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I dont understand my subs

 

Silver Member
Username: Nevertoomuchbass

2 Fi Q 12s, Mmats 3000.1

Post Number: 333
Registered: Aug-10
Okay ive had a couple Fi Q 12's for a couple years now, and up until last month I loved them. But last month, somehow I managed to blow one voice coil in each of my subs almost simultaneously. At first, I thought I just blew one. I had wood cut for a single 12 box in my garage so I threw that together, but the assumed good sub in there, and it did nothing. after i found out it too had a bad voice coil, I just said to hell with it and hooked my mmats 3000.1 to the good voice coil at 1 ohm. Ive been beating the crap out of it for almost a month now with no issue whatsoever.
 

Platinum Member
Username: Glasswolf

Columbia, South Carolina America

Post Number: 14671
Registered: Dec-03
test the coils with a VOM or DMM to see what the DCR is on each one for both subs. Typically if a coil is damaged, it's caused by the amplifier clipping, which is typiucally a result of one or several of the following:
-insufficient power wire gauge
-bad ground
-amplifier gain/input sensitivity being set too high (most common)
-insufficient current caused by an inadequate charging system (need bigger alternator, also somewhat common with big systems)

Also make sure none of your connections are loose or otherwise compromised, not just the ground points.

grounds should be made to sanded metal chassis points, not a seat retention bolt, or an existing screw into painted metal.

contact Fi and see if they'll repair the subs for you.
 

Silver Member
Username: Nevertoomuchbass

2 Fi Q 12s, Mmats 3000.1

Post Number: 337
Registered: Aug-10
Only thing I could think it was is the ground. It was a little bit loose. But I snugged it up when I put the single 12 back in. My gain stays at about 3/4. Frankly im more amazed the one voice coil is taking the 3000.1 as well as it is. I know fi does repairs but shipping is so damn expensive id be better off gettin a psi recone and takin a hack at doing it myself
 

Platinum Member
Username: Glasswolf

Columbia, South Carolina America

Post Number: 14673
Registered: Dec-03
is the gain set by ear? the best way to set it is using a meter so you know the voltage is correct and not overdriving the input stage of the amplifier, which easily elads to clipping and thus increased heat to the coil(s) and then damage.

That bad ground could easily cause the same problem, as without a very solid ground, current flow is severely limited, and the amp will again, clip.

Heck I've had cars refuse to start or even turn over simply because one of the battery terminals was "slightly loose." after a battery change, or work on the car requiring that I disconnect that terminal. That's how important a good connection is.
 

Diamond Member
Username: Wingmanalive

Www.stainles... .ecrater.com

Post Number: 25448
Registered: Jun-06
Yup. Indeed. My terminals on my Dodge PU kept slipping due to (and I have no idea why) a tapered stud on the battery. Why ANYONE would design a battery this way I haven't a clue. Anyway, I was getting voltage problems showing up on my dash. Under the hood I could, with slightly more than light force, physically twist the terminals on the stud. THAT was my problem. Replaced the SNAFU battery with another and viola, all is good. The bat was aged anyway so a swap out was needed regardless.


To this day I still don't know why on Earth the studs were tapered.
 

Silver Member
Username: Nevertoomuchbass

2 Fi Q 12s, Mmats 3000.1

Post Number: 339
Registered: Aug-10
i set the gain with my multimeter, which isnt a great way to do it, but ive never really had the funds or motivation to get an o-scope, or meades new gain tool.

the terminals were fine, but where i have my trunk battery grounded to the body of the car, that screw was somewhat loose
 

Gold Member
Username: Joe1234

Post Number: 1476
Registered: May-09
How were the subs wired when it happened?
 

Silver Member
Username: Nevertoomuchbass

2 Fi Q 12s, Mmats 3000.1

Post Number: 340
Registered: Aug-10
coils in series, subs in parallel = 1 ohm
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