Low amp output even with gain at maximum. Running out of options

[ModifierMR]

Hey all, Question for you guys:

I have a subwoofer and amp setup that i have had in 3 different cars now. In my past two vehicles the woofers slammed, and sounded great. On my current vehicle however I have run into problems.

Issue: The output of the amplifier is very low. The gain has to be maxed out in order to obtain even a low level of bass, but nowhere near what they should be. The Rear/Sub output is set to Subwoofer, the sub level is set at 80hz +4 (out of 6). The phase is set to Normal.

I have an old MTX Thunder 6500D amplifier hooked to two 12" MTX Thunder series woofers (newer woofers). This setup was in my old car and worked great, the only difference between my old car and new one is I bought a new head unit.

I have tried, different woofers, a new RCA cable, and all the possible settings on the HU. I have even opened the amp and inspected both sides of the PCB for any heat damage, or missing components. I have found nothing wrong.

I installed everything perfect, Nice big ground thats bolted to a bare metal area of the chassis. Upgraded the car's chassis and engine grounds, and used 4 gauge wiring to the amp. The RCA's are brand new, and the headunit is also brand new (pioneer DEHX5500HD). I have been doing installs since i started driving (10 years now), and have never had this much trouble with an amp setup.

The only thing I have not tried is a different amplifier. I dont have one handy so im trying to cover all my bases here before i go out and spend money on a new one. Any ideas or tips would be appreciated!

Click to read more...

 

[basswiigee]

whats the v output from headunit?

 

[Jes 42 10+ year member]

Did you try another hu?

 

[CrossoverOre 10+ year member]

out of phase?

 

[tc300 10+ year member]

Sound more like an wiring issue... Check the subs wiring

 

[ModifierMR]

whats the v output from headunit?

Using a DMM I checked the voltage coming from the RCA Cable, its next to nothing. (under 0.01v)

Did you try another hu?

I am going to try that next, I have an extra one laying around. I'll just hook it straight up to power and see if anything changes.

out of phase?

Everything is wired in phase. The settings on the HU are set to "normal"

Sound more like an wiring issue... Check the subs wiring

A while back I had a this same issue with this amp, but different subs. I found out that the spade connectors of the wires going to the sub (inside the box) were corroded and not making good contact. I ended up soldering the wire directly to the terminals of the sub. And that worked, the subs hit nice and hard and the amp worked as normal.

However, I tried that with these new subs (which worked fine in my prior vehicle with same amp), and after soldering the wires to the terminals, I got no change. I am pretty confident that the wiring from subwoofers to the amplifier are solid.

 

[basswiigee]

swap head unit if that don't work, start looking into wiring!!!

 

[ModifierMR]

I swapped the headunit with a cheap boss head unit I had, it made no difference. A friend of mine let me borrow his amp. Its a little more powerful Alpine MRD M1005. The gain didnt have to be turned as high as the MTX but it was still at 0.3v setting for sensitivity. Its working pretty good now, but its not very quality, its kinda lacking, Hard to put my finger on it. (i mean this same setup used to slam with the gain turned almost 1/4 the way down).

Ive already replaced my RCA cable with a new one, My ground goes to a bare metal chassis bolt (cant get much better than that IMO). And my power supply wire is solid as well. Battery terminals are clean, new chassis and engine grounds.

The only thing I havent tried is a HU rated for above 2v. I have an old 8v eclipse deck laying around I might try. But I just cant get over how this brand new out of the box Pioneer has such a low pre-out level. Im going to measure the voltages at the preout connectors on the back of the HU tomorrow to rule everything else out.

 

[jrdnhsnbrg 10+ year member]

I guess if all else fails pick up an inline converter. I've never had to use them but when my dad had a subwoofer installed professionally in his car (2010 Lincoln MKZ- I wasn't about to tear into the dash of it) they used them. He had to keep the factory HU because it's a big touch screen with navigation. The one thing that really shocked me was the fact that they used 0 gauge power and ground for a 150W RMS amp and sub.

 

[Side Show 10+ year member]

overkill is good lol

 

[robert420 10+ year member]

take the dmm to your power and grounding points both from the source and from the amp terminals. could be something failing there

 

[jrdnhsnbrg 10+ year member]

Ha yeah whatever works for them I guess... Funny though my system is 1200W RMS and I'm using 2 gauge. 8x the RMS wattage of his setup, yet he has larger wiring.

 

[Side Show 10+ year member]

easy system to upgrade when he wants a better system with more power

 

[ModifierMR]

take the dmm to your power and grounding points both from the source and from the amp terminals. could be something failing there

I did voltage drops and resistance checks on my grounds and power feed. They are checking out ok. Thats the thing that bugs me about this. Out of all my installs over the years, never once Did I have such a problem with getting output. Usually its always been ****** RCA's, grounding issue, etc. But on this car, absolutely everything checks out ok. Im starting to kick myself for leaving my old HU in my last car when I sold it. I would love to install it to see if it makes a difference. It was an older Pioneer Premiere with 4v preouts. My new deck is a Pioneer with 2v. I cant imagine it making that much of a difference in performance. Ive had plenty of 2v decks before.

Like I said, I am going to eventually get around to installing my 8v Eclpipse deck to see if that does anything. I will keep you posted.

 

[CrossoverOre 10+ year member]

get a new car?