# Crossover points: overlap, underlap, gaps?



## FoxPro5 (Feb 14, 2006)

In tuning my system I've found that my mids sound best LP at 3.15 @ 24db/oct and my tweets sound best HP at 1.6 @ 12db/oct. This would be a pretty good overlap in the range where a lot of the music is right? Could someone point me to an article, post or techinical explanation as to the benefits or drawbacks of this.

In my search, I've come across a few posts that have mentioned that a complete gap or an underlap is preferrable. Of course this depends on many things - especially what sounds good to my ears - but, again, I would like to know the in's and out's of proper selection of crossover points. 

I'm not all that well versed in the techincal aspects yet, but I think I have a good feel for the hands-on part. Just want to increase my understanding as to why I am hearing what I am hearing! Hear me?? 

Thanks all


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## chad (Jun 30, 2005)

I usually underlap as a form of EQ for interior discrepencies. 

What HF devices are you running? 1.6K at 12DB/Oct is pretty low!

But it IS DIY and whatever floats your boat and does not damage your drivers is just fine IMHO.

Chad


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## AzGrower (May 30, 2005)

From I have always known, when the mid-tweet physical distance is higher, you want to bring the gap closer. Vice Versa, if you have the mid and tweet closer to each other physically, you can have the gap larger. Was I taught wrong all these years??


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## 3.5max6spd (Jun 29, 2005)

There really is no right or wrong. How severe an underlap or overlap is in direct relationship in the position of drivers, how far they are apart, how they are angled and how the vehicles interior boosts or interferes key frequency areas.

For instance in my car , having tweeters closer to ear level ...using that low of a freq doesnt work well. Matter a fact i prefer using a gap between my midrange and tweeter with a semi steep slope because it takes some of the edge off that area (2khz/3.5khz)


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## FoxPro5 (Feb 14, 2006)

chad said:


> I usually underlap as a form of EQ for interior discrepencies.
> 
> What HF devices are you running? 1.6K at 12DB/Oct is pretty low!
> 
> ...


Seas Ref fabric domes mounted in the A pillars. I thought it seemed low, but they seem to play well. Right now I have them both crossed at 2.5k @ 18db/oct just as a reference point. Mids are Seas Performance, fyi.

There is a lot of work yet to be done in the tuning dept..just trying to gather techical info to help the process.


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## foley316 (Aug 26, 2005)

If it sounds good to you and makes you happy, then do it. If you blow your stuff, sucks to be you. Know the limits of your equipment and don't exceed them. Then tune it how you like it.


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## mvw2 (Oct 2, 2005)

I was playing with this a good bit. I'm not sure what the difference would be between the speakers being in close proximity versus far appart as I've only toyed with crossover adjustments with my woofers and tweeters apart(woofers in door, tweeters on sailpane). I initially did run them in close proximity using the stock passive crossover. Just this morning I went back to the passive crossover with them still seperate, to judge stock settings versus manaul settings versus addequate versus inadequate available power...to see which I'd prefer, lol. 

When toying with crossover settings, I've come to a few conclusions.

First off, you can't really push beyond the physical limitations of the speakers: 

For example, my tweeters Fs is 1700Hz, so I shouldn't really press below double that. However, one of my main goals, per suggestion, was to run the crossover point lower and use the tweeters as the more influencial presence. Playing with crossover settings 3kHz always sounded best. I tried running them low, 2.5, 2kHz to take some of the higher range off my woofers and to raise the soundstage. I think this is wholely doable with a larger tweeter that can run down to 2kHz or lower. However, my tweeter was straining to perform this range well. 2.5kHz was the limit.

My woofer was the reasoning behind my low crossover desire. The woofer I'm using can be quite lively in the higher mid range but seem to be happy running up to say 4kHz without much problem which offered crossover ranges toying upward in the 4 to 6kHz range. As of now, my woofers are in the stock locations, pointed relatively straight across and in still undeadened doors. High mids aren't nice in this environment. Running the mids down at 2kHz or lower keep them relativley mild and laid back and minimized the flaws of the current limited install. Running a high crossoever pulls the focus to the woofers while running a low crossover point brings the focus up to the tweeters.

This kind of brings me to my second finding, the greater the frequency range played, the greater the focus to that driver. This can be useful if you want to focus on a particularly good driver, ex. great tweets but mediocre mids where a low xover can give a lot of presence to the tweets. This can be done the opposite way as well, running a large range to the mids, you can hide a limited tweeter. The limitation falls on the workable range of each driver.

My third findind is crossover gap/overlap. This can be used sort of as an adjustable EQ. If you find your speakers have a strong or weak area in a crossoverable range, you could boost that range by overlaping the crossover points a little or you could tone down a certain strong point by creating a slight gap in the crossover point. 

Now this overlap/void has it's own benifits and pitfalls. A slight void between the crossover points creates a definate seperation between the woofer and tweeter. It creates a clean presence. A sharper slope also creates a more clean, well cut presence. If the void is large, you can easily tell there's a void presence and notice that something's missing. The effect is similar to EQing a particular frequency point way down.

Overlap has it's own effects. If you overlap, you start to mix sound from two point sources. It sounds mixed together in that range, not so clean and clear cut. If the tweeter and woofer mix well, you may not have much of a problem. If they don't mix well, you'll notice this effect more. Crispness and definition degrades. The effect is similar when working with very shallow slopes, say -6dB/oct. There's a lot of shared music, even at relatively well spread crossover points. The end result isn't as clean as with a sharper slope.

Speaking of slopes, I always seem to prefer a sharper slope, at least -12dB/oct. or more. My HU only runs to -18 but I would have liked to play with -24dB/oct some. I still find shallow slopes useful, though. A shallow slope could compensate for a woofer and tweeter that can not play close to each other, say a tweeter that can run down to only 3kHz and a woofer hardly capable of 2kHz. A shallow crossover slope can stretch that gap and make them work. You can also mix slopes to create desired effects or to compensate for a sharp cutoff point of the usability of one of the speakers. I used a steep slope on my woofer to keep it tame and diminish it's livelyness which seems to start around 2kHz. I have to cut it sharp at 2kHz or lower or start introducing a very strong high mid presence. My tweeter can't run excessively low, so I may run a -12 or -6 slope down to the woofer so I can reach far enough down yet not pushing the tweeter too low.

This is just me talking about my experiences with toying with crossover settings, however, I hope you begin to realize you've got a lot of options and tunablity introduced with crossover settings.


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## FoxPro5 (Feb 14, 2006)

Thanks for the great info mvw2!! Where are you located in Minnesota?


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## FoxPro5 (Feb 14, 2006)

foley316 said:


> If it sounds good to you and makes you happy, then do it. If you blow your stuff, sucks to be you. Know the limits of your equipment and don't exceed them. Then tune it how you like it.


Currently, I have the tweets HP at 2.5k @ 18db/oct....but when played alone they sound *best* to me at 1.6k @ 24db/oct. So what am I at risk of blowing here??  




npdang said:


> Seas Lotus Reference silk dome. This tweeter can be bought at www.mobilesq.com for a cool $220/pr. The construction of this tweeter is beyond compare, with a solid aluminum chassis, grille, rear chamber, and very stiff, well built terminals. No cheap plastic used here, or easily breakable terminals. * Now this is a tweeter that can be crossed over comfortably at 2khz*, and has a pleasant, laid back sound. Overall dynamics are not quite as good as the Max-Fi, nor is the top end extension and detail up to par with the Lpg 25nfa. *However, this tweeter has the capability to play lower than the others, and sound far more forgiving of bad recordings.* The lower treble region, or upper midrange is also a shade more revealing and natural sounding. A solid choice for people seeking the best in build construction and quality, a low crossover point and better lower end treble, and doesn't care too much about the extreme top end detail/presence.


Also, I can't find the fs on the tweets...anyone know where to obtain this info??


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## FocusInCali (Jul 3, 2005)

RT25F Specifications:

Nominal impedance: 6 ohms
Sensitivity (2,83v.1m): 89.5 dB
*Free air resonance: 830Hz*
Rec. frequency
range: 2000-25000 Hz
Nom. power handling: 90W*
*Using recommended crossover


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## FoxPro5 (Feb 14, 2006)

FocusInCali said:


> RT25F Specifications:
> 
> Nominal impedance: 6 ohms
> Sensitivity (2,83v.1m): 89.5 dB
> ...


Aaaaa [light bulb goes off in head] free air resonance = fs.....tricky  Thanks Focus


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## mvw2 (Oct 2, 2005)

Oronoco, just north of Rochester.


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## FoxPro5 (Feb 14, 2006)

mvw2 said:


> Oronoco, just north of Rochester.


Unincorporated?   Cool man I'm up in the cities. Good to know there are others around. Any good shops down there?


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## mvw2 (Oct 2, 2005)

Well...we have Best Buy, lol. _Had_ Ulitmate Electronics(Audio King), but they build a hugh store, lost money and left...lol.

There was one small audio shop in Roch, actually partially run by a friend of my older brother, I found out...again, closed.

Now, for maybe half a year so far, we've had a new audio shop, can't think of the name off the top of my head. They carry Eclipse, Kicker, and Diamond so far as well as all audio related hardware. The owner was going to carry Alpine, but Best Buy got a deal with Alpine to sell products, so now he says he can't make money on Alpine...so he's unsure about Alpine now... I wouldn't mind seeing a few more brands that aren't easily available locally: Focal, MB Quart, Clarion, JL, etc.

I'm a little weary of how long the store will last. They really need to start bringing in people somehow.



...unincorporated? You lost me on that one.


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## FoxPro5 (Feb 14, 2006)

mvw2 said:


> ...unincorporated? You lost me on that one.


Oh, I just have never heard of your town...so i was poking fun of you  Unincorporated basically means that the popluation is so small that they don't even put you on the maps  

So anyways...It's sad to hear that the local guy can't make with Alpine because of Worst Buy's corporate plague. Maybe that will motivate him to dump the supermarket stuff and roll with just higher end?

There are a few shops around town that are decent, but there are others that are just crap. Seems they went the way of the rims and bling-bling nonsense a few years ago and hired a bunch of kids to try and sell you a set of 22's, an intake and a JL sub!!


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## MHLY01 (Dec 15, 2005)

Surprising no one has talked about phasing between speakers or cabin gain.


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## FoxPro5 (Feb 14, 2006)

MHLY01 said:


> Surprising no one has talked about phasing between speakers or cabin gain.


Care to elaborate?


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## mvw2 (Oct 2, 2005)

Other things you can do to change the way things sound. Besides crossover settings, you can play with wiring speakers in and out of phase(swapping pos/neg) to create effects. This goes along with time alignment setttings if your HU has them.

Then there's the issue of cabin gain, what effect the car physically has on the audio. What is actually produced by the speaker and what you end up hearing are two different things as the cabin of the car will modify the sound: absorb, reflect, block, vibrate itself an create its own sound, etc. You can work with speaker aiming and placement to create the best compromise with the car's interior.

Now, none of this was really mentioned as the initial thread was simply for crossover settings: what, how, why stuff.

Just realize there are other factors involved, although I don't think of them as being related to crossover settings.


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## MHLY01 (Dec 15, 2005)

I do not think you can talk about crossover settings without everything else. I think they are all completely related to crossover settings. Phasing problems will definitely change your crossover settings if not correct. You can get 90' and 180' shifts in cars even if everything is wired in phase. Physical, not mechanical phase. Cabin gain will definitely change your crossover settings if not compensated for. You can properly tune your way around them by setting the crossovers correctly.

In my competition, I have different speakers in phase and out. My crossover settings with an Arc DXE are:

High Pass on tweeters in A Pillar: around 4800 w/12 db slope, it was pretty similar with Rainbow Platinum tweets or Focal TLR tweets
Bandpass Mids in kicks: 140-3600 w/ 12db slope, right mid out of phase, Rainbow Platinums
Subs under rear seat: 75 and down w/ 24 db slope 180 out of phase, JL 10W7

I don't believe much in time alignment so I do not use any and there is none on the DXE.

This is in a GM extra cab pickup. I have very wide gaps as you can tell. I plan on changing speakers soon and changing the speakers is definitely going to change my crossover settings as they have different useable bands. Crossover slopes in relation to roll off are very important to setting the correct points as well. Just what worked for me.


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## seahag (Nov 21, 2005)

Same here ^
My set up is 
mids bandpasses 200 -6db and 800-6db
Tweerer -12 @ 5 or 6 k 

tweeters are wired out of phase with mids. 


I`m running my sub with no crossover at all..
blends in very well.

With all the freq response talk aside I feel you get a better over all result with the speakers with minimal phase shifting.. specially in a car.

My set up sounds a bit thin at low levels but man does it get Loud and stay VERY clean


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## FoxPro5 (Feb 14, 2006)

MHLY01 said:


> High Pass on tweeters: around 4800 w/12 db slope,
> Bandpass Mids: 140-3600 w/ 12db slope,
> Subs: 75 and down w/ 24 db slope


Ok I chopped your post to analyze what you said here because I'm mostly concerned with getting the x-over part right.

Are running two way or three way active up front? What's playing between 75 an 140hz? And are you saying you have a gap between 3.6-4.8khz with a 12db slope between the points?

Just need clarification there, thanks


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## FoxPro5 (Feb 14, 2006)

mvw2 said:


> Other things you can do to change the way things sound. Besides crossover settings, you can play with wiring speakers in and out of phase(swapping pos/neg) to create effects. This goes along with time alignment setttings if your HU has them.
> 
> Then there's the issue of cabin gain, what effect the car physically has on the audio. What is actually produced by the speaker and what you end up hearing are two different things as the cabin of the car will modify the sound: absorb, reflect, block, vibrate itself an create its own sound, etc. You can work with speaker aiming and placement to create the best compromise with the car's interior.
> 
> ...


Yes I do understand the contribution of the other factors, but I'm trying to master each aspect of tuning one at a time. My post was really to find out if anyone had any good recommended reading on the technical aspects of setting crossovers in a car environment....or is it really just mess around with about 50 random combinations until it sounds good to me? Because this is litterally what I have been doing so far.


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## chad (Jun 30, 2005)

B-Squad said:


> Ok I chopped your post to analyze what you said here because I'm mostly concerned with getting the x-over part right.
> 
> Are running two way or three way active up front? What's playing between 75 an 140hz? And are you saying you have a gap between 3.6-4.8khz with a 12db slope between the points?
> 
> Just need clarification there, thanks


That's totally cool.

Think of doing a nice wide parametric dip with an EQ. Spacing the drivers like this will perform the same result.

For example the poster may have had a huge hump in the middle of the two XO freqs. In a car this can easily happen, in a room or larger venue it's less likely. This is one of the MAIN reasons I bought the Next amp. I can under/over lap everything! I just took care of the 2 major problems, the integration of drivers in 2 very different places, and any major EQ bump or fall from that fact It's half physics and half psycho-acoustics but it works well. Some of the finer aspects of system tuning. 

This is also a reason I chose drivers that can OVERLAP greatly, the Morels play to 2K easy, the Seas' up much higher. This gives me flexibility, I could have gone with a mid that would not play as high but it limited me in crossover flexibility. Now that I know what the car does I can chose my drivers more conservatively but as a first install I needed the ability to move a XO pretty much anywhere within reason. I like that stuff 

Chad


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## FoxPro5 (Feb 14, 2006)

chad said:


> For example the poster may have had a huge hump in the middle of the two XO freqs.


What do you man by hump? Like a big spike in the freq response? How would I know if I did...by my ears....an RTA analysis?

Thank you for you imput Chad!


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## chad (Jun 30, 2005)

Yep, vehicles are peaky. If you are lucky, you can nail a peak or two by manipulating the XO Freqs. If you think subtractive EQ, then a gain rise, you can EQ almost anything without an EQ boost, your system will like it much better.  Use the acoustics of the car instead of fighting them. If you have a bump, then HEY! It's free gain! Bring the system up around the vehicle instead of fighting the interior. 


Yes, a trained ear can get it damn near perfect, an untrained ear will eventually learn with practice. Find a friend in a band or go rent a 1/3 octave EQ. Put it in the tape monitor loop of your stereo at home and play with it for a long time.... You will learn quickly. Do so at a low listening volume, learn the frequencies and play with boosting and cutting each to learn the characteristics of each octave/semi-octave.

Also try EQing it to where you like it and hitting bypass. Here you will fine tune your ability to learn your OWN ears and what you perceive is "right." Everyone is different, from what you think to the next cat. From there you can learn to interpret your likings to others as what is deemed "right." This is a big thing in SQ judging. Everybody "hears" different, we all can be trained to “listen” the same. You have to split the middle at that point.

In other words... You drive the vehicle, It's your entertainment. Do what you want, make educated decisions, and I quote, "F*ck 'em if they can't take a joke, I dig it!"

Chad


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## FoxPro5 (Feb 14, 2006)

chad said:


> Do what you want, make educated decisions, and I quote, "F*ck 'em if they can't take a joke, I dig it!"


That's my MO!! Thanks dude


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## demon2091tb (May 30, 2005)

This may have been said already, but generally an octave and a 1/2 or 2 octaves (doubling of frequency) above FS should keep any driver in the safe range as far as staying in there operating range, and keeping the imp fairly flat, or any mechanical problems associated with the FS. But generally as i've been told for home audio use an octave for midranges/midbass, and 2-2.5octaves for tweets, for possible excursion problems. 

For instance the RT25F a good starting point on xover point would be say, FS = 830hz, octave up, 1660hz, 2octaves, 3320hz, so a good 3k-3.5khz or so should be ideal place to start.

So if you plan to xover a midrange at say 2k @ 24db/octave, at 4k, your at -24db, at 8k your 48db down, and so on. (or would that start before then, so at 4k your 48, 8k your 96db down and so on, not sure when the slopeing starts, thats the only thing that baffles me right now, and its late and i can't think straight lol). I like to use the steepest xover slopes that i have available, so that i can get the xover points as close as possible, without the additive cancelation effect (Not sure the real name of it).

As far as xover slopes and such, i'd start at a general point with as steep as possible, and widen from there untill the additive cancelation issues (2drivers playing same small range where its precieved louder in that range compaired to the rest of the sound) are non existant or wide enough that it makes the sound fairly flat, and you have no large peak at the xover frequency.

Alot of it has to do with driver placment, and how far they are apart. In my case i had a 3.15k @ 24db/octave over point Both b/w my CA18 and LPG26's and 1.6-4k was a little too much, ~ 2.5-3.15k was a huge peak (it actually hurt at louder volumes) because of the additive effect, NO EQing i could do would fix the huge peak i got from that problem, so i dropped my mid xover point to 2.5k and dropped my EQ a few notches from 1.6-2.5, and from 3.15-4k down a notch. Tweets were kept at 3.15k @24db as the lowest i was going to run them, and still keep a nice dash image. I was very pleased with the results, and a dashmat also kept stray reflections up on my dash from hurting as well, and overall dampen some of the reflections that i was getting even after the xover problem was fixed.


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## FoxPro5 (Feb 14, 2006)

demon2091tb said:


> This may have been said already, but generally an octave and a 1/2 or 2 octaves (doubling of frequency) above FS should keep any driver in the safe range as far as staying in there operating range, and keeping the imp fairly flat, or any mechanical problems associated with the FS. But generally as i've been told for home audio use an octave for midranges/midbass, and 2-2.5octaves for tweets, for possible excursion problems.
> 
> For instance the RT25F a good starting point on xover point would be say, FS = 830hz, octave up, 1660hz, 2octaves, 3320hz, so a good 3k-3.5khz or so should be ideal place to start.
> 
> ...


That seriously hurt my brain...but I love it!!!


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## MHLY01 (Dec 15, 2005)

I only have a two way front, 6.5 in kick and tweets in A-Pillar. The subs are in the rear playing 75 and down. Nothing is playing between 75 and 140 except cabin gain. I have very good up front bass as well.


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## demon2091tb (May 30, 2005)

B-Squad said:


> That seriously hurt my brain...but I love it!!!


I just hope i didn't go off on a tangent and completely murder it.

Someone correct me if i'm wrong?


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