M100 setup problems

[rsweet1]

Hello, so i bought a used m100 to power the 4 polk speakers in my doors. I planned on using 2 speakers per channel to give them about 125w a piece. When i hooked the system up, i hear static at low volumes and clipping at higher volumes. My HU has 4 4v preamp outputs so i used 2 y splitters because the m100 only has two inputs.
What sounds like the problem? i also changed the caps in the m100.
could it be the preamp voltage? thanks,
ryan

[todd217]

first you dont need the y spliters. does both sides of the amp do the same thing?

[kg1961]

yes it only a 2 channel amp so you only need rca on the in area
you should not and don't need it in a line out.
also 4 volt can make it clip but if you have the gain set right you should be fine
this is a great amp but did you check it before you changed the caps?

[tonym]

he said he changed the caps.....did you check it before you changed the caps?

[rsweet1]

no i never tested it before i changed the caps... they were leaking very badly....the y's take the four preamps from the pront down to two for the back .....i guess it isn't really necessary since the front and back preamps will show little difference anyways.

[waynehead]

yeah you dont want to do that either, thats probably the source of all your problems, You have two seperate signals fighting each other. remove the y cable and go straight from the front outputs of the deck and into the amps inputs.

[rsweet1]

ok so i changed the preamp wiring....from the pioneer head unit i have 2 preamps that are connected to the M100....at half volume with no gain the amp is distorting....i'm running 4 gauge wire to it and it has a solid ground..and the digital capacitor display reads 13.8V, so i know it isn't the charging system....there is no noise at low volumes so its head unit interference....caps have been changed......am i missing anything or is the amp toast?

[Eric D]

If you Y-cabled the 4 outputs of your head unit down to two, I would not be one bit surprised if you damaged the head unit by doing this. The amp will amplify what ever signal it gets, so if it sounds good at low volumes, it should still sound good at higher volumes, unless the input signal is what is distorting.

If your head unit has a 4V output, you should have the gain all the way down on the M100 (which you do from your above description), and you will get full output from the amp just prior to full volume on the head unit. The amp may start to clip with a 4V signal, but it should not be very audible with music.

[rsweet1]

well i took the y cables out, and it still distorts at about half volume.....how can i see if the head unit is damaged? .....the amp distorts so much at good listening levels that i don't even use the radio...its does the same thing even when it powers speakers in 4 ohm configurations..

[Eric D]

You need to try a different amp. Maybe a friend has one?

Do you have a 12V power supply? Even a small one from a computer would work. If you don't have an amp, you can run your head unit inside your house on a 12V supply, then feed the RCAs into a computer, or home receiver, so you can listen to them.

[rsweet1]

ok so i used a different reciever in the car and it did the same thing... i even ran an extra ground just to be positive that it wasn't poor wiring.... do you still do repairs? this is the second m series that i have bought in "great condition" that have been mysteriously broken....the other is an m50

[Eric D]

So both channels on it are distorted then? Do you have a fuse holder in line with it? If so, can you put a 10A fuse in it and let me know what happens? Just keep the volume low and turn the amp on.

[rsweet1]

i have a 100A in line because i was planning on building a full system....i removed that fuse and put a 15a in (i didn't have a 10a)...started it and nothing different happened this time...but i also have a capacitor...should i drain the capacitor first? what does this test?

[Eric D]

Well, sometimes when the amp sounds distorted an output transistor may be shorted, or partially shorted. If you put in a 15A fuse and it blew right away, that would indicate to me there was something seriously wrong with it. Since the fuse did not blow, the issue may be more preamp part of the amp related. Or even in the on board crossover.

Did you try running it full range to see if the crossover is to blame?

[rsweet1]

yeah i don't use the crossover on the amp, i use one in the head unit...but after testing it there is no difference which crossover i used....hmm well when i changed the capacitors in the amp, i didn't notice any burnt components or solder.

[tonym]

damn that suxs....hope you get it working

[rsweet1]

ok, new question....could it be the power caps? i checked them, they aren't leaking, but i never changed them. Could they potentially be causing the amp to put out low power to the speakers causing the clipping??.. if so what caps would you recommend? i have some 10,000uf 35V....will they work? if it is the output transistors, i'll have to find someone to repair. i just don't have a way to desoldier effectively, nor do i have good knowledge of the amps....

[Eric D]

I really doubt it is the caps.

I am willing to work on your amp, but it would be some time most likely. I am busy right now and I have a lot of other amps to fix first.