audio gurus, I NEED help-- this one stumped even me...

[Jando86 10+ year member]

maybe the amp can't handle 2 different loads?

perhaps.

my fader was all the way to the rear if it matters. fronts are diamond hex 4 ohm.

 

[Jando86 10+ year member]

fuck you and your ava. It is 2A.M. and I want some noms!!!!//content.invisioncic.com/y282845/emoticons/furious.gif.fc81ca146dbff91fede3ed290dbc4f4c.gif

its never too late to eat meat //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

light da grill boy! //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[KyleBechtold 5,000+ posts]

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two 2 ohm speakers, one on left, one on right in the rear (independent channels). that makes a 2 ohm stereo load.

also, it smelled like delicious bacon //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

actually couldnt get a good wiff...

i am thinking it is the mixed loads.. but i am no amp guru

 

[tomtomjr 10+ year member]

I was an audio repair tech for years. Here is what I used to see a lot of...

When you hooked up the speakers, it sounded fine for a minute. My guess is that your ground wire came loose, or had a bad connection. When this happens, it uses the ground from your RCA's. Will work for a short time. Kind of ... Then it burns the traces to the ground of your RCA input inside the amp. Or will fry the op-amps (8 to 14 pin IC's in the amp) . Open the cover, and around where your RCA's are you might see some burnt traces. Then again, it could have smoked the power supply, output *****, ect...

Saw a lot of this when either changing speakers, moving the amps, installing the amps, ect.

Another thing that can cause it is short on the wires going inside the speaker itself. The bare wires touch that go to the cone itself. That would cause an issue too. Bass hits, bare wires touch = shorted subs...

My 2cents...

 

[Jando86 10+ year member]

thank you Tom for that,

it seems the ground issue is a definite possibility, however everything works fine with 4 ohm speakers on all 4 corners.

the issue is with the 2 ohm speakers. only when I begin to raise the volume does the amp short out- it did this repeatedly till I swapped back the 4 ohm coaxials. I think i just have a crippled amp //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[IDSkoT 5,000+ posts]

It's a feature.

I was an audio repair tech for years. Here is what I used to see a lot of...
When you hooked up the speakers, it sounded fine for a minute. My guess is that your ground wire came loose, or had a bad connection. When this happens, it uses the ground from your RCA's. Will work for a short time. Kind of ... Then it burns the traces to the ground of your RCA input inside the amp. Or will fry the op-amps (8 to 14 pin IC's in the amp) . Open the cover, and around where your RCA's are you might see some burnt traces. Then again, it could have smoked the power supply, output *****, ect...

Saw a lot of this when either changing speakers, moving the amps, installing the amps, ect.

Another thing that can cause it is short on the wires going inside the speaker itself. The bare wires touch that go to the cone itself. That would cause an issue too. Bass hits, bare wires touch = shorted subs...

My 2cents...

No subs. Just speakers... and it smoked by the RCA's, says OP. I'd have to assume it's probably a bad ground, and the lower resistance load is making the amp look for a better ground...

 

[tomtomjr 10+ year member]

If you have smoke, there is a problem. Open up the amp and see what you can find. An amp can play even though it has some burned components. This will tell you what the problem is for sure. Or have someone else open it if you don't feel comfortable taking an amp apart. Has to be someone with a little knowledge of electronic basics... Then you will know for sure what the problem is...

 

[Jando86 10+ year member]

so lets say you have about 3 ft of 1/0 , one end grounded to chasis other leading to distro block.

then you use that block to ground your two amps using 4 gauge, say another 2-3 ft of that for each amp. This all equals bad ground correct??

 

[wesl56 10+ year member]

so lets say you have about 3 ft of 1/0 , one end grounded to chasis other leading to distro block.then you use that block to ground your two amps using 4 gauge, say another 2-3 ft of that for each amp. This all equals bad ground correct??

ehhhh not necessarily if its all good and connected properly... but ideally your ground wire should be as short as possible...

 

[snakeye 10+ year member]

figure it out yet?

 

[Jando86 10+ year member]

its the amp. i swapped it out for a smaller jbl (cs60.4) and it works beautifully with the mixed impedance. i guess my power series amp is only 4 ohm stable now. any one wanna buy it?

 

[Jando86 10+ year member]

4 years ive been running my px300.4 JBL amp I've gone through thousands of $$$ in audio; this game is not new to me but I am open to learn.

amp:

4x125 @4 ohm

4x 170 @ 2 ohm

CEA rated.

today i went to install 2 ohm speakers in the rears. some 8 inch jbl coaxials i bought in the UK.

they sounded AWESOME for all of 1 minute, then all music cut out, a high pitched twisted squeal was heard, the the amp started to smoke by the RCAs. volume input did nothing. I killed the amp by turning the radio off. I thought the terminals might've shorted, but this was not the case as they were well wrapped in E-tape.

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i replaced the speakers with 4 ohm speakers and it worked fine again after the smokefest. Whats causing this if my amp IS 2 ohm stereo stable?

PROBLEM SOLVED! apparently not enough E-tape! the terminals were grounding to the chassis just as I suspected. the amp now works fine even after all that abuse! I love it!!!! weeeee

 

[Jando86 10+ year member]

its the amp. i swapped it out for a smaller jbl (cs60.4) and it works beautifully with the mixed impedance. i guess my power series amp is only 4 ohm stable now. any one wanna buy it?

Design differences in both amps caused the smaller JBL amp to work even with shorted terminals in the speakers. This is why the PX300.4 smoked and the cs60.4 worked (although with engine noise). gotta love the DMM!!!