400 Watt Self Powered Speaker = How Many Watts at the Geny

augustIII · Post by **augustIII** » Wed Aug 15, 2007 5:31 am

I'd imagine that there isn't a hard and fast rule for this, but I'm trying to work with limited wattage. Is there a way to translate max power handling of a self powered speaker into how many watts it's going to draw from the generator.

400 watt self powered speaker = how many watts at geny?

MikeVDS · Post by **MikeVDS** » Wed Aug 15, 2007 8:17 am

I don't know if I quite understand. You have a speaker that usually runs off an outlet and has audio inputs rather than running off an amp? So it usually draws 400 watts max from the wall and you're wondering how much it will draw from your generator? If that's the case, it should still be 400w max (+ a little if you run long extension cords). Also keep in mind the altitude may lower the total output of your generator (example, a 2000w generator might only produce 1800w there). And keep your air filter clean to keep efficiency high.

zorro sings · Post by **zorro sings** » Wed Aug 15, 2007 8:30 am

Most likely referring to Mackie 450 self powered speakers.We have run these speakers ever since we were a camp and never had any isues with power.As MikeVDS says it is 400 Watts.We have run both our Mackies and some lights with a 1000 watt generator.That was an emergency deal and cutting very close.

phil · Post by **phil** » Wed Aug 15, 2007 9:51 am

I'm not sure I'm getting the full informaton. There's a difference between the imagined out put of speakers (400 watts, maybe?) and the electrical power required to run them (30 watts, maybe?).

My question is whether the 400W referred to is the output or the input? There may be no connection between what's required to run powered speakers and the output. Look on the bottom of the speakers (probably) and look for a tag that says something like 120VAC, 60Hz, 30 Watts.

Unless I"m totally confused and these huge honkin' suckers really draw 400 watts.

Post by **trilobyte** » Wed Aug 15, 2007 10:40 am

There is no hard and fast rule. If your equipment is 400 watts max output, then that's your max. What is actually being used will vary from moment to moment based upon what's being played. It's kind of like looking at the file size on a JPG picture. I have some 800x600 JPG pictures that take only 60K, I have others that are over 200K in size. In the case of the active powered speaker, you know that the theoretical max is 400 watts.

Yes, you may be able to get by with less than that. But you might not, and then you'll get a brown-out or a complete cutout.

As a general rule, for best performance of both the generator and the amp/speaker you want to have overhead. The more you tax your generator, the harder it has to work and the more fuel it will consume. Taxing it to the limit for extended periods of time will likely cause damage to the equipment. And has previously been mentioned, the high altitude on the playa does result in lower performance in the first place.

Good luck sorting out your sound/power!

~Trilo~

corpuscle68 · Post by **corpuscle68** » Wed Aug 15, 2007 11:20 am

Hello!
Does a typical generator feed a current stable enough to run a laptop? Is a surge protector advised? Is there such thing as a current stabilizer?

Regards

Rolf

Token · Post by **Token** » Wed Aug 15, 2007 12:41 pm

corpuscle68 wrote:Hello!
Does a typical generator feed a current stable enough to run a laptop? Is a surge protector advised? Is there such thing as a current stabilizer?

Regards

Rolf

Yes, yes, yes

corpuscle68 · Post by **corpuscle68** » Wed Aug 15, 2007 1:17 pm

Token, thanks for your replies.
What is a current stabilizer referred to as? I asked at my local very well stocked hardware store, and they didn't have one and seemed a touch confused on the issue. Is is a specialty item?

Regards

Rolf

Token · Post by **Token** » Wed Aug 15, 2007 1:55 pm

It is called a "AC line conditioner" and you don't need it. You won't find it in a hardware store.

Your laptop runs on DC and that little power brick will convert any AC from 90 - 240 V down to whatever DC it needs.

Just plug it in.

MikeVDS · Post by **MikeVDS** » Wed Aug 15, 2007 2:19 pm

It's kind of like looking at the file size on a JPG picture. I have some 800x600 JPG pictures that take only 60K, I have others that are over 200K in size.

You're a nerd. I don't think many people would find that analogy simplifying. Just nerds like us.

dragonfly Jafe · Post by **dragonfly Jafe** » Wed Aug 15, 2007 5:09 pm

speakers are rated in electrical watts, not acoustic watts.

if your self powered speaker says 400 watts, and you have the volume all the way up, and you put in a 2volt signal (max for RCA type inputs), the speakers will consume appx. 400 watts of electrical power.

They may only be putting out a few watts of acoustic power, but you don't care about that.

If you cannot power 400 watts, turn the volume down and/or reduce the bass setting. Bass takes the most power (each octave down takes double the power for the same sound level). But be careful - if your amp runs out of power, it can clip which can destroy your speakers (and it sounds really bad too)

gyre · Post by **gyre** » Wed Aug 15, 2007 8:47 pm

Unless you have an amp clipped, the power consumed by a driver will vary unless it is being fed a steady tone off of an instrument.
Most recorded music has some dynamic range.
And as said, most speakers will run off a very low power level.
There are diminishing returns as the power is turned up.

Here's an example of how a speaker I like is rated.

Sensitivity 100 db/1 watt
Rated 400 watts rms sine wave
800 watts rms music
1600 watts intermittent 3 seconds
2400 watts intermittent .5 seconds

In this case, the constant ratings refer to use at a tolerable distortion level.
The heat limit may be higher.
The upper ratings are probably heat limited.

The efficiency means this driver produces 100 decibels with one watt, if the amp has enough damping to work properly.

I hooked a portable radio producing less than a watt to one of my speakers once and the volume was quite adequate.
It was lacking in bass.
This was an exceptionally efficient unit though.
This was a portable radio running on C cells with a chip amp less than .5 watt and not impedance matched to a 16 ohm crossover.
The speaker runs well beyond 110 db/watt.

In this case, the rating may refer to power used by the electronics.
Many driver ratings are only good for a laugh.

The CO · Post by **The CO** » Wed Aug 15, 2007 10:31 pm

Sorry, the sound guy in me has to chime in here:

What the hell is an "audio watt"?

Watts (wattage) refers to the electricity being consumed. Watts are not a measure of volume, decibels(db) are. Db/watt(s) is basically a measure of efficiency.

gyre · Post by **gyre** » Wed Aug 15, 2007 11:14 pm

Unless you're talking to me, I can hazard a guess.
A kilowatt is a specific measure of energy and can be translated into any form of measurable energy such as horsepower.
I think it's a reference to the acoustic energy actually output from the driver to the air.
Force over time.

I see this measured for testing and lab use primarily.

1 horsepower = 746 watts of power

MikeVDS · Post by **MikeVDS** » Wed Aug 15, 2007 11:37 pm

I see this measured for testing and lab use primarily.

So the output sound power would just be the input minus the inefficiencies converting the electricity into mechanical then into sound energy? That sounds right but this is not a common way to talk about sound equipment outside of a lab setting; is it? Just trying to clear that up.

gyre · Post by **gyre** » Wed Aug 15, 2007 11:46 pm

No.
Decibels, watts, amps and efficiency is what most people need to know.

It is a reminder of just how inefficient most speakers really are though.

Flame speakers work, by the way.
There was supposed to be one at transformus but I never saw it function.
If you have to drag speakers to the playa, how about those?

MikeVDS · Post by **MikeVDS** » Thu Aug 16, 2007 6:18 am

It is a reminder of just how inefficient most speakers really are though.

Any idea how efficient they actually are?

gyre · Post by **gyre** » Thu Aug 16, 2007 6:48 am

Flame speakers or most regular drivers?

Most drivers range from 88 db to over 100 db/1 watt.
The ones I use are in the 100 db range.
I have one I think is over 120 db.

Polk car speakers are about 92 db as an example.
Not bad for what they are.

augustIII · Post by **augustIII** » Thu Aug 16, 2007 7:09 am

Fantastic.

So watts are electrical watts and if I clip the speakers, I can expect to draw more watts than the 400 they each "say" they have to play with.

Does factoring in a 100 watt buffer sound reasonable when calculating total draw on the generator (after taking into account altitude inefficiencies of course)?

The CO · Post by **The CO** » Thu Aug 16, 2007 10:46 am

Sorry Gyre, I may have come across as snarky in my earlier post; that was not my intent. As I said, sound guy...

augustIII, if your speakers list a 400 watt draw then thats what you can count on them needing from the generator. You won't draw that full amount all the time unless your are running full volume with really loud music all the time. Having a buffer is always a good idea, but more important with lighting than sound. you don't want to plan on maxing out your genny unless you have to.

gyre · Post by **gyre** » Thu Aug 16, 2007 3:33 pm

I didn't take it that way at all.

dragonfly Jafe · Post by **dragonfly Jafe** » Thu Aug 16, 2007 3:47 pm

MikeVDS wrote:
It is a reminder of just how inefficient most speakers really are though.
Any idea how efficient they actually are?

Typical speakers are maybe 1% efficient, really efficient ones might be 2 or 3%

MikeVDS · Post by **MikeVDS** » Thu Aug 16, 2007 5:08 pm

Typical speakers are maybe 1% efficient, really efficient ones might be 2 or 3%

So a speaker running around 400w is mostly a 400w heater (assuming the energy turns to mostly heat)? I have a hard time believing they are that bad.