Hi

I can't hear the stereo in my kit very well when i'm driving above 60, i dont want to fit bigger speakers and amps, so was thinking of earphones

Problem is my stereo doesn't have a socket, can i fit a socket off the speaker wires?

Adrian

I can't see why not?

I'm pretty sure that'd be way to much gain for a set of earphones. Walkman?

Connecting earphones across speaker outputs may blow your head off. Be careful and try resistors in series with the phones. 47 to 100 ohms would be a good place to start

ok, maybe not that simple then.

[Edited on 7/9/06 by Marlon]

MP3 players are nice and cheap nowadays. stereos are a waste of space in a seven, anything above 30 and you can't hear it, or if you can, when you stop EVERYONE knows you listen to boyzone!

quote:

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Originally posted by Marcus
when you stop EVERYONE knows you listen to boyzone!

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here's what you need.


click me

Ray

Be carefull. Ignoring the power issue for a moment, a set of headphones has a common ground (i.e. the jack plug has three connections, left, right and ground). A high power head unit (virtualy all modern head units) uses a bridged output configuration, which means none of the speaker wires is at ground potential. Connecting together two speaker wires from different channels to form a common ground for your headphones will blow up the output amp on the head unit.

There are a couple of ways of getting around this. Transformers on the speaker outputs will isolate the signals, allowing a common ground to be formed. The level converter in the link above probably uses this method, which also helps prevent hum from ground loops etc. However, that unit is designed to drive a 600 Ohm input for an amplifier etc. so it's possible that the output into a pair of headphones will be too low.

The other way is to return the headphone ground to the head unit power ground (i.e. the ground wire on the back of the head unit). You then use just the positive output from each channel. However, these will have a DC bias of ~6volts which will melt your headphones very quickly. You overcome this you use a capacitor to decouple the DC component. For 32 Ohm walkman type headphones a 220uF capacitor on each channel will give good bass response. Lower impedance headphones will need a larger value.

This configuration will give a 12volt swing to the headphones, which would be delivering a maximum of around 1/2 Watt to a 32 ohm driver. This is far too much for an in-ear style headphone, but a suitable resistor in series with the headphones can be used to reduce this.

Let me know if you want a circuit to show how to use this configuration.

[Edited on 7/9/06 by MikeRJ]

Look in the bikers mags. You can pick up great intercoms that take anaudio input for when theres no screaming going on!!
Lydls stock them from timetotime, so best try ebay.

Thanks guys

Looks a bit more complicated than i thought

I've tried a walkman/radio, but the radio reception was crap

The stereo has low level output for connecting an amplifier, would these work better?

Adrian

Defiately worth trying the low level outputs, they might have high enough level to drive 32 Ohm headphones (i.e. Walkman type buds), but almost certainly not 8 Ohm ones.

I think wearing earphones to listen to music in a car is illeagal! its OK on a bike and ear defenders are Ok if you are in a particularly noisy vehicle but earphones to listen to music are not as they can confuse or overwhelm car horns and police sirens. So i wouldn't use them unless you are wearing a helmet!

Caber

It is illegal, but enforcing it may be different as my mobile phone has a handsfree kit... which is a pair of headphones. If anyone can tell the difference I'd be surprised.

Steve

Well i doubt you will hear the siren of the Fire engine that will run you over above the screaming of your bike engine anyway

Caber

Hi

I didn't realise it would be illegal, seems odd that hand free car kits use earphones?

Adrian

yeah i believe it is illegal. good that ive already got some speakers located in the head rest of each seat..... mx5 seats are awesome.

I was going to get a cheap amp, possibly a kit from maplins to connect the speakers to then just have a loose 3mm jack that i can plug into my mp3 player.