stereo amp question

[OneTonGoldfish]

I just put a small 200w 2 channel amp in my bronco. it is powering 2 6" speakers. When the truck is not running it all works perfect. When i start it and its running the amp turns on for about a min then off for about 2-15 seconds. It repeats this over and over. It seems like there is not enough power to run the amp while the car is running...any ideas on how to fix this?

btw, it has 8ga power and grounds which should be plenty and the amp/wires are not even warm so its not overheating

 

[Viperwolf1]

Where are the power and ground hooked up? You have higher voltage with the engine running, maybe too much for the amp? or maybe the ground is not good.

 

[Broncobowsher]

Sounds like a fault detect logic kicking in.
Check what voltage you have with the engine running? a bad regulator could send it off in an overvoltage safety logic.
The other would be harder to find, eletrical noise messing with it. I would start with keeping an eye on the turn on power wire and see if that is blinking on and off. That would point to a head unit issue more then an amp issue.

 

[OneTonGoldfish]

power ran directly to the batt. ground is about 1 ft long bolted to the firewall.

no head unit, ipod directly to amp via rca cable

where else could i connect the power wire so it changes the running voltage?

 

[Viperwolf1]

Measure the voltage at the battery with the engine running and compare it to the specs on the amp. The firewall may not be the best place for the ground. I'd recommend putting it closer to the battery. The ground wire needs to be as big as the power wire.

 

[OneTonGoldfish]

power and ground are 8ga. The non running volts is 12v, when its running its at 13-14v.

 

[daves bronco]

it looks like your voltage is good, amps will run form about 8 to 16 volts but 12 to about 15 is what they like. check your ground, but usually if it is bad the amp wont turn on, a little grinding or sanding of the area around it. sounds like the amp is going into protection mode. what are you using for the remote turn on. also what kind of amp is it, where is the set gain at, and can the speakers handle that, most amps are rated like this say 200 watts @12 volts and maybe 300 watts @14.4 (what your voltage should be at with car running) so if you have a good amp and the gain is all the way up instead of it sending 100 watts to each speaker that maybe handles 80 it would now be sending 150 which would trigger the protection.

 

[BuffDragon]

move your ground.
I started with mine grounded to the body and didnt work right.
I moved the ground to the frame itself, sanded off the paint and 35 years of yuck so it could get to bare metal and now its fine.

always start with your wiring and go from there.

my daily driver has 0 gauge running to the cab, then split to 4 gauge to the amps/capacitors. my bronco is running 4 gauge as well.
and dont skimp on your connectors either.

not saying you havent run it right, but I'd move the ground before you started messing with anything else. rule that out, as its a pretty simple fix.

 

[gtownky]

I also think the ground is the problem. Can you take the ground staight to the Battery?

 

[OneTonGoldfish]

i ran another ground directly to the batt; it did not fix anything.
I put another amp in to see if it was a problem with the amp itself....once it warms back up I will take it on a cruise to test it.

 

[daves bronco]

the ground should not be ran to the battery (to long ) your ground is fine on the fire wall as long as the metal is clean and the connection is tight. if you think about it the fire wall is welded to the body which is then connected by eight bolts to the frame and your frame is grounded to the battery

 

[70_Steve]

the ground should not be ran to the battery (to long ) your ground is fine on the fire wall as long as the metal is clean and the connection is tight. if you think about it the fire wall is welded to the body which is then connected by eight bolts to the frame and your frame is grounded to the battery

I've never heard that it's possible to have a ground wire that's "too long"!!?:?

It's true that there are eight bolts mounting the body to the frame, but the body mounts electrically insulate the body from the frame.

The frame may, or may not, be grounded to the battery. All depends on where the ground wires are run. Agreed that it should be, just doesn't automatically happen. Has to be done intentionally.

 

[daves bronco]

I've never heard that it's possible to have a ground wire that's "too long"!!?:?
.

one of the first things any car stereo installer learns and any amp installing book tells you is to keep your ground under 18" so unless you put your amp in the engine bay hard to go to the battery. other things in the truck are also ran this way.

 

[76 bronco J]

>>>>> for amp installs, I would suggest getting 4 gauge welding wire run to a distribution block in the cab ......the welding cable is much cheaper & mutli strand like the fancy colored high dollar dedicated car stereo stuff... the 4 gauge will be more than enough for 99.9% of early bronco owners ,I haven't needed anything bigger since the mega car stereo days back in the late 80's/early 90's... for the ground I ran 4 guage from the battery to the frame then a short piece from the distribution block to the frame.............

 

[OneTonGoldfish]

one of the first things any car stereo installer learns and any amp installing book tells you is to keep your ground under 18" so unless you put your amp in the engine bay hard to go to the battery. other things in the truck are also ran this way.

this is what ive also heard....but like i said I still had my short ground hooked up but I also ran another one from that directly to the batt

 

[OneTonGoldfish]

>>>>> I would suggest getting 4 gauge welding wire run to a distribution block in the cab ......the welding cable is much cheaper & mutli strand like the fancy colored high dollar dedicated car stereo stuff... the 4 gauge will be more than enough for 99.9% of early bronco owners ,I haven't needed anything bigger since the mega car stereo days back in the late 80's/early 90's... for the ground I ran 4 guage from the battery to the frame then a short piece from the distribution block to the frame.............

this 2 channel amp I am using isnt even 100w rms. I have my gain at about 60% as well. 8ga is PLENTY.

I just dont understand why it works 100% perfect at any volume level when the bronco is not running. (I listened to it for 20-30 min while working in the garage) then as soon as I start the bronco it starts acting up.

 

[BuffDragon]

>>>>> for amp installs, I would suggest getting 4 gauge welding wire run to a distribution block in the cab ......the welding cable is much cheaper & mutli strand like the fancy colored high dollar dedicated car stereo stuff... the 4 gauge will be more than enough for 99.9% of early bronco owners ,I haven't needed anything bigger since the mega car stereo days back in the late 80's/early 90's... for the ground I ran 4 guage from the battery to the frame then a short piece from the distribution block to the frame.............

is that an a/d/s powerplate in the picture?

 

[BuffDragon]

this 2 channel amp I am using isnt even 100w rms. I have my gain at about 60% as well. 8ga is PLENTY.

I just dont understand why it works 100% perfect at any volume level when the bronco is not running. (I listened to it for 20-30 min while working in the garage) then as soon as I start the bronco it starts acting up.

is the volume any different between listening in the garage and when its running? I had an amp doing that for while at higher volumes. it was an amp I'd borrowed from a buddy who'd taken it out of his boat (so "used"). turns out it had a short and when you started pushing it (ie higher volumes) it would start failing.
I was pushing it at 2ohms too, but point being, when I pushed the amp, was when it started screwing up.

here's what's presently in the back of my bronco
2 pairs of fosgate 6.5" boat speakers, run off 1/2 of a "D Class" 4 channel kenwood (2ohms)
the other half of the amp is reserved for a JL 12w6 I havent built a box for yet
yes, its very loud and surprisingly clear for 2-way speakers:

 

[OneTonGoldfish]

is the volume any different between listening in the garage and when its running? I had an amp doing that for while at higher volumes. it was an amp I'd borrowed from a buddy who'd taken it out of his boat (so "used"). turns out it had a short and when you started pushing it (ie higher volumes) it would start failing.
I was pushing it at 2ohms too, but point being, when I pushed the amp, was when it started screwing up.

here's what's presently in the back of my bronco
2 pairs of fosgate 6.5" boat speakers, run off 1/2 of a "D Class" 4 channel kenwood (2ohms)
the other half of the amp is reserved for a JL 12w6 I havent built a box for yet
yes, its very loud and surprisingly clear for 2-way speakers:

well if the bronco has been sitting for a while i can start it up and listen to it full volume for a couple min then it starts to act up at any volume. as soon as i kill the engine it works prefect at any volume. I am thinking its a problem internally with the amp

 

[daves bronco]

I would reset the gain the proper way. this is with the truck running, so the amp is pushing full power turn your head unit to 2/3 volume (ipod) and then start with the gain a 0 and turn it up until you hear distorion, turn back a little and good. another possible would be speaker wires may be when the truck is moving it is pinching the wire causing the amp to go into protection. plus really need more info like whats the rms of the amp, on it birth sheet if possible, and what kind of speakers and what is there rms.