# Apple Pro Speakers Mod



## bjurusik (Mar 13, 2003)

Got a question ...<BR><BR>
Would it be possible to mod your Apple Pro Speakers with neon lights that light up to beat of the music?  Sometimes you see similiar things in cars, lights that go along with the bass, etc.  Now I'm no engineer, well in 3 years when I graduate I will be  , but it seems possible.  I'm not sure how speakers work, but I assume the current varies through out a song ... and maybe if the light was hooked into that it would cause the light to flicker?  Or maybe I'm completely wrong!


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## phatcactus (Mar 13, 2003)

GAAAH, oh no, I am getting visions of ghetto bass cars driving down my street at 3:00 am...

BUH DUH DUUUH...  BUH DUH DUUUH...  VROOOM!  BUH DUH DUUUH...

I've never seen car lights that go on and off with the music (had I, I'd've shot myself on the spot), but if you could do this to your speakers -- in the privacy of your own home, of course -- I think it'd be kinda fun.  As long as there's an off switch  

What ever happened to that Apple patent for color-changing hardware?  With that you'd be able to make the whole machine do it...

- Brian


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## Rhino_G3 (Mar 14, 2003)

It would be possible, although impractical, to do it for only bass. It would require you to create a bandpass filter to filter out the higher tones.  It could easily be done through the use of LED's and the entire range of music.  All you would have to do is find out what volts/amps you'll see on the output from within the speaker and find an appropriate LED(s) and solder to the + and - outputs.  The only drawback is that you might notice a volume decrease with this method.

If some real electrical engineers would care to speak up I'd love to hear your options.... I'm always willing to learn.


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## scruffy (Mar 14, 2003)

My mixer has these, it's wonderfully useful for beat matching.  In fact I can't imagine I'd be able to spin without the beat lights...


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## edX (Mar 14, 2003)

you guys are obviously young. they did this in the 70's and 80's. especially in night clubs though you could buy home systems as well. they looked better than they sounded and were expensive. which leads me to believe that there are better ways of doing it today. instead of cheap looking colored lights, how about speakers with screens and matching visuals like itunes?


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## macavenger (Mar 14, 2003)

I too would like to know if it is possible to modify my Apple Pro speakers in this way. Speaking as an electrical engineering major in his Junior year, it certainly sounds possible, although I don't have enough info on the components or enough confidence in my abilities to be sure  It would be nice to know if someone else has tried this though.


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## kanecorp (Mar 14, 2003)

i bought soundsticks and dont really need my pro speakers now, so i would love to try this mod out!


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## chevy (Mar 15, 2003)

You will have a power supply problem unless you add an extra wire.
Once you have some voltage always available, it's not that difficult to have LEDs that light up with music.
A nicer challenge would be to have it behave correctly for any loudness...
I agree with several rpevious readers... that may be boring after 1-2 hours... and represent days of work.


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## kilowatt (Mar 16, 2003)

Ed is right, they have had these out for quite a while. I've got two three-way units at my place. All they consist of is a three way crossover, isolation transformers on the inputs, diodes on the outputs, and plugs so you can connect christmas lights of whatever suits you.

For the apple pro speakers, it should be very easy. For now, lets just hook into the subwoofer.

*At this point, I warn you, I'm not responsable for whatever you do with the below information!*

Take a volt meter, or if you are more fortunate, a scope, and hook it up directly to the speaker. Put the volt meter on AC. Find a song that bumps. If you have a way of generating a 60hz tone, that will satisfy the volt meter greatly.

Take your reading (in volts of course) with the system cranked up to the max. Lets pretend you got 16 volts, for our example.

We're now going to use Ohm's Law to figure out the correct resistor. 

The first thing to figure out is, how much current will the light be drawing? To keep things as simple as possable, lets work with a low-current device, such as an LED (as apposed to an incandesent light bulb). A higher current device will pull more current from the audio amp, and possibly distort the sound (there are ways arround this, for now, lets keep it simple).

Four RadioShack 276-316 High Intensity blue LED's should be cool. We'll wire it up so two go on the first phase of a wave form, and the other two go on the seccond.

Because audio is (idealy) an ac wave form, and LED's act as diodes, they will naturally light for only one phase of the waveform.

This also means they only draw a signifigant amount of current for one cycle.

Thus, we'll just add the current for two LED's together.

each LED is 20ma, or .02 amps. We'll place two in series. (thats -->|--- -->|---). So, .04 amps.

Now, Ohm's law states that E=IR. Or simply, Voltage = Current times Resistance.

Now, take the voltage you measured, and find the difference between that and the required voltage for the LED. The above mentioned blue LED handles 3.7 to 4.5 volts. For a safty margin, we're going to use 4 volts as our number. 

So... if you measured a peak reading of 16 volts, and the LED wants about 4, your difference is 12 volts. (duh).

so...

12 = .04 * R

Divide both sides by .04

12/.04 = (.04 * R)/.04

R = 300 Ohms. That worked out nicely. Your result will more than likely be something like 372.04 or whatever. 

But wait, you don't run your system at peak volume at all hours do you? (well, if you're 'kilowatt' you might...)

So, rather than using the 300 ohm resistor, lets go variable!

You're not likely to find a 300 ohm variable resistor. But a value arroud 1k or 500 ohms may be avaliable. 

Bare in mind that 'Audio Taper' means the resistor's variableness is logarithmic. Not linear. This may not be desireable, though it will work.

Here is the complete ascii diagram for our circuit:


```
[apple pro sub]
(+)--/\/\/\/\/\---NC
          ^--------------|
(-)|-->|-->|-------------|
   |--|<--|<-------------|
key:
(-) Minus terminal
(+) Positive terminal
-->|-- LED, Anode to Cathode
--|<-- LED, Cathode to Anode.
--/\/\/\/\---
------^        Variable Resistor.
NC = Not conected
```

So basically, we put two LED's in series. Then two other LED's in series. The place those circuits in parallel, with one circuit's polarity backwards. Connect one end of the resulting circuit to the negative terminal of the speaker. Connect the other end of the circuit to the middle leg of the pot. Connect either outlying leg of the pot to the speaker's positive terminal. Leave the other leg as it stands.

Good luck, enjoy, and no, I won't buy you another speaker.

--kilo


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## kilowatt (Mar 16, 2003)

*UPDATE!*

I don't have a pair of apple pro speakers, and I didn't realize they don't include a sub. _So_, just do the above circuit to each speaker. Should be very cool .


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## kilowatt (Mar 17, 2003)

*Once again, an upate.... *

I gave it some thought, and if you don't have a multimeter, you can use a formula to calculate peak voltage:

E = SQR(P*R)
E=volts
SQR=Square Root of
P=Power in Watts
R=Resistance of the speaker.

Assuming the Apple Pro Speakers are 8 ohms, and that they do the 10 watts per channel they're rated to do:

E=SQR(10*8)
E=SQR(80)
E~=8.94427191 Volts.

If you have a multimeter, verify this before you attempt the circuit.


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## bjurusik (Mar 17, 2003)

Wow kilowatt you're my hero!  I take it you're an electrical engineer?  Or just have a lot of time on yours hands.  I'm a sophmore in electrical engineering and I would never know how to do something like that, ah well.  Thank's a lot and I may give it a try!


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## kilowatt (Mar 18, 2003)

Cool! Glad you're up for it.

I'm not an EE, though I did consider it briefly. I am a licensed Ham Radio operator, and I work at a radioshack store . 

So, comes with the terratory 

Post some pics or a movie when you get it working, that's got to look pretty sweet.


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