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Old 8th July 2013, 02:13 PM   #1
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Default JL 300/4 Problems any tips?

Hey fellow audio heads, I looked through some of the other 300/4 threads and didn't find a satisfying answer in there.

I have a JL 300/4 powering 4 JL c2 speakers in my car, when I hit some bumps in the road I get crackling and the front speakers cut in and out. I initially thought the speaker wires were loose so I tightened those down and doubled up on the copper. Later I realized when I touch the RCA cable for the front speaker the crackling happens. Before I spend half the day replacing my RCA cable, is there anything you guys can think of that would cause this? The RCA's are brand new and are good quality. The rear speakers seem to be fine.

More info that may be useful.

JL 300/4v1 4 speakers JL c2.
Mid grade RCA.
Amp is used but works otherwise.
No Low ohm light or thermal light.
Green power light is on.
All power connections feel solid.
Speakers started crackling several days after install.

One last question, can this cutting in and out of the speakers damage them?

Any help would be appreciated!
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Old 9th July 2013, 02:59 PM   #2
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One last question, can this cutting in and out of the speakers damage them?

**Yes, as it may be putting out some DC (tweeters are the first to go out).

I suggest opening the bottom panel and checking the daughter board, as it usually tends to separate from the main board...causing noise problems (mine was cutting on and off).

If this is the case, I suggest using a 3/8 fuel line (hose) and cutting it about 7/8" and placing it on the daughter board, once you place the bottom panel it will hold the hose and push the daughter board against the main board. This solved my issue and since then I've done it to several slash amps. The V2 version doesn't require this mod as they are screwed on.

While your inside, check all the legs/pins of all the transistors mounted on the heat sink as the rectifiers legs may break. Oh and with the amplifier's power hooked up check to make sure all the pre-amp boards have all 3 LED's on. If any of the LED's are off then that may be the issue.
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Old 9th July 2013, 05:16 PM   #3
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Okay so you're saying I should use a piece of tubing to squeeze the smaller chip onto the larger chip with the cover panel of the amp? I guess that would keep it from moving around on the bumps.. Thanks!

Any particular reason to use fuel line? Or anything soft and heat resistant would work of that size?
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Old 9th July 2013, 06:24 PM   #4
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Quote:
Originally Posted by Aleksrussian View Post
Okay so you're saying I should use a piece of tubing to squeeze the smaller chip onto the larger chip with the cover panel of the amp? I guess that would keep it from moving around on the bumps.. Thanks!

Any particular reason to use fuel line? Or anything soft and heat resistant would work of that size?

I suggested a 3/8" fuel line because it will be stiff (since length is 3/4-7/8) and has great thermal properties. It can even be a 1/4 fuel vapor line, as long as its stiff enough to hold down the daughter board without bending.

Like I mentioned, while your inside the amplifier...check the transistors on the heat sink to make sure all their pins/legs are good. I once received a JL slash amp with two rectifiers legs open (middle leg).
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Old 11th July 2013, 12:11 AM   #5
RiLoWa is offline RiLoWa  United States
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One thing I experience with this series of JL Audio amps is the center pin connection doesn't always "clamp" tightly on my RCA ends. This has been especially true for me on amps that have been plugged and un-plugged alot and it didn't matter on $.99 cables or $200 cables. You may need to "adjust" the clamping force on the center of the RCA jack in the amp.
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Old 11th July 2013, 05:14 PM   #6
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^^^ Very true, I didn't mention it, but its very possible.
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