volume control with optocoupler

I came across a very good volume control design today

http://www.diyaudio.com/forums/showthread.php?s=&threadid=80194&perpage=10&pagenumber=1

It is a optocoupler changes resistance depending on the intensity of the LED. However, the resistor that is soldered in, is a special Light Dependent Resistor (LDR) which according how much light is shone on it by a LED can vary it's resistance, so you can have control over the level of music by controlling the amount of brigtness of the LED by a pot which varies the voltage going to the LED.

Because the resistor is solder in, there is no contact point along the signal path giving better sonic, at least in theory.

Can buy the optocoupler in RS. ALso very cheap. I will try.

Anyone tried this before?

That's really interesting, let us know the result after you have done the test.

However, can the resistance keep stable as light source may vary as well.

I think having a stable power supply is important. May be use UCC power supply for that. Also since all photocoupler are arranged in parallel, the instability of the power supply is affecting all optocouplers equally at the same time as long as they are matched. So, the chance of imbalance is less...

For those interested in teh schematic

http://www.diyaudio.com/forums/attachment.php?s=&postid=958784&stamp=1152572550

[quote="ackcheng"]I came across a very good volume control design today

http://www.diyaudio.com/forums/showthread.php?s=&threadid=80194&perpage=10&pagenumber=1

It is a optocoupler changes resistance depending on the intensity of the ...quote]

might i ask which photo-coupler you have tried?
i really have no idea about that ^^