Designing and Building a simple HP crossover

[jaygeorge1979 10+ year member]

A friend of mine asked me to build him 4 high pass crossovers to block the bass from his door speakers in his car. I am not sure what speakers he is using yet, but does anyone have any suggestions? I am thinking something simple, maybe a 2nd order L-R...what freq should I aim for to protect his speakers but not take away too much sound?

I will post later what speakers/amp/HU he is using...just thought i would get a jump on asking.

Thanks

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[squeak9798 5,000+ posts]

No way to answer that question without knowing what speakers he is using. The HP frequency will be different for a 3.5" than it will be for a 6.5", different brands will like/not like different xover points, etc.

It will likely end up being somewhere between 60hz and 150hz....but there's no way to narrow it down any more than that.

 

[bimma85 5,000+ posts]

No way to answer that question without knowing what speakers he is using. The HP frequency will be different for a 3.5" than it will be for a 6.5", different brands will like/not like different xover points, etc.

It will likely end up being somewhere between 60hz and 150hz....but there's no way to narrow it down any more than that.

Sorry to but in, but might help the orig poster as well. Do you have any good links to info on making xovers as well as any progams to design them as well?

 

[MrSector9 10+ year member]

http://www.the12volt.com

There is a pile of crossover info on there as well as calculators to tell you what components you need.

 

[squeak9798 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/word.gif.64b12e39f936af3b4fff38a1c0bd0244.gif

That and BCAE. Those are the two "beginner" style write-ups I can think of off hand.

 

[qtipextra 5,000+ posts]

lol, if I would have looked at this thread first, I would have had to ask in the other thread.

 

[jaygeorge1979 10+ year member]

No way to answer that question without knowing what speakers he is using. The HP frequency will be different for a 3.5" than it will be for a 6.5", different brands will like/not like different xover points, etc.

It will likely end up being somewhere between 60hz and 150hz....but there's no way to narrow it down any more than that.

im aware that its impossible to decide an exact freq without knowing the drivers being used...i just needed a ballpark so i can use my calculators to figure out what size components to use so i can figure out about how much its gonna cost....tomorow, when i find out which speakers he has, i will research em, and post back so that i can make an adequate decision for the freq...thx for all replies

 

[jaygeorge1979 10+ year member]

//content.invisioncic.com/y282845/emoticons/word.gif.64b12e39f936af3b4fff38a1c0bd0244.gif
That and BCAE. Those are the two "beginner" style write-ups I can think of off hand.

what is BCAE?

PS the calculators i use are from the loudspeaker design cookbook volume 7 companion CD....but i was also gonna use the 12volt.com calcluators to cross-check my numbers

 

[bimma85 5,000+ posts]

ths squeak and reactor

and jay....

http://www.bcae1.com/

 

[PowerNaudio 10+ year member]

here is a simple one as well

http://www.pac-audio.com/crossover/crossovermain.htm

 

[jaygeorge1979 10+ year member]

thanks to all replies....check bak tomorow for more info on the project //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[jaygeorge1979 10+ year member]

i ran the numbers on the pac-audio.com calculator for a high pass 2nd order 100 Hz @ 4 ohm crossover....it gave 280 uF cap and a 9 mH coil....i checked partsexpress, the only type of cap that is close to that is the 100V Non-Polarized Crossover Capacitors

http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=027-370

will this one work?

....the only other cap with a value that comes close is the(Solen Metalized Polypropelene)...like 40 bucks each!

for the coil, i found this 9 mH one on PE also

http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=255-292&DID=7

way too expensive tho! he just needs to protect the speakers from low end signal...am i going about this the right way?

i know that we dont know which freq exactly we are using yet...i am just trying to do price checks to see how much its gona cost per crossover and thus far i am dissatisfied with my findings...so i gotta maybe just do first order crossovers...we will find out tomorwo when i know what speakers he using

 

[thch 10+ year member]

you might concider using a lower slope. typically you need large components for low frequency and low impedances.

if L-R is "linkwitz riley", and your talking about 2nd order, then there is probably no point. The LR crossover was designed to be phase coherent and sum acoustically flat when used with both high and lowpass filters. just using a highpass means you end up with a butterworth filter (at a different frequency). this is probably fine.

you may want an iron core inductor for that large of a value. the capacitor is realistic, but large.

 

[jaygeorge1979 10+ year member]

you might concider using a lower slope. typically you need large components for low frequency and low impedances.
if L-R is "linkwitz riley", and your talking about 2nd order, then there is probably no point. The LR crossover was designed to be phase coherent and sum acoustically flat when used with both high and lowpass filters. just using a highpass means you end up with a butterworth filter (at a different frequency). this is probably fine.

you may want an iron core inductor for that large of a value. the capacitor is realistic, but large.

thanks for your post...you seem very knowledgable...for the record, i am going to school for electrical engineering right now...what do you do?

as for the filter, i may just end up using first order, cuz that inductor is gonna be too expensive...the guy i am building it for said he tried bass blockers, but they dont work??? im gonna suggest crutchfields bass blockers before building em

 

[PowerNaudio 10+ year member]

one other thing you can do is try more comon values that are pretty close to the values you got calculated. like 220uF is a more comon value usualy less than a dollar. so using that value see what the inductor size would be for what ever freq cut off youre looking for.

great place for electronincs parts is http://www.mouser.com