VU Version 2

[Martin]

built a second set of VU's today for a friend who saw my first effort with a cardboard box and wanted to take a similar route.

he also purchased the 4 x blue LED kit which turned out quite nicely

[Chinagraf]

Hey Marty, maybe a little late now that it's all together but if you sand the top of those led domes the light will diffuse more rather than the narrow beams, if you wanted to make it more dispersed that is.

[Kurt]

This may be ignorant (probably is!)

I thought coloured leds were created by a coating on the "bulb". If you sand it even a little too vigorously won't it go yellow/green/red or whatever colour it makes natively?

[JulienG]

I thought coloured leds were created by a coating on the "bulb". If you sand it even a little too vigorously won't it go yellow/green/red or whatever colour it makes natively?

Not quite, these days most LED's are "waterclear", the diode bridge gives the right colour and the housing is tranparent.

For white LED's there's a phosphor coating *of*the*diode*bridge* that gives the yellow end of the spectrum.

Ordinary 3/5mm LED's are perfectly safe to shave, SMD ones not so much.

[Chinagraf]

That's why the different colours use different voltage's innit?

[JulienG]

That's why the different colours use different voltage's innit?

No, you can get most colours in most voltages, it's just easier to make blue and white at the higher voltages.

[rick]

has anybody ever tried to use a vu meter that is lit up blue ( which is all the rage these days ) its damn near impossible for me thats for sure
the background colours for vu meters was actually pretty well worked out half a century ago
you would not want to go against all the tests they did on all those poor soldiers during the war
would you ..? well...?

the buff colour vu backgroud is designed to be easy to stare at and blue leds are designed to make you feel like star trek is real, but even star trek is old school these days .
every time somebody does me a favour and replaces the light bulbs in our vu meters with leds ( any colour) i give it a try for a few months then i switch them back to the real thing .
leds just mix up the way the meters look to me .
but then again i use vu meters all day all week
end of rant

[Martin]

fair point...

i used to have meters with LED's in them, used for about 3 hours... then built robs buffer kit and they are glowing a nice standard light bulb green and have been for almost a year day in day out...


the LED's were installed at the 'customers' request

led's aren't pleasant to look at and the only place i've enjoyed their use is installed in the doors of the car to stop people taking your door off at night :)

[jmedigital]

Yep, pretty much over the whole blue led thang here as well. Blue leds are soooo cliche...... :)

I prefer the old standard globes as well. I find bright led lit meters a bit tiering on the eyes. Kind of like LCD screens as well....

[Chris H]

Well i still love the blue LED on my Avalon 747.......IMHO the perfect example of how the blue LED should be used.

[heathen]

The API 2500 has normal colour vu's though they are pretty small, it's the damn bright blue led which makes me pretty grumpy, it's right in front of me and almost like a blue laser, ahhh blu-tack saves the day again.

[rick]

i have an API 5500 mastering eq the very first thing i did was cut a tiny little piece of a white sticker and placed it over the led , i cannot believe how bright it was .

you could not get a blue led for the first 30 years of led technology , i can remember being VERY excited the first time i saw one , i think the world is trying to make up for all the lost blueness over the years so the over bright blinding light craze we see is trying to address this.

as i typed this i looked up at the blue neon glow that gives my room its nice blue ambience , and i am wondering if people that live in blue glass houses should be able to have a forum at all :)

[rob]

here's some tips for using leds
over the years as led technology has developed not only have we gained new colours, namely white and blue ( and yes i know white is really a mix of colours ) but significantly leds have become brighter and brighter for a given current passing through them. Back 25 years ago to get a red led reasonably bright you would run it close to it's full rated maximum current of 20mA. Today a bog standard cheap red led will give a similar brightness at around 7mA. One side effect of this is replacing the red 3mm led used in the optocell in LA-4 compressors. A modern led is just too bright and screws up the compression ratios. I've spend a good hour or so rummaging in old junk boxes to find a suitable old led to repair an LA-4.
So, it is current that sets the led's brightness and that current is set by the chosen series resistor that connects the led to the supply voltage, use ohm's law where current = voltage / resistance, where voltage is the supply voltage less the forward drop voltage of the led. This forward drop voltage is different for different led colours and ranges from typically 2 to 4.5 volts.
I remember the time i started putting blue leds into projects and finding myself pulling the lids off a couple of times to keep increasing the series resistor to try and dim down the led. Typically i run blue leds at around 1.5mA these days, this seems to set them up so they are just running and glow blue without the death ray effect.
One the factors that make ultra bright leds so bright is that the beam is much narrower than normal leds and this makes them extra useless for illumination of VU meters. Recently i replaced the lamps in a bank of 24 VUs. To diffuse the beam from the led i first up tried roughening up the lens of the led with emery paper. This helped but still didn't quite cut it. Then in a stroke of genius i grabbed a tube of white filler, the stuff in a tube that you load into a gun and fill the cracks in the walls. I removed the nozzle and pushed up a small amount of filler, then just dipped the tip of the led into it, pulling the led away left a white cap on the led. This was a doodle to do and in no time 48 leds were done and were dry in 30mins. This white cap allowed some light through but most of it was reflected back and then emerged in a diffuse fashion. installed into the rear of the modutec meters this worked a treat. So, no more blown midget flange globes to keep replacing at $2.50 a pop and current consumption reduced dramatically.

And after an hour of the client and i experimenting with red, amber, blue and white leds, we settled on the yellow....even this would make Rick happy.

Rob

[heathen]

i have an API 5500 mastering eq the very first thing i did was cut a tiny little piece of a white sticker and placed it over the led , i cannot believe how bright it was .

you could not get a blue led for the first 30 years of led technology , i can remember being VERY excited the first time i saw one , i think the world is trying to make up for all the lost blueness over the years so the over bright blinding light craze we see is trying to address this.

as i typed this i looked up at the blue neon glow that gives my room its nice blue ambience , and i am wondering if people that live in blue glass houses should be able to have a forum at all :)

I love a blue glow as well gives a cool vibe, my fav colour and the blue leds are pretty, my pendulum limiter has a blue led too though very diffuse and easy on the eye, sort of mesmerising.

I feel my vision is getting worse since buying my 2500, I wonder if api will gimmee a free 5500 to keep my mouth shut, hehe.

How do you like the 5500 Rick? Does it get plenty of use?

[rick]

the 5550 has a very limited application for me it has an extraordinary effective 240 hz boost and the top end is nice as well , despite the hype i am not convinced its the same eq as a 550 b , i think its different - better down low different in the mids better in the top , this is not what API think
though, but there is enough API stuff around this building to build a pretty flashy console so yeah its good but a little "non 550 b" )