LEDs

[mainestratman]

A question for you guys who are way smarter with electronics than me (which is about everyone.. lol)

In using LEDs for distortion, etc., does it matter what color they are? Would a green LED create a different sound than a red one, and so forth?

Obviously the LEDs with a colored plastic covering probably don't make a difference, but I have an LED flashlight that has clear LEDs on it and with different settings, creates clear light, red light and blue light... so I'm curious if there is some sort of odd little electronic difference in there that would create different sounds..?

[duhvoodooman]

The transparent ones that actually differ in the color of light emitted do differ in another respect--their threshold voltages. This is the voltage level at which they switch on and start clipping signal. Once the clipping starts, I don't think there's any significant diffence in the character of the clipped sound itself. Red LED's are at the low end of the threshold range, IIRC--around 2V. That's already requires a BIG signal to clip (which, BTW, is why the LED setting on switchable clipping setups is generally noticeably louder than other diode types), so I've never seen a reason to go to any of the higher voltage colors. I guess some of the blue and purple LED's get up between 3 and 4V.

[mainestratman]

:beer:

Thanks DVM... I've been reading about LEDs all morning, but never really found any info on the clear/multi-colored ones in regards to distortion effects.

It might be interesting to make an "amp in a box" with multiple channels for various levels of loudness.. and the "channel indicator light" be a multi-colored LED.

Or it could be a total waste of time and components.. lol

[Ch0jin]

Another tip;

As tempting as it maybe be to use one of the multi coloured LED's that cycle through a range of colours automatically as the indicator in a stomp box project, I'd advise against it. I put one in my tremolo pedal and they are -very- noisy. "Bzzz" "Bzzz" "Bzzz" every time the colour changes. You could probably filter it out, but it's not worth the effort IMO.

I kinda doubt they'd work as clippers either.

I'm with DVM on going Red if LED clipping is your thing. I tried a few colours in my modded TS based drive and settled on red, partly because it was the most musical clipping out of the three I tried (clear green and red).

The box your describing (kinda) could likely be achieved with a number of different designs. I modded my tube screamer based kit to have a rotary switch that selects Ge diode clipping (low volume), Si diode clipping (medium volume), LED clipping (high volume) and no clipping (maximum volume).

Is that the kind of thing you mean?

[sunvalleylaw]

I really like the Red LED clipping in both overdrive and distortion modes in my Rabid Rodent that DVM built me. It sounds GOOOD!

[mainestratman]

Ch0jin.. yeah, that's kind of it.. but I was thinking a "ground effects" kind of light show on a pedal... lol "If you can't stun them with talent, baffle them with effects"... lol

SVL... I'm looking forward to experiencing some of that happy red LED joy you have going on. ;-)

[BigBadWolf1171]

Ive never heard of this LED mod? someone willing to share the info? sounds interesting.:help

[mainestratman]

http://www.duhvoodooman.com/miscimages/musical/RRv2.htm

[BigBadWolf1171]

that cleared it up :nono:

[mainestratman]

Try this one then.. LOL

http://www.geofex.com/effxfaq/distn101.htm

[BigBadWolf1171]

:drool ill just read and learn lol

[duhvoodooman]

The most common mode of distorting a signal in an effects pedal is to "clip" the signal by means of a pair of diodes connected in parallel. When the threshold voltage of the diodes is exceeded, the signal above that magnitude is dumped, usually to ground. This is described in more detail in that Geofex article linked by Mainestratman.

Somewhere along the line, somebody got the idea that "Hey, LED's are just diodes that emit light--you should be able to use those for signal clipping, too!" And you can. But they have a very high voltage threshold (2V and up), so they don't clip as much signal as the traditionally used types (0.3 - 0.7V typically). Consequently, their output tends to be louder, less compressed, and less distorted overall.

This first showed up in "boutique" pedals, where some enterprising individuals figured out that you could substitute about 80 cents worth of LED's for 5 cents worth of other diodes, and then charge $200 bucks more than "regular" pedals, and some people would pay it. Google "Landgraff Dynamic Overdrive" if you don't believe me...

[Ch0jin]

The most common mode of distorting a signal in an effects pedal is to "clip" the signal by means of a pair of diodes connected in parallel.

They do this in amps too! Especially the solid state varieties.

[mainestratman]

Umm.. no (http://www.bluesangelmusic.com/details.aspx?item=2311580).

Might be worth the $400 to buy one, completely steal his design and sell the crap for $199. :-)