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Old 07-15-2016, 06:18 PM   #1
Moichumoi

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Subwoofer plays very quiet below 43 Hz

Hi, my problem is that my subwoofer plays very loud on higher frequencies but plays very quiet when it gets low at around 42-43 Hz and below that. At those frequencies, the cone isn't moving much and the sub doesn't play very loud. The size of my box and it's tuning are both correct, as I will state that below. I am using my factory headunit, which I think is the problem. I am suspecting it has some sort of built-in high passfilter at around 43 Hz, which causes my sub to not be able to play loud below this frequency. My headunit though is not replacable since it is a certain model, i'll state that below. So I can't switch it to an aftermarket one. I don't have a subsonic filter on my amp, so that is not the problem here.

My car and audio system specs:
-Car: Mazda 3 2015 GS --> So it has the touch-screen head-unit, which is irreplacable
-Amp: Pioneer GM-D9605 5 channel amp 75 WRMS x4 (4omhs) + 350 WRMS x1 (4 ohms)
Subwoofer: Alpine type R 1222D
Sub enclosure: 2 cu. ft. ported tuned to 32 Hz
-Wires: I am using High Power cables since my head unit is the factory one

So what I was wonering is, what could help me get those low frequencies? Because I've spent a lot of money on this system and it just doesn't sound right to me and it really aggravates me. I need your help guys. I've heard the fact that i'm using high-power cables shouldn't affect frequency response. I've also heard that adding an EQ to my system could maybe bypass the weird sort of high pass filter on my headunit? I need info on that please. Also I would like to know if switching to RCA cables with a LOC could affect this weird high pass filter my head unit seems to have. Thank you so much
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Old 07-15-2016, 06:51 PM   #2
ckeeler11

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How is the amp connected to the HU? Also make sure Freq. Cutoff is turned down.
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Old 07-15-2016, 07:59 PM   #3
Moichumoi

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Quote:
Originally Posted by ckeeler11 View Post
How is the amp connected to the HU? Also make sure Freq. Cutoff is turned down.
I don't know how the amp was connected to the HU, but my system has been installed professionnally by a business in my town that only do audio systems installations, so I think they hooked it up correctly.
I don't have a Freq. Cutoff on my amp/head unit.

Do you know anything about aftermarket EQs? Could that solve my issue? Cause I heard they can be used to restore the missing frequencies from the head unit before sending them to the amp. If you know anything of that matter, your help is appreciated.

Thank you for replying too!
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Old 07-16-2016, 01:09 AM   #4
basicxj

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You may be able to install an OEM integration audio processor to correct equalization in the factory radio.

Try plugging your phone into the amp's inputs (use a mini-plug to RCA adaptor) and see if the problem goes away with music/test tones from an alternate source. If it does, the problem lies upstream, if it sounds the same it is a function of the amp/sub/enclosure.
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Old 07-16-2016, 11:34 AM   #5
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Check output voltage at the amplifier outputs with a ~60hz test test and then a ~30hz test tone. This will tell you if the frequencies are getting cut upstream or if your enclosure is tuned improperly or you have a possible cancellation problem (although I doubt it's cancellation).
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Old 07-16-2016, 02:52 PM   #6
Moichumoi

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Quote:
Originally Posted by basicxj View Post
You may be able to install an OEM integration audio processor to correct equalization in the factory radio.

Try plugging your phone into the amp's inputs (use a mini-plug to RCA adaptor) and see if the problem goes away with music/test tones from an alternate source. If it does, the problem lies upstream, if it sounds the same it is a function of the amp/sub/enclosure.
I did that test, and the lows didn't sound loud. They were the same volume than with the head unit. So what you're saying is my problem is my amp, my sub or my enclosure, but I don't have a subsonic filter on my amp, I just changed my subwoofer box for this new one that I wrote the specs in my original post (2 cu. ft. tuned @ 32 Hz), and I'm pretty sure my subwoofer, the alpine type r 1222D, is capable of playing such low frequencies, as I've seen it on youtube. I don't know what my problem could be...
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Old 07-16-2016, 02:56 PM   #7
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Quote:
Originally Posted by Jimi77 View Post
Check output voltage at the amplifier outputs with a ~60hz test test and then a ~30hz test tone. This will tell you if the frequencies are getting cut upstream or if your enclosure is tuned improperly or you have a possible cancellation problem (although I doubt it's cancellation).
How can I check the output voltage at the amplifier outputs?
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Old 07-16-2016, 02:57 PM   #8
basicxj

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Quote:
Originally Posted by Moichumoi View Post
I did that test, and the lows didn't sound loud. They were the same volume than with the head unit. So what you're saying is my problem is my amp, my sub or my enclosure, but I don't have a subsonic filter on my amp, I just changed my subwoofer box for this new one that I wrote the specs in my original post (2 cu. ft. tuned @ 32 Hz), and I'm pretty sure my subwoofer, the alpine type r 1222D, is capable of playing such low frequencies, as I've seen it on youtube. I don't know what my problem could be...
If you've swapped the source and the hole in frequency response remains, it could be the enclosure or even something as simple as the way it is aimed causing some cancellation at that frequency due to how the sound waves bounce around inside the vehicle. Are both woofer cone and port on the same plane of the enclosure?

Post up a photo of the enclosure as you have it aimed inside the vehicle. Upload the pic to a hosting site and post a link here in your thread.
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Old 07-16-2016, 05:24 PM   #9
Moichumoi

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Quote:
Originally Posted by basicxj View Post
If you've swapped the source and the hole in frequency response remains, it could be the enclosure or even something as simple as the way it is aimed causing some cancellation at that frequency due to how the sound waves bounce around inside the vehicle. Are both woofer cone and port on the same plane of the enclosure?

Post up a photo of the enclosure as you have it aimed inside the vehicle. Upload the pic to a hosting site and post a link here in your thread.
When I did the test, the sub was aimed this way in my car:
https://gyazo.com/ccbe43b54a5d4a6470c11e19faf9c6c8

I tried turning it around, but no placement was a lot better than the other. When I ran the test though, the lows were louder with the RCA cables (no head unit involved) but were still a lot quieter than the higher frequencies.

Here is a link to my sub box: http://www.ebay.com/itm/12-Inch-CUST...5uwuJRW1lEg0tA
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Old 07-16-2016, 05:37 PM   #10
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If it isn't the way the sub is aimed, then that eliminates cancellation. Generally speaking if the problem persists when you open the trunk then it's probably not a cancellation issue.

If the problem persists with a different source, then either the amp has an SSF, which I don't think your amp does or is bad (probably not the case either).

So that kinda leaves the enclosure. If you can provide interior dimensions of the enclosure and port, then we could do a rough calculation to figure out the tuning frequency.j

As for testing with test tones, you just measure AC voltage at the output terminals of the amp with a digital multimeter (~$20 at Radio Shack, Harbor freight, etc). Check the voltage of the 2 test tones at the same volume and you should get roughly the same voltage. If voltage drops with the ~30hz test tone, then we know for some reason the frequencies are being cut by either the amp or HU. If the OEM system came with a sub, then you need to sum the subwoofer signal back into the chain.

Last edited by Jimi77; 07-16-2016 at 05:42 PM.
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Old 07-18-2016, 05:35 PM   #11
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Try flipping the box around and aim it towards the back of the trunk. the way it is facing there might be some cancellation. when I looked up your amp it showed a subsonic filter (Freq. cutoff).
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Old 07-18-2016, 09:11 PM   #12
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Quote:
Originally Posted by ckeeler11 View Post
Try flipping the box around and aim it towards the back of the trunk. the way it is facing there might be some cancellation. when I looked up your amp it showed a subsonic filter (Freq. cutoff).
I don't believe it has an HPF or SSF on the subwoofer channel. There is an HPF on the full range channels.
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Old 07-20-2016, 03:57 AM   #13
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On the account of i can't sleep. You need to download 4 testtones 60 50 40 and 30hz tones. Un plug the woofers and get a cheap multimeter. Read the voltage at each frequency.
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Old 07-21-2016, 02:45 AM   #14
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Quote:
Originally Posted by bassfreak View Post
On the account of i can't sleep. You need to download 4 testtones 60 50 40 and 30hz tones. Un plug the woofers and get a cheap multimeter. Read the voltage at each frequency.


Now take some drugs and get some sleep.
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