Connecting a 200uf capacitor to remove bass

[EuroDude]

I have some 5.25" speakers in the car doors, running of a small Amp.

The issue is that the speakers are outputting too much bass, causing them to distort and vibrate the doors when bass is played. (The Amp only has a LPF :o I need a HPF)

So Ive bought some 200uf 100v BiPolar Capacitors to decrease the frequencies below 200hz

I tested the capacitor inline of the (+) speaker wire, and it indeed works



Now the question is, the front Speakers are 2-way Boston S55 (non component), which already has a built-in capacitor/inductor for the tweeter.


Q. Can both the tweeter driver and midrange driver both run off the new capacitor? Can I simply place the capacitor inline from the Amp to the speaker? will that cause any problems? (ps. the tweeter still functioned ok when I tested it, so it should be fine, correct?)

Or do I need to re-wire the speaker itself and connect the 200uf capacitor from the (+) Y point to the (+) of the driver (where it splits the + to the tweeter and mid-driver), so the tweeter doesnt have anything to do with the 200uf capacitor?




Here's a diagram:
http://img157.imageshack.us/img157/886/speakerqz3.jpg

[D4rk4n63l]

so you are trying to limit the low freq? if it works, shouldn't the high freq pass to the tweeters still? I mean, nothing of the low freq that you limit will go to the tweeters anyway, so the new cap has nothing to do with the tweeter as it is now.. so if before the mod, the speaker/tweeter will get low-high freq range and the tweeter's cap will only allow high freq to pass, then after the mod the only diff is that the speaker/tweeter will get mid-high freq range yet the tweeter cap will still only allow high freq to pass...

but off the subject, have you tried sound deadening your door? I bet it will sound so much better then...

[EuroDude]

^ thinking logically, thats what I think as well - it should be fine.

I have already sound deadened the doors and it made a huge improvement. The problem is the speakers are only 5.25", and the Amp is sending full range frequencies to the speaker, causing the Bass to vibrate the doors and other areas too much. I have a sub in the rear so the fronts dont need to produce bass anyway.

[IZY-10]

some tweeters have caps already on them i believe

[IZY-10]

........

[D4rk4n63l]

some tweeters have caps already on them i believe

yeah, they're called inline caps...

[EuroDude]

Yes the tweeter already has its own cap, thats the whole problem.

I got confirmation from someone with considerable electronic knowledge, that running the caps in series wont do any harm, it doesnt matter which way I wire it up, it will sound the same.

[IZY-10]

Yes the tweeter already has its own cap, thats the whole problem.

I got confirmation from someone with considerable electronic knowledge, that running the caps in series wont do any harm, it doesnt matter which way I wire it up, it will sound the same.

running caps in series is like running resistors in parralel so

1/ct = 1/c1 +1/c2

Just in case you didn't know.

[IZY-10]

yeah, they're called inline caps...

What material are they derived from? Interesting never heard of them:o

[DC5TYPER]

Diagram 1 looks correct

Also your setup with a single capacitor will be 200Hz HPF at 6dB p/Octave.

Will 6bD slope be enough at 200Hz for a 5.25inch Speaker?

What Impedance is the S55 2 or 4 OHM?

[EuroDude]

running caps in series is like running resistors in parralel so

1/ct = 1/c1 +1/c2

Just in case you didn't know.

I see, thx.


Diagram 1 looks correct

Also your setup with a single capacitor will be 200Hz HPF at 6dB p/Octave.

Will 6bD slope be enough at 200Hz for a 5.25inch Speaker?

What Impedance is the S55 2 or 4 OHM?

200hz cut-off @ 4 ohms = 200uf

There is still some bass getting through, but its ok for most tracks unless they have excessive bass. If that happens, I just turn the Bass on the HU down to -1 (I had to turn it down to -3 before the Caps were installed, which lowered the Bass of the Subwoofer too far). The caps are actually 220uf, perhaps 300uf would have been better. Shame they are expensive http://www.jaycar.com.au/productResults.asp?whichpage=2&pagesize=10&keywords=&CATID=51&SUBCATID=877&form=CAT&ProdCodeOnly=&SPECIAL=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=


S55's are 35wRMS 4ohm 92db

[IZY-10]

can you use polarised instead?

[EuroDude]

No you cant used polarised caps, you can blow the speaker that way.

[Eclipsor]

To get a better cut off you will probably need to use a higher order filter. The problem is probably that even if you have the cutoff set correctly, the slope of the filter isn't very steep and you're not attenuating the frequencies that you want by enough. Changing the cap value will only do so much. You will probably eventually be able to get rid of all the bass but at the expense of some of your mid range.


can you use polarised instead?It's an AC circuit you would probably blow up the cap.

Also.


running caps in series is like running resistors in parralel so

1/ct = 1/c1 +1/c2

Just in case you didn't know.

You can't use this in this situation.

[IZY-10]

you might as well build your self high pass filters by the time you finish mucking around with everything lol.

[narchi]

i have an easier solution for ya. What headunit u running. and what amp you running.
If u feel ur getting to much bass use the EQs on the headunit to turn it down between the 150hz and 1000hz frequency. This will still leave ur sub sounding good but remove alot of midrange.
Sometimes Headunits have crossover features on them and u can use that to do the same thing.
Also check to see if u have ur loudness button on. This can destroy speakers and it basically raises all the bass frequencies to make it sound louder.

[EuroDude]

Headunit is the factory honda unit. No loudness or crossover feature. Only bass, treble, fade, and balance.
Amp is a small kenwood without a high pass filter.

Turning down the HU Bass works, but you lose the bass in the rear as well.
If I turn up the Gain in the rear, the rear becomes too loud
If I turn up the Subwoofer Gain, that works, but you lose mid bass from the 6x9's

So the only option is to get a different amp with a HPF, or simply add caps.

[narchi]

turn down the gains on the amp for ur fronts. It sounds like ur speaker is clipping which is not good for the speaker or the amp. The only reason y i am suggesting other reasons is so many ppl do what u have done and no1 has had to add caps or worry about a hpf on their amps as i know most ppl dont use amps with internal crossovers.

If a speaker is distorting and crackling when bass hits it generally its because u a working ur amp to hard. Trying getting ur amp scoped to find out if where ur gains is at is causing it to clip. Is ur amp running rears and front?

It sounds like u want ur system louder than what the amps can go. U shuold have ur gains on all the amps to sound about the same without clipping. at a set volume u generally listen to

EG... 25 is ur headunit normal listening. Leave it at 25 then set ur gains till u can hear it clip. Back it off a bit then tune the rears so it blends in with the fronts. Not overpowers.

[EuroDude]

The way its set up is:
-High powered Rear speakers/sub provide most of the volume (mid bass to high treble)
-Low powered Front speakers provide front fill so the music sounds centered for the front driver/passenger (mids and treble only)
-The Sub provides low bass for the whole car.
-Max bearable volume (and no clipping) is set at 35/40 HU volume

The front speakers dont clip unless I turn the volume up to an unbearable volume (when the HU is above 35/40). The front speakers actually provide decent bass at 35/40, but they vibrate the doors too much (even with sound deadening). I dont need bass at the front because the rear speakers+sub provide plenty of bass.

If I turn down the Gain at the front, the sound stage is not centered.



Anyway Ive tuned it, and it sounds good now.
Ive set HU bass to -1 and gave the 6x9's a bit more mid bass (by lowering the HPF setting at the rear). The only problem is that if music with excessive Bass is played, I need to move the HU's Fade to the rear so the front doors dont vibrate. Only 10% of the music played has excess bass, so its not a big problem

If I install 300uf Caps, I would be able to keep the HU Bass at 0, limit the bass at the front even further, and provide more Bass flexibility at the rear. That way, I wouldn't need to Fade to the rear for music with excessive bass.

[IZY-10]

simple don't run bass through your 6*9 replace them with 6" coaxial. No point having 6*9 if you have a sub. It will be noticeably more clearer. The roll of the sub is to play the lower frequencies whereas the speakers deal with the mid-high frequencies

[EuroDude]

yeh I was thinking that, but the JL 6x9's actually sound quite good so I'll keep them for now.

But the problem is that I have the Sub tuned to pump bass below 50hz, so I need bassy speakers to compensate the bass above 50hz.

I set the hz very low because mid bass frequencies from the Sub vibrates the rear too much and sounds bad. Sharp low bass hits sound a lot cleaner.

[narchi]

just coz ur box is tuned to 50hz dont mean it dont play more than that. It just means that 50hz in theory should be the loudest frequency when played. Subs can play up to about 300hz but only sound good playing under 100hz. This is still irrelevant for a system.
Ur Speaker woofers should fill in the gaps not overlap with the sub. That is why IZY-10 said get rid of the 6x9s. The only reason i didnt suggest yesterday is because u have a unique way u like to listen to ur system. Telling u the right way to do it doesnt mean it will sound the best for u as everyone has a different preference for sound.

But always remember. Its easier and safer to turn down a system than make it louder.

[EuroDude]

Yes I know what ur saying but the problem is that the Mid-Bass from the Sub is too loud and causes rattles, so I need the 6x9's to compensate.

Lowering the Sub frequency to 50hz made a huge difference. The Sub still outputs above 50hz off course, but those frequencies roll off (without excessive overlap) into the 6x9's bass frequencies which result in clean high powered low bass hits, with medium powered mid bass filler. Which in turn sounds much better than if I set the Sub cut-off to ~300hz

i.e.
http://img507.imageshack.us/img507/93/spkrsqn6.gif