What is HP Filter, LP Filter? What do crossovers do?

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Hey guys! I decided to do another video for you to explain what crossovers are and how they should be set in your car audio system. I also decided to clean off the dresser behind me in the video, because I think I looked like such a slob in the last one! Anyways, chores aside, let’s talk about crossovers. On many of the newer head units these days, if you scan through the audio settings you will see things like HP filter, LP filter and when you select them a few options for frequencies to select from. You may also see these settings on your amp and not really know what they do.

In the simplest way to describe this, crossovers are frequency filters. They allow us to filter out certain frequencies to certain speakers. So on your interior speakers, that would be your HP or High Pass Filter. High Pass means we’re only allowing the higher frequencies to play through, so this is what you want to adjust for your interior speakers. LP or Low Pass means we’re only allowing lower frequencies to play through. So ideally you want your interior speakers playing what they’re best designed to play, about 60-80 hertz and up and we have our subs playing about 60-80 hertz and down. The important thing to remember is you don’t want any gaps between these frequency settings as then you’ve cut them out of your stereo system all together. So make sure the cut off is about the same on both your low pass and your high pass filter.


The other important thing to remember is you never want to use both the crossover setting built into your head unit AND the crossover setting on your amp. Use one or the other. So never use the LP filter on your head unit and the LP filter on your subwoofer amp, that can cause weird phasing issues. Same thing on the interiors, if you’re using a 4 channel amp, either use the HP filter on the amp or the HP filter on the head unit, but don’t use both.

I hope this helps clarify what crossovers are, how they work and what they can do for your car audio system. If you have questions about where you should have your crossovers set at, just please comment and I’ll respond and help you out. Also, if you guys like what you see here, please submit this site to one of the social networking links, I would really appreciate the support. Thanks for stopping by and checking out the site!

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52 comments for “What is HP Filter, LP Filter? What do crossovers do?

  1. Nigel
    November 27, 2011 at 4:22 pm

    hi there just needed some help with my car stereo >basically ive had it installed about 4 years ago and i have only recently got to know more about sound technology >
    so this is what i have pioneer head unit with lpf hpf and sub controls model deh 6700mp
    and at the back ive got jbl cs 60.4 4 channel bridged running my 6×9 stereo and jbl gto 75.2 bridged running a pioneer sub in mono . and at the front just some pioneer tweeters running off the front channel on the head unit .. now my stereo sounds good but it just doesnt feel right as ive set the lpf and hpf on the head unit and the amp and when i change either i have a huge diference in sound which confuses me . i wanted to know if i should only set crossovers on either head unit or amp both have them but head unit is fixed lpf at 50 80 120 and 160hz and hpf 80 120 150 and 200 hz but the amps have an electronic crossover that lets u turn it from 32hz to 320 khz on both
    any help would be really helpfull as i cant seem to get it right..

    • November 27, 2011 at 5:08 pm

      Hi Nigel,
      Very good questions you’ve got here. You never really want to use both the crossover on the head unit and the crossover on the amp, one or the other. When you use both you get funky phasing issues which is why you are hearing such a big difference when you switch between the two. Since you have more control at the amps, I would recommend using the amps crossovers and leaving the crossovers off on the head unit. Generally speaking you would want the sub crossover around 80 and the 4 channel crossover around 80, no higher on either. What kind of car is it?
      Annie

  2. Nigel
    November 27, 2011 at 5:14 pm

    hey annie
    thank you for your prompt really dint expect that . my car is a suzuki swift 2006 model the new shape .. would also like to ask should i install front components or leave it since the car is small . and how would i know where is 80hz on my amps as it only has 32hz to 320khz nothing in between just turn it up half way or something ?
    thank you

    • November 27, 2011 at 5:34 pm

      Hi Nigel,
      It’s my pleasure, no problem. I would still do the front components in any car. To get that detail to where it needs to be heard, you usually need to have separate tweeters that are a little higher up than the door speakers. With coaxial speakers the tweeter in them is usually aimed at your ankles. Unless we start growing ears on our ankles, I say go with components and mount the tweeters up a little higher. Helps to bring your sound stage up to your level. There should be little notches on the amp to give you an idea.

      So if there are 5 notches, you could say there are 6 sections on the dial. You could then say that each section between notches represents 48 hertz (320-32 = 288, divide 288 by 6 sections = 48). 48 plus 32 equals 80, so chances are the 1st notch would be good.

  3. Nigel
    November 27, 2011 at 5:41 pm

    hey annie thank you for your replies i will try this out the next weekend am free am post my results or differences ..
    as for the components i will first set the amps and do some research as to which components are good for mid range as i like my mids clear. ..
    thanks once again

  4. ray
    February 1, 2012 at 11:20 pm

    i have a sony xav-60 cant cutoff crossover on headunit or on amp

    • February 2, 2012 at 12:58 pm

      Hi Ray,
      Check out the owner’s guide, Sony lists these features for that model:
      High-Pass Filter: The front and rear speaker outputs offer a selectable high-pass crossover frequency of 50Hz, 60Hz, 80Hz, 100Hz, 120Hz, or Off.
      Low Pass Filter: The subwoofer output is non-fading with a low pass filter with a selectable cut-off frequency of 50Hz, 60Hz, 80Hz, 100Hz, 120Hz, or Off. You can also adjust the subwoofer preamp output’s Phase (Normal/Reverse).

  5. Arun
    March 24, 2012 at 10:54 am

    Hello Annie,

    This article of yours helped a lot in clarifying me on the HPF and LPF settings in car stereo. I just got for a Sony car head unit for my Suzuki Swift hatch and based on your article, I have set both the LPF and HPF as 60Hz. I also see a settings called LPF Slop (1,2,3) and HPF slop (1,2,3) in Sony. Can you please clarify on what these setting mean as well?

    Thanks in advance,
    Arun

    • March 24, 2012 at 11:24 pm

      The slope is the amount of how sharp the crossover point cut off be. So if you picture a range of frequencies of say 20 hertz to 20,000 hertz. And you want to tell your interior speakers to play 80 hertz and up and your subs to play 80 hertz and down.

      Typically different slope options for crossovers are 6 DB, 12 DB, 18 DB or 24 DB per octave. The Slope 1 on Low Pass probably represents 6 DB per octave meaning the frequency of one octave above 80 hertz (160 hertz) will be 6 decibels less than 80 hertz. Slope 2 would be 12 DB less and slope 3 would be 18 DB less.

      On high pass this is opposite. If you have high pass filter on 80 hertz at Slope 1 or 6 DB per octave, you are reducing 40 hertz (one octave below 80 hertz) by 6 decibels. At Slope 2 you are reducing 40 hertz by 12 DB and slope 3 by 18 DB. They refer to this as Slope because this is how it looks on a chart:

      Full range – http://carstereochick.com/blog/wp-content/uploads/2012/03/fullrange-300×208.jpg
      High Pass 12 DB – http://carstereochick.com/blog/wp-content/uploads/2012/03/12DB-300×154.jpg
      Low Pass 24 DB – http://carstereochick.com/blog/wp-content/uploads/2012/03/mono24DB.jpg

      Now imagine laying the last two images on top of each other you can see the slope and blending point of the two frequencies. If the cut off is sharp, like 24DB you risk losing frequencies. If it’s too little you end up overlaying frequencies. I think 6 DB is a safe level, but every car is different.

  6. Jon
    March 30, 2012 at 3:03 am

    What would you suggest a person do if you cannot cut off the LPF on your head unit OR your amplifier? There seriously is no way to just turn them off, I can’t believe this..

    Sony DSX-S310BTX head unit
    Alpine MRX M50 mono amplifier

    I guess I pretty much have to waste money to ship my brand new amplifier back across the entire country, wait for my refund, and buy a different amplifier that has an option to turn the LPF off, right? Probably will go with a class AB that can be bridged down as those will generally have both filters and therefore an option to turn them off.

    • March 30, 2012 at 5:58 pm

      Hi Jon,
      It’s actually more of a head unit thing than an amp thing. Pioneer does this too, drives me batty. Overall, the Sony has a lot of other great features going for it. So other than upgrading to something like a KDC-X996 (which gives you selectable hi pass/lo pass filters on/off separately adjustable for front/rear/sub) then your best bet is to leave the lo pass head unit crossover as high as it will let you (like 120 or 150) and leave the amp lo pass around 50. You may need to reverse the phase on the sub which I see is an option on your head unit. Try it both ways and see how it sounds. The MRXM50 is a good amp, by the way.

  7. Jon
    March 31, 2012 at 1:04 am

    Yes, I agree with you Annie.. definitely a head unit issue. Just would be much easier to change the amp out LOL. Yes this drives me crazy as well.

    I read somewhere last night while searching various blogs that I should change the crossover on the amp as high as it will go, so 400 hz. I have the head unit as high as it will go right now, so 120 hz. The sub that I’m driving is a 12″ 1262w DVC Infinity Reference. Both voice coils are wired parallel for a 2 ohm load, sealed in the recommended 1.25 cu. ft.

    The first day I was confused as to what the heck was going on, I’ve been away from car audio for a handful of years now and this is my first system in awhile. The sound was so muddy and I wasn’t sure what was going on until I started to realize I couldn’t turn off either LPF. I originally had them both around 120, obviously sounded as terrible as you can get. Now I have it with the LPF on the amp maxed instead of at minimum like you are suggesting. It sounds 100 times better the way I have it now, but I’m probably going to try what you are suggesting and see how that works out.

    Can you elaborate a little more on why minimum LPF on the amp would be better than maxed out LPF in my situation? Also I have played around with reversing the phase and it sounds quieter at reverse with my current setup.

    On another note, I’m looking to swap out the infinity for something with a 500 rms rating in order to match up with the highs in the car. I have CTR audio tweeters run series parallel with small front coax speaks, powered by an older Pioneer that delivers 50×2 @ 2ohms rms, and the bass cannot keep up. Maybe your suggestion for the LPF alteration will make an improvement, we shall see tomorrow.

    • March 31, 2012 at 1:08 pm

      Hi Jon,
      You’re essentially crossing over the sub over at 120 and that would explain the muddiness. Assuming you’re using the head unit crossover around 80, and slope 1 (minus 3 db), this is essentially what you’re doing. So from the graph you can see how your sub is seeing 120 and down. So by switching it around to having the head unit at 120 and your sub amp at 50 – 80, you will be essentially using the amp crossover which is probably more precise than the Sony crossover anyways. It will eliminate some of that muddiness.

      What kind of music do you like? For sound quality, I recommend JL either the W3 or W6. They’re very accurate, clean and warm subs. Best in a smaller sealed box. Actually they sound best when you build the enclosure to spec.

  8. Jon
    April 1, 2012 at 1:06 am

    Thanks Annie,

    It sounds a lot better crossed as low as possible on the amplifier. So what frequency am I actually crossed at approximately after both of these filters are in play?

    I listen to a lot of music with beat, dance, etc. Some rock here and there. Another question I have is will there still be a LPF cut off on outbound RCAs from the Alpine amp to any future amps that I may want to use for another subwoofer? I’m sure that the Alpine makes sure not to send its own LPF signal through the RCA outputs of itself, but what about that 120 LPF that’s coming from the deck?

    Thanks much for your help.

  9. George
    June 20, 2012 at 6:49 pm

    Hey Annie,
    Was trying to tune my car stereo out and came across your page. I am trying to figure out what the best way to tune my car’s stereo to sound its best. I have alpine for everything. Alpine CDE-103BT deck, Alpine SPS600 Components for front and Alpine SPS600 for rears. The speakers are powered with Alpine KTP-445 mini amplifier outputting 4x45watts rms. For the subwoofer I’m running a
    Alpine SWS-1043D in a ported box with Alpine MRX-M55 amp outputting 550watts rms @ 2 ohms.

    After reading up more and playing with my system, I have a lower end head unit with less play so I was wondering whats the best way to tune it given what I have. The head unit does not have a Lowpass filter. I have the amp set at 80hz LPF and the the head unit HPF is 80hz with bass center frequency at 80hz narrow. Enabling SUBW SYS 2: Subwoofer level change is different from the main volume setting. For example, even at low volume settings, the subwoofer is still audible. (Allows for the subs to be louder then the speakers) Bass Eq is at 0, Gain is in the middle, and subsonic filter set to 30.

    What are your thoughts? is the bass center frequency the same as low pass filter on the head unit?
    Thanks in advance!

    • June 20, 2012 at 8:31 pm

      Hi George,
      Alpine does make some great products. It sounds like you got most of your settings figured out. You may want to turn the bass boost up if you find as you drive, you lose a lot of bass (opposed to when the car is sitting still).

      The Bass Center Frequency is a little different than a crossover. It’s basically the frequency that you are adjusting when you turn the bass up or down. The Width refers to how wide a range of bass frequencies you are adjusting when you turn your bass level up and down. So when you bass center frequency set to 80hz and narrow, that means you are pretty tightly turning up or down just 80hz when you use your bass level adjustment. Since you have your HPF set to 80 hertz, that adjustment probably isn’t really doing anything for you as your basically cutting that frequency out from your interior speakers anyways.

      I would try changing the center frequency to 100hz, then set the bandwidth to 2 and see if that gives you a bit more control over boosting/reducing your midbass. I copied this straight from the manual if it helps:

      Setting the Bass Center Frequency
      Press BAND to select the desired bass center frequency.
      80 Hz 100 Hz 200 Hz 60 Hz 80 Hz Emphasizes the displayed bass frequency ranges.

      Setting the Bass Bandwidth
      Press SOURCE/ to select the desired bass bandwidth.
      Changes the boosted bass bandwidth to wide or narrow. A wider setting will boost a wide range of frequencies above and below the center frequency. A narrower setting will boost only frequencies near the center frequency.

      It’s one of those things you just kind of have to try and see how it sounds. You may also want to try it narrow at 100hz, and then try the same two configurations at 200hz and try to remember what sounded best! You’ll get the hang of quickly switching between all the options, just listen to a variety of music while you do it. Pretty soon I’ll be doing a post/video on how to tune using an app for the iPhone and pink noise (way easier than it sounds). If you want to be notified when its up, just sign up for the RSS feed. Good luck!

  10. George
    June 21, 2012 at 5:16 am

    Thanks for the reply Annie.
    So if I’m understanding it correctly, bass center frequency and the width only applies to the interior speakers and has nothing to do with the subwoofers and that my subwoofer will need to be tuned directly from the amplifier. If that is true then when “Adjusting Subwoofer Level”, does that mean its increasing the volume (loudness) of the subwoofer?

  11. Sriram
    July 27, 2012 at 2:14 pm

    Hi Annie,

    Having read your brief but informative post, I thought this would be the best place to post my question over which I’ve been tearing my head apart. My car has certain limitations and I do not wish to modify the structure of the dash or lose any boot space. Hence I went in for an Auditor 4″ on my dash and 3-way EarthQuake VTek 693 on the rear parcel tray plank. The headunit is a Sony XAV-601BT and there is a 2-channel Hertz EP2 Amp powering the rears only. The sound that I get even without a Sub is pretty earth-shattering for my liking but then I still wanted to make sure that I was not under or over powering the speakers. For starters, the installation done by the dealer wasnt all too great coz the sound used to crack up even at volume level – 25 which is like 40% of max. But then since the max RMS of the amp was well within the speakers’ recommendation, I decided to play around and after a bit of tweaking, I did manage to get a distortion free 35 on the vol control which is roughly 60%. I dont think I will ever need anything more than 30 though. But still am curious to explore what’s the max I can get. I just had a couple of questions in this regard. Firstly, the amp has a high-pass/full/low-pass option for the x-over filter. As you mentioned earlier, lpf is definitely not for my rear full-range speakers. But then which of hpf or full should I use? There are 2x other knobs which say level and boost. I just wanted to confirm whether level means gain and and boost is specific to boosting the low frequencies only? If so, do you think boost will be of no use to me since I dont have a sub?

    Thank you

    • July 29, 2012 at 8:12 pm

      Hi Sriram,
      Well if you don’t have a sub, you pretty much want to leave the crossover section alone (Full setting). If you do add a subwoofer, you can put the crossover on high pass (if selectable frequency, usually around 80 hertz). Level or Gain is really just a way to level match to the sensitivity of the head unit’s pre-amp RCA connections. It does sound like the dealer didn’t know how to tune if you were hitting distortion at 1/2 the volume on the head unit.

      As a rule of thumb, all head unit’s pre-amp section reaches distortion at a certain level, usually around 80-85% of volume. So if your volume on your Sony can go up to 60 for example, chances are the pre-amp outputs of the deck are distorting around 48. So when you tune your amp, you would want to have your volume level on the head unit just below the point of pre-amp distortion. Then you can bring the level of your amplifier gain/level up to your listening tastes or to a level just before distortion occurs on the amp. You should tune using a variety of music that you listen to.

      Your assumptions are correct, boost is typically used for subwoofer applications (low pass) and usually boosts a select frequency which should be noted in the amplifier’s owners manual. Typically bass boost is around 40-50 hertz. So you wouldn’t be using this feature.

  12. Darnell
    July 31, 2012 at 1:26 am

    Hey Annie,
    You sound like you may be able to handle this one in your sleep if this post happens to reach you for real. First time stereo buyer so I kept it cheap and simple. I have a dual xd1228 deck installed with a 400w dual xpe2700 amp. I have it hooked up to a 12″ Ts-w304r subwoofer. I figured not to much can be done with the head unit seeing that I’m already using the low level input with the rca jacks. Now with the one speaker (looking for that powerful really deep bass) should it be wired for a 2 ohm minimum or bridged seeing that I only have one speaker? After that I’ve got some knowledge from prior posts, am I keeping my lp on and set to about 80? Because it has a range from 50hz-500hz Then my bass boost has always been set at 6db with the options of off 6db and 12db. I know to easy my gain up as to require that peek bass but what about this whole lp being set low, how low Annie!! It seems too low but I kinda understand because I feel like I’m almost there. Btw I have bridged this speaker yet either, let me know if I’m missing out. Thanks a bunches.

    • July 31, 2012 at 9:10 pm

      Hi Darnell,
      Well, it sounds like you’ve got your settings about right on the amp. LPF on around 80 hz, try to keep bass boost off or minimal if needed. Your weaknesses will lie in the head unit and possibly the enclosure you’ve used for your subwoofer. That subwoofer should be a single voice coil 4 ohm sub, so you can safely bridge the amp (the amp will see half that or share that impedance 2 ohms per channel).

      So let’s talk about head units. By upgrading to something that has built in crossovers and higher voltage output you will get a LOT better sound quality. Without changing any settings on your amp and going with a deck with higher voltage, you will get more kick and sensitivity out of the amp and will have a better/cleaner bass response. Built in crossovers will allow you to filter out the bass going to your interior speakers, even if they’re just stock speakers, allowing them to play louder and cleaner.

      The quality of the head unit will make a big difference in sound quality too, there’s definitely a difference among manufacturer’s and models. By going with something like a Kenwood Excelon KDC-X396 you will gain 4 volt preouts, built in crossovers and will have better detail and resolution based solely on the better quality components used to reproduce sound in the head unit (aka DAC or digital to analog convertor).

      The other thing you will want to check out is the enclosure you’re using. Look up the owner’s guide to your sub and build a sound quality box (sealed) to spec. The manual will give you Pioneer’s exact recommended enclosure size to give you optimum sound quality. We like to use trupan which is lighter than MDF and a lot easier to work with. Most lumber yards carry it. We use glue, lots of nails using a nail gun and liquid nails to make sure its solid and sealed.

      I hope that helps!

  13. sammy
    August 2, 2012 at 5:43 pm

    Hey Annie , Just wanted to ask for some help setting up my 4 channel amp for mids and high. Its a sundown sax-100.4d, It has alot of stuff i don’t know what it means.Mind helping me out? I have a sub running for bass at around 80hz and under. Head unit is a jvc jvc nt50hdt.Thanks

    • August 6, 2012 at 10:00 pm

      Hi Sammy,
      That’s a high power 4 channel amp, but they have kind of crap owner’s guide. Manufacturers like JL Audio actually tell you what all that stuff means and when and how you should use it. Regardless, here we go.

      Since you’re running this on your interior speakers, you’re going to want to select HPF for both your front and rear channels (switch choices are HPF, FULL or LPF). Leave your subsonic filter off. That’s normally used for running LPF on subwoofers if you have subs in an enclosure that is prone to distortion by resonant frequencies. The slope adjustment dial for the crossover reads 6DB, 12 DB or 24 DB per octave. That’s how sharp the cutoff will be with your crossover. I don’t recommend going more than 6 DB. If it’s too sharp, you’ll find a gap around that frequency. You kind of want that blended with your crossover on your sub. But it also depends on the car acoustics. That’s one of those try it and see how it sounds settings. I have no idea what that “X 10″ setting does and the owner’s guide doesn’t really explain it either. I would leave it off or at “1 X”. I think it means one times the crossover setting or 10 times the crossover setting. May want to email the manufacturer on that and see what they say. Maybe for if you were running an active crossover system (in other words, not using the crossover from your component speakers between tweeter and mid bass and running the tweeter off channel A and the mid range off channel B)?

      P.S. if you’re using crossovers on your amp, leave them off on your head unit.

  14. lee
    September 26, 2012 at 10:42 am

    hi mateHi i know everyone has different tastes in music but i just want some ideas on best settings for my car audio based on what i own and what you have your settings too.If it helps i listen to anything dancy & hardcore

    i own a fiesta st and have just currently bought a kenwood KDC-DAB451UU too replace me old kenwood.All my speakers are default ones that came with the car the only thing i have added is a 10 inch sub powered by a 300 watt amp with the switch on the amp set too 80hz set up by rca goin into back of head unit
    Now what i want too know is the best settings or ideal settings for each of these please
    SUB-W-LEVEL -15 TOO +15
    BASS BOOST LVL 1 OR 2
    SYSTEM Q-(WHICH I SET TOO USER)

    BASS CTR FRQ 60/80/100/200
    BASS LEVEL -8 TO +8
    BASS Q FACTOR 1.00/1.25/1.50/2.00
    BASS EXTEND ON/OFF

    MID CTR FRQ 0.5/1.0/1.5/2.5
    MID LEVEL -8 TOO +8
    MID Q FACTOR 0.75/1.00/1.25

    TRE CTR FRQ 10.0/12.5/15.0/17.5
    TRE LEVEL -8 TO +8

    LPF THROUGH/85/120/160/

    • October 7, 2012 at 6:14 pm

      Hi Lee,
      I really can’t answer to that level of detail without physically listening to it and tuning it myself, but I can give you some guidance so you can learn how to tune it yourself:

      -Read my article on sub/amp tuning. Make sure when the volume is cranked, have your sub level at 15, then do your tuning. You want to make sure even at peak volume and sub level, there is no distortion at the sub.
      -Always leave bass boost off. It’s an easy way to blow speakers and you’ve got an amp and sub, you really don’t want to use that feature, I see a lot of customers damage speakers using bass boost on head units.
      -For bass, mid and treble settings and explanation of how to use/eq those, check out this post on how to use an equalizer. There’s a nice app you can download to help you really utilize those features.
      -Leave LPF on through if you’re using the crossover on your amplifier. If there is an HPF (or High pass filter), turn that on around 80.

  15. Erich
    September 28, 2012 at 4:32 pm

    Hey Annie, I was wondering if you could give me a second opinion on my amp crossover setting. I have a Hertz system with Hi-Energy components, HDP-5 Amp, and Kenwood KDC-X996 installed by JML Audio of St. Louis (running factory subs until a 12″ Hi-Energy sub in a ported box goes in next week).

    The passive crossover was left out and we are running the 6.5″ to the “rear” and the tweeters to the “front” on the headunit with everything passed through. On the amp the tweets are set to 3.2kHz which match the owner’s manual, but the mids are bandpassed at 3.2kHz – 60Hz. 60Hz seems a bit low to me and I’m getting some unpleasant (to my ears, anyway) noise in the mid-to-upper midrange frequencies. The EQ was tuned by JML on their analyzer and it matches the “ideal” curve you showed us in a different post.

    Am I just oversensitive to those frequencies? Are the mids making weird noises because they are playing such a wide range of frequencies? Is that just a characteristic of Hertz speakers or maybe my car’s acoustics stink? I had to cut the EQ for 500Hz – 2kHz way down just to keep my ears from hurting. Any thoughts?

    • October 7, 2012 at 7:09 pm

      Hi Erich,
      I have two responses. Mine and my husbands. Here was my take: Everyone’s ears are indeed different and I often tell customers don’t pay for something if you can’t hear the difference! Some people have terrible hearing and can’t tell the difference between a $200 amp and a $600 amp with the same power handling. Some people and animals are more sensitive than others to sound and particular frequencies (I have a cat that responds with seizure like behavior if we turn on a light using compact florescent light bulbs which emit extremely high frequencies).

      Have you sat in the car and seen the curve yourself? On paper, it sounds like everything is set up right. If you haven’t done so, I would download one of the tuning apps and sit like you normally sit in the car and run the pink noise test yourself. While you’re at it, run a speaker phase test. Something as simple as the mids being out of phase with the tweeters can throw everything off and even us pros can make a mistake and miss those basic things once in a while. And when you rely on an RTA to tune, you sometimes overlook common things like phase that can make it sound not quite right.

      Here’s my husband John’s take (he’s been installing for 30 years): lower the output at the amp for the mid’s slightly and re-listen continuing to do so until it doesn’t sound as harsh. He said he had to do the same thing yesterday in a Porsche where he installed a Bit One, a 4 channel JL HD600/4 and some Morel components. He was using the Bit One for the crossover settings, but had to lower the mid range gain level at the amp because it was sounding harsh despite setting everything up with the RTA.

      His take actually reminds me of something else. The time correction. If not perfect, it can do exactly what you described. In the same car he did yesterday, when I 1st sat and listened, it sounded really harsh in the mid range. I’m shorter than he is and shorter than the driver of the car. I lifted my head up to where they would sit and the harshness was gone. Maybe re-do the time alignment as well of simply shift your head around and see if you can find a sweet spot.

  16. Steven
    October 5, 2012 at 1:36 pm

    Hi Annie.
    I have a Memphis amp that is 1600 watts plus a 400 watt amp for my door speakers. And a alpine stero deck. I have my low and high pass filter on 80 on my Stero deck. And my low pass filter on my amp halfway turned up. I also have twitters to .. Just wondering what you can do to see if I’m on the right track or not!
    Thank you!

    • October 7, 2012 at 7:38 pm

      Hi Steven,
      Sort of. Turn off the low pass crossover either on your head unit or your amp, you just don’t want double crossover. Some sub amps don’t have the option to turn off the crossover, only allow you to select the frequency. If that’s the case, set it around 80 hertz at the amp and turn the lo pass filter off on the head unit. Either way, leave the high pass filter where you’ve got it. Check out the post on equalizers for more tuning tips.

  17. Erich
    October 8, 2012 at 9:57 am

    Thanks Annie! I’m throwing in a bit Ten D as well as the Hertz Hi-Energy sub (to replace the factory Rockfords in my car which, I kid you not, Rockford says on it’s website are “legendary long-throw subs”…LOL!). Hopefully that will smooth out those mid-hi frequencies, as the X996 is a fantastic head unit but a 13 band eq can only do so much. If not I will try those suggestions you mentioned.

    Also a quick FYI, I watched your excellent review of the X996 and you made a good point about the display washing out in the sunlight. Not sure if you played with the deck much since then, but you can reverse the display to be white (or whatever other color) lettering on a black background instead of black on color. It helps the ability to read the display immeasurably.

  18. TJ
    February 15, 2013 at 6:33 pm

    Hello annie,

    i’ve been reading all your postings and they are very informative. Just a quick question. I notice you say dont use both crossovers on deck and amp. However, i notice when i use the crossover on head unit, it makes the mids and high crystal clear even at loud vol (45 out of 62 ) and im almost postive the crossover on the amp is active. However, when i turn the hpf off as u recommended there is a noticeable difference in mids n highs. At vol 23 the mids start to rattle and distort the clarity. I had multiple ppl listen and they all agreed it sounded better x-over at 100hz on the hpf with the sub x – over at 80hz.. Just so you know i used to have both x – over at 80 until i was told it was cleaner and louder at 100hz on the hpf. Please explain your opinion of this.

    • June 30, 2014 at 3:36 pm

      Hi TJ, that is weird, it could just be the acoustics of the vehicle amplifying that 80 – 100 hertz range where it just sounds better with it cut out completely. The other alternative answer is the crossover on the head unit is superior to the one on on your amplifier which I have found to be the case many times with Kenwood Excelon decks. I would probably make sure the crossover on the amp is off and in full range mode (for your mids and hi’s) and just use the one on the head unit, trying both at 80 and 100. When it doubt, goes with what sounds better.

      Also, you may just need some sound deadening in the door to eliminate rattles and distortion. It also depends on what size the speakers are. If they’re smaller speakers, I’m sure they’ll sound better at 100 hz. Maybe leave it at 100 and try raising crossover on sub to 100 so you’re not missing any frequencies, see how that sounds.

  19. Alberto
    December 10, 2014 at 5:29 pm

    Hey Annie, I have a 02 suburban and have changed out the stereo. My alternator went up and the setting the installer used are gone. I have a Sony Bluetooth head unit with HPF and LPF settings. The interior speakers are being powered by e head unit and the sub is powered by an amp. I would like to know what you recommend for the setting to get the best sound. I listen to a wide range of music but like my lows. What would you recommend?

    Thanks for your time.

    Alberto

    • December 13, 2014 at 1:34 pm

      Hi Alberto,
      Chances are the installer set the LPF on the amplifier itself for the subwoofer, but the only way to be sure is to actually look at the amp and see if it’s set. If the crossover on the sub amp is already set (we usually set it around 80hz) then leave it at that. If it’s not set, you can set it on the head unit, you just don’t want to have them BOTH on. For HPF also set that around 80 hertz. This way the interior speakers are playing 80 hertz and up and the sub is playing 80 hertz and down. Hope that helps!

  20. john
    December 25, 2014 at 3:13 pm

    I stumbled across this site today if you guys really listen to what she is saying its simple,those small 4×6 or 4′ speakers in your front aren’t designed to produce low freq’s, I actually run my hi pass a little higher than what she talks about which is 120 and I have run it at 140, but the low pass is always on 80 sometimes I will go from 3-4 on my sub’s my system is very straight forward Sony head, 4 alpines in the front, and two 10′ alpines in a ported enclosure.with the hi pass at 120 it warms the front up just a little but its clear as a bell and loud as hell.I only use a amp( alpine) for my sub’s the head unit does everything up front

  21. john
    December 28, 2014 at 12:08 pm

    Annie my current setup is very simple,head unit is sony gtx270mp,4 alpine speakers in front 2 in the doors and two in the dash firing off the windshield, in back a alpine mrv500 running two alpine bass line subs in a built to specks ported enclosure(has a chrome tag on it says BBOX by usatrends). seems like i am doing something a little different than what you talk about to some degree. I have a little over a grand in my system but i am very critical about how it sounds,my settings are
    amp settings LP-80
    BASS EQ-+6
    gain is about half
    head settingsLP-80
    SUBS-+3
    HP-120
    LOW EQ -3
    MID -+3
    HIGH +10
    I know i might be loosing just a little mids but it sounds great no distortion at all even at hi deck levels(40-45),and the subs kick like a mule, even at low volume they are still right where they need to be compared to the fronts.on some music i will go from 3 to 4 on the deck for the subs.all this is in a show S-10 extended cab.what would you suggest if i wanted to take my syster to the next level,maybe a amp for the fronts?thanks for your time

    • December 30, 2014 at 5:32 pm

      Hi John,
      Technically there may be a slight gap between 80 – 120 hertz the way you have your crossover set, but I have a feeling have the BASS EQ at +6 and MID at +3 is correcting for that since those tend to boost those frequencies you’re cutting out. You may want to try it with the crossover at 80 on HP and then turn the BASS EQ down to +2 or +3 and the MID at 0 or +1.

      Amping the interior speakers will help, however you would also really need to upgrade the deck too. Sony makes great head units, but the one you’ve got only has one RCA preout and you’re currently using that for your sub amp. The RCA’s are also only rated at 2 volt.

      If you stepped up to something like this Sony, you’ll get the 3 RCA preouts you’ll need if you decide to go for the 4 channel amp AND you’ll bump up that voltage on the RCA to 5 volts. That means without changing anything else, just changing the head unit alone, you’re subs are going to hit even harder. The higher the voltage on the preouts, the more sensitive the head unit will be to the amplifier, the more output you’ll get without having to crank the gains on the amp.

  22. Dee
    September 19, 2015 at 3:15 pm

    Hi Annie. I just installed a Sony Mex-xb100bt with built in amp along with 4 6.5″ 3 way interiors. I have not added the sub yet so I’m looking for help with the lpf/Hoffman settings on this setup. I currently have hpf/lpf set to 80hz and slope 1 for both. Sometimes I want the sterep louder but the bass is heavy and I don’t wanna blow my interior speakers before I even get the sub installed.

    • October 9, 2015 at 8:09 pm

      Just saw your other comment – check your EQ settings. I would probably turn things like bass boost off (I think labeled megabass) and leave the EQ at flat or base. If you’re still getting distortion then you could set crossover to where you mentioned. If you’re still getting distortion you just like it loud and may need a separate amplifier that’s closer to 75 x 4 RMS or even 100 x 4 RMS if your speakers can handle it.

  23. Dee
    September 20, 2015 at 4:03 am

    Hi Annie. What do you recommend for hpf/lpf/slope settings for the Sony mexxb100bt with four 6.5″ interior speakers? I have not installed a rear sub yet.

    • October 9, 2015 at 8:07 pm

      Hi Dee – leave the crossover off until you add the sub :)

  24. Matthew M
    September 21, 2015 at 3:16 pm

    Hi Annie,

    I recently bought a used truck which came with an aftermarket sound system. This kept the truck’s factory stereo, but added a HiFonics HFEQ 4-Band Equalizer / 2-wayCrossover, followed by a NVX JAD900.5 amplifier.

    From your articles on these HPF/LPF filters and Properly Setting an Equalizer, I take it that the best recommended way of handling crossover frequencies would be to leave my HFEQ crossover settings at OFF (i.e. FULL), and then make all of the relevant HPF/LPF frequency adjustments at the amplifier level instead?

    Thanks!
    Matthew

    • October 9, 2015 at 7:57 pm

      Hi Matthew – yes I would do that assuming you have a traditional 5 channel set up. Like front components, rear coaxes and a sub where each channel really has it’s own dedicated channel on the amp. You might just want to use the EQ as an EQ and leave that crossover off. See how it sounds, you can always switch it back, but sounds like this method will give you more control over each channel than the EQ.

  25. Chewy
    March 22, 2016 at 3:11 am

    Hi Annie,

    I got a stereo installed in a car many moons ago, sold the car with the stereo but then had the guy pull what he could of the system out before he sold it – which was a Alpine V12 Amp (mvrf340) and a pair of SPR694A Alpine 6 x 9 speakers. Anyways, I am wanting to at least fire up the speakers again for an enclosed trailer, but an audio guy in town has told me I am missing a crossover box when I asked what the 2 x sets of terminals were on the speakers. As they are oldish, I found a reference on the web saying the box was a 12db high pass 2 way crossover. Do I need this, does my amp facilitate this, or can I buy a crossover to get me out of trouble again, or do I ditch the lot and buy new?

    Regards

    • April 6, 2016 at 8:15 pm

      You know normally I’d say you wouldn’t need crossovers for 6×9’s but apparently that Alpine model did come with external crossovers for the tweeters – here is a link I found on Crutchfield for the original manual. It’s specifically to protect the tweeter, so yeah, you do still need some type of crossover filter for the tweeters. You could pick up a generic set of bass blockers for tweeters like these Pac Audio BB-6PR. I hope that helps!

  26. Bruno
    May 2, 2016 at 8:45 pm

    Hi Annie

    I’m new to this and very confused, I got my system installed by professionals. It sounds awful. This is my set up
    Front rear speakers alpine ddl 6.5 r170c
    Alpine cde 153 ebt head unit
    Kx 400.4 kicker amp 4 channel
    Kicker pack amp 125w 12″ sub 375w

    Hpf and lpf what should I have it at? I read on your post both should be at 80Hz on both lpf and Hpf on just the amp? (kicker 400.4) just want to know with my speakers and head unit what would be the best setting to do?

    I listen to hardsyles and hardcore music so I need that mid range kick to shine. At the moment it sounds very light. My previous system was no amps n just alpine 6×9 type g n had more mid bass where that kick sounded nice and heavy. I had a sub n mono amp too.

    Much appreciated

    • May 21, 2016 at 12:04 pm

      Hi Bruno,
      Yeah, normally we run the crossover at 80 Hz for lpf and hpf, in some cases you can go lower on the 4 channel amp – just depends on what the speaker can handle and the size of the door panel/enclosure. In many cases the speaker can handle it, but it ends up over extending and slapping the door panel so it varies from car to car. You probably just need it re-tuned. Maybe start with the gains all the way down, try those crossover settings, put the head unit to flat and put the volume at 3/4 of peak volume. Then slowly bring the gains up, if you hear any distortion, back it back down. Start with the 4 channel, then do the sub amp. Hope that helps!

  27. Ashley
    June 16, 2016 at 7:07 pm

    Hi Annie,

    Please can you help with my setup, I would like to enter a local SPL Competition but I’m unsure on the best settings for my system to achieve a high SPL. I would just like some direction on the best settings to use, especially on the head unit.

    My system specs below;
    Head Unit: Sony MEX-BT3150U
    AMP: Jensen Thunderbolt 4120 5000W 4-Channel (Output @ 4 ohms 120Wx4, Bridged @ 4 ohms 480Wx2)
    SUB: Pioneer TS-W310 SVC 300W RMS 4 ohms (Connected to channel 3 & 4 bridged LPF)
    MIDS: Sony XS-GTF1027 30W RMS (Currently connected to front out on the head unit)
    MIDS: Sony XS-FB1330 35W RMS (Currently connected to rear out on the head unit)
    FULL RANGE: Sony XS-FB6930 60W RMS (Connected to channel 1 & 2 respectively on the amp NO FILTER)

    Your help is greatly appreciated.

    • September 24, 2016 at 3:47 pm

      Hi Ashley,
      I would recommend buying a dedicated subwoofer amp to power the Pioneer sub and then use the 4 channel to drive the interior 5.25″ and rear 6×9 speakers. That will definitely give you more output. I hope that helps!

  28. Shishani
    July 25, 2016 at 7:15 am

    Hi Annie
    Thanks for helping us with your experience in this field
    I have sony head unit connected with 4 interior speakers and powered sub Pioneer
    So after sitting the LPF and HPF to 80hz what about the powered sub sitting ?there is gain and freq from 50 to 125 hz ? And after all from the head unit sub level and bass equalizer ?
    Thanks

    • September 22, 2016 at 4:37 pm

      Hi Shishani,
      If you have an amp that doesn’t have an LPF on/off option and your only option is 50 – 125, I would put it up to 125. This way it doesn’t interfere with the the 80 Hz LPF setting on the head unit. Ideally you want to use one or the other, but when you don’t have that option, you should bump one up higher than the other. Normally we would tune with the sub level 1/2 way up on the head unit with a few different tracks of music with varying level of bass. The idea is you want to be able to have some play on the head unit up or down without distortion. Normally you want to leave things like bass boost off. I hope that helps!

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