Got a Problem - Need Solution

[mbarber25 29]

Ok well here's the scenario:

I am running a 15" BTL off of a JL Audio 250/1 (not the v2 one). On the amp along with the power light and protection mode light it has a light that is labeled "low Ohm" with the little ohm symbol. This amp's lowest rating is 1.5 ohm. My woofer is wired down to 1 ohm. But i figured it wasn't a big problem.

OK so here's the problem - just now I noticed that on a certain note of a song (Lil Jon-Throw It Up) the light labeled low ohm blinks. Then i noticed sort of a popping sound coming from the box. So i went around to the back and popped the trunk. Then i could really hear the popping sound. I believe the sound it coming from the sub itself and not the port. But i could be wrong. I could never hear the sound before in the driver's seat so i don't know how long it's been there.

I have no idea why or what's causing this. Can any one explain to me what's the problem? Am i harming my woofer? Any trouble shooting?

Thanks guys.

If any more info is needed please let me know. I'm trying to figure this out before the morning when i go to work so please help me out.

[mbarber25 29]

Oh yeah and volume was at 22 which is the highest i would play it at and not be worried.

[playmysong 2]

Why such a low wattage amp for a btl?

[mbarber25 29]

Why such a low wattage amp for a btl?

need a better electrical to support my SAZ-2000D sitting on my bedroom floor.

[mbarber25 29]

anyone...?

[jcarter1885 995]

first suggestion, dont run a subwoofer's ohm load under what the amp can handle; your not harming your woofer more than your harming your amp. Take the sub out and examine the wiring (connection) and the tinsel lead (could be slapping). Cover up the port whole and play the system and see if you still here the popping noise.

even though I dont think that small amount of power and running the amp passed its ohm load would hurt the sub, dont be alarmed if it does in some way. maybe someone will chime in with better info than me.

Edited July 27, 2009 by jay-cee

[shizzzon 461]

this is what is happening-

There is a term called impedance rise. This means that you have your sub wired to 1 ohm which in reality it's probably around 0.7 ohms.

During playback of a song, this impedance will change with every note the sub plays back. So when playing bass, each individual note has a different impedance. the impedance will never be as low as it's resting load which is 0.7 ohms for you.

So, you have what's called "impedance rise" or just "rise".

Everybody has this. However, your problem is there are certain notes that is being played where the "rise" is falling below 1.5 ohms. When this happens, the subwoofer is receiving the most power possible.

Now, i dont know how the amp's subsonic is setup or the tuning of the box and NET volume, etc... but there are only 2 things i know fo that would cause it too pop-

1 - bottoming out caused by playback of frequencies far below tuning.

2 - amp is shutting output off in rapid intervals causing the sine wave to whatever frequency is being played to abruptly STOP and not finish it's cycle.

to eliminate one of these is easy, you can either use one of your Lifelines which would be a 50/50 , or u can do the following-

Play the same song but at a lower volume like 18 and see if it does it.

If it doesnt, then slowly turn it up to 19 for about 15 sec, then 20 for 15 sec then 21 for 15 sec then 22 and leave it there.

If it does it with more power, then it's bottoming out, if it does it at slightly lower volume, the amp may be rapidly shutting off it's output to prevent failure.

[mbarber25 29]

this is what is happening-

There is a term called impedance rise. This means that you have your sub wired to 1 ohm which in reality it's probably around 0.7 ohms.

During playback of a song, this impedance will change with every note the sub plays back. So when playing bass, each individual note has a different impedance. the impedance will never be as low as it's resting load which is 0.7 ohms for you.

So, you have what's called "impedance rise" or just "rise".

Everybody has this. However, your problem is there are certain notes that is being played where the "rise" is falling below 1.5 ohms. When this happens, the subwoofer is receiving the most power possible.

Now, i dont know how the amp's subsonic is setup or the tuning of the box and NET volume, etc... but there are only 2 things i know fo that would cause it too pop-

1 - bottoming out caused by playback of frequencies far below tuning.

2 - amp is shutting output off in rapid intervals causing the sine wave to whatever frequency is being played to abruptly STOP and not finish it's cycle.

to eliminate one of these is easy, you can either use one of your Lifelines which would be a 50/50 , or u can do the following-

Play the same song but at a lower volume like 18 and see if it does it.

If it doesnt, then slowly turn it up to 19 for about 15 sec, then 20 for 15 sec then 21 for 15 sec then 22 and leave it there.

If it does it with more power, then it's bottoming out, if it does it at slightly lower volume, the amp may be rapidly shutting off it's output to prevent failure.

ok the box is like 3.9 cubes and is tuned to around 33hz and the subsonic is set at 30hz because 30 is the only thing I can put it at when the subsonic is on

I played the song at 18 and it didn't do it, so I moved up to 19 and it started to do it a little bit.. so I didn't bother going any higher

so it's bottoming out right?

and what did u mean by 50/50? hope I didn't misunderstand something ha

so what's my best bet? hook up my saz 2000 and set th subsonic to 33hz?

or is there another solution?

and did I just do damage to my woofer?

thanks! you're a huge help!

[shizzzon 461]

put it back to 19 when playing that song and watch the sub.

Watch the label on the dustcap.

If it's bottoming out, it should appear to be moving almost or around 3" peak to peak.

[mbarber25 29]

put it back to 19 when playing that song and watch the sub.

Watch the label on the dustcap.

If it's bottoming out, it should appear to be moving almost or around 3" peak to peak.

ok just did.. but i had to do it at 20 since it wasn't really doing it at 19 anymore

(just sanded my ground in between time.. idk if that would do anything)

but it was going it again at 20 and i'm pretty damn sure it wasn't moving 3" peak to peak.. i've seen videos of btl's flexing a lot and it didn't really look like that

so now what?

could it be that the subsonic being set at 30hz is preventing the amp to play certain notes causing it to make that damn popping sound?

thanks

[shizzzon 461]

no that wont happen.

Look at the amp and see if everytime it pops that low ohm light u say thats on there comes on.

If it does, it's the amp cutting the sine wave off too early making it reproduce that frequency unevenly.

[mbarber25 29]

no that wont happen.

Look at the amp and see if everytime it pops that low ohm light u say thats on there comes on.

If it does, it's the amp cutting the sine wave off too early making it reproduce that frequency unevenly.

yea the light only comes on when it makes that sound

its a bitch because that only subsonic filter setting is for 30hz..

it's either no subsonic - or subsonic on 30

so any easy solutions?

[jcarter1885 995]

well its bad that you dont have an adjustable subsonic filter but in your case your good since it is set a few Hz below your box tuning and not at20 or 25Hz like most fixed subsonic filters.

whats the actual measurements of your box:

outside (d x w x h)

port (l x w x h)

and is there any bracing inside the box, what size mdf was used?

Also turn your subsonic filter off and see if it is still doing the slapping or popping noise at volume 20-22.

Edited July 28, 2009 by jay-cee

[shizzzon 461]

well then there's your answer.

the light only comes on when it makes that sound.

Let me show you what is happening- (this isn't drawn perfectly obviously but just follow me)

The top graph shows a normal wave in motion

The bottom graph is showing what is happening when your amp rapidly shuts off output-

When the bottom graph occurs, it isn't allowing the wave to fully finish. when this happens, u get a POP.

[mbarber25 29]

well then there's your answer.

the light only comes on when it makes that sound.

Let me show you what is happening- (this isn't drawn perfectly obviously but just follow me)

The top graph shows a normal wave in motion

The bottom graph is showing what is happening when your amp rapidly shuts off output-

When the bottom graph occurs, it isn't allowing the wave to fully finish. when this happens, u get a POP.

i see what you're talking about. why would the amp shut off output?

[mbarber25 29]

well its bad that you dont have an adjustable subsonic filter but in your case your good since it is set a few Hz below your box tuning and not at20 or 25Hz like most fixed subsonic filters.

whats the actual measurements of your box:

outside (d x w x h)

port (l x w x h)

and is there any bracing inside the box, what size mdf was used?

Also turn your subsonic filter off and see if it is still doing the slapping or popping noise at volume 20-22.

outside:

17 x 40 x 16

port:

13.5 x 3.5 x 5.5 or 4.5

the port numbers are rough since i'm sort estimating.. give or take on those number.. that's why i keep saying around

but also no bracing and 1" mdf was used

[shizzzon 461]

well, the way u describe this low ohm light, playing below the lowest rated stable ohm load for a given amp can cause immediate damage depending on the power level being created!

I'm assuming this is a fast safety option to prevent the amp from overheating due to excessive current output from the amp!

It's letting you know stop now... hehe

[mbarber25 29]

well, the way u describe this low ohm light, playing below the lowest rated stable ohm load for a given amp can cause immediate damage depending on the power level being created!

I'm assuming this is a fast safety option to prevent the amp from overheating due to excessive current output from the amp!

It's letting you know stop now... hehe

yes. the amp's been running hot lately. and before when it was ran above 1.5 ohms it would stay ice cold.

so what's my bext bet?

back down the gain? dont go past a volume of 19?

or any other suggestions?

just effin hook up my SAZ-2000 which is 1ohm stable? (the only downer to that is i don;t think my electrical is ready for it.. so idk

thanks

[shizzzon 461]

ur best bet is to wire the BTL in series!

That amp you have will output the same power at any load between 1.5-4 ohms.

So, wire it in series then hook it back up. You will still be getting the same power output, just safely this time

[jcarter1885 995]

well, the way u describe this low ohm light, playing below the lowest rated stable ohm load for a given amp can cause immediate damage depending on the power level being created!

I'm assuming this is a fast safety option to prevent the amp from overheating due to excessive current output from the amp!

It's letting you know stop now... hehe

do you think that if he turns the sub sonic filter off it will benefit him or no really matter?

I am currently running my 3-12" cvx's(1.3333 ohm load) to my profile ap1200 (2 x300 @2ohms, 1x600@4ohms and I know its a bad idea dont really care about those amps since they will be replaced soon) and do not run into that problem no matter how much power I through at them. But the amp does not have SubsonicFilter on it?

I also ran a Memphis at .5 ohm load (2-12"' cvx's) and didnt have that problem neither, even while the amp died on me a year later.

So could it be some type of technology that JL audio has since I've never ran into this problem myself?

[jcarter1885 995]

ur best bet is to wire the BTL in series!

That amp you have will output the same power at any load between 1.5-4 ohms.

So, wire it in series then hook it back up. You will still be getting the same power output, just safely this time

x2 thats what you should of did from go since they do have the same rms no matter what ohm load and their is no stability at 1 ohm.

[mbarber25 29]

ur best bet is to wire the BTL in series!

That amp you have will output the same power at any load between 1.5-4 ohms.

So, wire it in series then hook it back up. You will still be getting the same power output, just safely this time

ok that would work

thanks

so i will be getting a 4ohm load, correct? or........ instead of ripping my btl out of the box

what's your outlook on my other situation? (hooking up 2000) i just have to be very careful with the gain with my 2000.. my car should hold up for the time being? until i can purchase batteries

i have stock alt., ac delco battery- nothing special, and big 3 in 1/0

[shizzzon 461]

do NOT do that!

When i was building my wall, i have a 250A alternator but no battery in the back off of a single 3500w amp, it was causing havoc on my electrical system until i had put batts in the rear next to the amps.

Without something next the amps to get immediate power from, you will likely cause a low voltage scenario and you dont want that on a new amp like that.

[mbarber25 29]

do NOT do that!

When i was building my wall, i have a 250A alternator but no battery in the back off of a single 3500w amp, it was causing havoc on my electrical system until i had put batts in the rear next to the amps.

Without something next the amps to get immediate power from, you will likely cause a low voltage scenario and you dont want that on a new amp like that.

haha good lookin out

definately don't want to abuse that amp like i do my 250

[Tirefryr 1,742]

this is what is happening-

There is a term called impedance rise. This means that you have your sub wired to 1 ohm which in reality it's probably around 0.7 ohms.

During playback of a song, this impedance will change with every note the sub plays back. So when playing bass, each individual note has a different impedance. the impedance will never be as low as it's resting load which is 0.7 ohms for you.

So, you have what's called "impedance rise" or just "rise".

Everybody has this. However, your problem is there are certain notes that is being played where the "rise" is falling below 1.5 ohms. When this happens, the subwoofer is receiving the most power possible.

0.7 will be the DCR. That is a constant value, it never changes. Impedance changes because AC voltage changes the direction of the field; heat also comes into play, and back EMF, or better yet, impedance rise is caused by reactance.

do NOT do that!

When i was building my wall, i have a 250A alternator but no battery in the back off of a single 3500w amp, it was causing havoc on my electrical system until i had put batts in the rear next to the amps.

Without something next the amps to get immediate power from, you will likely cause a low voltage scenario and you dont want that on a new amp like that.

The reason it was causing havoc is because the system was still not up to par. That alt will only output 250 amps in ideal conditions. In all reality, the only reason the batteries helped is because they were there to absorb the strain from the alt. It wouldn't matter where in the line they were placed.

OP, try the Sundown and see how it works. Don't try to go balls out, but hook it up and see where it gets you. You could even wire it to 4 ohms while drawing less current, running more efficiently, and adding the power boost you need. When your system is up to par, then you can drop it down to 1.