BurningSkies
CRAZY BALDHEAD
- Feb 20, 2005
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Easy. Each of the speakers in the 2x10 is getting 250w, each of the speakers in the 4x10 is getting 125w.
That poor 2x10
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Speaker power distribution
- Thread starter jpatt2
- Start date
Easy. Each of the speakers in the 2x10 is getting 250w, each of the speakers in the 4x10 is getting 125w.
That poor 2x10
If you run it at full volume, each speaker in the 2x10 will see 250, each in the 4x10 will see 125... or actually the 2x10 speakers will see 25% of the load, the 4x10 speakers will see 12.5% of the load each.
How does all this apply to a fEARful, which have several different drivers? If split evenly, wouldn't this destroy the speakers with a lower power handling or cause phase problems?
- Jun 29, 2006
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- President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
No, because you have a crossover, and speaker power demands vary with frequency.
Here's a chart I found somewhere - high frequencies require less power, though more than I would have guessed.
xover freq/power to bass/power to mid-high
250/40/60
350/50/50
500/60/40
1200/65/35
3000/85/15
5000/90/10
So If you have a 210 cab and a 410 cab both with the same speakers and wired the same, you should therefore run a 4ohm 410 and an 8ohm 210 so each speaker gets roughly the same amount of power then?
- Jun 29, 2006
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- President, CEO, CFO, CIO, Chief Engineer, Technician, Janitor - Reiner Amplification
billfitzmaurice
Commercial User
- Sep 15, 2004
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- Owner, Bill Fitzmaurice Loudspeaker Design
With broadband music power density changes at a rate of 3dB per octave increase/decrease. That means what it takes 100 watts for at 100Hz requires 200 watts at 50Hz, 50 watts at 200Hz. Rule of thumb with a 3 way crossed at 500Hz/5kHz is that 75% of the power goes to the woofer, 20% to the mid, 5% to the tweeter. That gets skewed a bit with the lower frequency content of the bass. But still it points out the folly of using a ten as a midrange driver along with a fifteen or eighteen.
How so? Each cabinet gets half the power. Within each cabinet, the power distributes evenly among the drivers, regardless of whether the 410 is four 16 Ohm drivers in parallel, or four 4 Ohm drivers series/paralleled. We can safely assume that the 210 is two 8 Ohm drivers in parallel (2 Ohm drivers being rare), not that it matters.
If the speakers have the same efficiency rating, and excluding other factors like cab design and cone surface area, in theory, yes. I used an 810 and 215 many years ago live. The 2x15 had more sensitive (better efficiency) speakers so it was louder with the same amount of power applied, even though the 810 technically had more cone surface area. I used a stereo power amp, so I would dial the 810's side of the amp up a little more so they were putting out the same volume.
I know there's a lot of discussion on here about driver size, cab design, and power to cabs. I'm not disputing anyone's technical knowledge, because that is what makes a good speaker cab sound good... and my theory is VERY limited. However, the real deciding factor should always be your ear. If it sounds good to you then go with it. If that 410 and 115 stack sounds good to you, then forget what others have said and use it. I used that 810 and 215 setup with great success live for many years, and always had compliments on my tone. I currently run (2) 4x12s with speakers that aren't best suited to the cab's design. I think they sound good for my application, and I still get compliments on my tone. Use what works for you. The only issue that comes into play is if you have a bad ear... lol. But then any "good" combination of cabs will probably still sound like crap because the amp will probably be dialed in wrong.
The problem here is power. Look at how it works if you talk about voltage instead of power:
Q: How is the voltage distributed when two speakers are hooked up in parallel?
A: Both speakers get the same voltage.
Historically, engineers cared about power because we're interested in the thermodynamic efficiency of systems. Also, power is a crude way to compare systems that have different impedances. Today, power is a nice thing to put on a spec sheet, but a poor quantity to use when trying to understand what's going on with amps and speakers. Most basic testing is done with voltage measurements.
Amps and speakers are voltage devices. What's this mean? An ideal amp is designed to reproduce the input voltage at a higher amplitude. Its output voltage is proportional to its input voltage, over a wide range of output current levels. Mainstream speakers ideally produce roughly constant SPL within their passband when fed with signals of equal voltage amplitude. Frequency response and sensitivity curves assume a constant voltage input signal, not constant current or constant power.
Thus it's the nature of speakers -- as voltage devices -- that makes it useful to design amplifiers as voltage devices as well.
Now, hooking up those two speakers: The one with lower impedance (at a given frequency) will receive more current, and thus draw more power at that frequency.
Q: How is the voltage distributed when two speakers are hooked up in parallel?
A: Both speakers get the same voltage.
Historically, engineers cared about power because we're interested in the thermodynamic efficiency of systems. Also, power is a crude way to compare systems that have different impedances. Today, power is a nice thing to put on a spec sheet, but a poor quantity to use when trying to understand what's going on with amps and speakers. Most basic testing is done with voltage measurements.
Amps and speakers are voltage devices. What's this mean? An ideal amp is designed to reproduce the input voltage at a higher amplitude. Its output voltage is proportional to its input voltage, over a wide range of output current levels. Mainstream speakers ideally produce roughly constant SPL within their passband when fed with signals of equal voltage amplitude. Frequency response and sensitivity curves assume a constant voltage input signal, not constant current or constant power.
Thus it's the nature of speakers -- as voltage devices -- that makes it useful to design amplifiers as voltage devices as well.
Now, hooking up those two speakers: The one with lower impedance (at a given frequency) will receive more current, and thus draw more power at that frequency.
Unless you wire them in series then current is constant and the driver with the higher impedance at a given frequency will get more voltage and thus more power.
I've seen schematics for series wired crossovers. More of a novelty than anything else but an interesting spin.
I'd wager that the majority of players pay no attention to impedance, even less with anything to do with impedance curve over the frequency band. They just plug things in together and go with it. If they hook together, they must be meant to hook together.
I've seen schematics for series wired crossovers. More of a novelty than anything else but an interesting spin.
I'd wager that the majority of players pay no attention to impedance, even less with anything to do with impedance curve over the frequency band. They just plug things in together and go with it. If they hook together, they must be meant to hook together.
