Effects of modifying an existing passive crossover

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For my winter beater, I built a big 12dB/octave passive crossover network (mounted in my headliner!), to run my subwoofer, midbass drivers, and a component set - all from a 2 channel amp. I used nice components, tried to use good design - fun little project.

The amp, Xover, speakers etc. are just pieces I've had around.

I have a few issues though, and I would like to modify the crossover - but I'm unsure of the results I'll get.

Most fundamentally, I put my subwoofer/midbass crossover point at about 80hz.
I was trying to strike the balance between
1) "not being able to locate my subwoofer" (bass-up-front)
and
2) "able to crank it loud without bottoming the midbasses"

Unfortunately, I can somewhat locate the subwoofer as coming from behind me, and I can bottom out my midbass if I bring them up to a respectable level (I have a 2/3 octave EQ installed in the hatch as well) and really try to crank it hard on rock.

It's probably not that my Xover point is wrong (since I'm getting both symptoms I'm trying to avoid :rolleyes: ), but rather that the Xover simply isn't steep enough.

I'd like to avoid messing with the sub's LP filter for now anyway - it's really not that bad, from a location standpoint.

My midbass drivers really are just 5.25" Parts Express speakers - I have two per door (phase aligned by location, sort of a mini-array). They worked real nice in an old install that I had, but I may not have been playing them as low.

So I think two things could help me:
1)
make my midbass high-pass steeper - probably go right to a 24dB/oct to avoid phase issues (if that is possible with a mix of slopes ;)).
2) pick up some higher-excursion 5.25" midbass drivers (if anyone knows of any that are decent but cheap).

So..If I made my midbass high-pass steeper - could that be as simple as duplicating the existing 12dB/oct HP Xover, and putting that in-line with my original one?

That would be ideal, because I wouldn't have to unmount my big Xover from my car headliner - I could install the secondary Xover behind the door panel, like a standard passive Xover. :cool:

Would I be changing the Xover point, in using this strategy - or would I be just changing the slope?
(obviously I'd be changing the response and phase characteristics around the Xover point, but being so low, I'm hoping that won't be an issue with respect to the benefit I'd get - this isn't a mid-to-tweet Xover, right?)

I don't have any tools for Xover design on this computer, unfortunately. :(
Any help is appreciated!
(even if it's just to point me to a higher throw 5.25" :cool: )
 
Any help?

Passive crossover design a dead art here? :confused:

I'd like to put a filter in-line with the existing filter, if that is possible.

Unmounting this behemoth and fundamentally building a new, steeper filter is probably prohibitively time consuming. :(

(and of course - higher excursion 5.25's would help too, although I doubt to the degree that I wouldn't need to steepen my HP filter)
 
hey geo a couple of 5.25,s id reccomend around the price range are the peerless csx-x car driver model 850517 avail from madisound 2.5-3 mm x-max -4-ohm-good driver for around 35.00, and if you can wait pe- dayton is coming out with a 4-ohm-car lineup in a month or two ,perf should be very similar to their 8 ohm alum cone versions avail now- 5.25 i believe should be in the 25-30.00 range,excellent drivers and the price cant be beat!
 
good piont cal ,he would end up spending as much or more on decent to hi-q passive parts in the end,i would def look at new inexp. drivers save the time and cash on the x-over,an x-over , going from an 12db-24 db slope wont improve the parameters of the speakers improve the area in wich is lacking
 
I'm not optimistic that it's really an 'either/or' sort of thing. ;)

The 5.25's that I have now are cheap, but work well as midbass drivers - at least down to some point. I only used them in this install because I had great luck with them in an old install - but in that install, I was cutting them off at about 100hz (possibly even higher) with the filter built into my amp at the time. And they didn't bottom at all.

In this install, my Xover point is about 75hz, and I'm not so much noticing them bottoming even in the 75-100hz range - I'm noticing them bottoming when I'm getting strong stuff in the 40hz, 50hz, 60hz range.
...hence my inquiry into steepening my Xover slope. ;)

I'm sure upgrading the 5.25's would definitely buy me a little more output before they bottom out, if I can find a driver with enough excursion capability...
Maybe I'm pessimistic, but I can't think of a 5.25 that could have such great throw to completely eliminate the problem.

It WOULD be great, ideally, if that was the case - because then I'd still have that 50hz, 60hz presence up front - that would ideally help keep the bass image up front. :cool:
5.25" high-throw midbass drivers aren't too common. :(

But I also wouldn't mind experimenting at least with steepening the Xover slope - but if I did that, I'd like to build another 12dB/oct module to put in-line with the existing one (I could tuck it into the door for this one), if that's possible.
 
And no, I don't have a lot of caps and coils lying around. :(

The components I used in my main Xover are decent, midgrade components. No exotic components, but no cheap components.

I think I ended up spending around $250-$300 for my parts, in total, to build a 3-way... so I was figuring maybe $75 or so to build this "add-on" Xover - again stressing the 'if that is possible' side.

I think you guys are right ideally, if a 5.25" driver is available, that is the best solution - but remember, I need four of them. :(

I'd spring for it though, if they were good. I have power to spare, if efficiency need be sacrificed. :cool:
 
dodgerblue said:
hey geo a couple of 5.25,s id reccomend around the price range are the peerless csx-x car driver model 850517 avail from madisound 2.5-3 mm x-max -4-ohm-good driver for around 35.00, and if you can wait pe- dayton is coming out with a 4-ohm-car lineup in a month or two ,perf should be very similar to their 8 ohm alum cone versions avail now- 5.25 i believe should be in the 25-30.00 range,excellent drivers and the price cant be beat!
I've had good luck with the Peerless stuff I've owned in the past... but I don't know if that excursion capability really beats the throw of what I have here. That's the kicker.

I could wait for the PE stuff - I'm not really hurting, stereo is working, just not as much impact as I'd like, since I have to EQ down my midbass a touch.

Probably a post-CES release?

Thanks!

...I guess ultimately something like a 6mm 5.25 would give me more comfort than a 3mm one - and that might be asking too much. :(
 
dont know wich diy drivers you are using or if they are mounted in the doors of your veh,but drivers that made specifically for the ib-door locations can perform much better than a driver built for example a sealed environment due to the parameters of the driver,unless you did work to your doors-dynamat etc. for instance,you cant expect any driver to perform well,if your drivers is built for another app. might explain the bottoming out prematurly or be suspesion noise ,most aftermarket 6 in speakers have less than 3 mm linear x-max,so for an good 5.25 built for ib-door locations to have 2.5 - 3mm linear is pretty good ,and may not give have the bottoming out or suspension noises you are exp. just a thought , i dont have any extra passives or parts or i would send them to ya! i do know some of the older mb quart passives for their 5.25 in and or 4 inch model seperates did have an 12 db 100hz hp option on them if you find a set on ebay might help- woops forgot you had 4 of them 4-8 ohm or 4 -4ohm 5.25,s?
 
try moving the speakers forward using kicks....and raise your crossover point for the sub to around 200 hz....

the depth of sound coming from your mids, need to be a bit farther away for a longer wavelength to develop.

raising the crossover point for the sub will help to blend with the mids...

and believe it or not, my car sounds best with 6db slopes, helps to blend things together...a steep slope doesnt help much for sq in my car, it makes it easy to locate the origin of the sub...

if you have an octave eq, tuning the octaves helps heaps...

the only problem i have with 6db slopes is that i crank it...

works for me :)
 
I did do extensive work to the doors - they are dynamatted inside the cavity, dynamatted heavily on (and over, anywhere there were access holes) the outside of the door cavity.

Of course, there is only so much you can do - the drain holes at the bottom of the door must remain, the holes for the pressure clips for the door panels must remain, and the window opening at the top edge of the door cavity must remain.

I don't believe this is an issue - even if the door were perfectly sealed off, there would be so much internal volume as to be pseudo-IB anyway (since we're talking about a pair of 5.25's here) - and the goal was really more along the lines of making that door work as a better baffle.

The speakers are also mounted on an MDF baffle, with new holes cut in the metal structure of the doors, with a closed-cell foam weatherstripping sealing the new baffle to the door metal, and screws pulling them together as tightly as possible. While both the midrange and midbass speakers fire into the door cavity, on the MDF baffle they are separated via the foam tape.

But I'm not getting any "air spring" help from the door cavity, I'm sure - so essentially I'm running them IB... that's what you are asking, really. :cool:
So an IB 5.25" probably would work great - but are any out there with a good excursion AND a low Fs?

As far as these little midbass drivers go - I believe the ones I have likely fall into the 2-4mm range for excursion, as they really are just midrange drivers that work pretty well as midbass drivers - at least when you cut them off more around 100hz.

I've found some subwoofers on the market -5.25" subwoofers - and 6mm Xmax seems to be a good target, I know at least those are out there...
...the problem is, they are things like the new Focal Be 5.25" subwoofer, and those retail at something outragious like $800. :rolleyes: (Focal also has a K2Power that is somewhat less expensive, but still too much for a 5.25" IMO)

Maybe more promising, I visited Aura's booth at CES this year, and they had a prototype 5.25" subwoofer on display - and a cutaway of it right next to it - that looked impressive. And the rep said he thought the cost would be closer to $125.
Bear in mind I need to buy four of these... :dead:
 
i agree to richie boy. it's better if you play active when u don't have any driver datasheet.

trial and error can be a pain.

for steeper slope i don't think you can easily add some series and parallel of components.
and i think maybe u pick the wrong crossing point or maybe ur mids can go that low due to their aging.

some midbass you can pick are peerless' i forgot the series but they called it limited edition mids. the vocals were good too but not too low...

and i think that u wouldn't want to put subs as your midbass :) because where did you want to put mid range (above 100 hz- 2/3 k) sound (frequency)?

for soongsc : it's still possible if the freq. cutting were "click" with the midbass freq. and the driver character's sure taking a roll here :) if you use some paper cones driver then u would get some nice bass in front, but if you use some alumunium or titanium driver i don't think so...

but it's just a newbie opinion :)
correct me if im wrong :)
 
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