how do I read amp power by fuse rating?

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11-28-2004, 07:18 PM

Vanilla Gorilla

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Hi there, I've seen some people fairly accurately read the amps power by going by the amperage of the fuses. I know digital amps make great use of what power their given, but could anybody (that honestly knows what there talking about!)give me approxiamates of power output in relation to the powe input. Like What wattage would 2 X 30 fuses give me for a class A/B amp? [img]graemlins/dunno.gif[/img]

11-28-2004, 09:40 PM

Newb

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Quote:

Originally posted by GMonette:
Hi there, I've seen some people fairly accurately read the amps power by going by the amperage of the fuses. I know digital amps make great use of what power their given, but could anybody (that honestly knows what there talking about!)give me approxiamates of power output in relation to the powe input. Like What wattage would 2 X 30 fuses give me for a class A/B amp? [img]graemlins/dunno.gif[/img]

Well, that only works if the amp designer is honest with the fusing... I've seen some really crappy amps with huge fuses. With 2 30a fuses you could probably expect a good 100x2 @ 4 ohm out of a class A/B, assuming it's your standard 2 ohm stable amp.

11-28-2004, 09:57 PM

Derek Jerome

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60 amps * 12.5 volts = 750 watts of input energy available

now depending on amp efficiency and current capabilty (the aforementioned designer truthfulless) your output could be darn near anything

but I agree most amps with that fusing run about 100-150 watts per channel

11-28-2004, 10:25 PM

Father Yuli

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well if a/b is about 50% efficient then i think its something like 300watts for 60amp fusing.

so what dodgeram said, about 150 watts per channel

11-29-2004, 07:41 AM

Dave MacKinnon

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Actually, based on my testing, most amps make around 8-10 W per Ampere of input current.

So, a 30-Amp fuse should be roughly 300W, and 90-Amps is roughly 900W...

11-29-2004, 07:55 AM

JordyO

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My amps have no fuses... does that mean they don't put out any power!?! [img]graemlins/cry.gif[/img]

11-29-2004, 09:30 AM

Haunz

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Hmmm... I had a Pioneer premier that did 500rms with 14v fused at 60..

also a Jensen I benched doing more then 400rms and it was fused at 50...

[img]graemlins/dunno.gif[/img]

12-02-2004, 10:02 AM

Big Sexy

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Is that figure of 8-10 watts per ampere at 14 volts or higher Mr. Dave? Are these mostly class a/b amps? What is the efficiency of most class a/b and class d amps that you have tested and at what voltage?

12-02-2004, 10:14 AM

Haunz

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A/B amps are usually %50 - %60 near output
saturation (almost clipping)... I think %66 is the theoreical maximum...

An average Class D is %60-75 but some can achieve greater then %90

12-02-2004, 01:41 PM

#10

Paul Niwranski

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"...can achieve greater then %90..."

^ maybe on paper..

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