Blown fuse or blown subs?


mobbdeep

Member
May 5, 2015
46
2
Tucson, AZ
Hello,

Tonight I was on my way home from work to Walmart listening to my music as usual and next thing you know, I lose bass completely. As I was driving and noticing I had no bass, I started smelling something really raunchy. At that point, I pulled into the Walmart parking lot and started doing some basic troubleshooting. I shut my car off and back on, checked the power to the amps and they power on fine, but still no bass. Based on smelling around and touching stuff, I can't really tell if a fuse was blown in one of my amps or if one/both of my subs are blown. I have a high possibility that the raunchy smell was coming from my sub box but I'm not too sure.

If a fuse or a few blew in my amp, my amp wouldn't receive any power, correct? I didn't hear any pop or indication something blew out; just lost bass and a raunchy smell. I'll be taking my car back to the shop tomorrow where I bought the subs from and have them take a further look but I just wanted to ask here beforehand to see if there's something maybe I can do.

Hardware:
- Alpine X-Power MRX-M100 Mono Power amp for the subs
- Rockford Fosgate Prime R250X4 amp for the door speakers
- 2 x 12" Rockford Fosgate P2 subs

Thanks!
 

ThxOne

AudioFreak
Jun 8, 2018
1,039
178
Saint Marys, GA
Great Alpine amp... if you are running it at 2ohms. I ran a single P2 12" on the same amp for a long time at 2 ohms, then I let my sister use it, she melted the voice coil and dust cap. It DOES NOT like 1ohm though. Raunchy burnt smell... sounds like voice coil(s). What are your subs wired down to ohm wise? 1 ohm? 2 ohms? 8 ohms? What are the voice coils on each sub? Dual 2 ohms or dual 4 ohms? What is the gain on the amp set to? Is the amp properly grounded and what size cables and wire are you running?
 
  • Like
Reactions: mobbdeep
OP
M

mobbdeep

Member
May 5, 2015
46
2
Tucson, AZ
Great Alpine amp... if you are running it at 2ohms. I ran a single P2 12" on the same amp for a long time at 2 ohms, then I let my sister use it, she melted the voice coil and dust cap. It DOES NOT like 1ohm though. Raunchy burnt smell... sounds like voice coil(s). What are your subs wired down to ohm wise? 1 ohm? 2 ohms? 8 ohms? What are the voice coils on each sub? Dual 2 ohms or dual 4 ohms? What is the gain on the amp set to? Is the amp properly grounded and what size cables and wire are you running?
I'm not 100% what they are wired down to as I had my car audio shop install them when I purchased them. As far as the voice coils on each sub, they're dual 2 ohms. Attached is a screenshot of what the knobs are set at on the amp. I didn't do any of the knobs, the car audio specialists did them. I am having grounding trouble with the amp. I've managed to go straight into the solid chassis of my car but can't seem to get it bolted down tight enough. Regarding the cables, I'm running 4 AWG welding cable Class K for the ground and wire cable on both amps.

I know I don't have many answers to your questions but I wanted to see if I can figure something out before I go back to the specialists. Also, not sure if this matters, but I am in Tucson, AZ which was 111°F today so I'm not sure if heat plays a factor either.
 

Attachments

ThxOne

AudioFreak
Jun 8, 2018
1,039
178
Saint Marys, GA
Dual 2ohm subs... They could potentially be wired to .5ohm or 2ohms. Hopefully they did it right and wired it to 2 ohms like the attached image. If so, you may have blown your voice coils. I can't tell if that amps gain is set to max or not... if so BAD IDEA. I bet they were hitting hard before they blew though. OH!!! and that bass EQ... turn it ALL the way down... it will only help blow the subs.
 

Attachments

  • Like
Reactions: mobbdeep

ThxOne

AudioFreak
Jun 8, 2018
1,039
178
Saint Marys, GA
Heat is ALWAYS a factor. However, if the gain is not set properly and bass enhancements are used like "loudness" "Bass Boost" "Bass EQ" and the like, it will add crap tons of distortion and will melt coils pretty fast... even if under powered. Speaking of which... I'd run at least a 1200w amp on that pair. Gains properly set of course. If your ground is bad, the amp may not be getting enough power to send to the subs and could be sending a distorted signal which may blow them as well.

This is the ground block I use... makes pretty good contact and I have never had an issue. The brand I use is Fierce. I am sure there are other brands. If all else fails, you can run a cable right back to the negative terminal on the battery.
 

Attachments

Last edited:
  • Like
Reactions: mobbdeep
OP
M

mobbdeep

Member
May 5, 2015
46
2
Tucson, AZ
@ThxOne You've been nothing but good help my man. I am hoping that either The Specialists (the car audio place) offers at least a one year manufacturer warranty and will cover the sub(s) as I've had them for less than a year or at least Rockford Fosgate themselves. I've never had this issue before and prior to my P2's, I was pushing 2 x 2" Kicker CVR's on the same amp for well over 2 years with CCA wires which was my very first car audio setup. Anyway, I will be looking into a bigger amp soon because I want my subs to get what they deserve.

I went ahead and purchased the Fierce FGT-20 negative dual input ground terminals. I was able to find someone selling 2 for $6.88 which was cheapest compared to everywhere else they were being sold. I do remember a while back I was looking at the one by Kicker but never got around to purchasing it then eventually forgot what they were called. Question regarding the ground terminals, do I just drill it straight to a cleaned off area of my chassis then connect the grounds from the amp to the block?
 
  • Like
Reactions: ThxOne

ThxOne

AudioFreak
Jun 8, 2018
1,039
178
Saint Marys, GA
@ThxOne You've been nothing but good help my man. I am hoping that either The Specialists (the car audio place) offers at least a one year manufacturer warranty and will cover the sub(s) as I've had them for less than a year or at least Rockford Fosgate themselves. I've never had this issue before and prior to my P2's, I was pushing 2 x 2" Kicker CVR's on the same amp for well over 2 years with CCA wires which was my very first car audio setup. Anyway, I will be looking into a bigger amp soon because I want my subs to get what they deserve.

I went ahead and purchased the Fierce FGT-20 negative dual input ground terminals. I was able to find someone selling 2 for $6.88 which was cheapest compared to everywhere else they were being sold. I do remember a while back I was looking at the one by Kicker but never got around to purchasing it then eventually forgot what they were called. Question regarding the ground terminals, do I just drill it straight to a cleaned off area of my chassis then connect the grounds from the amp to the block?
Yes, remove the paint to bare metal, clean off the bare metal with 91% rubbing alcohol or suitable cleaner then bolt that baby down tight with self tapping screws. Just make sure it's a flat surface so that it makes the most contact. That listing, I did the same one a long time ago. Make sure they send you two blocks because that sounds like the same eBay listing I got mine from. They sent one then argued with me about it then eventually sent me the second. If it is the same listing and they didn't fix it, make sure you get both because they are usually 1 for that price.

I say "bigger" amp so that you have more headroom... more available power on tap. Once you have this, you can push the same power you are pushing now but with far less distortion going to the speakers which means, typically, less chance of blowing them. Keep in mind that if you are using a 1000 watt amp on two subs that handle 400w rms such as those P2 12's do, does not mean you are giving them 1000w or 500 to each sub. They will be getting much less during normal listening which is why most people will try to add bass by using loudness, or bass boost or some kind of bass enhancer be it an eq or whatever. So let's say during normal listening with music they are getting 275 to 300w each during peak bass notes... that is under their rated RMS power. Now let's add the bass EQ on the amp which should boost bass at 45hz. Sounds pretty good, it is making more bass, you are happy. Ok, maybe there is a sub control on the head unit... let's turn that up a bit too... ok, a little louder now. What you don't see or may not hear is that bass signal that was clean at one time is probably now clipped causing inaudible distortion because you have added gain to the signal by boosting the bass. It may take a while but it will eventually, sooner or later, melt some copper coils in your subs.

When you have that new amp (a good rule of thumb is twice the rated power of your sub(s)) You can set the gains properly with all EQ's flat and no bass enhancers on and with any remote bass knobs maxed out( all the way up). Set the sub amp gain with a -10db test tone. Once all that is set up and done, turn the remote knob all the way down, hop in the car and play some of your favorite music. Adjust your bass on the head unit. Now adjust your bass knob. Enjoy CLEAN power from your amp. There should be NO need to use loudness or any bass boost, be it in the head unit or on the amp.
 
OP
M

mobbdeep

Member
May 5, 2015
46
2
Tucson, AZ
@ThxOne Thank you for all of that information. I'm going to bookmark this thread for when I buy a new amp. On the flip side, I took my car in and got it looked at. They used the meter to test the subs and definitely confirmed one of them was completely toast. The installer literally blew air from his mouth across the subwoofer and you can see the numbers spazz on the meter. Good news is, I'm getting complete replacements on both of them since I was still within the one year warranty. The installer did find that there was loose connections inside the box where the speaker wire connects and was thinking that all the power was being pushed from the amp across the subs causing one of them to receive all the power and essentially burn out.

Anyway, I am going to be hooking everything back up with a better ground so let's hope it all works out.
 
  • Like
Reactions: ThxOne

ThxOne

AudioFreak
Jun 8, 2018
1,039
178
Saint Marys, GA
No problem. On a different note... After my sister blew my Punch P2 12", I decided to get a Punch P3 10" sub. I am running it on a RF Prime 1200-D amp at 2ohms. Hits just as hard as the 12 did and shows no signs of ever giving up. The Alpine was the same as yours that blew my 12. 1000w rms @ 2ohm. Now I am running a 1200w amp but it is only pushing 6... maybe 650w peak to that lil sub on really loud signals. I can only imagine two Punch P3 12's with a 1500w amp... food for though.
 
  • Like
Reactions: mobbdeep

Create an account or login to comment

You must be a member in order to leave a comment

Create account

Create an account on our community. It's easy!

Log in

Already have an account? Log in here.


Users Who Are Viewing This Thread (Users: 0, Guests: 1)



Latest posts

Trending topics

Latest classifieds