Which is blown, subs, amp, or installation?

[drgadget]

So I wanted a little bass and didnt want to spend a fortune. I stumbled upon an old sub/box that a friend gave me in college. My parents used it for a little while for a sub on their home theater system, and then it collected dust for a few years. I then found a used amp at a pawn shop and hooked it up with a wiring kit I bought at a car audio store.

Here's what I have hooked up.

HU: Dual - recent model with HD radio, blue tooth, and USB. Has only a front RCA output and Rear RCA output. I used the Rears RCA outputs for the sub.

8 Ga install kit - 8 Ga power and ground, 14 ga Monster brand speaker wires. I did not bridge.. as the box had imputs for each speaker I plugged in one channel per speaker.

Rockford Fosgate 325.2 amp - should give 2 x 160 W @ 4 ohms, or 1 x 325 W bridged. Bought it USED from a pawn shop. I have a 1 week warranty.

One sealed box with 3 cu ft, and 2 Kenwood 12" subs. They're probably over 6 years old so I couldnt tell you a model #, like I said, I got them from a friend in college, never had them hooked up on a car, but I seem to remember them sounding ok on the surround sound system at home. Don't remember if we blew them or not turning them up too loud.

Got it all hooked up, turned it on, and played with the tuning. The sound DOES come on, the power light on the amp came on, thermal and protection lights did not. I messed around with the tuning. I set the frequency between 80 and 150, and turned the gain up till I heard distortion and then backed down.

I gotta say, there's not much sound coming out of those speakers. If I turn the gain up, the sound comes a bit louder, but distorted and ugly.

I'm thinking the problem could be one of these.

1. Is my amp too weak to run 2 old 12" speakers?

2. Did I get a busted or fried amp from the pawn shop and should I return it?

3. Is it the amp, or is it just some blown speakers?

I am planning on getting an multimeter tomorrow and running some tests to be sure the amp is getting the right power and to measure the impedence of the speakers. I know I'm looking for 12/14 volts off/on, and probably 4 ohms on each speaker. If the voltage is bad, I know to check the connections, more likely to be the ground if I had to guess, had trouble finding a good one during install.

So what if the speakers don't show 4 ohms? How can I tell if its the amp, the speakers or both, without borrowing someone elses sound system?

Should I bag it all and take it into the sound shop and pay them to tell me? I know they're going to look at me like a cheapskate for using all the old busted stuff, but hey, I am out $100 for an entire system at this point.

Any and all help would be appreciated.

Thanks,

Dr. Gadget

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[SicAudio 5,000+ posts]

your on the right track so far that amp may not be enough.

 

[Villeza1 10+ year member]

your on the right track so far that amp may not be enough.

Check your system over again b4 your follow this advice. If you see nothing wrong, then get a new/more powerful amplifier.

 

[TKCARAUDIO 10+ year member]

well check the conections in the box... Bridge it and check it out... Post pics of the subs/amps

 

[thevic24 5,000+ posts]

also make shure that both subs are in phase with each other.

 

[drgadget]

OK Multimeter reads 13.6 from + to - on the amp with car running. I also found a friend with a system and a Rockford Fosgate 1000.2. I hooked my box up to her amp and it sounded GOOD!. We also checked things over and decided to ground the box in a different spot. The multimeter reading above is with the new ground. The fuse on the amp was good, but we noticed that it is a 30A fuse, and right above it it says 40A. I haven't found a 40A fuse yet in that size, going to the autoparts store today for one more try before I take the Amp back. I have a few days left on the warranty from the pawn shop.

So the speakers/box are good. Does the 13.6 indicate a bad ground or is that OK? everything else about the install looks good.

So will the 13.6 and the 30 watt amp kill the amp or ??

One more thing... we noticed two things about the speaker. It sounds almost as good with one of the speaker inputs hooked up or two. Also both cones move in unison when one speaker is plugged in. It's a sealed box so I figured it was just moving from the air movement inside the box from the other speaker. Does this warrant taking a speaker out and seeing if the speakers are bridged inside the box?

 

[drgadget]

Oh, when I hooked up to my friends 1000.2 RF amp. I only hooked up one speaker, and it still sounded great.

 

[Haunz 10+ year member]

Are the subs 4ohm or 8ohm ?

Sounds to me like they might be 8ohms each and you are not sending them much power...

 

[gearhound17 10+ year member]

If they are home theater subs wouldnt they be 8 ohm to begin with?

 

[cj407]

or he has bass boost too high on the headunit...why your bass frequency on amp set so **** high...they are subwoofers not mid-woofers....sub bass is low frequency...