SOULMUSIC

iTrader: (8)

2k memphis mojo - 1- 1500wrms 2ohm dvc
We went for a long ride the other day, after a couple hours of driving and bumping, we came to a stop at a light, turned it down as ussual.
When we started moving, I turned it back up, just as we hit the volume we usually play at, a VERY loud distorted sound came from the sub, almost like I had turned it up full bore and burped it!!
WTF!! We quickly turned it down, pulled over and checked things out. The subs were not hot , so it wasn't them I guessed. The amp was warm, not too hot though.

So after we checked things out and came up with NO ideas, we continued with the volume down.

So we can turn it up to say 3/4 of normal and it sounds perfect, then when we reach a higher volume level the "burp" comes back.

We switched out the sub and got the same "burp" from it

Any ideas?

AyZe

Did ya check the ends of rcas and all wiring? i had a rca get hit by trunk hinge once and it did somthing similar sounding.

SOULMUSIC

iTrader: (8)

We did check the RCA's for tightness but not for possible contact during movment. Its on the check list! Thanks

Another thing I'm wondering, for whomever is reading... I do not know amps any more than the basics so if this sound dumb, you know why..

Is possible to blow one part of the amp( a mosfet of something similar) in a way that it only effects performance at higher output levels when that part becomes active? Like say , the last mosfet in a line?

SOULMUSIC

iTrader: (8)

bummer, not the RCA's . Good tight connections, not close to any metal at all.
I am replacing a couple "too long" RCA's when the new ones come in. If it is possibly still a problem with them , I can swap them out as a test soon.

?????

Father Yuli

iTrader: (17)

are the subs going out of control when this happens?

SOULMUSIC

iTrader: (8)

Don't think so, no extra excursion at the point where it distorts, if that's what you mean. Whats you're idea bro?

Another thing we just tried is a little confusing too

The decks volume number go to 40 , the other day before the problem first happened we were running the HU at 32-33 max.(settings flat or - db only ). When it did first happened, the distortion would happen at 29 or 30.
So last night, We turned the gain down a measurable amount and the distortion is still happening at the same point, 29-30, only not as loud now..

Don't know what it means, but its more info anyhow.

DeadlySones

iTrader: (4)

Is there any DC voltage on the speaker outputs? Take a reading with the volume low, moderate, and finally when it is "burping", lol. Post both the A.C. and D.C. readings at 3 levels.

Does the amp suddenly pull crazy current when this occurs?

I would not recommend putting the amp into that state too much until you find the problem. Try to have someone help you to get these readings so the "burping state" is at its minimal time frame. If an output transistor is open (or intermittently) or worse yet shorting and sending full voltage to rail, this could pop stuff very quickly. That amp should run properly at low volume with a 15amp fuse. If it blows a 10 amp fuse with no speaker attached, there is something wrong that needs to be addressed.

Also, do you get the same readings with and without a speaker load connected? Where is this amp mounted in your van?

Father Yuli

iTrader: (17)

sounds like deck output is dying

SOULMUSIC

iTrader: (8)

WOW, it was an easy fix on the first reading. No need to list anything. The cause took us a while to figure out. Its a ummm!!

Sooo. Using a 45hz tone (about our peak) The output at the speaker terminals with the deck on 29 was 56+ volts!!! WTF!! It was set at 40v (or about1600w) at deck setting 33 just a few days ago!! Thats way odd.

Well, I go to turn down the gain yet again, but I can only move it a millimeter !!! Down to 54v..
OK So I have to turn down the linedriver , which is now installed out of sight, back behind the side plastic panels along with the crossover , 2nd battery, and bundled RCA's.

A quick check and....whoa!! the linedriver with the HU at 29 was giving 5 volts to the sub amp, NOT where it was set!!

Well look at that!! The "extra too long" RCA , a 20 footer I had bundled and tucked away near the linedriver was now sitting on the face/dial. What a crappy installer,
So I turned it down and secured the rca better.. Set the amp gain/HU at 40v and there we go, no problems

So as sad as it is, the only explaination I have is this...
....My crappy install skills and I, left RCA's bundled up and unsecured, hidden behind panels that we never look behind.
- Wires came loose at some point while driving. Then when we stopped at the lights, the RCA's( a 20ft bundled for 5ft) slides forward, turning the linedriver up, clipping the crap out of the amp signal!!
Then-
It must have shifted and moved the dial again last night. That would explain why even after turning the gain down some, it was still producing the problem at what we thought was the same level.

So if that wasn't the problem, then the problem fixed itself for now.
Thanks for the help guys. Feel free to bash me a touch

Father Yuli

iTrader: (17)

feel free to bash me hahahahaahahahah

dont think you need a line driver unless u are running a crap load of amps