Aftermarket car subwoofer is VERY quiet, can barely hear it even when ear is right up against the speaker

[spaghetto15]

So I got this supposedly 800w sub and amp combo for 20 bucks from a friend who doesn't know much about these things, he got them for free.

The speaker is from some random Chinese manufacturer, about whom I can’t find much about. The only image I could find online (mine is in a box) -


The amp is a Philips DAP 4020.

I bought a wiring kit, hooked everything up to my car's factory stereo, including a cheap line output converter. The amp's power LED is on, but the audio that comes out is EXTREMELY quiet. I hooked up the amp to my phone via a 3.5mm cable, and I could only hear a little bit of the low end and only when I put my ear right up against the speaker.

I have tried turning the gain up and down, filter on and off, nothing works. At first I thought that maybe I hooked up the LOC to speakers that don't output the full range of frequencies, but as I said, the problem persists even when the amp is hooked up just to my phone.

Any help would be appreciated.

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[KicktheSDbasshead]

if you can try another sub first then try a different amp. To barely hear anything could be the settings on your headunit but i would check sub then amp.

 

[Deiimos]

Pretty simple amp, so not much to check. Do you have any other speakers to test with the amp, like from a home stereo or something?

Test each channel individually. Filter switch to OFF. Set the "Input Mode" switch to ST (middle position), then hook up the sub to the left channel, turn up the head unit volume and or phone, and adjust the gain up and down to see if any change / how loud it is. Then test the right channel the same way.

Note that older amps, the potentiometers and switch contacts can become oxidized and not make good connection and require cleaning. You can also try, while playing music with the volume up, adjust the Gain potentiometer and all of the switches rapidly to see if any change in sound level. I've had to clean switches in several amps over the years. This may not be the issue at all, but something to keep in mind.

 

[1aespinoza 10+ year member]

Any help would be appreciated

The amp is only 40 watts per channel so I would not expect it to really move the sub. A few subwoofer factors play a role on your issue; is it high power, is it dual voice coil, is it wired in series. One can usually tell by looking at the back of it.

 

[Deiimos]

To me, it looks to be a typical budget sub, so 100w should make it move fine, however, the OP could take it out of the box for magnet size, etc. I agree it is a low power amp and it isn’t going to be crazy loud, but it should do somewhere around the 100w RMS range bridged, and will move the sub reasonable well / shake the review mirror. If you have to put your ear next to the sub to hear anything, something is wrong somewhere. I've never heard of that sub, couldn't find much from a quick search, so a rough guess, it takes 150-400w RMS or so, give or take a little, and if all working, that amp would be fine to power it. Again, pics of the magnet, voice coil size, etc., may help with that.

Another question to the OP; does the sub cone move down and up when you gently push on it without feeling it rub or make scratchy noise? I've seen blown subs make a little sound, but won't move because the coil former is deformed, seized to the pole, or unwound. Hell I've had and used subs that only started to move once you fed it enough power to over come being stuck, lol.

 

[1aespinoza 10+ year member]

To me, it looks to be a typical budget sub, so 100w should make it move fine, however, the OP could take it out of the box for magnet size, etc. I agree it is a low power amp and it isn’t going to be crazy loud, but it should do somewhere around the 100w RMS range bridged, and will move the sub reasonable well / shake the review mirror. If you have to put your ear next to the sub to hear anything, something is wrong somewhere. I've never heard of that sub, couldn't find much from a quick search, so a rough guess, it takes 150-400w RMS or so, give or take a little, and if all working, that amp would be fine to power it. Again, pics of the magnet, voice coil size, etc., may help with that.

I agree, but if it is wired in series, it will present an 8 Ohms load (if dual 4s). Another thing to consider, if it is a dual voice coil, it could be wired out of phase.
But just from that picture, I assume a 300w RMS single VC.