# MTX 500d problem.



## NonSenCe (Jun 4, 2011)

ok the old d class amp i got, mtx 500d. it seems to be missing lot of power. it sounds more like 50-100w amp than +500w amp. 

i need to screw the gain pretty much all the way up to get just something out. seems like nothing happens when i turn it for first 50% of the turn. 

didnt need to do that in old system.. i always leave the gains etc settings "as they were" when removing the amps (makes re installation easier, as i normally do intend to put them "right" back.. hahah). this time it just took me good 6-7 years or so. 

so gain wasnt more than 1/4th open originally. and i know my old alpine h.u. still should have better pre out voltage than the old kenwood it was used on before. (if my memory is correct the alpine has 4.5v in sub channel and 1.5v on others.. kenwood had maybe 0.5v) and still with gains up i still need to turn the dreaded bassboost to make the cone move atleast some.. (yeah cone is more like vibrating..not really moving back and forth) 

tried it with peerless xls10 and hertz hx300d (both also decade old stuff) 

and on top of that there is a whining noise that comes out of my subwoofer. it happens when it is on, can be heard with music turned down, and the car is not running (so not alternator whine).

that whining part of it, might be shoddy installation (rca wires are run near power wire and are coiled into a loop) 

amplifier does dim slightly the lights of the headunit (wired it also temporarily out of same power distrubution block) when it tries to make music.. so it does seem to take the juice but output is pathetic. 

but the powerloss i dont know what gives.. 

rca wires are bad? they are old and used, in atleast 2 different cars earlier, but some 10 years ago last time. did check that they do have about correct resistance between middle prong of the race and the outer shell when connected to the headunit. 

the power wire is big enough and so is the fuse (200a). ground wire is big and short, but it might be having a bit weak connection. (but not that weak that it would take ALL the power) just installed under the bolt that holds the safetybelt. not cleaned the paint etc. 

-no other amplifiers in the system. just the headunit.. with new 100ah battery. 

so im thinking maybe something in the amp is shot? -but what problem would cause it to still run somehow but with lot lower output? just the gain screw beeing broken off somehow? some capacitors leaking inside? what?

or is it just my over 10 year old headunit that somehow has lost its mojo while sitting in dusty garage shelf for last 3 years.

or combination of it all, old and untested equipment with quick n dirty install with somewhat shoddy wiring job.
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hate winter. too cold to do anything outside. thats why whole setup is just thrown together.


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## armyvet (Mar 15, 2013)

try and wiggle the rcas.sometimes if the rca solder is cracked on the board this will happen.it wont always jack hammer or make subs act funny when a rca is shorted out.this happend on a 1000d of mine.resolderd a rca bung to the board problem solved


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