# LED Size



## Diatrive (Jun 12, 2019)

Hello all,

Does the size of the LED ever affect the sound of the pedal? If so how drastically? Also would the color affect it?
I put 5mm in most of your pedals. I also change the color to match the cases.

Thanks for any insight!


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## phi1 (Jun 12, 2019)

For the on/off indicator, the size and color makes no difference. It doesn't affect the sound. You can also adjust the resistor in series with the indicator led to change the brightness.  

There are other times when an LED is used as part of the circuit and does affect the sound. This is in some distortion/od pedals, where the leds act like clipping diodes. The color will definitely matter since different color leds have a different forward voltage. So socketing and experimenting with these is recommended. The size often doesn't have and impact on the forward voltage, but it doesn't hurt to check. 

Other circuits used leds with light sensors (ldr) to affect the sound. phasers, vibes, tremolos, compressors, etc can use leds like this. In these circuits both size and color can affect the sound, because it can change how the ldr detects the light. The forward voltage can also affect how bright the LED lights up, which would also affect the sound.


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## Jovi Bon Kenobi (Jun 12, 2019)

^
The resistor value that affects brightness on all the builds I've done so far has been 4.7k. sometimes it's easy to spot since it's the only one of that value. If you are using diffused LED's it's the perfect value; not too bright, not to dim. If you use ultra bright clear LED's, sometimes it ends up being too bright for my preference so I either change the value of said resistor on the PCB to something around 50k or just solder in a 47k right onto the anode(+) of the LED. This doesn't affect the sound in any way as previously stated. 

Lately my favorite LED's to use are 5mm clear UV and coincidentally, they don't need any change in value from 4.7k even though they are clear and not diffused.


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