouldn't that leave me with only mids going to the "mids"

I guess where I am confused about your recomendation is that the JL crossovers don't keep the lows (80hz and down) from reaching the mid/bass cones. Wouldn't a high pass filter set at 80hz acomplish that, essentially leaving me with three seperate frequency ranges.

BTW: I really appreciate you taking the time to "school" me. I just want to understand all of this as well as possible.

[Pimpinda93camry]

Originally Posted by Waterwookiee

Dude, I totally don't mean to be difficult but....

The passive crossovers for the JL speakers are "two way" as far as I know.

So they split the signal into two paths 1) "the tweeters" and 2) everything below (including down below 80hz)

If the sub is taking care of 80hz and below, why do I want my mids getting 80 and below as well?

If I use the high pass (on my amp or headunit) (at 80 hz) would it work out like this.

Sub 80hz and down

Mid 80hz up (due to the "high pass at 80hz) to where the JL crossover splits to the tweeters

Tweeters on the top end.

If I use a low pass to isolate the sub and the stock crossovers to isolate the highs for the tweeters wouldn't that leave me with only mids going to the "mids"

I guess where I am confused about your recomendation is that the JL crossovers don't keep the lows (80hz and down) from reaching the mid/bass cones. Wouldn't a high pass filter set at 80hz acomplish that, essentially leaving me with three seperate frequency ranges.

BTW: I really appreciate you taking the time to "school" me. I just want to understand all of this as well as possible.

I get what you are saying, Basicly yo are saying if you have a pass for tweeter, mid, sub then you will have each only playing only what they need. But as far as i know when you get tweeters u also get a pass for the tweeters. So if you want to make the mids play 80 hz and up then set your pass on your hu at 80 for mids. but if you have your amp suppling the power to the midsand sub then you need a crossover and put mids on 80+ adn sub on 80-. But i play bass trought my mids amd i have no effect on clarity. Well execpt for when i make it super loud adn it clips. But i like the bass through my mids because then the bass surronds you more. but you say that the cross over that you have if you set it at 80+ then won't the tweeters play 80+ to. the crossover that comes comes with for the the sepation of mids and tweeters. But then again i am not an expert.

[88 LE]

Originally Posted by Waterwookiee

The passive crossovers for the JL speakers are "two way" as far as I know.

You should of stated that earlier, but o well.

If the sub is taking care of 80hz and below, why do I want my mids getting 80 and below as well?

Well its a 6.5" driver, so its kinda a midbass and mid. According to the specs, it'll play down to 48Hz.


From: http://mobile.jlaudio.com/products_c...hp?comp_id=120

System Frequency Response: 48 Hz - 25 KHz ± 3 dB


As for why you would want to them to receive 80Hz and below. Some people actually prefer that they play down that low. It makes it seem like the bass is coming from the front, instead of localized in the rear. The idea is to have them play as low as possible and have the sub handle the real low frequencies (sub frequencies).

When your at a concert, everything is coming from the front including the bass. Hardcore car audio nuts that compete in sq (sound quality) try to create this effect in a car.

If I use the high pass (on my amp or headunit) (at 80 hz) would it work out like this.

Sub 80hz and down

Mid 80hz up (due to the "high pass at 80hz) to where the JL crossover splits to the tweeters
on the top end.

Yes, but the sub also has to be lowpassed at 80Hz.

I guess where I am confused about your recomendation is that the JL crossovers don't keep the lows (80hz and down) from reaching the mid/bass cones. Wouldn't a high pass filter set at 80hz acomplish that, essentially leaving me with three seperate frequency ranges.

Yes.

[Waterwookiee]

Cool, now I see where we were on two different pages. I guess I assumed that you knew that the JL crossover was only a "two way". If they were a "three way" your original post would be dead on and I wouldn't have gotten confused.

If only I had a markerboard to make a diagram when I first posted

But now that we are on the same page, I see exactly what you mean. I have a day off tommorrow and I planned on spending the day, doing the final cable routing under the carpet and whatnot. I will play around with the levels and see what I like best.

Thanks again for all your help.......

[88 LE]

Originally Posted by Waterwookiee

Cool, now I see where we were on two different pages. I guess I assumed that you knew that the JL crossover was only a "two way".

Theres a saying that I got from a movie. Assumption is the mother of all f**kups.

Kinda my fault to, for not checking the specs on those JLs and assuming you wanted them to play as low as possible. Most people just hook them up with the supplied passive crossovers, run a full range signal to them, and let the crossovers deal with it.

If only I had a markerboard to make a diagram when I first posted

But now that we are on the same page, I see exactly what you mean. I have a day off tommorrow and I planned on spending the day, doing the final cable routing under the carpet and whatnot. I will play around with the levels and see what I like best.

Kewl deal.

Thanks again for all your help.......

No prob.

[FUGUBOY]

Do the crossovers on a two way component speaker system filter out low frequencies to prevent damage woofer ? I thought they just sent highs to tweeters and you need high pass on amp to keep lows from blowing woofers or trying to reproduce lows that are meant for subs. No room for subs in my truck and crutchfield advisor suggests not to run amp full range but to use high pass.

[cam2Xrunner]

I'd set the crossover on the amp to fullrange and the HPF on your headunit for the components at either 63hz or 80 hz. Turn off the sub and after setting the gains for the speakers, play your test music at as loud as you would ever listen to it and see if your mids can handle 63hz. Try going back and forth between 63 and 80 hz to see which one sounds cleaner.

Right now, in my install I am using 80hz on the mids HPF and 63 hz LPF on the sub. I'm still playing with it though.

But definitely use a HPF setting on your front speakers.

[FUGUBOY]

Thanks Cam what about bass boost , does it only work on subs? My amp is a alpine MRV F-345 and factory h/u . component fronts and coax rears no subs maybe later.I'm just an old fart but i like to crank up my FREEDOM ROCK 80's cd and maybe some Neil Diamond and pure funk cds

[Waterwookiee]

Yeah, my tweeter is really freaking me out. If it's a clipping issue and not a blown tweeter, why than would only one tweeter be making that "clicking" noise under relatively high pressure?

Is it possible to be clipping only one channel? (on the same gain knob)

Furthermore, I am only pushing 65% of the rated power, so I should (in theory) have a lot of head room. At least that was the idea.......

I don't feel as though at 50% my amp should be clipping and a certianly shouldn't be peaking these speakers......



Side note, I played with the crossover in the HU and the amp, and I think the crossover in my amp sounds better. Perhaps it has a different rolloff character or something?