another 'my amp fuses keep blowing'

curious12 · 06-30-2009, 07:22 AM

hey
firstly im new here so hello everyone

as the title states i have a problem
firstly my set up

0guage from batt to 80a fuse to 10a fuse to head unit and a 2guage to a distro block powering 3 amps (through 4 guage wire)
1 4 channel and 2 2 channels
then 4 guage to another distro then 2guage to a hole that used to house a clip for the trim in the side of the boot (metal is thin, maybe this is the problem?).
the remote from the HU goes into a 2 channel then piggybacks from there to the other 2 amps.

The problem
i put in 6 new speakers into the car (well 4 and a set of splits)
and my 4 channel to run them (the 2 channels are not connected to the subs right now because the boxes are out being carpeted and ported but the amps still power up)

anyways today i turned the system on to start tuneing.
played some music and slowly increased volume to hear for distortion (amps gains were at 0 no boosting in either head unit or the amp and high passes were set at about 100htz)
i got fairly high (say 80-90% percent, didnt check because i quickly turned down the volume because of what happenend)

everything was working fine, then one of the 15a fuses in the 4 channel blew so i quickly turned down the volume and sound came back on so i started to increase again even slower and it cut out earlyer as t he other 2 15a fuses blew.
i figured i just went too high for the amp so i replaced (had a slight spark as i put in the 1st fuse even though the amp was off due to head unit being off)
and powered up. and the protection was on straight away. checked fuses and theyre all blown.

i decided there must have been a short somewhere so i disconnected the speakers and rcas . disconnected the power from the amp. replaced fuses then reconnected the power ground and remote to the amp.
powred up and still no volume. checked fuses and again they were blown. (this is the most amount of fuses ive blown in my life.

so im pretty stumped now

i thought it might be an impedence issue but wihout the speakers connected then that shouldnt be an issue.

(which brings up a 2nd question

the speakers are as follows

2 6 inch JL audio splits (on the box says 4 ohms so i assume this includes both the tweeter and the woofer) in front doors
2 alpine 2 way type S (4ohms) also in front doors. (these are connected in parallel to the JL crossover. so thats channel 1 from amp into jl crossover then from there to the alpines. the outputs on the xovers go to the appropriate woofer and tweeter)
then the rear speakers are connected directly to the rear channels of the amp

can anyone please help me.
tomorrow ill get a new ground and connect the remote directly to the 4 channel and see what happens but id rather get more info before blowing my last 3 fuses and the risk of more damage to my amp.

curious12 · 06-30-2009, 10:21 AM

tried my own little bench testing

got a low power jump starter

fused it and ran all wires to the correct terminals and the same result the amps fuses blow.

so im guessing its an internal fault?

durwood · 06-30-2009, 10:32 AM

Does it blow fuses with only power, ground and remote-no speakers? If yes, internal to the amp, if no then check your install for shorted speakers. BTW, it is not a good idea to connect multiple speakers through a passive crossover if you change the designed impedance load.

soundman98 · 06-30-2009, 10:36 AM

First, welcome to the wonderful world of car computing, and system integration!

on to your problem-- could you provide us with a couple more details on the what type of amp and its model #? also, I am a little confused about how the speakers are hooked up you said that the type s' are connected to the jl crossover?

[DISCLAIMER: this is assuming that your amp is a 4 channel, 4 ohm stable amp]

the type s' should be connected to the amp (never to the jl crossover), on all 4 channels, and the jl's should be connected in series with one of the left/right pairs on the amp, to create a 8 ohm load on the amp for those 2 channels(it will be quieter, but will work).

here's why: originally, when the you had the type s' on one pair, and the type s and jlon the other pair, you had them in parrallel, creating a 2 ohm load, and causing the amp to think that there was a short somewhere.

there is also the possiblity that you really do have a short somewhere, or a bad ground that is causing the issue, but the primary issue that i see from your post is the parallel speaker hookup.

edit: I started my reply when there were no replies, so some of what i have posted might have already been covered.

curious12 · 06-30-2009, 07:18 PM

sorry if i wasnt clear

the amp is a response digital 4 channel amp stable to 2 ohms or 4 ohms bridged

the alpines work in parallel to the jl splits they are not on the output of the crossover

thanks for the replies so far

curious12 · 07-01-2009, 09:03 AM

just really trying to figure out what ive done wrong

would turning the volume up too high (even with gains all the way down) be the reason it happened or was it just because of a grounding problem.

or something else
o want to fix this before i bugger up the replacement amp

thewizard · 07-01-2009, 03:02 PM

It sounds like you fried your amp, most likely due to an inadequate ground. Your ground wires should ALWAYS be the same size (or larger) as your power wire and should be connected to the chassis (or back to the battery). If you can get to a seat or seat belt bolt or to something else that bolts directly to the chassis then that should suffice. Grounding to just sheet metal on a uni-body vehicle is bad news for a heavy 12 volt load.

curious12 · 07-01-2009, 07:54 PM

thanks for your reply.
ill relocate the ground this arvo. im just glad i didnt try the sub amps. they cost me alot more and would have drawn alot more power

curious12 · 07-02-2009, 08:20 AM

got my replacement amp today. just waiting for my sound proofing to come in tomorrow before i rip apart my boot again and relocate the ground.

just a few questions before anything else goes wrong.
on the box for the jl audio box it says 4ohms impedence. is that the impedence of the the woofer and tweeter together or what?

like does it mean 4 ohms for the crossover or for the woofer?

just trying to make sure i dont try and run the new amp under 2 ohms

also ive been mapping out my subs in winisd and wondered would it be a good idea to tune each box to a different frequency so they both peak at different frequencies or would it be better to have them 'roll off' together and be consistent and back each other up?

both subs are the same and in different boxes (1 on each side of the boot)

also with my ground if i cant get the new location within a foot would it be a beter idea to get thicker ground wire to compensate the extra length? (btw yes i have upgraded the ground from alt to chassis and from battery to chassis. im not a total noob with car audio)

soundman98 · 07-02-2009, 09:59 AM

the easiest way to figure out the jl components would be to use a ohm meter, but i believe that the 4 ohm stament should be corrct for both teh tweeter, mid, and crossover.

for the subs, it is best to have them setup exactly the same. winisd wont show it, but you will get cancelation of certain frequencies(and amplify others) if you set them up differently. if you are planning on a ported system, make sure you run a high pass right below the port freq.

winisd is a great program, but it can never model the exact wave that will be produced in your car(this would cost thousands to do). just remember, it only models the sub/box interactions.

curious12 · 07-02-2009, 08:13 PM

thanks for all the help everyone.

curious12 · 07-06-2009, 08:38 AM

yayyy new amp works
i have now earthed to the seat mounting points
subs are going in 2morrow

quick question
whenever i turn off the ignition i get a sort of pop/crackle through the speakers

what would be the cause of this?
i imagine it will only be worse when the subs go in

is it dangerous?
is it a sign of somethings going to go wrong?
is there a way around this?

mroverkill · 07-06-2009, 09:20 AM

Quote: Originally Posted by soundman98

the easiest way to figure out the jl components would be to use a ohm meter, but i believe that the 4 ohm statement should be correct for both the tweeter, mid, and crossover.

remember that an Ohm Meter will be a DC measurement if resistance. A Speaker has an Impedance measurement which is an Ac measurement of many factors such as resistance, capacitance and inductance being a few. resistance just being one of them. and that resistance will change with frequency. it is not a set measurement. it will generally get higher (more ohms) at the the Fs of the driver(s) and the box tuning frequency. it will generally get lower around the crossover points.

Anyway, you can use a Ohm meter to get a close idea of a woofer. an 8 ohm woofer typically measures around 5-6 ohms, a 4 ohm woofer maybe around 2-3 ohms etc.

but measurements through a crossover with an ohm meter don't work as the crossover blocks DC from passing. Looking at the resistance of a system with say a woofer, midrange and tweeter with a 3 way crossover. the woofer see's a very complex load. but. in simple terms, the amp will "see" the impedance of each driver withing each drivers frequency range plus whatever loading the crossover adds.

So lets really mess this up and take a look at what would happen. say you have a 2 ohm woofer, and 8 ohm midrange and a 4ohm tweeter. with crossover points of 300hz and 3khz and lets forget for the moment the mess this makes.

the amp, will see only the 2ohm woofer woofer from 0 to 300hz, then the 4ohm midrange from 300hz to 3khz and then the 4ohm tweeter from 3khz to however high the tweeter will go.

now this isn't 100% true as the drivers overlap a bit at the crossover frequencies. how much overlap depends on how many db per octave your crossovers are. and we haven't taken into account whatt he inductance and capacitance of the crossover does. but....you get the idea.

Most better home speakers will have a chart with an impedance curve that looks pretty much like a roller coaster. peaks at the box tuning points and valleys around the crossover areas where the amp will see both drivers.

To me it sounds like you had some speaker wires shorted to ground or, you had amp channels shorted together.

Part of your comment i am confused about:
2 6 inch JL audio splits (on the box says 4 ohms so i assume this includes both the tweeter and the woofer) in front doors
2 alpine 2 way type S (4ohms) also in front doors. (these are connected in parallel to the JL crossover. so thats channel 1 from amp into jl crossover then from there to the alpines. the outputs on the xovers go to the appropriate woofer and tweeter)

so you have one channel of the amp powering a set of JL audio speakers and the alpine speakers? that would then be a 2 ohm load.

curious12 · 07-06-2009, 09:28 AM

Quote: Originally Posted by mroverkill

remember that an Ohm Meter will be a DC measurement if resistance. A Speaker has an Impedance measurement which is an Ac measurement of many factors such as resistance, capacitance and inductance being a few. resistance just being one of them. and that resistance will change with frequency. it is not a set measurement. it will generally get higher (more ohms) at the the Fs of the driver(s) and the box tuning frequency. it will generally get lower around the crossover points.

Anyway, you can use a Ohm meter to get a close idea of a woofer. an 8 ohm woofer typically measures around 5-6 ohms, a 4 ohm woofer maybe around 2-3 ohms etc.

but measurements through a crossover with an ohm meter don't work as the crossover blocks DC from passing. Looking at the resistance of a system with say a woofer, midrange and tweeter with a 3 way crossover. the woofer see's a very complex load. but. in simple terms, the amp will "see" the impedance of each driver withing each drivers frequency range plus whatever loading the crossover adds.

So lets really mess this up and take a look at what would happen. say you have a 2 ohm woofer, and 8 ohm midrange and a 4ohm tweeter. with crossover points of 300hz and 3khz and lets forget for the moment the mess this makes.

the amp, will see only the 2ohm woofer woofer from 0 to 300hz, then the 4ohm midrange from 300hz to 3khz and then the 4ohm tweeter from 3khz to however high the tweeter will go.

now this isn't 100% true as the drivers overlap a bit at the crossover frequencies. how much overlap depends on how many db per octave your crossovers are. and we haven't taken into account whatt he inductance and capacitance of the crossover does. but....you get the idea.

Most better home speakers will have a chart with an impedance curve that looks pretty much like a roller coaster. peaks at the box tuning points and valleys around the crossover areas where the amp will see both drivers.

To me it sounds like you had some speaker wires shorted to ground or, you had amp channels shorted together.

Part of your comment i am confused about:
2 6 inch JL audio splits (on the box says 4 ohms so i assume this includes both the tweeter and the woofer) in front doors
2 alpine 2 way type S (4ohms) also in front doors. (these are connected in parallel to the JL crossover. so thats channel 1 from amp into jl crossover then from there to the alpines. the outputs on the xovers go to the appropriate woofer and tweeter)

so you have one channel of the amp powering a set of JL audio speakers and the alpine speakers? that would then be a 2 ohm load.

that is correct. the amps stable to 2 ohms
seems thats all fixed as i had the speakers working today (although i haven't gone louder then 26)

any info on the latest question
with the popping/crackling noise i get when i turn off the car?
btw: thanks for the info about the crossovers

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