Bring down the volume?

[grrr_arrghh]

Hi.

In audio terms, is the volume of a signal determined by a the current, or the voltage?

Presumably if the answer is current, a resistor would reduce the volume, or if the answer is volume, a simple resistive divider would reduce the volume.

Either way, I have a problem. on the front of my computer, I have a headphone socket. This headphone socket is a normal 3.5mm stereo socket, but with two contacts that break when a pair of headphones is inserted. When a pair of headphones is not inserrted, however, the signal flows from the sound card, to the headphone socket, then through the 'break contacts', to the line out socket on the back of the computer. The diagram below should help.

The idea of this setup is that a pair of speakers can be connected to the line out, but a pair of headphones can also be plugged in to the front - when this happens, the speakers conected to the line out are effectivly disconnected.

Here is the problem: when I put a pair of headphones in, the volume is far too loud, and I have to turn it down so far, that it is extremly difficult to control it. What I would do normally, would be to put a fixed resistor or something (see my first question) to bring down the volume. However, if i do this, it will also bring down the volume of the output going to my speakers, and my speakers can't amplify the signal enough to make it listenable to (I've tried). Its a bit of a dilema.

Does anyone have any ideas on how to get rounbd this?

Thanks

Tim

 

[Nigel Goodwin]

Hi.

In audio terms, is the volume of a signal determined by a the current, or the voltage?

Both - it's the power which determines the volume, which is why amplifiers are rated in watts, and not volts or amps.

Does anyone have any ideas on how to get rounbd this?

You just need a resistor feeding the headphones, well two resistors, one for each channel. Make an adaptor, 3.5mm plug to 3.5mm socket, with a series resistor in each live lead - pick the resistors to give the volume you want (try 100 ohm or so to start with). Plug the headphones into the adaptor socket, and the adaptor plug in to the computer.

 

[grrr_arrghh]

Both - it's the power which determines the volume, which is why amplifiers are rated in watts, and not volts or amps.

hmm, thats makes alot of sense , when I think about it, its obvious (of course power = current x voltage).

I don't know why I didn't think of an external adapter. I'm obviously not really thinking straight today.

Thanks

Tim

 

[samcheetah]

like nigel said, use a resistor. u must have seen headphones with volume controls. actually they have a variable resistor. u just change the resistance, the power to the speaker changes. so if u have a variable resistor near u, try using it