How much less amp draw for high frequencies?

[installerblizz]

I know that amplifiers draw less current when running in high-pass mode, but how much less?

For example, if I have an amplifier with a 50 amp max draw, what will it draw if I run it in high pass at 80 hz? Thanks in advance guys.

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[maylar 10+ year member]

Watts is watts. It makes no difference what the frequency is.

 

[T3mpest 10+ year member]

Watts is watts. It makes no difference what the frequency is.

Actually it will make a difference. Get a DMM and test it out using pink noise if you don't believe me. When you reduce the frequencies going to an amp you area also limiting it's power output given the same source material. If the whole track has X amount of energy, cutting all the lows would reduce the output of an amp. A 1000 watt full rangeamp playing airforces will drop ALOT of power consumption if you were to high pass it at 200hz, effectively cutting out all the bass.

To answer the OP's question though, it won't make a heck of alot of differnece. Something like 1/2 the power in most music is located in the last 2 octaves up to 80hz. Most generally centered around 40hz, so crossing at 60hz vs 80hz won't be a huge difference. When you crossover at 80hz your reducing the level of 1/2 the bass, but not eliminating it. I'd imagine it works out to about 75% of it's max current draw at the same volume on bass heavy tracks. If your dealing with stuff that doesn't have as much bass, then it might not be as dramatic. Point is, I wouldn't count on it making a major difference. On music, most amps put out around 1/2 of their max current draw anyway since max current draw is based on an amp on full duty cycle. This is actually a fairly complicated issue, but not a critical thing.

 

[installerblizz]

Thanks T3mpest! I did read about how amps don't draw anywhere near their max current figure while playing music, thanks to their on-board capacitor bank. But what about music with long drawn out bass lines like Bass Mekanik? I fully expect my sub amp to be drawing max current, but what about the amp for the highs crossed over at 80 hz?

 

[maylar 10+ year member]

Actually it will make a difference. Get a DMM and test it out using pink noise if you don't believe me. When you reduce the frequencies going to an amp you area also limiting it's power output given the same source material. If the whole track has X amount of energy, cutting all the lows would reduce the output of an amp. A 1000 watt full rangeamp playing airforces will drop ALOT of power consumption if you were to high pass it at 200hz, effectively cutting out all the bass.

Yes, if we're talking about music or pink noise. But 100 watts at 1000 Hz draws the same power as 100 watts at 50 Hz. That's what I meant by watts is watts.

 

[maylar 10+ year member]

Thanks T3mpest! I did read about how amps don't draw anywhere near their max current figure while playing music, thanks to their on-board capacitor bank. But what about music with long drawn out bass lines like Bass Mekanik? I fully expect my sub amp to be drawing max current, but what about the amp for the highs crossed over at 80 hz?

It depends entirely on the program material. If the long bass notes are like 30 Hz and you're amp is hipassed at 80, then the amp won't play the bass and therefore won't draw more input current. But system tuning is usually driven by the low end limits of the speakers, not the current draw of the amps.

 

[installerblizz]

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[installerblizz]

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[installerblizz]

Ah. That answers my question. I should have been more specific about what I was trying to determine - if my Eclipse amp for my highs that is high passed at 80 hz and has a 50 amp fuse and my Fosgate amp for my sub that is low passed at 80 hz and has a 70 amp fuse would trip my 100 amp circuit breaker at the battery at full volume. By the way - it hasn't. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[T3mpest 10+ year member]

Don't forget your fuse at the battery should be fused due to the ability of your wire to carry current, not the the amps ability to draw current. In case of a short, impedence will drop to almost nothing if your wire can't handle that (it can't) it will burn up and possibly catch fire, that's why you fuse within 12 inches of the battery. To protect the wire, not the amp.