Car audio guys...

[BigBrand]

Anyone help me out here please.

Got given a free Sub & Amp, and tried to put them in my sons motor today.

Essentially I've wired it all up, but the Amp kicks into Protection mode pretty quick.

Sometimes it'll last 10 seconds before kicking in to protect, or sometimes it'll last a minute but never longer.

Wondering why, I've checked the inline fuse from the battery and this is all fine, I've double checked the remote wire into the headunit and this is solid. Also the connections into the AMP seem fine.

The ground seems OK to be, I found a hinge for the rear car seats that's boltong to the frame of the vehicle, so scrated off the paint and used this. At first I was using a metal ring pressed onto the grnd cable and then onto the hinge. The nut and bolt I used were some kind of steel with a black coating, so then added a washer either side and scratched the paintwork off down even more, so it's connected fine.

I guess the only things it could be are

* Hinge doesn't actually ground too well?
* Headunit is too shit and can't provide the powere via the RCAs (headunit is a £10 Media player form Ebay, so very very basic!)

The fact it does power on, and does play for very short times, says the Amp itself and fuse are OK, the Sub does actually work, and that the connections to it power wise are all OK.

Anyone any input at all?

Few pictures to show what I mean RE the hinge it's grounded too.

http://gyazo.com/b10bd89880a6b9d77f3f81a2d7962913

http://gyazo.com/4f721d8980c5a1c7d916aebd5dbda1ab

[Over Carl]

I'm guessing it either isn't getting enough power via the 12v/gnd, or the impedance on of the speakers is too low (or you have a wiring fault with the speakers)



Very much doubt it's anything to do with the headunit/RCA's.


The gnd using the hinge looks shabby but should work.


What I would do first - confirm the speaker impedance required (normally 4ohms with car audio kit). Check your speakers have same or high rating - if they have a lower impedance, this is your problem. If not, borrow a set of home audio speakers (normally 8ohms but still check). Swap the speaker and cable to see if the problem still persists.


If it's gone we know it's down to speakers or cable. If not, I would consider getting the whole lot out and powering up via some small cables that are known to be good direct from a car battery that is known to be good. This will let you determine whether running new power cables will help.

[BigBrand]

Cheers for that bud. Is there anyway to check the level of GND to see if it's sufficient?

I've only got the Sub wired into the Amp, with all car door speakers working as normal via the Head Unit.

This is the AMP wired up.

http://gyazo.com/dd3e1146603c3b81a6e41d039abdd05e

GAIN is on lowest currently.

http://gyazo.com/6dad7da5724a580f79a9e9de0fc0313b

So I need to check the impedance of the Sub?

Is it worth using another Amp to see if the wires are at fault or the amp?

[Zippeyrude]

haha jetsound

i have 3 of them old school bad boys, i used to run a 15" kicker and 2 x eminence 12" hyper subs back in the days

[BigBrand]

Gather they're old then! No wonder it was free.

[Over Carl]

Yeah - I suppose my post translated to english basically says swap stuff over till you find what's wrong!

[Zippeyrude]

they were ok for their time (90s)

have you tried running them with the engine running?

where are you taking the power from?

[dav]

discount the sub and see if the amp states on it could be the sub is no good

[BigBrand]

It's the same from ignition to engine running.

I'll try disconnecting sub, didn't think of that.

The power is connected straight to the battery with an in line fuse

[Pegasus]

2 things I see wrong there.

1. The wires that run to the sub from the amp are way too small, get some proper sized cable that can handle the amount of power that is being delivered.
2. Unless that amp has a "bridge mode" switch, you need to have a load (speaker) present on that left hand output.

Do NOT run the amp without speakers connected, it won't like it in the slightest.

[MHP]

Unless that amp has a "bridge mode" switch, you need to have a load (speaker) present on that left hand output.

Do NOT run the amp without speakers connected, it won't like it in the slightest.

Yep I have to agree. Your lucky its it's got a protection circuit. If the amp was of 80's vintage or older you would have fried the transistors by now. Subs need mono/bridged power amps not stereo.

[Zippeyrude]

It does have a bridged mode iirc

[BigBrand]

2 things I see wrong there.

1. The wires that run to the sub from the amp are way too small, get some proper sized cable that can handle the amount of power that is being delivered.
2. Unless that amp has a "bridge mode" switch, you need to have a load (speaker) present on that left hand output.

Do NOT run the amp without speakers connected, it won't like it in the slightest.

Cheers buddy, further up in the thread, it was recommended to test where the fault is from, disconnect the sub, and just run it with power, GND and remote, and see if it stays on, to check if the fault is in the SUB & Wires?

Any idea on wire sizes to look at?

Yep I have to agree. Your lucky its it's got a protection circuit. If the amp was of 80's vintage or older you would have fried the transistors by now. Subs need mono/bridged power amps not stereo.

Can I bridge it by running the sub across the two channels? IE Positive of one and negative of the other?

It does have a bridged mode iirc

Is this like above, can't see any other switches on it?

[evilsatan]

I'm pretty sure I use 8 gauge on subs usually. Try to find the manual and see how it says to bridge the channels, often you bridge them like you said but sometimes it can differ. It's usually labelled on the amp itself but doesn't seem to be the case here.

[Pegasus]

Cheers buddy, further up in the thread, it was recommended to test where the fault is from, disconnect the sub, and just run it with power, GND and remote, and see if it stays on, to check if the fault is in the SUB & Wires?

Forget the test process for now, get the cable from amp to sub sorted first because I can guarantee you that the current cable you are using is nowhere near man enough for the job (it just about qualifies as bell wire).

Any idea on wire sizes to look at?

What is the alleged power output, and is it quoted as PMPO, Peak, or RMS?

Can I bridge it by running the sub across the two channels? IE Positive of one and negative of the other?

If that amp had bridge capability, I would expect to see a switch marked "Bridge Mode" as well as seeing it marked on the output stage.
Your's has no such switch or indication, so I would say no.

[Zippeyrude]

friggin hell, all this has made me go the the garage and visit my box of memories and dig out a couple of my amps...

there were two models of the jet sound 400watt amp.

also, the power and earth cable looks like 8 gauge which is fine for this application. the speaker cable could be better but i dont think that would cause the amp to go into protection mode, clip (cut out), etc.

so, depending on the speaker you are running, id say that you need to change the wiring of the speaker out to run bridged.

[BigBrand]

Forget the test process for now, get the cable from amp to sub sorted first because I can guarantee you that the current cable you are using is nowhere near man enough for the job (it just about qualifies as bell wire).


What is the alleged power output, and is it quoted as PMPO, Peak, or RMS?



If that amp had bridge capability, I would expect to see a switch marked "Bridge Mode" as well as seeing it marked on the output stage.
Your's has no such switch or indication, so I would say no.

Ok cool, I'll get some more speaker wire in and see how we go with that. No sure on the power specs to be honest, as I've not looked into the exact model, but obviously mine doesn't say bridged mode, so does this mean it can't be bridged or that it just wasn't labeled for it?

friggin hell, all this has made me go the the garage and visit my box of memories and dig out a couple of my amps...

there were two models of the jet sound 400watt amp.

also, the power and earth cable looks like 8 gauge which is fine for this application. the speaker cable could be better but i dont think that would cause the amp to go into protection mode, clip (cut out), etc.

so, depending on the speaker you are running, id say that you need to change the wiring of the speaker out to run bridged.

Fucking hell Zip, rolling back the years

I think for further use, I'll upgrade the speaker cable and run it in bridge mode and see if that cures it!

Worth getting a voltmeter on it to establish how good the ground is? Think I'm good with the live as the power doesn't flicker to it, and the cable is solid to the batter.

Would the remote cause it to jump into protection mode? Might be worth revisiting this as well?

[Zippeyrude]

Fucking hell Zip, rolling back the years

too right, jeeze. I might dig out all the bass cds / mp3s i had too....

Anyone remember "its the quaddddd, its the quadddddd, its the quad and im a basshead BOOOOOOMMMMMMMMM" ?

the power and earth cables are fine. I suspect you wont see an earth issue unless you measure the amp draw but it will be minimal. id test the earth point as continuiuty across it and the power. make sure it isnt hindered by paint etc.

beef up the speaker cable, run it bridged, make sure the head unit isnt maxxed out on gain (start it off at 1/3) and make sure the speaker is 4ohm impedance.

[BigBrand]

Cheers Zip,

Do you think this stuff would be OK?

http://www.ebay.co.uk/itm/4mm-SUBWOOFER-SPEAKER-CABLE-WIRE-USE-with-BASS-SPEAKERS-1-Metre-/350818110269?pt=UK_Cars_Parts_Vehicles_Terminals_Cabling_ET&hash=item51ae638b3d

[Pegasus]

the speaker cable could be better but i dont think that would cause the amp to go into protection mode, clip (cut out), etc.

Trust me Zippey, you start trying to pump (say) 100W through that bell wire that BB is currently using and it will be breaking down internally due to the fact it simply cannot carry that much current.
A good analogy would be trying to run a kettle from a mains lead that is only rated for 3A. Sure it will work (in the beginning), but you won't successfully boil that kettle as the cable will give up long before the water has managed to boil.

@ BB
Get yourself a length of mains cable that is at least 1mm² in cross sectional area, for example a mains extension lead rated at 10A will be sufficient to act as the wire from the amp to the sub.
The remote won't cause it to go in to protect mode, all the remote does is provide a trigger (in the form of a constant 12v) to tell the amp to switch on. If that 12v is missing, the amp switches off.


PS
@ BB again

That cable you linked to will be fine, but you can also use a bit of old mains extension lead if you like.