what is the right Forward Voltage of LEDs?

[coldmoon]

Kevin did not show Forward Voltage of LEDs in his designe,and I think it will not be 1.5V .

so I want to konw it's 1.7V or 1.8V? 

[Bespav]

Different kinds of LEDs have different forward voltage requirements. Non-bright LEDs tend to require less voltage than bright LEDs, since bright LEDs need more power to work. Typical VLED values are 1.7V for non-high-brightness red, 1.9V for high-brightness high-efficiency low-current red, 2V for orange and yellow, 2.1V for green, and 3.4 to 3.6V for bright white and most blue types.

[UFN]

I believe Kevin's schematics normally assume 1.7V red LEDs, e.g. Mouser p/n 859-LTL-307ELC.

 

//UFN 

[mwl168]

Can confirm UFN's answer based on my own builds - 1.7V red LEDs on my KG designed Dynalos and ES amps.