vorgath

Circuit city carry 99Hz and 199Hz passive crossovers. I got 4 inch Infinity Reference speakers in the dash, which ones should I get ?

Speakers are jumping up and down real good during certain songs .. Children of Bodom .. Metallica .. etc

Jim85IROC

iTrader: (2)

Forget about those. They're overpriced. Just find a radio shack or better yet, some sort of local electronics supply store that carries capacitors.

All a "bass blocker" is is a non-polarized capacitor. Just find a non polarized capacitor that's rated for 100 volts or higher.

A 265uF cap will give you approximately a 150hz high pass, which I think is ideal for a 4" speaker. A 200uF cap will give you a 200hz high pass, and a 500uF capacitor will give you a 100hz high pass. For what they cost, I'd buy all 3 and try them all. You'll be looking at about a dollar each.

vorgath

OK, thanks. Another question though, I soldered the connectors to the speaker wires, so I could disconnect the speakers when needed. Different color coding though, speaker one black and red, factory hmm blue and grey I believe, how do the correspond with each other ?



Hmm just checked Radioshack, no exact capacitors like those you mentioned. What's the formula you use to determine which one's needed ? Most of theirs are rated at 50V.

Jim85IROC

iTrader: (2)

That's why I suggested a real electronics house. Radio Shack sucks.

You'll probably be just fine with a 50 volt cap though.

To figure it out yourself, use the following equation:

F=1/(2*pi*RC) where f is the desired frequency, R is the resistance of your speaker (assume 4 ohms) and C is the capacitor value.

Rearranged, this is:
C=1\(2*pi*RF)

Remember that the answer will be in Farads, and most caps are rated in uF (microfarads) so you've got to multiply the answer by 1,000,000 (10^6).

As an example, using the equation above with R=4 and F=100, you get C=.00398 or 3.98*10^-4. This is the value in Farads. Multiply by 10^6 and you get 400, which is the value in uF.

vorgath

Awesome, thanks.

Yeah I agree Radioshack is real bad, but it's the closest one to me, plus I don't even know where they have a real electronics store here.

Jim85IROC

iTrader: (2)

In a city the size of San Diego? I'm sure there are dozens of places to buy caps.

Crayz9000

I actually called up a few electronics stores down in SD a while back, when I was in Tijuana working on a bigass printer. I don't remember the names of the places I called up, but there were a few big wholesalers there.

Try this: go to local.google.com, and search for "electronics near san diego". Start calling up the ones that look promising.

rx7speed

with that highpass filter what ohm of a resister are you using?

jimp2001

Not a resistor, a non-polarized capacitor.

Jim85IROC

iTrader: (2)

The speaker represents a 4 ohm resistor for the sake of the calculations.

rx7speed

I'm well aware what the difference is but usually a high pass or low pass filter is made of a RC circuit
or another words a resistor and capacitor.



that is why I asked what value resistor he was using.
if your going to roll your eyes and give a doh face at least maybe understand what I'm asking

rx7speed

couldn't that cause some weirdness as the speaker impedance is changing all the time based upon frequency? so while it might be 4 ohms at at one point it might be closer to 16 ohms at another.

might not make that much of a difference as I'm to lazy to find out right now so I'm not sure, but wouldn't there be a better way to do this

NEEDAZ

Your absolutely right. But if he's asking about 'bass blockers' he's not going to be making a zobel filter to smooth things out. The caps will work for he's needs. If not he should be getting something active. Passive filtering is vary common and the short comings are vary easily over looked.

Jim85IROC

iTrader: (2)

Needaz hit it spot on. Yes, the impedance of the speaker has a resistance that varies with frequency, and to compound the problem, there is a very high impedance spike at the speaker's resonant frequency, which for a typical 4" speaker, is probably around 80 to 100hz. The result is a very non-ideal rolloff when using a simple filter like a single cap, but it will help prevent over-excursion, which is the whole idea behind "bass blockers" in the first place.

vorgath

Yeah I just need it rather quick, because besides that only thing left is trimming my home made speaker adapters and I can finally throw my dash top back on. Looks pretty ghetto right now with everything exposed while I'm driving

vorgath

Cost me 7 bucks for two 200uF 100V capacitors, damn didn't expect them to be that big Anyway, so now I just install each one, inline, i.e. in between one wire and the speaker ? Doesn't matter which way the cap goes right ?

Also, which is which, in the factory wiring, my speakers had red and black wires, the factory connectors were hmmm grey and blue or something like that

NEEDAZ

Just pop them in series with the speaker and you're golden.

vorgath

Which wire though ?

Jim85IROC

iTrader: (2)

it's not really important which wire, but generally the standard method is to put it in line with the positive wire.

vorgath

Which one's the positive one, in factory color coding ?

Jim85IROC

iTrader: (2)

It doesn't matter. Just be consistant with your selection. Use all the "left" or "right wires.

vorgath

Right on, thanks.

devestator_x

iTrader: (1)

The only time positive vs negative will matter is when you wire up some of the speakers backwards but not all of them. If you're running the factory head unit, I believe grey is negative. if not, then look at your wiring coming from the back of the unit, figure out which color is which and see which ones those are connected to. I know for the rear speakers, yellow is positve left, brown is negative left, dk blue is negative right, and lght blue is positive right.

Just always remember, if you wire your fronts reversed, make usre you wire your rears and subs reversed to eliminate wave cancelation.

vorgath

I finally installed them, twice, because it looks like I had the wires backwards, negative was not positive baaah doesn't matter

Anyway, can't really tell any difference, but I guess as long as the speakers don't distort, nor break, it'll be fine.


Maybe I should have gone with different caps but hey ... sounds good.. I just hope the dash will fit over those Infinity speakers

NEEDAZ

It may be hard for you to notice a big difference because the speakers will not reproduce the lows vary well even with out blockers. You may be able to see the difference if watching the speaker though.

vorgath

And that's what I was looking at, because I've had the dash off for a while now, and once I installed the speakers, up and down they went, still do, but I guess it'll be ok.

NEEDAZ

You should be able to 'see' the differance. ?

vorgath

heh trust me ... my speakers were ready to jump up through the windshield *LOL*

sully91rs

Vorg, how are those caps working for you?

I get distortion when I turn up my system (right now, 2 6.5 and 2 6x9 powered by HU). I can tell it is the bass that sounds distorted. If I install bass blockers (500uF about 80 hz) at the speakers, will I still get distortion when I turn up the volume?

I want this to be a magical fix, but ultimately I feel that I'll need to buy a new HU with 80hz cutoff feature.

vorgath

Distortion ? hrrmmmm I wouldn't say that no ... however they sure hit pretty good on lower notes

Ever heard 2000 Man, the cover version, by KISS ? Only thing you hear in the beginning is Ace singing, playing guitar and then the speakers jump at the bass drum.

But I guess as long as they don't blow it'll be fine .. uhmm I hope ..