Like many, I need help please.

 

Bronze Member
Username: Calaway

Austin, TX

Post Number: 61
Registered: May-04
My amp powers on fine, no thermal or overload lights. But I only get a tiny bit of sound from the subs. I've already counted out the RCA input cables. I've used a probe to make sure the amp is getting voltage. I am down to the sub wiring being a problem:

I have a Fosgate P5002(using it for 2-chan, 250x2 at 2ohm rms).

I also have 2 Fosgate HX2 8 inch subs that are 400rms. They have dual 4ohm coils.

I wired the subs in parallel to get 2 ohms each according to http://www.bcae1.com.

For each sub/channel: I wired each coil's neg together on one sub, then plugged that to a neg channel on the amp. I then wired the two coil's pos together, and plugged that to the pos of the channel. I repeated this for the other sub/channel.

Any ideas? Thanks!

 

Gold Member
Username: Carguy

Post Number: 2865
Registered: Nov-04
How is your gain/level set on the amp? It has to match your HU's preout voltage.
Describe the type of sound you're getting. Is the cone moving? Do you get any low bass sound? If you reverse the polarity of the voice coils, they tend to give very little sound. Double check your sub wires.
To isolate your problem, test one sub at a time.
 

Bronze Member
Username: Calaway

Austin, TX

Post Number: 62
Registered: May-04
My HU gives 4 volts(Alpine 9831), so I have the gain set like 1/4 of the way up I think.

I put my hand flat on the cone and feel a little vibration that goes along with the music. Not enough to tell if it is just bass, or full music. I will check polarity.

Other info: The Alpine has a sub on/off option for its RCA outs and I have it on. I have the amp crossover set to LP. I am using the cheapy grey pre-wired sub boxes you find at walmart.
 

Bronze Member
Username: Calaway

Austin, TX

Post Number: 63
Registered: May-04
I went and concentrated on one sub.

I double checked the wires and they are all pos to pos, neg to neg. I made some adjustments on the HU sub settings, and I am getting a bit more sound now(more bass) but no where near what I feel I should for 250rms.

Could it be because I am underpowering the subs? I figured since RF amps are underated it would balance out. With 8's obviously I am not trying to play with the big boys. I may take it out of the Walmart box(it has like 18 gauge) and try straight 14 gauge wire from sub to amp.
 

Gold Member
Username: Carguy

Post Number: 2873
Registered: Nov-04
Scotty, 250w is not much when it comes to bass. Unlike mids and highs, your ear can and will handle much more bass before it aches. From my testing, 8" subs don't put out much anyways. 10" is the minimum, 12" is best for everyday listening.
I think the results you're looking for can be achieved with 500w rms or higher.
 

Bronze Member
Username: G3nocd3

San Jose, Ca USA

Post Number: 77
Registered: May-05
Whats the power rating for rms power on those subs. If your greatly underpowering them or even by 100 watts or more It will greatly reduce sound. Even 100 rms underpower. You will hear a 20+% sound loss even at 100 Rms under. Well thats what i have experienced. So check that out also.
 

Silver Member
Username: Goon

Post Number: 178
Registered: Feb-05
like isaac just help me find out, to little power and they won't even kick on. but im talking liek 250w under the rms. sucks. peace

goon
 

Bronze Member
Username: Calaway

Austin, TX

Post Number: 64
Registered: May-04
Subs are rated 400rms each.

I just wanted to get a little more foundation than my 6x9's were giving.

The amp can do 500rms bridged. I should bridge it to one of the subs and if that gives me a lot of bass then I will know I am underpowering the two.
 

Bronze Member
Username: G3nocd3

San Jose, Ca USA

Post Number: 84
Registered: May-05
250 under rms is a diasaster waiting to happen. lol you like the subs. Distortion Kills. Get new amp. :-)
 

Bronze Member
Username: G3nocd3

San Jose, Ca USA

Post Number: 85
Registered: May-05
Yea. Try that scotty. You could always do what i did. Take one sub out. ANd have just one in the vehicle. With that one amp. Save up. Get a 2nd amp. And put the 2nd sub back in. Thats if you dont wanna get just one big amp for both.
 

Bronze Member
Username: Calaway

Austin, TX

Post Number: 65
Registered: May-04
yea, I just may get one 10 inch I can push with that amp and be done. Can't seem to find one that will take 500rms though.
 

Bronze Member
Username: G3nocd3

San Jose, Ca USA

Post Number: 91
Registered: May-05
I know alot of 10's that can push 1000 rms. Look around. Alumapro,Eclipse,Fosgate,Jl, and others. I just listed a few. Anyone feel free to post more companies that you think i should have added. :-)
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