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View Full Version : no 'bass blockers' with the specs i need?



jgarcia9102
11-05-2005, 06:58 PM
IM looking for high pass filters with the roll of slope that i need. Everything is -6db, but i need something sharper. anyone know where to look?

i need something for 6.5" alpine S Coaxials. They cant handle any low bass, and i will be getting a sub to cover the low end.

i can get 150hz with a -6 slope, but i want them to cut off faster than -6db/octave. I was thinking like a -12 slope? or even like a -18 at 80-100hz.

does that sound way off? i just dont like the sound of -6db/octave, that seems like its too slow, although ive never actually filtered my speakers before, so i could be wayy of with all this.

GSteg
11-05-2005, 07:09 PM
You may certainly do a 6db slope at 150hz (-6db at 75hz, -3db at ~113hz).

The Bass blockers are essentially capacitors wired inline with the speaker:

http://www.the12volt.com/images/hpass6db.gif

Here is a second order (12db/octave) network:
http://www.the12volt.com/images/hpass12db.gif

Lastly, a 3rd octave (18db/octave):
http://www.the12volt.com/images/hpass18db.gif


There are all high-pass networks. All pictures are taken from www.the12volt.com. There is a calculator on there that you can use to help calculate the value for the capacitor/coil you need in order to get your desired crossover point.

http://www.the12volt.com/caraudio/cross.asp#hp

jgarcia9102
11-05-2005, 07:47 PM
i see, the bass blockers can only have a -6db slope since they only attatch to the positive cable. that makes sense.

would the -6db slope sound good from the 150hz?

could i get a beter sound if i were to build my own 2nd or 3rd order at a lower crossover point?

i wouldnt mind doing the extra work if it would make a difference.

would it help any to get test tones and find the exact point that the speaker starts to distort? i think ill start doing that now.

GSteg
11-05-2005, 07:53 PM
Generally, you would use a 2nd order slope at around 80hz for the mids. Thats what most people use for starter.

150hz with a 1st order slope is probably not what you're looking for. I would do a 2nd order at least. 3rd order if you want more protection for your speakers. I can't tell you which crossover point and what slopes are the best because all cars sounds different. Which is why I went with an active setup (1st through 5th order selectable :D)

jgarcia9102
11-05-2005, 08:02 PM
i wish i could have that flexibility, But im not about to go out and by a crossover for 4 coaxials.

eventually ill get a component setup, but thats a different topic all together.

Could i buy a passive 2nd/3rd order setup? or do i have to make one myself? im rele not that lazy, im just afraid of messing something up.

GSteg
11-05-2005, 08:08 PM
I dont know anybody that sells a crossover already made. Go to Partsexpress.com and find the things you need. It's not too expensive for what it does.

jgarcia9102
11-05-2005, 08:28 PM
alright man, thanks for all the help!

GSteg
11-05-2005, 08:45 PM
No problem. Good luck with the setup :)

jgarcia9102
11-05-2005, 08:56 PM
oh, one more thing here, im getting confised because on parts express, the Cap values are in a different unit ( i think uF) than on 12 Volt, which uses microfarads.

and how do i get a value as precise as 331.74837 micro farads? everything on parts express is rounded off...

sorry, ive never had to pick out my own caps before, so its quite a bit confusing....

GSteg
11-05-2005, 09:09 PM
Use the round off number. You're not going to get an exact number. The difference is very minimial, and virtually undetectable with music in the car. Also, you can wire two value capacitors together to get another value.

http://www.partsexpress.com/resources/xover.html

Go down to "Combining Components To Achieve Needed Values"




If you ever need an online conversion calculator that deals with capacitors, look at:
http://www.unitconversion.org/unit_converter/electrostatic-capacitance.html



Microfarad=uF

jgarcia9102
11-05-2005, 09:22 PM
ooooh. i see.

wow. thanks again!