car subwoofer to phone

[Rahul_23]

Hi,
I got these sony Xplode car subwoofers they are like a decade old, my cars music system got stolen last year, so now I am trying to connect these two subs to my phone via a 3.5mm jack.

What I did, is I took one of my old earphones and cut it to get the 3.5mm jack I needed, and joined the two subs in parallel, and directly connected to my car battery.

I am not certain but I guess they are 4ohm subs so connecting them in parallel makes them 2ohms.
My question is should I use an amp or can I directly connect this to my phone, coz one of my friend told me this arrangement will cause a considerable amount of current through the 3.5 jack hence damaging it.

 

[Someone Somewhere]

You need an amplifier.You cannot connect them directly.

Don't connect them directly to the battery, either... that's a great way to destroy them quickly.

 

[BrandonYoung]

Use an amplifier.
<phone>--<audio signal cable>--<amp --<battery>>--<speakers>

It may be better to wire in series vs parallel for a 8 (+/-) ohm load to the amp (make sure your amp is 2ohm stable if going parallel).

Phones have a difficult time driving unamplified 5 watt speakers, wiring your subs to your headphone out on your phone will not provide enough wattage to do anything. If you hear anything at all, it will be very very quiet. You -NEED- an audio amplifier of some type.

I'm not sure how you would do it, but if you connect your subs directly to a car battery, you will destroy your subs for sure unless perhaps they are incredibly high wattage.

In the concert audio business, we would connect a 9v battery to speakers (75-2000 watt) to see if they work. This forces the cone in or out depending on the polarity. If you attempted this with a car battery, the speaker would fully extend in, or out, then the diaphragm would probably fuse itself to the driver rendering your speaker useless, then it would probably catch fire or melt the insulation off your cables. Sounds like a fun experiment, but I would not advise this if you hope to use your speakers in the future.

 

[Rahul_23]

This is the sort of arrangement I am talking about:

https/www.youtube.com/watch?v=Vg96mz8WJlQ

About connecting them directly to the battery, I guess a fuse should solve the problem I guess

 

[Someone Somewhere]

A fuse is a good idea, if you have an amplifier.

You'll need a larger amplifier than that to effectively drive a pair of subwoofers.

How did you connect the subwoofers to the battery previously? You may have fried them already.

 

[Rahul_23]

I didn't connect anything yet.
I will upload pics of my subs tonight, they seem to be of the same size(maybe they are a bit larger) as in the video.
So how big an amp are we talking about here can it be built or do I have to spend bucks on it?

 

[Someone Somewhere]

Oh. Those aren't really subwoofers; they're just speakers.

You'll need a pile of fairly unusual components to build an amp, but you should be able to get a moderately decent one pretty cheaply if you're not nuts about sound quality.

 

[Alabalcho]

If you have only subwoofers left (without speakers), you will get only "boom-kaboom" sounds from them, without any real music / vocals.

 

[BrandonYoung]

If your speakers aren't much larger than the ones in the video, you really might be able to drive them only using your phone. It probably wouldn't get very loud however.