Monday, December 21, 2015

Are Light Emitting Diodes Too Noisy For High End High Fidelity Use?

Though it has become ubiquitous as a power on indicator of consumer electronics since its introduction back in the 1960s, are light emitting diodes just too noisy for high end hi-fi use? 

By: Ringo Bones 

Ever since I started my audio equipment and musical instrument modifying business back in the early 1990s, I’ve noted that some audio equipment – especially very high gain solid state moving coil cartridge phono preamplifiers – will improve its noise floor when you replace the red or green LED power on indicator or light emitting diode power on indicator with a miniature tungsten filament power on indicator light bulb often used in older audio equipment. In my experience, the main beneficiaries from such moddings are vacuum tube based moving coil phono preamplifiers that use the ECC88 / 6DJ8 / 6922 small-signal vacuum tube and those iconing solid-state moving coil phono preamplifiers that use FETs and transistors or a mix of both like the DNM 3B and the Michell Iso and Michell Argo. 

During the first decade of the 21st Century, I also discovered that organic LEDs are noisier than their plain vanilla LED counterparts. Even though the invention of organic LEDs made possible those relatively affordable and indispensable part of 21st Century home theater unnecessarily large video monitors, blue LEDs that had become fashionable add-ons of power conditioners like the MIT Z-Center, produce an audible buzz when used with critical high gain moving coil phono preamplifiers. 

What’s weird about organic LEDs – even those green ones that emit a more vivid green light than their plain vanilla counterparts is that they can be as noisy as their blue colored counterparts. Weirder still, when viewed through a diffraction grading – either a CD or DVD surface – organic LEDs lack the monotonicity of their plain-vanilla counterparts. Ordinary green and red LEDs produce a pure green or and red light when viewed through a diffraction grating while their organic LED equivalents produced a distinctive rainbow streak. Though it is only noticeable in practice, do LEDs – organic and plain vanilla ones – produce more noise when compared with those tiny tungsten filament power on indicator lamps because LEDs are solid-state semiconductor devices and in the solid-state semiconductor world, noise is directly proportional to operational current? 

1 comment:

Ady said...

There might be some truth to this "light-emitting-diodes-are-electrically-noisy" premise given that older Naim equipment use those tiny green colored tungsten filament bulbs as power-on indicators.