Strobe Lights and Bass

[CARTRulz]

Hi all,

As some of you know, I recently completed my 2 Peavey Low Rider 18" subs thanks to guidance from here. So now, I've got another question that some of you might not be familiar with. I only have one subwoofer and 2 of my floorstanding speakers with me in my new apartment. However, they are both in our "party" room, and a few of us recently started to talk about the addition of strobe lights. We would only want them to go off during the bass hits. However, many of the strobe lights out there are based on a microphone, and I ould tend to think that when music is very loud they would constantly be on. However, we had an idea of somehow runing the strobes off the subwoofer amplifier, so they would only light up temporarily on the bass hits. I was wondering if it is at all possible to simply put 4 strobes in series and connect them to the terminals of the unused chanel on my EP2500. With some quick math I found some strobes that are 1.5 ohms in resistance, so 4 would be a 6 ohm load, and the EP2500 can handle all the way down to 2 ohm loads. But I could even add a resistor to make it an 8 ohm load, and since each bulb can handle 125watts, that would be an 8 ohm load at 500 watts, which is exactly what the EP2500 can put out. Still, theres the matter of current. According to the EP2500 manual, It draws 9.6A in regards to power consumption, and then it says 5A at the mains connector. Basically I want to know if you guys think this will work or if theres an easier way to set this up for a relatively small price, as I dont know too much about lighting and effects.

Thanks guys

[CARTRulz]

I was wondering if there was a way of measuring voltage and current put out of my amp myself. Can I simply connect a multimeter in parallel to the terminals for voltage and then put it in series to measure current? Should I measure it while its driving the sub?

Thanks guys.

[electroaudio]

You can not connect a strobelamp directly to an amplifier.

A strobe works with a capacitorcharge over the terminals ranging from 300volts for small camera flashunit to 1000volt for larger DJ units.

AND it also uses between 2000 to 10000 volt to ignite the flash.

Not only that....
The glass of a strobetube can explode if you apply the wrong voltage and energystorage to it.


Sorry, i cant help you...
because the only controller that i know of that has the necessary function is a old lightingdesk that was a bit weird to write programs for.

[bremen nacht]

Originally posted by CARTRulz
I was wondering if there was a way of measuring voltage and current put out of my amp myself. Can I simply connect a multimeter in parallel to the terminals for voltage and then put it in series to measure current? Should I measure it while its driving the sub?

Thanks guys.

Yes, yes and yes.

[pinkmouse]

OK, are these home-made strobes, or do they have the industry standard trigger on the leading edge of a 0-10V square wave?

You don't want to connect them directly to an amp because of the amount of electrical noise they produce when they fire.

[DigitalJunkie]

Hum,Perhaps put a low-pass filter on the input to the strobe..that way it only responds to bass frequencies.
You could probably even couple it to the amp by replacing the little mic element with a 600ohm 1:1 transformer or something.

[rtarbell]

Do a google search for: 3 channel color organ

There are many off the shelf kits out there (put together and solder, compnents already supplied).

A 3-channel color organ usually has three outlets (so you could plug in Christmas lights, strobe lights, or what have you), and the lights flash according to bass, midrange, and tweeter frequencies. If you just want strobe lights to flash at the bass frequencies, then simply don't plug anything in to the midrange or tweeter plugs.

[Dryseals]

I built one in the mid 70's using some SCR's, that were triggered by the voltage level and used a bandpass filter to capture the freqs I was interested in. It was crude but worked very well. I didn't use strobe lights but instead used some colored flood lights. The brightness of the light varied with the amount of bass and the duration followed the bass.

[electroaudio]

Are you speaking of a real strobelamp like a xenontube?



Or a prefabricated strobeunit with rectifier capacitorbank and triggercircuits already inplace to ignite the xenontube?



A xenontube cant be used on its own which i tried to explain in my previous post.
But prefabricated units should still be used very carefully because they work directly on rectified 220v (Some also have a stepup transformer) and they cant be connected to a lightorgan or any other controller without zero crossing detection, if so the rectifiers or triacs will blow when the caps are recharged after a flash.


The analog (or dmx...) input on a professional unit can not be connected to the amp, it will burn the input curcuits. However an analog input can be driven by a hot preamp in paralell with the bassamp since it is possible to trigger an analog strobe with less than 10v, often 5v is enough.
But there are also strobeunits with inputs for a passive remote, these inputs may very well have 600volts or more on them and they cant be controlled externally, the only possible solution on that is to use a relay and a resistor (between 100k and 1M depending on the strobe) in series with the relay+input.



OR are you speaking of a normal household/car type of lightbulb...
This is a very nice effect, but you need to rectify the amplifiers output and add a capacitor in paralell with the lampchain, otherwise the lamps doesnt get hot enough to emit light on the bass-hits.
If you want to use 220v lamps then you connect the preamp to a rectifier,capacitor, resistor into an analog stagedimmer input instead.
In both cases, You need to play with the capacitorvalue until you find the right balance between light and darkness.
This effect doesnt only work on bass but is also very effectfull on mid hi or on the whole spectrum, since the light will reflect the energy in the music, which lightorgans doesnt do very well.

[CARTRulz]

So at first I was leaning towards strobe lights, but Im now leaning towards just colored floodlights. They seem easier to work with and less expensive. So if I understand electroaudio's last post, if I use colored floodlights I can run them off the sub amp, but I just need to throw a capacitor across the terminals so I build up enough voltage to light the bulbs. Is that correct? Do I run a risk of damaging my amplifier by doing this? Because I just bought this thing over the summer and Im certainly not willing to risk damaging it over some lights. But, if I add resistors so that the lights and capacitor have an equivalent resistance of, say, 8 or more, and I attenuate the gain from the sub amp I should be ok right? Do you guys have any idea what the voltage and amperage should be set to for floodlights? Wont the amp just put out way too many amps and not enough volts? If its a 150watt bulb, and its running off 120volts, the current is 1.25amps, but wont the sub amp put out far less volts and more amps? Or is that alright as long as the voltage and amperage gets up to 150watts, no matter what the ratio. But by the way, the capacitor kinda scares me becasue I know theres gonna be a very dangerous amount of voltage on it. Hell, when I power off the EP2500 it takes about a minute for the power lights to finally dim and shut off as I can hear the capacitors discharging through the subs with tiny pops and crackles. But then again, the capacitor across the terminals should simply discharge through the lights once powered off, so I guess its somewhat safe.

Let me know what you think. And thanks so much again for all the help, I really really appreciate it guys.