Lighting LED's by with your speaker amp

[MrGuitardeath]

I have seen some speakers with built in LED's that light up from the amp powering the speakers.

I am very interested in incorporating this into some designs and have not a clue where to start.

I'm assuming it is done by incorporating a small inverter circuit of some sort because I can not find ANY LED's that are made specifically to be powered by an audio amp.

Can anyone help??

[rcavictim]

You could run the speaker line in parallel with the existing speaker through a low value (determine by experiment at maybe 15 ohms minimum and go higher as possible the better) to a bridge rectifier. Output of the bridge to an electrolytic cap and this power supply runs to the LED's through small current limiting dropping resistors. This will screw with the sound though, so why would you wanna?

If you want a light show from your speakers without extra electricity you could alternatively spray them with lighter fluid and set them on fire. This would not initially affect the tone as much as the LED power draw.

The second idea is not safe though and should not be attempted without a fire department pumper truck and crew standing by outside your house.

[MrGuitardeath]

While I will try that circuit, I know it is possible to do it without screwing with the sound.
I mean LED's draw hardly any power......
A 100 watt RMS amp shouldn't be affected what so ever nor should the
the sound of the speaker be compromised.

There are a number of woofers on the market with LED's inside of them.
Some even grow brighter from the music peaks.

Hmmmm, why would I want to do this?

Because it looks badass!!

I'm also working on engineering a speaker that I had created in a dream....they were really wicked man and maybe not COMPLETELY original, they would still be very unique

[davesaudio]

no, you're not likely to hurt anything if
calculate your max amp power supply voltage
max current the led can take
and calculate a "safe" resistor.
consider can the led take the same as a reverse voltage?

or do you need a pair of leds parallel but (pos to neg)

now,suspect this won't light often so you will likely lower the value-how long can your led stand it when you crank it up is the question?

search for schematics of drivings leds directly from mains
they have some techniques that may be useful

having fun is part of diy

[DigitalJunkie]

Powered by the output?

Are you thinking of a power meter?
An LM3914/3915 can do that.It samples the output and has built in comparator and LED drivers.. I don't think I've ever seen a meter like that powered straight from the output.

[phase_accurate]

I don't think I've ever seen a meter like that powered straight from the output.

But I have ! There was once a stereo System by ITT (manufactured by Mitsubishi and labelled ITT actually) at the end of the seventies. These were supplied with large speakers (built with SEAS drivers and sporting a 12" woofer) that actually had a power meter on their front which was powered by the audio signal !

Regards

Charles

[sam9]

I think there are even a couple of kits that do this in the form of a VU meter. Velleman probably. Check out www.qkits.com, I think I saw one there If you don't want the bar graph format you could still midify the kits by running leads from the pcb to wherever you want the LEDs to be located.

[SupraGuy]

A VU meter is much better off being an active circuit and having its own power supply, or power in the form of AC signal can be run to the speaker boxes (Requires 2 more conductors) which can drive an LM3914/3915 IC to make a completely conventional VU meter which will have no impact on sonic performance.

To actually power the LEDs from the amp output WILL have an effect on sound output. Even with a limiting resistor to keep the current going through the LED to a few mA, the problem is that the load represented by the LED is variable, which will introduce distortion to the loudspeaker.

If you were to run say 16VAC alongside your speaker wire (Since this is only going to need low current this is unlikely to introduce any audible noise) you could run that to a voltage doubler, rectify, regulate and filter it to give you a +/-15VDC supply, which could then be used to power a VU meter. Alternately, you could give each speaker box a wall wart to supply power to a VU meter.

IMHO, this is a much better approach, and gives you much more flexibility.

[acenovelty]

http://store.qkits.com/moreinfo.cfm/K4307

[rcavictim]

Originally posted by MrCheeks


There are a number of woofers on the market with LED's inside of them.
Some even grow brighter from the music peaks.

Sure and folks here who are after the highest possible sound quality are flocking to these in droves because the added LED's show clearly that much emphasis was placed on making the driver top notch sound quality.

I have a pair of Sansui SP9393 kabuki type speakers in the lab that I use as dummy load for amp testing. I didn't pay any money for them. Anyhow, they have built in LED power meters that ramp up as the speaker gets driven harder.

This all reminds me of how the Europeans gave shiny trinkets and mirrors to the North American Native Indians in exchange for goods of actual value when they arrived on our shores not so long ago.