# How friggin hot do JL Slash amps get ?



## UNBROKEN (Sep 25, 2009)

Just fired mine up. A 300/2, 300/4 and a 1000/1 and after 15-20 minutes they're so hot I can hardly touch them. 
What has me concerned is the maxi fuses in my distro block are getting hot too. I double checked all power and ground connections...all solid and tight all the way up to the batteries. 
I did blow a 60 amp maxi fuse on the 1000/1 but found the battery connection loose...thought it was a bad connection and that amp drawing a lot of current. 

Anyway...thoughts on that and exactly how hot these things should run?
They're in a wide open space right now. I reused all power and ground wires when I swapped amps and never had an issue before now.


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## severedthumbz (Apr 7, 2011)

u should have a 100 anl on the 1000/1


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## Blister64 (Jun 13, 2010)

Are your gains just completely maxed out? Idk man, but just for reference, I'm using 2 500/1v2's and have had them working pretty hard for over an hour and I can gold my hand on them no problem. They do get warm but wouldn't say hot. They are the v2's tho, not the v1's. Might be a difference


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## jmerick (Nov 12, 2008)

I have a 300/2, 300/4, and a 500/1 and when playing my system hard on a hot day I can touch them no problem. Gains up about half way on mine.


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## UNBROKEN (Sep 25, 2009)

Gains at about 1/2. Could t resist a quick listen after working on it for the last week. lol
Figured that fuse might be small but it's all I had. I'll look up the fuse ratings for all 3 and grab the right ones tomorrow. 

So if yalls stay cool...what'll cause mine to get so hot?
I'll set the gains with a DMM tomorrow...but they weren't too high I don't think...could be wrong. 
If it matters...I use 0/1 wire from a pair of 950 cca batteries to a block then 4 gauge to the amps. 4 gauge grounds bolted through the floor of the truck then under the truck to the frame. Been like that since 05 or so with zero issues.


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## UNBROKEN (Sep 25, 2009)

Correction...gains at about 1/3. Just checked. 
Could the fuses being too small act like a bad connection and cause them to overheat?
I have a 40 amp in the 300/2 and a 30 amp in the 300/4....neither of those fuses get hot.


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## sonikaccord (Jun 15, 2008)

Nope too small is good. It hasn't blown yet so you're amp isn't drawing excess current, but it is drawing an abnormal amount. Can you checking for voltage drop?


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## 9mmmac (Dec 14, 2010)

How are they mounted? If they are just smooshed into the floor carpet and screwed down, I'd bet they're goona get pretty friggin' hot because there's no real convective air movement. Try unscrewing them, and putting a piece of wood underneath them. Then elevate them off the wood 1/2 inch or so- legos work great for this. Amps always seem to run MUCH cooler if air can get underneath them. 

Pics? Always helpful...


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## UNBROKEN (Sep 25, 2009)

The fuse for the 1000/1 has blown. 
Measure voltage drop where? My distro block is a volt meter also...haven't seen it get below 13.8ish while I was playing it.


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## UNBROKEN (Sep 25, 2009)

9mmmac said:


> How are they mounted? If they are just smooshed into the floor carpet and screwed down, I'd bet they're goona get pretty friggin' hot because there's no real convective air movement. Try unscrewing them, and putting a piece of wood underneath them. Then elevate them off the wood 1/2 inch or so- legos work great for this. Amps always seem to run MUCH cooler if air can get underneath them.
> 
> Pics? Always helpful...


They're mounted on an aluminum amp rack. Pics in my build log thread here on DIYMA.


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## nutxo (Feb 24, 2008)

I run crossflows, they work pretty nice


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## UNBROKEN (Sep 25, 2009)

Got some fuses today and pulled the amp rack to double, double check the power and ground connections. I did find a very slightly loose ground which was the sub amp. 
I fixed that up and dropped an 80 amp fuse in. The guy only had one 100 amp fuse and I didn't wanna waste it. lol
I know...still not right but it was closer than a 60. 
Anyway...played it for about 15 minutes and popped the 80 but the amp was cool to the touch now. 
I'm not sure now about setting the sub gain with a PAC LC-1 level controller installed online for that amp. 
Started another thread about that in case this part goes unnoticed. 

So...I set it originally with the controller all the way down, put the amp gain at 1/3 then turned up the controller about 1/2 way so maybe I do have the gain set too high ?


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## JWAT15 (Mar 6, 2011)

this EXACT problem is happening to my BRAND NEW 300/2v2
Also happened to my 300/4v1...

and just to make a comparison... i run nearly 1500rms with my other amps combined and literally i drive for 2 hours straight cranked on the highway and they stay cool...

i DRIVE FOR 15 MINUTES WITH THE JL 300/2 AND I CANT EVEN TOUCH IT.. ITS SOO HOT...

if someone can help me out as well with this issue id be greatly appreciated. iv since removed it because i just cant run it anymore and it went into thermal..

yes iv double and triple checked all connections and fuses. 0GA DISTRO'D TO 4 GA ALL OFC 

fuse for the 300/2v2 is 60 amp
my sub amp 60amp

SOOO LOST. this has never happened to me in over eight years or building systems and using the same wiring methods as i always have


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## jmerick (Nov 12, 2008)

I agree, put in the larger fuses and let us know if it gets hot. The small fuses might be restricting the current too much...

What type of fuses are they?


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## jmerick (Nov 12, 2008)

jmerick said:


> I agree, put in the larger fuses and let us know if it gets hot. The small fuses might be restricting the current too much...
> 
> What type of fuses are they?


Nevermind on the fuse, reread your first post..


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## UNBROKEN (Sep 25, 2009)

It's a possibility. The last amps I had in here didn't have near the current draw. 
Lemme see what this 100 amp fuse does and I'll go from there. If it pops I'll run a 4 gauge to the batteries. Or should I run 0/1 to match the power wire?


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## UNBROKEN (Sep 25, 2009)

OK...fuse is warming up still. Gonna run another wire straight to the batteries.


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## UNBROKEN (Sep 25, 2009)

Random thought....I wired the big 3 thing a while back with 0/1
That should make the chassis ground be as good as possible. 
Does the fact that I have all 3 amps grounded at the same point make any difference at all ?
I'll still run a new ground all the way to the batteries tomorrow...just curious.


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## SoulFly (Mar 15, 2011)

well if its really "too hot", it does have thermal protection. i think it even has a light on it for high temp doesnt it?
If its not on, i wouldnt worry about it. But for the record i don't recall my 450/4 feeling anymore excessive than any other amp i had and that was on 8 guage and not the most ideal ground.
is it hot in your trunk? got plenty of air space for the heatsink to function? other than that i'd let the thermal protection do its thing before got too involved.


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## UNBROKEN (Sep 25, 2009)

They're mounted on a rack under the back seat of a crew cab F250. 
Airflow shouldn't be a problem in the long run...all my other amps had been in the same place. 
This was happening with the seats up and windows down in my air conditioned garage. 

I'll check the battery to chassis ground tomorrow. I'm gonna add the new run anyway. I have a whole roll of new welding lead at work, I'll just cut off a chunk and grab some terminals. 

Everything else is spot on though...other than being in serious need of tuning. lol


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## Bluliner (May 16, 2011)

Perhaps the voltage is dipping too low at the amps. Regulated amps will then draw more current in order to maintain output. 

Bad grounds, cheap-ass distribution blocks, too small power wire, as well as a number of things can cause the voltage to drop too low at the amplifier.


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## UNBROKEN (Sep 25, 2009)

I'm looking at the grounds. 
I wouldn't call a Stinger block with digital voltmeter or 0/1 Phoenix Gold power wire cheap though. lol


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## matdotcom2000 (Aug 16, 2005)

UNBROKEN said:


> It's a possibility. The last amps I had in here didn't have near the current draw.
> Lemme see what this 100 amp fuse does and I'll go from there. If it pops I'll run a 4 gauge to the batteries. Or should I run 0/1 to match the power wire?


Your power wire should always match your ground wire... You dont have to run the ground all the way to the battery just make sure you have a sufficient ground with the same gauge wire as the power wire. 

What is the voltage coming off of the battery???
What mode do you have the amps in as far as accepting RCA voltage from HU???
What are you using to set the gains??


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## Jlchevy66 (May 6, 2011)

My 1000/1 gets so hot, you can barely touch it, but it never clips or over heats. I often crank it up for demos and its never thrown a fault. I just installed the final 1/0 wire from the frame to negative terminal, I now have 14.35 volts at the alternator and at the amp. Gain is about 60% up. 
I don't worry about hurting the amp, if it was too hot it would fault out. I will check how hot it gets with digital gauge today. 

Sent from my ADR6400L using Tapatalk


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## 96jimmyslt (Jan 31, 2011)

Both my RF amps get hot - almost to the point you can't touch them.

I have a 4080dsm in the center console and I push it to it's limits with the center console door closed and it never over heats.

Same with the p500-2 in my cargo area, although it has lots of air (I have felt it while demo'ing though and it's just as hot)

I think the best question for this would be what your gains/bass boost settings are at if you are concerned.

Unless the amp goes into thermal protection mode, I think you are fine.

I don't know off hand, but you can probably lookup the safe temperature ranges for your amps.

Then if you REALLY wanted to, hook up a thermometer to them and monitor the temps in the dash.

BTW, it's been 80-95F (but "feels like 100-110F) and my amps have been fine as well.

If they aren't shutting off, and you aren't clipping the signal, I think you are just over-reacting.


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## UNBROKEN (Sep 25, 2009)

Let me clarify. The 1000/1 gain is at zero. The PAC LC-1 is at about 1/2. 
I've asked but nobody answered about how that affects things when setting the gains. 
The 300/2 gain is at zero and both gains on the 300/4 are at zero. 
I have not set them with my DMM yet. 
Until I get to the bottom of this fuse blowing issue I don't see the point. 
I double checked the 0/1 gauge battery-chassis ground last night. It's good, clean and tight. 
The 0/1 motor-chassis ground is the same. I'm going to replace the 4 gauge wire that is bolted through the common ground point for the amps under the truck to the frame with 0/1 today. 

All 3 have the input voltage set to low. The DRZ says 4 volts up to 0db...8 volts at +6db. 0 has always been my max volume before. 

Voltage both at the batteries checked with a DMM and at the distro block reading it's gauge is 15.0 at idle. Average listening levels shows 14.8ish at idle and 13.8ish on heavy bass lines at idle. I never listen without the truck running. 

As far as heat...they seem to be running cooler than before so maybe me putting a wrench on all the ground bolts helped?

As far as air circulation around the amps....there's more than enough. 
They are mounted to a plate, not carpet so there's nothing smothering the bottom. The tops have an inch or so clearance, the back side which is the heat sink side has 4-5" clearance and the control side is open to the cab. Again...it's a crew cab F250. 

This has been happening with the seat bottoms folded up and the windows down, doors open in my air conditioned garage. I keep it about 73* when I'm working in there. 
In short...this case of them getting hot has absolutely nothing to do with insufficient airflow and since the gains are at zero it's not a case of the gains being cranked to oblivion. 
I'm gonna continue on the beefing up the ground path theory until I rule that out. 
Ive triple checked every wire inside which would be all the power connections and the 3 ground wires to their common spot which is clean and tight bolted through the floor pan where again, there's another 4 gauge wire to the frame.


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## matdotcom2000 (Aug 16, 2005)

You should reset the input voltage to high as per the manual ( low is for 200mV - 2V and high is for 800mV - 8V) That could definately be an issue with your amps.. If you set it to high you can also play with the gain alottttt more than with it set to low.. I would make those changes before replacing and sinking more money into it.. Also I am not sure how that PAC thing works, I am assuming that it just allows you to turn down the voltage being sent to the amp SO max would be where I would set it before setting gains when using it...


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## UNBROKEN (Sep 25, 2009)

Interesting. 
I wondered a lot about the input switch, it's a lot louder with it set to low. There's a very noticeable volume decrease when it's switched to high. That would play into your comment about playing with the gains more. 

I'll be the very first person to admit I know jack **** about tuning and gain setting. That's why I wanna defer to more knowledgable people for the fine tuning. 
Every time I rebuild it I learn something about the fabrication part...but I've never had this much tuning capability and I'm admittedly lost.


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## matdotcom2000 (Aug 16, 2005)

Yea if you reset that input button to high you should be fine.. Remember just because its louder does not mean that its an acceptable signal.. Clipping can greatttlllyyy cause your amp to over heat.. I have had many JL amps and playing with that gain mode always messes with the ghetto part of me VS the SQ part of me.. If you run those amps correctly they can be great amps especially if you have the electrical system to hold them up.. Which in your case I would say soo.. Because they will do their rated power regardless of battery voltage 12-14.4 volts I think..


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## UNBROKEN (Sep 25, 2009)

I switched the inputs, moved the gains up to about 1/3 (figured that was safe enough for a test) and beat the holy hell out of it for about 30 minutes. 
All the amps got warm, not even close to hot but a temp I consider just fine. 
I didn't play it much at all after the addition of the extra ground wire but one or the other seems to have done the trick. 

Now for some real tuning...y'all let me know when I can come bug ya.


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## Bluliner (May 16, 2011)

UNBROKEN said:


> I switched the inputs, moved the gains up to about 1/3 (figured that was safe enough for a test) and beat the holy hell out of it for about 30 minutes.
> All the amps got warm, not even close to hot but a temp I consider just fine.
> I didn't play it much at all after the addition of the extra ground wire but one or the other seems to have done the trick.
> 
> Now for some real tuning...y'all let me know when I can come bug ya.


Be careful with JL amps, they "hide" clipping very well. 

While they're not the most musical things to ever hit the shelves, setting the gains the way JL Audio recommends is your best bet. If you live near an internet you can easily find the JL site & tech. 

The switch you're talking about is to change from low-level (RCA) inputs to high-level (speaker) inputs you'd solder onto a **** male RCA end. If you're using the outputs on a HU; use the low levels and set the gains w/a DMM per JLA.com.


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## UNBROKEN (Sep 25, 2009)

JL's site says the high setting is also for "certain high output preamp signals" I'm addition to speaker level inputs. My DRZ is 4-8 volts output.


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## Bluliner (May 16, 2011)

UNBROKEN said:


> JL's site says the high setting is also for "certain high output preamp signals" I'm addition to speaker level inputs. My DRZ is 4-8 volts output.


...not high enough.


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## UNBROKEN (Sep 25, 2009)

JL's specs for the high side are 800mV-8V
DRZ9255 output voltage is 4-8V
What's not high enough ?


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## Bluliner (May 16, 2011)

UNBROKEN said:


> JL's specs for the high side are 800mV-8V
> DRZ9255 output voltage is 4-8V
> What's not high enough ?


Play 1khz sine wave through your HU and test AC at THE END of the RCA going into the amp. Don't be shocked when it's nowhere near 8v...


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## matdotcom2000 (Aug 16, 2005)

Man dont listen to this guy find msmith he is the JL expert here.. He would be able to back up what I have stated, if not elaborate further. When you use the settings in the way I have described you will have great results.. You can prolly crank it a little higher than a 1/3 if you want it depends on your headunits clipping point.. The only way I would use the LOW is if I was using a low level pioneer hu that puts out that type of voltage 2V and such. If you want to come out to the house next week sometime I am open. Hit me on the PM and we can link up.. Trying to finish my install now for HeatWAVE gonna be close to the deadline though.. I am not a guru by no means but I do kno a little bit about a lott and what I do kno I have used myself, NO hearSAY..


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## Bluliner (May 16, 2011)

RCA's coming out of Clarion's DRZ = low level. It's not an 8v output and it sure in the hell isn't anywhere near 4v at the end of the RCA where you'd plug it into an amp when the radio is at 3/4 volume as stated in JL Slash's user's manual. I'd be surprised if it's 2v. 

So ya, low input it is. This isn't a bad thing as if you were to set the gains with a DMM, just like JL's website tells you, you'd probably find your gains being set very-very low while still making max power. This is what you want (gains at minimum while your amp is making max power). 

"IF" the voltage reading on your DMM is too high when the gain is all the way down, then and only then should you use the high level inputs. I highly doubt this will be the case though...


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## matdotcom2000 (Aug 16, 2005)

Directly from the JL manual

The “Low” position on each “Input Voltage”
switch selects an input sensitivity range between
200mV and 2V.This means that the “Input Sens.”
rotary control will operate within that voltage
window. If you are using an aftermarket source unit,
with conventional preamp-level outputs, this is most
likely the position that you will use.
The “High” position on each “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V.This is useful for certain high-output
preamp level signals as well as speaker-level output
from source units and small amplifiers.To use
speaker-level sources, splice the speaker output
wires of the source unit or small amplifier onto a
pair of RCA plugs for each input pair.

Man please dont be as retarded as I think you are.. Yes he maynot see 8 volts all the time but he is seeing more than 2 volts.. Please stop suggesting things that could possibly blow this guys amp. We are here to help people when at all possible suggest on the side of caution.... HE SAYS HIS AMP is over heating NOW not soo much problem fixed.. Volume may not be as loud but an amplifier has its limits... I may not be a guru but common sence is common sence.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

I got board of reading(sorry) but just for reference, in my 15+yrs of car audio, I've never blown a fuse, that I wasn't doing something wrong... 

an 80 amp fuse is no slouch to blow.... you are driving things pretty hard, weather it be over-gain in the pre-amp stage or over gain in the amp stage, it sounds like things are being driven to limit and then some... for whatever reason (I did read you have like 1/3 gain on the amps)


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## Blister64 (Jun 13, 2010)

I've had 3 different HU's with my 500/1 amp ranging from 2v to 5v _rated_ pre-outs. And I know that doesn't mean they are putting off that much at the RCA ends. With every setup, I've never used the high position on the input voltage. This would most likely be reserved for using a speaker wire after the HU's amp that is cut and split and ran through a converter to use RCA ends. I'm not saying anyone's wrong by any means, I just don't know why high input would be selected. Especially if the manual says that most likely low should be used.


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## UNBROKEN (Sep 25, 2009)

Hell if I know man. 
All I know is the DRZ manual says 4 volts up to -0db and 8 volts at it's max of +6 volume.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

Maybe time to upgrade?

FWIW my Continuum gets BLAZING hot... it's also close to class A biasing and rocking an OG unregulated PS... so she cooks...


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## UNBROKEN (Sep 25, 2009)

I just spent about 80 hours doing this install and a whole new interior all at once. 
I'm not upgrading a damned thing unless something blows. lol
With wiring, deadening, materials and all the stuff in my sig pic I've already spent twice what I planned.

And really, at this point what do I upgrade to?
I've already passed the point of diminishing returns on my money.


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## Blister64 (Jun 13, 2010)

UNBROKEN said:


> Hell if I know man.
> All I know is the DRZ manual says volts up to -0db and 8 volts at it's max of +6 volume.


Yea my Pioneer is rated at 5v and I still use the low input level.. idk, just thought that was what you were supposed to use with most if not all aftermarket preouts


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## UNBROKEN (Sep 25, 2009)

How do you measure the output with a DMM?
Is it as simple as it sounds ?
Head unit volume at 3/4 or so, then touch the RCA ends with the leads and read the voltage?


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## Blister64 (Jun 13, 2010)

UNBROKEN said:


> How do you measure the output with a DMM?
> Is it as simple as it sounds ?
> Head unit volume at 3/4 or so, then touch the RCA ends with the leads and read the voltage?


Yea as long as your DMM is set to the right setting.. But to be honest man, I didn't even test that with my meter tho. I set it to low like it should be, used the meter to tune my mids and highs on my 600/4, and then adjusted the 500/1v2's by ear.


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## goodstuff (Jan 9, 2008)

mmmmkkay.....

I've got a DRZ and a JL 250/1 v1. I also have a jl e-series 6 channel. The 250/1 never gets anything beyond warm, and I can pound the everfuckingcrap out of it. The e series on the other hand, I can't leave my hand there after 30 minutes on a warm day, but it has never gone thermal on me.
I would guess you have some rca/ signal issue. I know amps can get hot if one side of the rca is disconnected. Going to post more brb.


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## trojan fan (Nov 4, 2007)

Hot enough to melt a popsicle...LOL.....A bad ground will cause a amp to run hotter than normal


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## UNBROKEN (Sep 25, 2009)

They seem to be running normal temps now. I'll play it more tonight to check again. 
My grounds are as follows:
All 3 amps are grounded with 4 gauge to a common point which is the floor pan, paint obviously ground off. They are bolted through with a 4 gauge wire run to the frame. I left that and added a 2nd 0/1 wire from that bolt to the frame yesterday....again the paint was ground off. Both frame points were then coated with rubberized undercoat. 
I also have both batteries connected with 0/1, engine to chassis ground is 0/1, battery to body is 0/1 and battery to frame is 0/1. 
This son of a ***** is grounded as good as it's gonna get. 
I did use crimp terminals on all the wires but I have the right size crimping tool for that wire. 
I used sold copper lugs on all of it also. 
If I haven't eliminated a bad ground as a possible issue by now then I give up.


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## Bluliner (May 16, 2011)

matdotcom2000 said:


> Man please dont be as retarded as I think you are.. Yes he maynot see 8 volts all the time but he is seeing more than 2 volts.. Please stop suggesting things that could possibly blow this guys amp. We are here to help people when at all possible suggest on the side of caution.... HE SAYS HIS AMP is over heating NOW not soo much problem fixed.. Volume may not be as loud but an amplifier has its limits... I may not be a guru but common sence is common sence.


Setting the gains the proper way (well, the JL way at least) is the 1st step in diagnosing the overheating problem. To do that, you switch the input voltage switch to LOW, turn the gain down all the way, and test the speaker outputs for voltage. Voltage too high? Well, then you switch the input voltage selector to high. 

In my experience, a 4-6v pre-out HU will still use the LOW setting on a JL amp. 

You want the gain knob as low as possible while still making max power. Nothing retarded about that. But the old 'gains 1/2 way up' recommendation? That's retarded. Following what I laid out will not blow up his amp. If you installed the amp...maybe...but I'll give the OP the benefit of the doubt. 

I still don't think it's a gain issue. But it's never a bad idea to get those set properly and go down the proverbial flow-chart to find out what's wrong.


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## Blister64 (Jun 13, 2010)

UNBROKEN said:


> They seem to be running normal temps now. I'll play it more tonight to check again.
> My grounds are as follows:
> All 3 amps are grounded with 4 gauge to a common point which is the floor pan, paint obviously ground off. They are bolted through with a 4 gauge wire run to the frame. I left that and added a 2nd 0/1 wire from that bolt to the frame yesterday....again the paint was ground off. Both frame points were then coated with rubberized undercoat.
> I also have both batteries connected with 0/1, engine to chassis ground is 0/1, battery to body is 0/1 and battery to frame is 0/1.
> ...



Is this with the input voltage on low or high? I got lost to where you ended up having it.. 

^^^ And I agree with Bluliner above. Do what the factory recommends and go about it systematically. If there still seems to be an issue, then possibly look into switching it to high input. Another thing you could do is call JL and see what they have to say about the issue. Ask if they've had some HU's that need the high input selected.


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## UNBROKEN (Sep 25, 2009)

With the ground updated and the inputs set to high it seems to be ok. That's where it's at now. To be fair though I haven't played it a whole lot.


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## matdotcom2000 (Aug 16, 2005)

Bluliner said:


> Setting the gains the proper way (well, the JL way at least) is the 1st step in diagnosing the overheating problem. To do that, you switch the input voltage switch to LOW, turn the gain down all the way, and test the speaker outputs for voltage. Voltage too high? Well, then you switch the input voltage selector to high.
> 
> In my experience, a 4-6v pre-out HU will still use the LOW setting on a JL amp.
> 
> ...




Either way making the switch from LOW to HIGH fixed his problem. And it does clearly state to use the high level setting with 800mV to 8V in the manual, regardless. Not sure what HU you were using but his maybe putting out Quite a bit of voltage.. 

The “High” position on each “Input Voltage”
switch selects an input sensitivity range between
800mV and 8V.This is useful for certain high-output
preamp level signals as well as speaker-level output
from source units and small amplifiers.

It does not state that it is prefered to use it for either or....... 

BTW UNBROKEN if you want to set your gains using DMM I have one at the house.. Hit me up to let me kno if you want to use it..


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## UNBROKEN (Sep 25, 2009)

I have a Fluke in the truck...just no time to mess with it right now. 
I'd love to use yalls ears and RTA one day though. 
I literally don't know anyone in Houston that can help with tuning.


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## JLAudiow6v2 (Jun 28, 2011)

I run a Slash 1000/1v2, and it barely even gets warm. Assuming that your gains are set correctly, and that you are not pushing the amp past levels of distortion, where the amp is generating excess heat, the amp shouldn't get 'hot' at all. 
As far as the fuse goes, I would definetly put a 100amp fuse at the battery for that particular amp. Make sure to match the fuse at the battery, with the same fuse rating as the fuses on the amp. Slash amps have internal fuses, but you can go to JLAudio.com to find out what the internal fuse is.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

UNBROKEN said:


> I just spent about 80 hours doing this install and a whole new interior all at once.
> I'm not upgrading a damned thing unless something blows. lol
> With wiring, deadening, materials and all the stuff in my sig pic I've already spent twice what I planned.
> 
> ...


HD series? 

Not JL?


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## UNBROKEN (Sep 25, 2009)

I think the Slash amps will do what I want them to in terms of good sound. 
Plus...I need matched amps that fit a certain space and they are literally perfect in that aspect for my truck. 
It's not a daily driver...it's a weekend toy and show truck. It's been featured in 4 magazines and I intend to get it in more after I finish freshening it up. So...looking good is a priority. 

I'm gonna say the heat issue was a ground issue. Everything is fine now that I changed that. I spent some time last night going back and forth between high and low on the input and it made no difference I could tell in temps. 
I see Manville reading this now...I hope he chimes in on that subject since we covered it quite a bit and still don't have a definitive answer.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

Odd... a poor ground would seem to cause more heat AT the poor connection, no so much make the amp heat up... 

Veddy strange indeed...


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## ZWOW6 (May 23, 2010)

I have a question too. maybe it could help the OP. When setting the gains, starting at 75% volume then turning up the gains to the correct voltage per JL, which would be better ? 1) having volume set at say 26 of 35 of my Kenwwood Hu and have the gains turned up to xxx spot or using volume 28-29 ( which will have more voltage at end of rca) and having the gain at xxx ( which would probbally be lower) . Not sure if this makes sense, but i wonder if having the Hu at a slightly higher volume to set the gain is better than lower ?? I assume the gains at the higher volume setting would be turned up to a lower amount because the voltage at the higher volume is stronger. I know my Hu can go up to a pretty high level of volume before sending a clipping signal, per my last installer.

Maybe if the op reset his gains with the volume set at a differnt level it could keep his amp from working too hard and getting hot ? My new amp seems warm to me and i plan on checking the ground from battery to frame soon. I just wonder myself what the best volume to use when setting my amp up.


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## nick650 (Feb 7, 2011)

This stuff on gains I skip it. Set the gains on the amp 90%. Why? The amp is a better amplifier then the deck and you don't want to use it as much as possible. So I just set my amp at 90%, turn the volume up until it clips/ distortion. I have a anti clip meter so this is very easy for me. Just remember were that max is and never pass it. Why is this the best still I don't get it! First off the headunit is not made to produce clean signal all the way up to its max, maybe 77% max (what mine is). So by having your amp that high will make it very easy to know it's your headunit that is the limiter.

Fuse wise: ALWAYS better to have one size under whats needed.

Grounding: Most important part of any audio system. Bad ground, all bad.


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## sqshoestring (Jun 19, 2007)

Amperage tends to cause heat, voltage not so much. So if you run an amp at a lower ohm load that means you have more amperage and same voltage, it usually runs hotter. Yes that is more power total, but even if not it will. If supply voltage is lower and you get the same wattage to the sub from a regulated amp or lower ohm load, then that means you are using more amperage and less voltage. If you used a high current amp and a high voltage amp to make the same watts to a sub, the current (amperage) would make more heat the electronics are just less efficient at passing amperage. You should be able to see the voltage at the amp, it will be less if the ground is bad, but can be difficult to measure unless you use a sine and then be careful.

Traditionally you run more RCA power and gain the amp down for a lower noise floor, but sometimes that is not the best way it depends on the preamp and how it was built particularly older amps can be overloaded. It should not matter long as you are in spec, but sometimes it does. I would go by the amp maker specs however; they should be correct.

You will only see max voltage of a HU or line driver right at clipping, and you might need a scope to see the peaks. Similar to if you had a wattage meter on a speaker it would be far lower than max most of the time excepting sinewave or similar input, or a peak in the music. Since power is a log scale to dB, for amp or HU you will be outputting WAY less than 75% power at 75% 'volume'. You will only see power output ramp up to max right at the highest setting near clipping. Look up 'audio taper' that will explain it better. Never expect to see close to a HU's voltage rating until you max it out.

A good HU will play max voltage with no clipping, usually with no EQ as that will change it. If yours does well hard to say, lesser ones may not. I have run HU on a scope and verified it. There is also a difference in peak voltage and RMS voltage your meter may show on an RCA output, depending on how the HU maker rated it.

The whole problem with gains is source material. I can gain to play music and then put in an old CD that is not compressed and can only get 3/4 of my volume. So mine is gained to max the volume on that old CD, I can't turn it up all the way on other music or a sine of course.

Make sure it is not your fuse holder getting warm from a poor connection. Is a good idea to put dielectric grease on the contacts. Good idea from a reliability aspect too. Fuses will pass more than rated for a short time. Music will not take as much power you can run a smaller fuse that will power peaks in music above its rating and not blow, but it may blow the first time you play bass music or a sinewave hard...there is quite a difference in average power used. It is also hard to hear clipping in subs, if you think you are close likely you are clipping them.


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## ZWOW6 (May 23, 2010)

My HU is a kenwood excelon 9960 with a 5v output, but I know it doesn't get close to 5v unless the volume is maxed out, I get a very weak signal at volumes under 25 (out of 35). My last installer set my gains so that my hu could be turned up to the max and still not clip, I know he used a scope or something. I still wonder after all that if I should set the amp up at volume 26 or volume 28-29 ? I'm following JL's specs on a HD 900/5 amp. I want it to run as effiecient as possible, and keep it from getting hot, since it gets too damn hot here in AZ anyway ! Can I just add a 2nd ground from battery to the frame ? Also My frame on my vette (Z06) is aluminum if that makes any difference.

thx for the good info guys


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## johntharkins (May 14, 2012)

This is an old GM Technical Service Bulletin, but it should help anyone wanting to verify that their amp has a good ground:

METHOD OF VERIFYING ' GOOD ELECTRICAL SYSTEM GROUND ' #87-8-139 - (04/07/1987)
VEHICLES AFFECTED: ALL MODELS

When diagnosing electronic systems for incorrect operation, it is often necessary to verify that ground circuits are good. This article is intended to clarify what is meant by the term "good ground" and the preferred tools and methods for verifying it.

A "good ground" is a ground circuit that has a resistance of zero OHMS.

Ground circuit resistance can be measured in OHMS using a digital volt OHM meter (DVOM). When using a DVOM, it must be set on the 200 OHM scale to obtain an accurate measure of the circuit resistance. Many meters have both a 200 OHM scale and a 200 K scale. The 200 K scale will not measure zero OHMS accurately. If you are not sure how the meter is to be set for the 200 OHM scale, refer to the meter operating instructions for proper settings. If the meter is an autoranging or self-scaling meter, read the meter carefully to be sure which scale it is setting itself to.

Before measuring resistance in any circuit, the resistance of the meter should be measured by touching the leads together. A meter with a good battery and leads in good condition will read less than .2 OHMS usually zero. If the leads measure anything more, an accurate measure of the circuit resistance may not be possible.

Always remember - resistance cannot be measured accurately on a "live" circuit, All current flow through a circuit must be stopped by disconnecting its power source before measuring resistance.

Ground circuit resistance can also be checked by measuring the voltage drop across the circuit with a DVOM set on, the 2 volt scale. The voltage drop will be zero across a "good ground" circuit.

Remember, fully understand a meter's functions before using it!
To add to this, a good ground for car audio applications will have a return resistance reading of 1/2 ohm or less. I have yet to have a return reading of 0 ohms. If a ground return reading cannot be made to get below 1/2 ohm by means of the "BIG 3", then it is adviseable to ground direct to the battery. Electricity is an algebra equation, what you do to one side you must do to the other. Pay as much attention to the ground wire as you do the power wire.
The BIG 3 is a great place to start for a good ground, however it is the assumed proper method of grounding. What we are talking about here is the older and wiser 4th brother to the BIG 3 (the BIG 4). 

So a proper ground wire will be as follows.
- clean of residue and paint.
- secure.
- have a resistance return of 1/2 ohm or less.
- be of adequate gauge to carry the return as compared to the power wire.
To simplify the measuring of the return, use your meter as described. Disconnect the - battery terminal and disconnect the ground wire from you amp. If your dmm probes are not long enough, you will need to create a jumper extension out of some primary wire or whatever wire you have handy. Measure this wire for any resistance reading and subtract it from the total. 
Many installers are not aware of this nor practice this method. It takes time and time = $ so don't get all pissy if you had a professional install done and this was not checked. A poor ground connection or high resistance reading may seem trivial under no load, but once you are pounding your nice new amp and it is drawing large amounts of current, this little reading has become a monster reading that has caused many an amp to fail for no apparent reason. It may be noticeable as a extremely hot running amplifier in a short time period, poor output levels or diminishing levels and of course a blown power supply or output section in the amplifier.
While the original article was written for the years gone by, it still is applicable to the newer generation of vehicles. A good ground is not about the amount or size of the metal in the return to the battery but about the resistance through it. Todays vehicles are a combination of metals, spot welds, glued together unibody panels and isolated chassis components. The return through these components is where the resistance reading comes into question and this is what we need people to understand, why the BIG 4 needs to be done if the BIG 3 does not solve the problem.


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