PLEASE HELP! JL HD750 Mono amp not providing power/bass to 2 JLT10W3 Flat woofers?

[Trueduckfan]

I have a 2013 Chevy Silverado 2500HD Crew cab truck,

Recently had an enclosure custom built by pro shop who is a certified JL dealer and one of the best in the Northwest reigons or western US for two new JL 10TW3 flat subwoofers provided by the shop and a New JL HD750 mono amp that I purchased on Ebay with 3 yr warranty.

They also installed my Alpine INE 920 something double-din head unit a couple months prior along with a brand new pair of JL 6.5" C5 component speakers in front stage with my older Alpine MRV V-12 2ch amp to power them and run stock rears off of head unit.

All was well for the first couple weeks and bass was tremendous and almost overpowering at times unless I adjusted the bass output in the Sub level options on head unit. Sounded great 99% of the time though.

I noticed my projection headlights would dim at night going down the road when the bass hit so I installed a Red Top Optima battery and this fixed that problem and did a great job of maintaining pretty constant 14volts.

A few days later I was waiting for the bass to drop on a powerful song sitting in my driveway after I pulled in and the bass cut out and noticed for the second time within a couple days that the battery volt gauge dropped down to probably around 12v. Ever since then I cannot turn the volume up over about 7-8 (which is not loud by any means in my truck and is nowhere near the 19-24 setting I had been rocking out to) without the bass cutting out completey and the subs sounding like they are clicking cause they are missing power!!!

I felt around and gave the eyeball check around the mono amp for loose RCA connections or battery wire connection. So what Im getting at as far as question is:

Could my JL amp be bad or blown already?
Could the Subs be blown already? (I don't think they are cause they sound ok at very low volume level or atleast consistant bass which is trying to produce)


I might also add that the settings on my head unit for Xover settings are as follows: FRONT CHANNEL= cutoff at 100HZ, REAR CHANNEL= cutoff at 125HZ and SUB CHANNEL= cutoff at 80HZ which is what the shop initially set it up at when it was sounding great.

Please help if you can and feel free to request any other info you could use to diagnose.

Thanks!!!

[bryanATX]

Get a capacitor

[Trueduckfan]

Well the shop was finally able to get me in and diagnose this afternoon and turns out one of the brand new woofers is already blown!! Its the voice coil.

I had my JL w6's for about 15 years and only blew one of them one time and these things are blown after a week! But, it's all that monsterous power from the JL amp I guess and playing for long durations.

And by the way, those caps are only good for very short periods of play such as competition for lots of monsterous power. Once it sucks the power out of it you're back to battery only till it recharges or restores, so they're not good for long duration.

[bryanATX]

Used to be into that stuff and I always had one to combat lights dimming. Now im old ;)....glad you got it figured out but not glad about your brand new blowout. Warranty at least? ??

[Trueduckfan]

Used to be into that stuff and I always had one to combat lights dimming. Now im old ;)....glad you got it figured out but not glad about your brand new blowout. Warranty at least? ??

Oh yeah, atleast a year. JL is pretty darn good about there warranties if I remember right. And like I said, they usually don't blow out. Its really hard to blow one unless your just reckless and rip on it waaaaay to hard. They set up the amp according to my setup and there experience but never really played with it to make sure as they finished up the sub enclosure at end of a week and I came in on a Saturday morning for them to install it with the amp and I ended up picking up the two new subs that morning to make sure the sound was right for the set-up I had.

They couldn't quite build a box big enough for two of my older 10W-6's for proper airspace and talked me into the new ones that fit better and would do a lot better espeacially being new technology vs my old subs.