Car Audio Gurus

fredfifty

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Nov 23, 2011
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SF Bay Area
I just installed an amplifier and head unit in my car. alls well, did the gain adjustments on the amp (volume up on deck til distorts then backed off, then gain up on amp til distorts then backed off) but i am kinda in the dark on the 60/80/100 Hz settings on the amp. its 4 channel, 45x4 RMS. I have the 6 speaker setup in my coupe. the 4 channel amp pushes all 6 speakers (im assuming the dash and door speakers are wired in series(?).

how do i know if i need the high pass and low pass filter off or on and at what setting (Hz)?

the speakers are rated at (2) 3.5" @ 90-20k Hz / (4) 5.25" @ 70-21k Hz and the amp is the alpine KTP-445U.

thanks for any help
 
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Have almost the same set up in my Cobra. But the headers to tailpipes w/no cats and small glass-packs overrule what ever music is coming out :):):):flame:
 
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LX Dave

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Jul 2, 2017
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Went through the same thing when I first installed mine earlier this summer. I ended up setting things for full range to get the best sound. If you set the switch at 60, 80, or 100hz, the amp will filter out anything under that setting, so without a sub, you will loose some of the sound range. Play around with it and find the setting that sounds best to you.

I am seriously thinking of getting rid of my 3.5" dash speakers and installing the door speakers instead. It seems like the dash speakers are what's holding back the overall quality.
 
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Dan02gt

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Mar 2, 2003
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Ideally if you don't have a sub you will leave the low pass filter off. The problem is with your setup 3.5" in the dash. While your door speakers and rear speaker can handle a full range signal, the little dash speakers really need to be high passed around 200-300 Hz. What I would do if possible is connect the dash speakers to the head unit directly and install a bass blocker on them. Then allow your 5.25"s and 6x8"s to run full range.

What I did was install a component set with the tweeters in the dash and the mid-range in the door.
 
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fredfifty

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Nov 23, 2011
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Ideally if you don't have a sub you will leave the low pass filter off. The problem is with your setup 3.5" in the dash. While your door speakers and rear speaker can handle a full range signal, the little dash speakers really need to be high passed around 200-300 Hz. What I would do if possible is connect the dash speakers to the head unit directly and install a bass blocker on them. Then allow your 5.25"s and 6x8"s to run full range.

What I did was install a component set with the tweeters in the dash and the mid-range in the door.
thats what i was thinking to do (have head unit push dash speakers) but its all wired up and heat shrinked...would be a pain to undo everything lol i'll see about doing that after i try to set the Hz on the amp first
 

Dan02gt

10 Year Member
Mar 2, 2003
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Greenville, NC
Even though they are wired in parallel with the door speakers. You could still put in line bass blockers on them. I would probably do 300Hz on them.

If you turn on the high pass crossover on you are going to kill your bass to all the speakers. Would be easy to pop out the dash speakers and add the bass blocker.
 
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a91what

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+1 bass blockers on the dash speakers. I have my tweeters in the dash and am about to swap things around for more midrange vocals. I plan to use bass blockers myself.
 

FoxMustangLvr

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If you like it loud, protect your speakers from bass distortion and enjoy cleaner sound with Bass Blockers. Each Bass Blocker handles up to 50 watts RMS with a 6 dB per octave roll-off. You'll find some general guidelines below for matching Bass Blockers to speaker size. For smaller speakers (3-1/2"s, 4"x6"s, 4"s), the 600 Hz Bass Blockers work well with low-powered systems, while the 800 Hz Blockers are a better choice for high-power applications.

Speaker Size Cut-off Frequency

6-1/2", 5"x7"/6"x8" — 150 Hz
5", 5-1/4" — 300 Hz
3-1/2", 4", 4"x6" — 600 Hz (low power)
3-1/2", 4", 4"x6" — 800 Hz (high power)
 
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fredfifty

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Nov 23, 2011
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SF Bay Area
got truconnex bass blockers from best buy....so I installed them inline on the positive lead on each of the 3.5 dash speakers. in the package there were 2 14uf and 2 133uf (microfarads) whatever the hell that is. anyways, I used the 133uf, does anyone know if that's okay? and do they need to be installed a certain way or are they NOT polarity specific?? there were no directions in the packaging or specific instructions online that I could find...