# can low voltage to your amp cause severe clipping from your subs



## jblw10gtimk11

Im trying to figure out why my subs are clipping severely, when they just start to get loud. the xover is set to 60hz, the gain is less than a 1/4 up, bass boost 1/4 up. I have 2 jbl w10gtimk11 subs in a atrend sealed bbox, with .95cft per sub. there wired to a jbl 1201.1 11 amp at 1.5 ohm. I have 0awg power and ground, and 12awg sub wire. The amp is ran off a brand new kenwood excelon xx94, which has 4 volt preouts., via top notch monster cable rca jacks, that are 2 years old.. I havent done the big 3 or upgrade my alt. i have a odessey pc1500dt under the hood, and the alt is a cheap replacement probably 60amp if lucky. My ground is ran through the floor to the bare frame, with a stainless steel bolt, and star washers. i then sprayed undercoating on the ground connection, which was just done recently. any info please help, dont want to ruin my 600 dollar subs. so can low volts to your amp cause severe clipping, when you try to wang.


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## kyheng

1.5ohm load are good, to bring your amp's voltage down. Enjoy it... 
Better use 1 sub only and ported, less power required and should be friendly to your limited power supply.


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## jblw10gtimk11

Well today i checked voltage at battery,and amp. With the truck started and stereo off, voltage for amp and battery were 14.4v. With the truck started and stereo on with subs distorting a little both at battery and amp the voltage didnt drop below 13.2vThanx for a little info, but i need more info about a low amp alt not giving your amp enough power therefore can this make your amp clip before the amp even reaches its full potential, i would say its at about half the potential of the amp when the subs clipps realy bad. Even though my voltage doesnt drop below 13.2v can the amp still not be gettin the correct amount of amps from the alt, therefore it would clip alot sooner compared to having the 120 amps my amp needs to produce its rated rms of 1118 watts.


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## t3sn4f2

I didn't read too closely into the thread but it sounds like you have enough power and are simply asking too much from the subs. Try playing a severely clipped test track at low volumes on the head unit and see if you can _hear_ clipping. If it's no where near as obvious then you know its the sub giving out and not the amp.

That or you are REALLY asking too much from the amp.


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## jblw10gtimk11

I know i have enough volts, but my alt is a cheap 60amp replacement, so if my amp is not gettin 120 amps, its starved correct, or am i wrong. i know my amp is in no way to much power for my subs.well my subs handle 600rms a piece and 3000 peak a piece, the amp is 1118 watts rms in 2 ohm. i dont know if i mentioned it but i have 4volt preouts on hu, also. amp is less than a 1/4 way up when it distorts severely, and bass boost is about the same. could a passive on hu xover fight against a active xover on the amp, causing clipping.


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## Chaos

*The gain knob is not a volume control. * 

Here's what you need to do: 

1) Disconnect or turn off everything except the source unit & sub amp (no other speakers should be playing except the sub)

2) Turn the input sensitivity (gain) on the sub amp all the way down. Defeat any eq you might have, but leave the crossover set to about 80 hz.

3) Set the volume of the source unit at about 3/4 of the way up, playing tones or bass-heavy tracks. (If the deck has dedicated subwoofer outputs with independent level control, and you are using those, set it to "0" ) 

4) Slowly increase the gain on the amp until the subs begin to distort, then back off. Repeat process until you are satisfied that you are hearing the output you want without audible distortion. This would also be the time to adjust the x-over, if the sub is playing too high.

5) Turn everything else back on and listen. If it sounds good, you're done level setting. However, after more extensive tuning, you may need to re-adjust.



If that doesn't produce satisfactory results, and it sounds like your ground & battery are good, then the problem is most likely that puny alternator. Even though you've got the voltage, without enough current the amp is still going to clip too much.


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## jblw10gtimk11

I hope its the alt, or ground from the battery under the hood to the trucks frame. I hope its 1 of these and not something wrong with my amp. Today i went outside to mess with my system and i noticed with the volume really low, and my head up to the subs, i can hear distortion that sounds like the letters shhhhhh, . It sounds like when you turn on a tv with fuzzy reception and you get that static noise, well i hear this from the subs but only at low volume, with the hu and amp at a higher yet very modest volume the subs clipp. What do i put my dmm on to check my voltage on hu sub out. also can i use a dmm to check how many amps my alt is putting out instead of how many volts. Its bothering me cause if i dont turn around and put my head by the subs i cant hear the heavy clipping, and im worried im going to **** up my subs. It Almost always clipps with tight punchy bass, and higher frequency bass. The low low bass is preety solid. Let me remind you that The amp starts to clipp on higher frequency bass when the amp is barely up on these frequencys. I have my hu xover, and amp xover around 50hz and it clipps on higher frequencies, if i set the xovers higher it realy clipps and i have to turn the amp way down and then its super quiet. Anyone live around the chicagoland area that has a amp i can hook my subs up to , or a vehicle and subs i can hook my amp up to to see any variables. I need help im stumped. Is there a way to test my amp to see if its bad. Thanx for all info. sorry its so long, just wanted to get and give as much info as possible.


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## jblw10gtimk11

Ive tried doing exactly what you said, as that is how ive always set my systems. To give you a example, my last setup consisted of a old cheaper pioneer premiere radio, a older 600 watt 2 channel kenwood, and 2 old 12in rockford fosgate p1. The subs were in a small homemade sealed box, installed in a reg cab pickup. I only had 6awg power, ground, hooked up to a interstae battery, and my old system was about as loud,or louder, only way clearer. I now have a ext cab truck, with a kenwood excelon xx94, a jbl 1201.1 11 amp, 2 jbl gtimk11 subs, in a bigger sealed box than the twelves, with oawg power and ground for amp, and a odessy pc1500dt battery. I think it would sound way better, and much louder than my last setup. **** i think my 2 infinity perfect 10s hooked up to a old school 150 watt hifonics odin sounded better and nearly just as loud.


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## Aaron'z 2.5RS/WRX

jblw10gtimk11 said:


> Im trying to figure out why my subs are clipping severely, when they just start to get loud. the xover is set to 60hz, the gain is less than a 1/4 up, bass boost 1/4 up. I have 2 jbl w10gtimk11 subs in a atrend sealed bbox, with .95cft per sub. there wired to a jbl 1201.1 11 amp at 1.5 ohm. I have 0awg power and ground, and 12awg sub wire. The amp is ran off a brand new kenwood excelon xx94, which has 4 volt preouts., via top notch monster cable rca jacks, that are 2 years old.. I havent done the big 3 or upgrade my alt. i have a odessey pc1500dt under the hood, and the alt is a cheap replacement probably 60amp if lucky. My ground is ran through the floor to the bare frame, with a stainless steel bolt, and star washers. i then sprayed undercoating on the ground connection, which was just done recently. any info please help, dont want to ruin my 600 dollar subs. so can low volts to your amp cause severe clipping, when you try to wang.


I just found this at ROE.com



> *Brand: *JBL
> *Model:* gto 1201.1
> 
> *Rating:* 4/5
> 
> *Pros: *Puts out very clean power, slightly underrated (clamped at 13xx @ 2 rms) , desirable price tag
> *Cons:* *Not recomended to run @ 1 ohm
> *
> *Overall Opinion:* Great amp for ppl on a tight budget.


A. it's not enough power to share with a pair if GTi's 
B. it's not "1 ohm" but it's close enough, if it's sited that it doesn't like 1ohm, it's not going to like 1.5ohm (as it's a constantly changing figure anyway) very well.. 

Putting low ohm stress on amps that don't care for it, is a SURE way to find you in the realm of distortion pretty quick...

C. The amp likely has a regulated PS, so it really doesn't matter the input voltage as long as it's not below 11-11.5v

D. AFA your alt... yeah it's small, but I've run 1500w+ on a 60a hot alt... You'll go through batteries faster, but I doubt it's your problem.. 

The car runs off of the alt while it's running, when you exceed it's output, you dip into battery reserve.. 

I say (if you want to listen to me) you need a second amp of the same value on the other sub, those are some power hungry subs for sure..


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## Oliver

I'd turn the distortion off = *kill the bass boost*

lil stuffin in da box and call it a day


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## jblw10gtimk11

When i bought the amp and subs, i called jbl 3 different times to ask them if its ok to run 2 jbl gti 10s off a jbl gto1201.1 at 1.5 ohms, and every time they told me dont worry all are amps are 1ohm stable, there just optimized for 2 ohm. He also said the gti coil resistance doesnt rise as much as other subs, so not to worry. Oh by the way if i just hook up i sub for a 3ohm load it does the same thing, and starts to clipp badly. My box doesent leak, but can a certain sealed box size make my subs clipp. My box is sealed with .95cft per sub. Can the cheesy terminals that came with my atrend e10d bbox cause distortion. The sub wires are soldiered to the cheesy box terminals. Can it be the stock truck wiring used for the hu. Im just trying to eliminate 1 thing at a time out of the equation. Thanx for replies, keep them coming.


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## jblw10gtimk11

1 more thing, ive turn the bass boost all the way off, and it still clipps,. Can time allignment on your hu cause distortion. Is there any certain settings on my kenwood excelon xx94 that i should know about that if not set properly can cause clipping, and distortion. I know its not the subs, maybe a defective hu, or amp. Also i have a very good set of monster cables rca jacks that are a few years old, can theses go bad and cause sever clipping. The subs sound sweet when i bring them in and hook them up to my house receiver. Ive never had a problem with my systems clipping like this, even if i turned the gains all the way up. Im so frustrated, almost feel like crying. lol


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## kyheng

A 100W sub when in sealed enclosure you need at least 200W to drive it....


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## jblw10gtimk11

Also i have no turn on, or turn off pop, nor alt whining. Just a static noise at verry verry low volumes when you put your head up to the subs, and hard clipping at medium volume.


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## trojan fan

If all else fails, buy some new gear....lol


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## Dukenut

are you sure you used the low passxover and not the highpass?


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## jblw10gtimk11

Hey Andy from jbl you out there, maybe you can clear some stuff up, and let me know if i was bull ****ed, and possibly ruined my amp, or subs because the info i got when i called jbl everytime was wrong. I understand that a sealed box is not as efficient as a ported, but my subs are 6oo watts rms, and as stated above the amp i have is clamped at 1300 watts rms . If i turn the amp up and let the subs clipp, they really start to move, and gets decently loud. Ive seen people on you tube with my amp and there whole car is flexing, everything inside the car is shaking with 1 sub. My mirrors barely move, and they had deadening and i dont, its pathetic. ive herd jbl gti subs and they sound awesome, mine sound like ****. Ive always had jbl and infinity, and never had a issue.


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## jblw10gtimk11

I have a mono subwoofer amp, it doesnt have a highpass xover, or subsonic filter. It only has a input sensitivity, 12 db bass boost at 50hz, and a low pass filter from 32hz-302hz.


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## Dukenut

in 1 of your posts you mentioned the hu xover


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## jblw10gtimk11

I dont have 1000 dollars to go out and buy all new replacement jbl gear, This system was all just bought throught the last 6 months, i had to buy it piece by piece and cant afford to replace my jbl equipment. It has to be something simple unless i finally in 13 years of buying nothing but jbl and infinity got some bogus jbl gear, i hope not. Anyone know how i can get in touch with Andy from jbl, as he knows what hes talking about, instead of talking to some jbl tech on the phone who mite not of known what he was talking about. thanx


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## Dukenut

also test the resistance of your ground with your dmm. since you say the subs hardly move it sounds like that is a bad ground. i had that happen to me, once i had a good ground, subs played like they should.


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## jblw10gtimk11

Yes the hu xover is fo the sub out, and is at 50hz. It hits the low low bass good, with little audible distortion even with ear by sub, i can crank the remote gain control to a ok level with low bass , but certain bass from about 45hz up clipps badly.


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## jblw10gtimk11

I actually had a bad ground to begin with, when the ground was hooked up to my seat bolt, so i read about grounding and pickups, and how the best ground is to the bare frame of the truck. When i first had it grounded to the seat bolt my alt gauge use to dip down and the amp would turn off then back on. tHATS when i joined this forum to find out what would cause the amp to turn off and voltage dipp, well grounding to my frame solved that problem. =Good connector, 0awg wire, bare sanded frame, Stainless steel bolt/nut, star washers, and then undercoating sprayed on top to resist corrosion. I Installed everything within the last month, but just within the last 2 weeks got it all installed. I just recently redid the ground, and upgrade power/ground with 0awg wire. Thats why i was asking if it mite be the ground coming from the battery under the hood to the frame of the truck. I dint do the big3 yet. I did have 4awg power and ground wire.


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## jblw10gtimk11

Instead of buying new gear, why dont JBL sponsor me lol.


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## jblw10gtimk11

So which 1 is it. a,b,c,d, or the small low amp alt. Most of the things you said to do, ive done over, and over with it still just sounding like **** at medium volume. Im not being hard headed, any advice i will try. It isnt loud to my dad either, and he hates loud music now, hes becoming a old fart lol. My dad dad had hifonics amps that i took over when i was 15 lol.


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## sqshoestring

First, if you put a DMM on the amp and crank it up and it has ~12v then it has enough power to run. If it is regulated 14v is not going to change its output, if not the actual dB you get is hardly any more unless you are doing an SPL comp. When the voltage drops from 13+ to 12v you have exceeded the alternator and are running on the battery, after a while of that constant the battery will go down if it can't charge. If you have a ground problem the voltage at the amp will be low, not 12 or more, under load.

So it sounds like a problem with the amp/subs/install or maybe a crossover issue. A 10 in that small a box might wail at 50+Hz but I've never run one of those. Then you have to xover lower than you normally would. If this is the case it will get louder if you move the xover higher to say 80Hz....that is just the response of the sub in that box; smaller boxes kill low bass. Either force it and EQ it, or change the box.

*Make sure* you don't have them out of phase, had that happen on here before with same results. Makes sure that is not a pure SPL tuning, if you don't like that it will not work for you. I had a 12 that was that way it would hardly play under 40 I hated it, went loud as hell over 40Hz. I like low bass to 30 at least like a 12 should be able to.

There has to be a reason, don't get all worked up, we've (us that have done this a lot) all run into serious problems and sometimes stupid problems, you never know sometimes something is all messed up and sometimes you might have made a simple mistake.

Most amps will shut off around 10v, and if your battery is weak and it hits a hard note it will.

I suppose the amp could be messed up, but it is very uncommon for an amp to run at half power like that. You could also try to run it off an ipod or something in case you think it could be upstream.


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## jblw10gtimk11

jbl recommends .75cft per sub with poly fill, so i went a little bigger .95cft per sub no polyfill. IT WILL WANG DOWN LOW, but clips badly above say 45hz. I have xover at 50hz and some of the bass still clips modestly, but turn the xovers to 80hz and yah it gets alot louder but then it really clips. Thanx for the reply


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## Chaos

Dude, settle down. I know it's frustrating when you run into things like this, but it will work out if you just start double checking everything in the chain from the source on down, especially power and signal polarity connections. 

Don't assume anything - I see professional installers with years of experience doing the same thing everyday because of a simple brain fart somewhere along the line. That's why trouble shooting is such a big part of this hobby, no matter how much you "know" about it.

It could just be that you need to run a ground strap from your battery to the frame.

It could be that your amp is bad.

It could be that the response of those subs in that box just isn't going to deliver the performance you want. If it's still no good once you get through verifying your connections, I would try a different alignment for your enclosure.


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## sqshoestring

Right, you can put some bricks or something in the enclosure to make them smaller to test, but I would check other things first. If they get louder above 50 then they are not tuned too low for sure....but again I never used those. I can run 200 LP on my IB pyles and hardly notice the difference from that to 50, but the 12s I ran before that I had to put HU and amp at 50 LP just to get control of them plus EQ 50 down...that is the difference in tuning. See if you can swap the amp or run them off another amp. Typically if you have a power problem the low bass will cause issues not higher bass, as it takes more power....but like I said either you have 12v at the amp or you don't, if you do (under load) its not a power problem. 12 to 14v is not much of a difference in dB. If the enclosure is partitioned try running one sub what happens?


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## Aaron'z 2.5RS/WRX

It's quite possible you have a bad amp.. 

Can you test with a different input?? Like an iPod with a phono/rca cable? 

You already said the subs sound fine in the house... you've got 2 things before the known good subs, the amp and the HU.. 

Could it be a SETTING on the HU that you don't know what you are doing with... how hard have you read the manual??? 

You can sit here and ask for help all day, but if you don't know how to use your gear, you could be wasting ALL of our time..


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## jblw10gtimk11

What do you mean by polarity connections? The subs are definitely connected in the right polarity.What do you mean by sub alignment? Do you mean where the subs are placed in the truck, because that wont help clipping. I read the manual for the hu. Plus the kenwood xx94 is really easy to navigate the menu. Well today i went out side and 1 of my subs is making a light rattling sound at low volume and as the volume rises it gets a little louder. I hope this amp didnt **** up this sub. Another thing my voltage didnt drop below 13.2 but i think thats because before i can get it to a decent volume its starts to clipp. Im going to try new rcas, and check to see if i have dc voltage on the amp outputs. Im praying that its just the ground strap from the battery to the frame. CAN IT BE the factory wiring to the hu. How can i tell if its the hu rca jacks that are messed maybe causing clipping.


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## trojan fan

It's about time to take it to a local shop...sounds like you are losing sleep over it


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## jblw10gtimk11

1 more thing i dont have a ipod or any other source to hook up to the amp to see if its the radio or radio rca. All i know is im bummed and i hope i didnt get a bum amp and it ruined my new sub that techcronics just repaced cause it was making the same rattling noise that my new sub is making only it was a lot louder of a rattle, when i pushed on the old sub and new 1 it was very smooth. I also checked vc impedance of the sub and it was factory spec. Same with the sub i had replaced.


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## jblw10gtimk11

Hell yah im loosing sleep. Will a local shop charge me, cause im broke till me and my twin brother start cutting grass. I wish there was someone on this forum that lived near me could lend a helping hand. I have a filling when i take it to a shop there just gonna say your amps ****ed and try selling me a bunch of expensive **** i dont need. It seems like it happens to me every time i walk in a shop , they try selling me everything but the things i want. lol.


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## sqshoestring

Test the shields out of the HU RCA for ground, they should be grounded.

Have you turned the amp down, and turned the HU way up to see if its clean?

Clipping will not hurt subs, power hurts subs and exceeding xmax hurts some subs and not others.

You can also check the AC voltage on the subs on a sine to get an idea of power level. Note that some cheap DMM don't like to measure Hz far away from 50-60.


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## jblw10gtimk11

i have a fluke 87 III dmm. So when my amp starts to clip and my subs start to pop it wont hurt them, because the sub i had replaced made a rattling noise, now my new repacement is making noise, the other original subs is fine.. I know the subs are not over xmax. Ive tried turning the amp down hu up, and hu down and amp up. Ive tried bass boost and a little gain, and i tried no bass boost gain up a little. Ive tried turning my hu 5 band eq to flat. Ive tried turning the sub out on hu to 0 and adjusted again. How do i check to see if the rca on hu are grounded.


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## Fight

you have a cool shop nearby that can take a look and offer suggestions?


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## Oliver

jblw10gtimk11 said:


> Hey . . . Ive seen people on you tube with my amp and there whole car is flexing, everything inside the car is shaking with 1 sub. My mirrors barely move,


U fekked up !

*If your ride ain't shakin ...*


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## Aaron'z 2.5RS/WRX

jblw10gtimk11 said:


> Hell yah im loosing sleep. Will a local shop charge me, cause im broke till me and my twin brother start cutting grass. I wish there was someone on this forum that lived near me could lend a helping hand. I have a filling when *i take it to a shop there just gonna say your amps ****ed and try selling me a bunch of expensive **** i dont need. It seems like it happens to me every time i walk in a shop , they try selling me everything but the things i want. lol.*


Would you like to help prevent this??? 

If so, please, VVVVVV start here VVVVVV and well, you've got a month or so of reading.. :laugh:

Basic Car Audio Electronics


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## jblw10gtimk11

Ive read most of it already, but ill read it again. Ever since this has been happening ive been searching on a bunch of different forums, just gaining knowledge lol. I have a landscape buis so i have alot of free time on my hands. Ive been on the forums, and messing with my system all day everyday, besides the really cold days. I guess it never hurts to read it again.


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## Aaron'z 2.5RS/WRX

OMG... well thank you for bein cool, most people for some silly reason, take that as some sort of insult? I never understand.. but thanks... 

Really, you should take amp input voltage off the table for now... 

Go here.. AmpGuts.com - Test Tones

DL and burn a 50hz and 1000hz sine wave tone on a disc... 

Are your front speakers amped?? If so or not, this is a basic gain setting procedure using tones to start.. 

Go to the car and turn everything to zero on the amp... At the HU, shut off all EQ, loudness (if that's even still a setting) EVERYTHING, bare signal

Whichever crossover you use (HU or AMP) now, set it to ~80hz

UNPLUG the RCA's from the sub amp and play the 1000hz tone on repeat.(yes, you are doing this without the sub for now).. Turn the HU up until you hear a distinct change in the tone, back off, try again... Once you find that spot, back off a notch and call that your HU MAX for now... 

now, plug the sub amp RCA's back in... Play the 50hz tone on repeat now... play it at your new found HU MAX..

Now, are you getting the distortion?? 

If so, you have problems... If not, continue.. 

Turn the amp gain up until you hear a distinct change in the tone, back off, back up.. find the spot where it changes and back off slightly.. 

Now, this should be pretty close to a gain match... some testing with your own music is in order... IF you got this far... 

As you test with music, let your ears judge and apply EQ and boosts sparingly... for every 3 DB of volume gain, you have to DOUBLE power...


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## jblw10gtimk11

ok lata today i will download the test tones, and in the mourning try to adjust everything again. The only thing im confused about, is when i go back back and read basic car audio, it says that most hu sub out dont distort even at max volume. I can see you not wanting to turn it up with hu amp cause it will distort your small speakers. Is this correct info or did i misunderstand.


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## Big joe

“amp is less than a 1/4 way up when it distorts severely, and bass boost is about the same. could a passive on hu xover fight against a active xover on the amp, causing clipping.” It can fight each other turn one of them off see if that helps


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