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xfish

OHM 1 vs 2 OHM vs 4 OHM

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Hey guys, I'm trying the old "installing my sound system in the back yard" trick. But i have some confusion with OHMs. I understand 1 OHMs is better bass than 4 OHMS for bass, and have watched a video on youtube how to wire 2  4 OHMS subwoofers down to 1 OHM. But can someone clearly explain what the OHMS are, and they're fuction....thanks

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I have one sub. 4 ohms. My amp gives it 300watts RMS. If I connect another so that they are connected in parallel then I get a load of 2 ohms and my amp will supply 500watts RMS. If I connect a total of 4 I have a 1 ohm load and a smoking amp as it is only rated at 2 or 4 ohms. There are dual voice coil sub's which change it all. I'm not familiar with them though. Mine is a single 4ohm coil.

 

I guess the difference in ohms decided how many watts your amp is delivering. In my case 300 watts@4 ohm or 500 watts@2ohm. I will eventually run 2 sub's for that reason.

 

Not sure if that's any help but a tired little 3 yo is calling me so that's all I've got.

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On speakers OHMS is the rating of resistance of the Speaker coil. Single Coil speakers can be hooked up in Parrallel or Series to OTHER speakers.

On Amplifiers it is the rated resistance the amp can handle.... as PH351 stated.

Dual Coil speakers can be wired in series or parrellel to themselves.

 

I would not drop to 1 OHM unless your Amp is rated to run at 1 OHM, or the magic smoke will escape and it will not work again.

 

Also be careful with speaker power ratings PMPO or Peak Music Power Output is what it can put out momentarily before it explodes into tiny bits.

The only TRUE power rating for speakers/amps etc  is RMS (root Mean square), everything else is bullshit.

a 1500w PMPO sub is actually about 300-500w RMS.

 

I get guys telling me all the time about their "1000w amps" that get shitty when you try and explain to them it's really 250w RMS.

Not their fault some stereo gear manufacturers are dodgy pricks.

Also to run subs properly a Capacitor MUST be fitted in line for the amp, so when it draws current to pump the sub, it is not 'choked' by not enough supply.

 

Me, I just listen to me motor.......

 

Jack.

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Voice coils are measured in ohms impedance which is the inductive resistance of a coil and changes with frequency.  

The lower the impedance you run the hotter the amp will run, you will also have higher distortion, the only benefit is more output from the amp if it can handle it.

Capacitors are largely wank factor and are generally used to assist an otherwise inadequate electrical system, if your voltage is dropping too much you need a bigger alternator and ideally a second battery in the boot with a short wire straight to the amp.

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Outback Jack, you have hit the nail on the head! An old bloke told me years ago that max watts are wank watts, and rms watts are what count. I've seen lots of clowns get sucked in to these big power rated speakers at a bargain price then they almost cry when they realise that their bargain was only rubbish quality!

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The trick is finding the lowest impedance your sub(s) can be wired down to, and then using an amp that is stable at that impedance.

Your not actually making better bass at low impedance, your just allowing the amps to flow power with the least resistance.

Class D monoblock amps are great at handling low impedance, as that is what they are primarily designed for.

Almost every class D mono will handle a 2ohm load easily, and others can go down to 1ohm (or even 0.5ohm like mine).

A little off subject...

When looking at amps to suit your setup, be wary of the usual BS sales tricks a lot of company's use. Some company's will say an amp might make 1500wrms, but fail to tell you that this rating was made at 16 or even 18 volts for a couple of seconds before it blew up, not at the 13.8v most charging systems make.

And always look at the fusing for the amp to get a good idea of what power it'll really make, a 2500wrms amp won't make that power with 60A fuse, the rule of thumb is 10A to 100wrms (though some company's now use larger fuses to fool consumers too these days).

Any decent amp will come with a "birth sheet" that will show the power it makes at different voltages and impedances).

But none of it will matter if your running an inadequate charging system, big power audio means big power charging systems, this is a trap most beginners fall into (I did too).

A 100 amp alternator and a normal battery will not support 1000wrms setup, and the rest of the vehicles ancillaries.

It's all a balancing act with a lot of ways to screw up, but if you know about it, you can put together a decent setup that won't cook/blow itself, or leave you stranded with a busted alternator/battery.

Hope this helps a bit, as I have been in this same boat myself.

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Voice coils are measured in ohms impedance which is the inductive resistance of a coil and changes with frequency.  

The lower the impedance you run the hotter the amp will run, you will also have higher distortion, the only benefit is more output from the amp if it can handle it.

Capacitors are largely wank factor and are generally used to assist an otherwise inadequate electrical system, if your voltage is dropping too much you need a bigger alternator and ideally a second battery in the boot with a short wire straight to the amp.

You are right Sir, but a capacitor is basically a battery , it stores power. Dragging large amounts of power from a Battery or an Alternator in bursts instead of how they where designed to work, trickle feeding the battery, or supplying a low amperage constant supply to instruments etc is bad for them.

It is a great way to kill your regulator on said alternator or stuff lead batteries.

A Capacitor inline on the amp Power line prevents scavenging for power and stores power for when it's needed. Also reacts fater than any wound up alternator.

 

Jack.

saves all the puss of installing a second battery and all the extra wiring.

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A capacitor isn't a battery and nor should it be considered to be used instead of a second battery.

In fact, the only thing it may help is your lights and accessories from flickering in some instances because it actually prevents power getting to the amplifiers properly, and instead everything wired before it gets the power.

The money spent on a capacitor would be better put towards a alternator capable of running your audio properly, as your audio will be powered primarily by the alternator, while using the battery to backup any large amp loads.

The reason a cap is pretty much useless, is because it discharges itself in a matter of milliseconds, and then takes minutes to actually recharge itself properly, which it will never do while the audio is on because it'll keep discharging on big bass notes and slowly recharge till the next big bass note...

It's because of this that it'll actually create a higher load on the alternator and battery.

This pretty much makes a capacitor a expensive, useless, blingy volt meter (well the ones with a voltage display anyway).

There really is no substitution for a good alternator.

Even a second battery is only a bandaid fix for inadequate alternator current, as it too requires charging by the alternator which again means less power to the amps.

There's been mixed opinions on the value of a good capacitor for years, but you'll usually find that the only people that say they work usually are the people that sell them.

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Arguement against.....

http://fatfist.hubpages.com/hub/Car-Audio-CAPACITORS-Why-They-DONT-Work

 

Arguement for.....

http://www.caraudiohelp.com/car_audio_capacitors.html

 

Make up your own minds.

 

You are right about the recharging of the cap, if not matched properly and with some people thinking "bigger is better" you end up with a cap that takes too long to recharge for a system that only needs a small storage amount, effectively making it work against itself.

 

Personally, I prefer fitting a bigger Alternator for anything over 2500w and good thick guage power wire is a must.

I've wired up some giant killers in my time, low wattage set ups that have blown away much fancier , more powerful equipment.... just by installing it properly, not scrimping on wiring and matching the speakers to the amps ability properly.

I have made systems with and without caps, depends on the situation, everything that ever left my hands has never come back with a problem.

Thats more than I can say for twats who still use connectors on the wiring instead of soldering everything.

Second batteries are only needed if you don't use good quality deep cycle batteries.

 

Best of luck with ya car stereo xfish, let me know if ya need a hand planning it out.

 

Jack.

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