Reasons for lack of bass?

[Reggie Lives 10+ year member]

I'm fairly new to car audio, but just finished installing an amp and subwoofer into my truck. I was pleased with the sound of the sub, considering I built the box and it was my first attempt.

After driving around for a few days with plain mdf, I decided to paint the box and stuff it with more polyfill (sub manufactorer calls for 24liters with 16oz polyfill).

When I droped it back into my truck, it's significantly weaker. With the gains on the amp and HU maxed out, and bass set to +5db on the HU, it now hits as hard as it did with only my amp gains set fairly high and a flat EQ setting from my HU.

Could too much polyfill be causing this problem? I went from about 5oz to the recommended 16 when I noticed the difference. Or is it possible I messed up my amp when I re-installed it? The remote lead was poorly crimped to begin with, and when i went to unscrew it a few sparks flew. But the amp still runs...is it possible to damage an amp so that it still runs, just weaker output?

Also, I havn't trimmed down any of my wires (power, ground, remote lead, rca) because I'm still not 100% sure on the amps placement. If those wires are too close to each other, would it affect the output, or just contribute to ground noise?

I checked to make sure the speaker wire wasn't accidently switched, and fooled around with the phases and rca connections.

I'm at a loss.

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[savagebee 10+ year member]

triple check your wiring

if they're arent any changes after that, then take out the polyfill

 

[2000LaDe 10+ year member]

out of phase and check without the polyfil

 

[Snow90 10+ year member]

gain isnt meant to be turned all the way up. you should set your gains properly. its there to match up with your headunit.

 

[Reggie Lives 10+ year member]

So if I ****ed up the amp, it probably wouldn't still be working to the degree it is now?

Snow: ya, i didn't set the gains to max, I was just using that as a comparison. I can still get the same amount of bass, it just requires maxing everything out.

 

[mil81 10+ year member]

Is the sub a Dual Voice Coil. Is it possible that one of the wires fell off the sub, inside the box, and you are only running on one voice coil? If that is all the same, then it has to be the only other thing that changed, the Poli. Unless something else got damaged on the box when you had it out.

No chance something on your HU got mis-adjusted in the mean time?

 

[Reggie Lives 10+ year member]

mil81; no it's a single voice coil.

I took out over half of the polyfill, and it didn't seem to change anything. I also trippled checked all my speaker wire (amp to box, box to sub) as well as rca connections (on amp and behind HU).

Would a leak in my sealed box be a culprit? When I cut the circle for my sub, I slightly angled the cut, and one of the screws was only catching half of the mdf. After installing and reinstalling the sub a few times, the screw became completely useless, but it's only one screw and I figured the rubber surround would still seal it in. Maybe I'll try pointing the subwoofer up so that more pressure is placed on the surround, which might increase the seal and hence increase sub output? If that's the case, I guess the simplest solution is either gluing another ring onto the outside of my box or just buidling a whole new one.

Also, when I first reinstalled my sub, it wasn't hitting any bass notes and would just rumble when the HU was turned out. That's when I noticed that I had a shitty connection on my remote lead, and when I fixed it the rumbling stoped. Could that have damaged anything?

I'm going down to radioshack to grab a DMM to see how much the amp is outputting. This is my first system, and I really have a lack of knowledge so I appreciate everyone's input. I just find it odd that I CAN achieve the same bass ouput, but it just requires maxing everything out. Is there somethign I'm overlooking?

 

[mil81 10+ year member]

If you had a leak in your box, it would make your sub move more than it did before, just give out a crappier sound. You would hear a crackle type noise.

It sure does sound like you have reverse polarity going on and the subs are cancelling out. But I guess you wouldn't be able to get the bass you used to have, even if you cranked everything up.

And if you damaged something with the remote wire problem, I would think it would be the speaker, and you would hear funny noises from them.

I don't know man. You've used up the little bit of knowledge I have.

 

[bterz 10+ year member]

Does your H/U have a "Loud ON/OFF" Feature? lol

 

[Reggie Lives 10+ year member]

So I hooked up a previous subwoofer to my amp and it was also underpowered, so I think it's either a wiring problem or something wrong with the amp.

How do 2channel amps work? Would it be possible to blow one of the channels and still get power from the other, when it's being bridged?

I bought a DMM but then quickly realized I didnt' know how to use it. I was checking the speaker terminals on the amp while running a 50hz test tone through the deck, and the highest rating I got was 1.9v using the setting of 200V AC. I wasn't sure if it was AC or DC i was looking for, but got no reading on the DC side.

Whats the proper way to check how much power your amp is producing using a DMM?

 

[Reggie Lives 10+ year member]

In case anyone was wondering or was in a similar situation, I found the culprit; the HU. (Alpine 9886). I pluged my mp3 player directly into the amp, and it played at full strenght. I then pluged the mp3 player into the AiNet adapter, and it was alot weaker.

I went out and replaced the HU at Best Buy, and it's now working like a charm. I think the problem was a blown Pico Fuse, or something that affects the HU's RCA output.

 

[mil81 10+ year member]

Wow. That is whack!!!

I'm sorry to hear that. And you're sure there's not some stupid setting that you missed? Did you run am amp before this new setup?

Murray

 

[Reggie Lives 10+ year member]

Yeah, pretty positive it was the head unit. As I said, I hooked up an mp3 player directly to the amp, and it sounded perfect.

And by replace at best buy, I mean I got a direct exchange. I'd be super pissed if I had to pay for a new one.

 

[mil81 10+ year member]

As long as you didn't have to pay for a new one that's perfect. I hate it when a stupid problem takes so much of your time.