Ok well decided to do some DB testing tonight (lol) and heres how it goes.
HU i know goes to max of 50
and i had it on 20, plenty of boom boom..
25, still going alright.
i hit 28 and its like the bass almost drops? like it wasnt even there..

Im just curious, what could be casuing the bass to just drop out? Not TOTALLY cut out but just DROP to like i was only running 6x9's?
FYI
Subs are JBL GTO 1202D's running @ 2ohm to the jaycar 1000W mono.

sounds like your amps not setup right
then again maybe not have enough power to do what you are asking it to do
are these the subs you running?
http://www.jbl.com/car/products/product_detail.aspx?prod=GT4-12/230&Language=ENG&Country=AU&Region=EUROPE&cat=SUB&ser=GTS
and what are the specs of the amp?

Nooo
I have the JBL GTO 1202D's
300WRMSish
DVC 2+2ohm
Amps is A Jaycar mono
700W @ 2ohm
1000W @ 1ohm

May not have the amp set up right just trying to get a few ideas before i try this out in some carpark tomrrow

Also, could it be my ports are the wrong size?

Gains up too high me thinks...

Asking too much from your amp. As it's loaded down to 2 ohm it cant produce that much power... So its going into protection.

edit: although going by those figures it should be alright... maybe something else... Is the amp going into protection, or just not loud? are the subs still working?

Gains up too high me thinks...

Asking too much from your amp. As it's loaded down to 2 ohm it cant produce that much power... So its going into protection.

Would it be better suited if i put it down to 1ohm?
Or just fiddle with the settings until it does not cut out..
Damn i could of used you when you were there damm it!

']Would it be better suited if i put it down to 1ohm?
Or just fiddle with the settings until it does not cut out..
Damn i could of used you when you were there damm it!

those subs cant be wired up as 1ohm, if you try to you'll end up getting 0.5ohm which is no good for your amp
play around with your settings im no expert but this worked for me got my amp to stop cutting out
set your gain to about 5/8's towards max
db somewhere between +3 - +6
fq between 55 - 75

I say it's your gain up too high as well. Have you opened the boot and had a listen to your subs when this cutout occurs? If you can hear any clipping i'd say that could be your problem. Otherwise is it possible that you're asking too much from your subs?
Mr_Roberto - There's no guarrenteed gain position you can use for any HU/amp combo. You need to make sure your output signal is matched to the right input strength on the amps gain control, but even then minor tweaking will be needed.

what size wires are you running to both your amps and your subs? the thicker the better.

what size wires are you running to both your amps and your subs? the thicker the better.
2ga from battery split to 2x4ga abd earthed with 4ga and there are 4x4ga earts gong back to the battery.
havent had time to check this problem as i just had to get the car towed home :cry: so this is the least of my worrys

what did u do now?

why are u earthing to your battery?

why are u earthing to your battery?

4 earth points from the engine bay chassis to the - terminals

I am not all completly dumb:P

I had a similar problem when I made my first sub box... It turned out to be the box itself becoming resonant at high volumes, cancelling out the bass.... Once I reinforced it, it was better, but I eventually decided to make a better box in the end...

Has this problem just become apparent now?.. Or has it always been the case?

I'm just wondering if it could be (a long shot) sympathetic resonances in either the boot or the box that are letting you down. These resonances may not become apparent until the volume is turned up, and as such, the resonances become worse.. limiting your overall bass output...

I'd check to see how much your sub box resonates at higher volume levels, then check the boot lid (and seals). I'd also check to see if the problem worsens (or becomes better) depending on particular freqs.

If it occurs at any given frequency then I'd say its most probably a component problem, but if it occurs (at its worst) at a particular frequency, then its a resonance problem....

If its only recently become apparent, with no system changes recently that you can think of that would upset the subs, then it could be another common problem:

It could be that one of the subs has lost its signal input, or the speaker wire has come off at the speaker terminal... Its hard to see by watching the subs move (especially if the 2 subs aren't in seperate chambers), because the sub that's "become loose" (or has become a passive radiator) still will move in sympathy to the other sub... This sub will actually reinforce the bass at certain freqs (much like a port), and it will look like its functioning normally, untill you crank up your system, to which it may respond by becoming totally out of phase at certain freqs, thus giving the impression that there is less bass at higher volume levels. IT HAPPENS AT LOT!!!! And because you see both subs moving, you naturally assume that both are recieving wattage...

So I'd check that both subs are getting a signal also....

I had a similar problem when I made my first sub box... It turned out to be the box itself becoming resonant at high volumes, cancelling out the bass.... Once I reinforced it, it was better, but I eventually decided to make a better box in the end...

Has this problem just become apparent now?.. Or has it always been the case?

I'm just wondering if it could be (a long shot) sympathetic resonances in either the boot or the box that are letting you down. These resonances may not become apparent until the volume is turned up, and as such, the resonances become worse.. limiting your overall bass output...

I'd check to see how much your sub box resonates at higher volume levels, then check the boot lid (and seals). I'd also check to see if the problem worses (or becomes better) depending on particular freqs.

If it occurs at any given frequency then I'd say its most probably a component problem, but if it occurs (at its worst) at a particular frequency, then its a resonance problem....

If its only recently become apparent, with no system changes recently that you can think of that would upset the subs, then it could be another common problem:

It could be that one of the subs has lost its signal input, or the speaker wire has come off at the speaker terminal... Its hard to see by watching the subs move (especially if the 2 subs aren't in seperate chambers), because the sub that's "become loose" (or has become a passive radiator) still will move in sympathy to the other sub... This sub will actually reinforce the bass at certain freqs (much like a port), and it will look like its functioning normally, untill you crank up your system, to which it may respond by becoming totally out of phase at certain freqs, thus giving the impression that there is less bass at higher volume levels. IT HAPPENS AT LOT!!!! And because you see both subs moving, you naturally assume that both are recieving wattage...

So I'd check that both subs are getting a signal also....

Thanks for the reply mate
Both the subs are In 55L+ Boxes, Box is made from 18mm MDF All around.
Still gotta get round to putting foam inside the box but yeah it could be that problem.
This happened when i was listning to heavy metal, so it was a very fast double bass, i just thought the double bass was going too bloody fast for the sub to keep up with!

I'll have to check settings though aswell...

Yeah... I've had similar probs since I've run 2 subs... But you've had that setup for a while so its wierd that its just recently become a problem....

It may be that the battery is on its way out too...

BUT!!!!

Before you go crazy and put in more earths and change your battery n stuff, do a little testing to save your hard earned cash from being spent on something you don't need...

Give yourself piece of mind and check that the amp is getting good, stable power to it...

I'll give the following info. for future reference to ppl that may have the same probs (not because I think you don't know how to do it:) )

If you don't have a multimeter... then GET ONE!!!! They cost like $13 at K-mart, and they are useful as!!!

The best way to check your battery, power cable and earthing is good, is by placing a multimeter across the amps power input terminals to test that it is recieving over 12 volts at all power levels.

STEP 1:
* Test with the ignition off to start with, placing the the red lead on positive terminal on amp, black lead on negitive terminal on amp, with multimeter set to VDC. It should show 12-13VDC, depending on the battery. If you have less than 12VDC (or nothing at all) goto STEP 2.
* Now turn your ignition on (but don't turn the motor over), and check the amp is still getting 12-13VDC with low volume (easy to talk over) music. If the voltage lowers by over 0.2VDC from the original reading goto STEP 2
* turn the volume up slowly, checking that the voltage at the amp terminals is still close to the original reading. It shouldn't go lower than 0.2VDC from the original reading. If it does start to drop, lower the volume and goto STEP 3.
* Keep turning the volume up, checking the reading at the multimeter to see if the power has dropped... up until you consider the volume level to deem its loudest, and check to see if the voltage has dropped. If the voltage hasn't fluctuated lower than 0.2-0.5VDC from the original reading then congratulations!!! Your cabling and battery can cope with your sound system requirements.
* If you have noticed a drop that fluctuates lower than 0.2VDC (as in it sits around the normal voltage, but drops by over 0.2VDC when the music demands a high current) then goto STEP 4.

STEP 2
So your power is lower than 12VDC or you ain't getting anything?
* Check your multimeter leads are good by putting the multimeter into "resistance mode", and then touch both the positive lead and the negative lead of the multimeter together. It should read under 1 ohm. Use the reading you have (which will probably be around 0.1-0.3 ohm on dodgey multimeters) to minus from all of your resistance readings, for an accurate result in future. This is your multimeter fudge factor. If you need more length in your lead, simply wind a length of wire onto the end of one of the leads. Redo the resistance check...
* Turn your ignition on and check that you haven't got your ignition cable to the amps input by mistake lol ...If you have done this, you will have 12VDC at the amps terminals only when you have the ignition on (which is bad mkay?). You should have at least 12volts at the terminals at all times. O.k. good, I was just checking!!! goto STEP 3

STEP 3
* -NEGATIVE lead check- Move the negative lead on the multimeter to an earthing point on the chassis. Something you are sure to get a good earth from, free from paint and gunk. If the voltage become better then the first reading then your earthing point, or the cable is bad. Its got nothing to do with the size of the cable either... Its just plain BAD!!! Change your earth point to a better spot (eg: the spare tyre retaining bolt hole, a chassis rail,handbrake mount, seat and seatbelt mounting points). If the problem still is apparent, then your earth cable is bad. Change the cable and go back to STEP 1
* -POSITIVE lead check- Check the voltage at the battery terminals (same way as on the amp). If you see the same problem here then its your battery letting you down, but if you have good voltage here then I'd say you have either blown a wiring fuse or the positive lead is broken. Check the fuse by using the multimeter in "resistance mode". Put the positive lead on one side of the fuse and the negative lead on the other side. If the resistance is over 0.1 ohm (minus your multmeter fudge factor) then it should be replaced. If it is good, then do a resistance check from the positive wire on the battery to the positive on the amp terminal. It should read under 0.2 ohms (minus multimeter fudge factor) If it doesn't, then your positive lead has a breakage, and needs to be replaced. If you have a breakout terminal for multiple positives out, then check there as well. Still haven't found a solution? goto STEP 5


STEP 4
Hmmm... So you have noticed that your system plays fine until it starts to get loud, and then the power starts to drop at the amps terminals... 0.2VDC drop ain't too bad but can be improved, but over 1.0VDC is starting to show problems
O.k. We are gonna have to now see if its the cabling or the battery.. so:
* repeat proceedure 1 and check the voltage up until you get an undesirable drop (over 0.2-0.5VDC from original reading)
* keep the volume the same, and now take the multimeter up to the battery itself, checking to see if the voltage drop is the same at the battery terminals (not the amps terminals). If the multimeter is showing the same results at the battery to which you were seeing at the amps terminals, then I'm afraid your battery is choking under the pressure of your system... You'll either have to change your battery, or limit yourself to lower volumes unless your engine is running. test to see if your power system copes with the engine running by checking the voltage as per step 1 with the car engine running.
* if the battery is showing hardly any change in voltage, but your amp terminal voltage is fluctuating by over 0.2-0.5 (depending on how picky you wanna get) then I'm afraid your cabling has issues....move to STEP 5

STEP 5
Active cable testing YEEEEEEHAR!!!! Be careful, always be mindful that you don't zap yaself in the following proceedure!!! Your multimeter should be in DVC mode.
* turn the volume up until the voltage problem becomes apparent at the amp terminals

* active -NEGATIVE- check: Carefully place the negative lead on your multimeter onto the negative terminal of the battery.
* Put the positive lead of the multimeter onto the amps NEGATIVE terminal. You should see NO VOLTAGE. If you do see voltage spikes of 0.2VDC or more then your negative cable has either a bad ground, or cannot handle the power expectations of the amp.
* Move the positive lead to the grounding point. If the problem goes away, its the lead from the earthing point to your amp that is the problem.
* If the problem is still there, move the positive lead of the multimeter to another couple of different earthing spots in the same broad area, free of paint and grit.
* If this solves your problem, then your earthing point has to be changed. If the problem is still there, then I'm afraid that your earthing cable from the battery is too small in guage, and must be replaced. Alternatively, run a dedicated earthing cable from the battery right through to your earthing point for a stronger earth.

* -active -POSITIVE- check: VERY carefully place the positive lead of the multimeter onto the positive on the battery terminal
* Place the negative lead of the mutimeter onto the amps positive (yes the positive) terminal. You still have those tunes cranking yeah? O.k., with a good power cable, there should be no voltage showing here whatsoever... The voltage you see on the multimeter is your actual voltage drop from the battery to the amp.
* If the voltage drop is more than 0.2-0.5 at high listening levels, then it may be wise to upgrade your lead in the future. Its not bad, but its still a substantial loss in power. More than 1 volt loss through the line almost definately requires an immediate cable upgrade... Check that the fuse isn't the problem by checking the voltage drop on either side of the fuse (the same proceedure you did for the positive cable).


Phew.... did I leave anything out?

Oh yeah!!! Check your speakers are connected and coils are good by checking the resistance at the amp. Pos lead to pos on speaker out (with speaker attached), and neg to neg speaker out (same speaker). Should read the nominal ohmage of the speaker (say around 3.3-3.8 ohms resistance for a speaker with 4 ohm impedance....

That is one mighty Impressive Write up!
Will be doing just that when i get my car back and working.
Thats the most informative post on AMC in months!

Yeah... I was bored I guess.. Plus, I've seen how much work you have put into your install and I'd hate for you to be having a small problem let you down on an otherwise awesome setup...

I wrote up a concise testing proceedure on power cabling after seeing a close friend of mine spend over $350 in cabling and terminals in an effort to make his system perform better. After noticing absolutely no change in his setup, we later found out that the battery terminal had become slightly corroded, and we gave it a quick clean which immediately fixed the problem...

If your not planning on building a power delivery system to cope with future upgrades, and your cables do their job well already its money wasted IMO to spend big dollars on oversized cable when there are other more beneficial things you can put your money towards (eg soundproofing).