# JL 300/4 Low Ohm Light?



## quiXilver (Jul 21, 2008)

I saw a JL 300/4 amp on ebay but the guy said the "Low Ohm Light" was on when he removed the amp from his car. Anyone heard of that or what it is?


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## rc10mike (Mar 27, 2008)

Probably had something lower than 1.5 ohms connected.


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## JeremyC (Dec 20, 2007)

That or the wiring was screwed up, or the speaker was blown showing a direct short to ground. 

Either way, beware.....


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## kyheng (Jan 31, 2007)

Change to other speaker and test again before conclude anything....


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## JeremyC (Dec 20, 2007)

kyheng said:


> Change to other speaker and test again before conclude anything....


It was on ebay, for sale. The guy selling it said the light was on when he unhooked it.


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## chad (Jun 30, 2005)

Manville can prtobably answer this but I would suspect that light comes on when "the other" rail voltage is selected by the amp's sense circuitry.


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## Oliver (Jun 25, 2007)

quiXilver said:


> I saw a JL 300/4 amp on ebay but the guy said the "Low Ohm Light" was on when he removed the amp from his car. Anyone heard of that or what it is?


I believe they are rated from 1 to 4 ohms of resistance.

Music causes the impedance to go both up and down.[ at fs the impedance can be in the high 50's ],{ at other times the current running through the amplifier can be excessive }

Lights I've seen that are important 

1] power
followed by all the other ones 

power light = good

Some of the other ones let you know if you have made a "Boo-Boo"


This may be helpful

quote>

!
If you connect a load higher than 4Ω nominal per channel in stereo mode (or 8Ω in bridged mode), power will drop by half with every doubling of impedance above 4Ω stereo / 8Ω mono. If you connect a load lower than 1.5Ω nominal per channel in stereo mode (or 3Ω in bridged mode, the amplifier protection circuitry activates a “safe” mode which reduces amplifier power to protect the circuitry from failure (the yellow “Low Ω” LED lights to indicate that this has happened). See page 10 for details.

quote>

http://mobile.jlaudio.com/products_amps.php?amp_id=437


It's from a site called JL Audio


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## guitarsail (Oct 12, 2007)

a$$hole said:


> It's from a site called JL Audio


Haha


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## msmith (Nov 27, 2007)

If the yellow LED lights with no speakers connected, the amp is broken (bad output FET).

Don't buy it unless you can budget $120.00 for repairs into the overall deal.

Manville Smith
JL Audio, Inc.


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## chad (Jun 30, 2005)

msmith said:


> If the yellow LED lights with no speakers connected, the amp is broken (bad output FET).
> 
> Don't buy it unless you can budget $120.00 for repairs into the overall deal.
> 
> ...


OT but is 120 a flat rate for all JL amps or that one or a flat rate at all? JUST IN CASE I NEED TO KNOW :blush: Sometimes things happen


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## msmith (Nov 27, 2007)

chad said:


> OT but is 120 a flat rate for all JL amps or that one or a flat rate at all? JUST IN CASE I NEED TO KNOW :blush: Sometimes things happen


$120.00 is the flat rate for the 250/1, 300/2 or 300/4

$180.00 is the flat rate for the 450/4, 500/1, 500/5 and 1000/1

Return shipping is included in the price (Continental U.S. only, additional charge outside of 48 states)

The flat rate covers all functional repairs (not cosmetic repairs).


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## chad (Jun 30, 2005)

Thank Manville, I have a 500/5, if you nuke an amp "like a pro" 150-180 bucks really is not that bad for parts + labor, some of those FETs ain't cheap!


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## msmith (Nov 27, 2007)

chad said:


> Thank Manville, I have a 500/5, if you nuke an amp "like a pro" 150-180 bucks really is not that bad for parts + labor, some of those FETs ain't cheap!


Yes, it's usually a good deal, sometimes we make out ok if it's one FET and a couple of resistors or caps, but in many cases the flat rate really works to the customer's benefit.


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## Oliver (Jun 25, 2007)

JL made those as close to wormproof [ oil field saying , think I dee ten tee proof ] as any amp you are gonna see  !


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## quiXilver (Jul 21, 2008)

Ok, thanks for the replies. I have a friend I'm getting one from locally at a better deal anyway. This way I can just go cut his head off if it doesn't work right.


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