# Sub crossover frequency



## snaimpally (Mar 5, 2008)

Finally got my sub amp (Cadence A7Hc) and sub (Arc Audio 10" in a .7 cu ft enclosure). It is very satisfying to have low end bass with my PG RSD65cs comps. In fact, the PG RSD tweets used to sound somewhat harsh on occassion but now they blend right in because there is bass to round out the frequency range.

I played around with the amount of boost and the boost frequency using the amp controls and it sounds decent, fairly transparent as the bass seems to originate from the mids. Not sure if the trim pots are linear or logarithmic but I have the crossover frequency fairly low, probably 70-80 Hz.

I want to get my 3sixty.2 involved. I still have a passive setup so what I want to do for now is to highpass the mids+tweets and lowpass the sub. Any suggestions on what frequency I should start with? Would there be any reason to use a crossover frequency of greater than 100 Hz?


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## 60ndown (Feb 8, 2007)

sub 80hz and down

speakers 100hz and up

yes there is a gap, and the gap is good.(x over points dont stop dead, there is under and overlap)

also reverse the wires on your sub (phase) after a few hours and see if you like the bass better.

(unless you can switch the 'phase' at the hu?)


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## ehiunno (Feb 26, 2008)

I have my RSD55cs active and I can say that you can cross the front lower than 100 especially with the 6.5. they should be able to handle an 80 hz 4th order, with the sub playing 70 or 65 and down (try it and see what you like). 100 and 80 might work, higher than that and you will probably get localization issues. Call me crazy, but I had localization issues at 100 and 80, so I am doing 80 and 70 which solved that problem.

Do some listening with the mids and tweets. I absolutely despise the RSD tweets. I can't for the life of me get them to sound right regardless of crossover point. There was a great thread around about running RSD's active which a quick search should turn up. It gives a great crossover starting point, but thats if you want to go active. Staying passive you can just ignore this .


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## soundq1 (May 18, 2008)

Subs round 63 and down not higher than 80.
The lower you crossover, more bass up front.
Good luck!

Larry Chijner


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## 89grand (Nov 23, 2006)

Actually, proper sub to midbass blending has much more to do with "up front bass" then crossover points. Real low sub crossover points can make sub localization even worse if the front speakers are not up to the task of playing the lower frequencies. 

80hz is a pretty good starting point and unless you have at least an 8" up front, I really wouldn't try going much lower than that. Let the sub play the frequencies is was designed for and let the mids do their thing. A 6.5" really isn't going to get down below 80hz with very much authority.


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## envisionelec (Dec 14, 2005)

soundq1 said:


> Subs round 63 and down not higher than 80.
> The lower you crossover, more bass up front.
> Good luck!
> 
> Larry Chijner


Not true. The more you pay attention to flattening cabin gain boost and ensuring transient perfect response (T/A) between subwoofer and transitionals (door, kick midbass), the more bass "up front". Crossover point is the _last_ thing you set after the above is optimized.


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## snaimpally (Mar 5, 2008)

Thanks for the suggestions! The sub sounded horrible after the install. I could hear it distinct from the mids, it seemed like it had a time delay. After playing with the crossover freq and level, it sounded better but still seemed slightly "boomy" in the 100-200 hz range. I reduced the crossover freq a little more and now it seems fairly natural. 

The PG RSD65cs mids can actually play pretty low but I'd rather the sub do the heavy lifting now that I have it. The suggestion that there be a notch in the crossover seems very interesting, but doesn't that run counter to the notion that the crossover point should be selected for a seamless transition between components to produce a smooth frequency response? I have read many reviews of home audio speakers and the reviewers generally frown upon notches in the curve. But hey, I'm learning about tuning so I am going to give it a shot and see what it sounds like.

Also, I do want to go active. Hopefully next week.

The PG tweets can be a bit harsh sounding. With the sub they seem less harsh. I have heard that going active helps. I have some Oz audio comps and I'm thinking of swapping out the PG tweets for the Oz tweets. Any comments on the PG tweets vs the OZ audio tweets? Any suggestions for a set of smooth tweets?


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## ehiunno (Feb 26, 2008)

The exact reason you leave a gap is to allow for seamless integration.

The crossover you use, say a 4th order LR, will cause a 24 db/octave drop in response at the crossover point. It is not a "brick-wall" style filter. Lets look at the sub, say you have it crossed at 70Hz LP, then 1 octave is 70 to 70*2=140 Hz. That means that your sub will be playing at -24dB at 140 Hz. At that point, its pretty inaudible. But at 80 Hz you are only 1/7th of an octave away from your crossover frequency. At this point you only have 24/7=3.42 dB drop, so you want to leave a gap, otherwise the frequencies sum and you seem like you have MORE output at the crossover frequency. Thats why you have to play around with the XO points to get a flat response.

There are some great threads about how stuff like this. The Basic Guide to crossovers Pt I can be a lot of help here  check this out:

http://www.diymobileaudio.com/forum/showthread.php?t=7160

About the harshness: yeah, I like my highs laid back generally, so I have done a lot of eqing and am using a high XO point for them and that helped a LOT. Still, I am going to be replacing that set soon with something else. They were great for making the transition from casual car audio to really into SQ though, since they offer good quality at a low price point!


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## snaimpally (Mar 5, 2008)

Ahh, I see, so if I didn't notch the frequencies I'd end up with a bump due to the overlap in energy because the crossovers have a slope not a 90 degree drop. That totally makes sense to me now.

Thanks for the link. That thread has excellent information about crossovers.



ehiunno said:


> The exact reason you leave a gap is to allow for seamless integration.
> 
> The crossover you use, say a 4th order LR, will cause a 24 db/octave drop in response at the crossover point. It is not a "brick-wall" style filter. Lets look at the sub, say you have it crossed at 70Hz LP, then 1 octave is 70 to 70*2=140 Hz. That means that your sub will be playing at -24dB at 140 Hz. At that point, its pretty inaudible. But at 80 Hz you are only 1/7th of an octave away from your crossover frequency. At this point you only have 24/7=3.42 dB drop, so you want to leave a gap, otherwise the frequencies sum and you seem like you have MORE output at the crossover frequency. Thats why you have to play around with the XO points to get a flat response.
> 
> ...


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## bhagwan (May 18, 2008)

*what order ?*



soundq1 said:


> Subs round 63 and down not higher than 80.
> The lower you crossover, more bass up front.
> Good luck!
> 
> Larry Chijner


63 is low; but what order ?
Do you XO @ 2nd order ?
I prefer to use 80 cycles @ 2nd or 3rd order.
Works most of the time.


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## 60ndown (Feb 8, 2007)

snaimpally said:


> Thanks for the suggestions! The sub sounded horrible after the install. I could hear it distinct from the mids, it seemed like it had a time delay. After playing with the crossover freq and level, it sounded better but still seemed slightly "boomy" in the 100-200 hz range. I reduced the crossover freq a little more and now it seems fairly natural.
> 
> The PG RSD65cs mids can actually play pretty low but I'd rather the sub do the heavy lifting now that I have it. The suggestion that there be a notch in the crossover seems very interesting, but doesn't that run counter to the notion that the crossover point should be selected for a seamless transition between components to produce a smooth frequency response? I have read many reviews of home audio speakers and the reviewers generally frown upon notches in the curve. But hey, I'm learning about tuning so I am going to give it a shot and see what it sounds like.
> 
> ...


do you have any time alignment for your sub?

if not, try reversing the wires on the sub, it may make the 'delay' disappear


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## snaimpally (Mar 5, 2008)

When I did my initial tuning, I got it to blend in. Now that I have the mids rolled off at 100 hz, I am again having problems. If I turn up the sub, I can hear it coming distinctly from the rear, if I turn it down, then I have very little low end.

Let me try reversing the phase. I'll also play with the 3sixty.2 some more and set a lower crossover. I was reading one of the tutorials which suggested starting off with no sub and crossing the mids at a frequency that they can play distortion free.



60ndown said:


> do you have any time alignment for your sub?
> 
> if not, try reversing the wires on the sub, it may make the 'delay' disappear


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## 60ndown (Feb 8, 2007)

snaimpally said:


> When I did my initial tuning, I got it to blend in. Now that I have the mids rolled off at 100 hz, I am again having problems. If I turn up the sub, I can hear it coming distinctly from the rear, if I turn it down, then I have very little low end.
> 
> Let me try reversing the phase. I'll also play with the 3sixty.2 some more and set a lower crossover. I was reading one of the tutorials which suggested starting off with no sub and crossing the mids at a frequency that they can play distortion free.


ive been playing with my 3 way active front and sub for over a year, everything i do sounds a little different better/ worse, its hard to tell, im sure i could play for another 2 years and never get it 'right' n every disk i play?

i like to leave things alone for a few days, then change 1 small thing and see if i prefer it or not, then try again in a few days.that way it easy for me to tell if its better or worse.

i know someone with 'training' could set things up for me very quickly (that was done at marvs bbq last year) but ive since changed drivers and tweaked all the settings  

id recc going to a nice quiet place to park, with some food and drink and sit for an hour or 2 with a VERY WELL RECORDED DISK as experiment.

reflections, group delay, cone break up, modal ??, phase, image, stage etc etc etc the list goes on, bottom line is,

if you want to compete, set it up the way they want it,

if you want to enjoy your sounds in your ride, set it up the way you want it.


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## BlackSapphire (Apr 16, 2008)

60ndown said:


> bottom line is,
> 
> if you want to compete, set it up the way they want it,
> 
> if you want to enjoy your sounds in your ride, set it up the way you want it.


Some of the best advice you can give right there.


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## theothermike (Dec 20, 2006)

id oem 6.5's (hessdawg) have them crossed at 74hz 18db with 120 watts. im running 3 way active keep in mind. sub was at 65hz @ 24 db. blends beautifully.

however im subless and im sure ill change it all again.

polarity = norm across the spectrum.


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## ZoNtO (Sep 20, 2005)

I have mine set to about 80-85 hz @ 12 slope for front (on amp, that's why the range given)

Sub is at about 65hz 12db slope.

When I measured imprint the response was very linear between the two on it's measurements which makes me happy. If I leave the sub gain level down to a reasonable level, sometimes you can't even tell it's on (until you turn it off that is). I'm very happy with those points, slopes, and the underlap is great!


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## br85 (May 2, 2008)

Sub localization (even at higher XO points) can be minimized with proper treatment of the floor of your car. If you don't mind spending the money, the easiest (but certainly not the cheapest or "best" option) is to dynamat your floor, followed by a layer of dynapad or some other form of heavy sandwich material.


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## owdi (Apr 4, 2008)

60ndown said:


> sub 80hz and down
> 
> speakers 100hz and up
> 
> yes there is a gap, and the gap is good.(x over points dont stop dead, there is under and overlap)


That's a pretty broad generalization, especially when you don't know the details of the install, or the type of crossover involved. I could see it helping with a 3rd order butterworth, when the sub is further away than the mids, but the same arrangement would leave a big hole in response with a 4th order linkwitz-riley.

Dan


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## mattldm (Apr 27, 2006)

So what is the preferred subwoofer crossover slope???

I am looking at two different sub amps, one with a 12db slope and the other with a 24db slope on the LPF....

So is there a "better" or preferred slope for subs? 

Will either be easier or harder to tune?


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## ehiunno (Feb 26, 2008)

^ I think the preferred slope is generally 24, but don't quote me on that. It depends on your front stage and where you are crossing at. For example, if you are using a strong midbass that can play 60 Hz with authority you might use a lesser crossover slope on the sub because you can cross it lower, but if you have no major midbass and you are crossing at 80 Hz then 24 might be better so you don't start playing localizable freqs.


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## Grindcore (Dec 12, 2012)

89grand said:


> Actually, proper sub to midbass blending has much more to do with "up front bass" then crossover points. Real low sub crossover points can make sub localization even worse if the front speakers are not up to the task of playing the lower frequencies.
> 
> 80hz is a pretty good starting point and unless you have at least an 8" up front, I really wouldn't try going much lower than that. Let the sub play the frequencies is was designed for and let the mids do their thing. A 6.5" really isn't going to get down below 80hz with very much authority.


Proper sound deadening in the doors etc will get your 6,5s pretty low,of course depending on the quality of the driver...I'm using Boston pro60se and crossing them down at 63hz with no dramas


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## ZAKOH (Nov 26, 2010)

This was a zombie thread


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## Spyke (Apr 20, 2012)

Lol. Yeah, that guy has already blew those 6.5's and wrecked his car long ago. Wife left him, he's paying child support, addicted to crack, living in a box....really sad stuff. You get the idea.


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## BuickGN (May 29, 2009)

I believe anyone who thinks a 6.5" will get down below 80hz has never heard a large midbass setup. 

I love having the flexibility of the 9s in the doors but I guess the joke is on me, even though my midbass can handle 40hz effortlessly and my subs will handle 400hz effortlessly I'm back to a more typical 80hz for the midbass, 65hz for the subs. I do run a more shallow filter so that counts for something and practically no excursion which is always good. With the current processor, up front bass is easy. I've actually played the subs full range when doing time alignment and since they will play past 2khz it's really easy to get them dialed in. I've had crazy thoughts of playing the subs up high, really high but eq'd way down past 63hz for a poor man's ambient fill but I doubt that could ever work. I believe the dustcap has a resonance between 400-500hz and the cone or surround around 1.5khz if I remember right.


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## Pitmaster (Feb 16, 2010)

:snacks:


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