odigg
500+ Head-Fier
- Joined
- Apr 1, 2008
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I've been thinking about amps a little (not building them, just thinking) and I've been running some calculations.
It seems like, as a general rule of thumb 30mw should be just enough to destroy your ears with most headphones.
From that I came up with the following.
With a 25 ohm headphone you need about 0.85 volts and .34 amps.
With a 300 ohm headphone you need about 3 volts and .01 amps.
With a 600 ohm headphone you need about 4.25 volts and .007 amps.
Three AA batteries could supply this much or even two batteries if you value your hearing. Assuming 30mw is very loud on something like a AKG 240M (88dbl/mw), three AA batteries is enough even for those headphones.
So why in the world are there headphone amps with 12volt, 15volts, 24 volts supplies, etc?
Is it simply a matter of headroom?
It seems like, as a general rule of thumb 30mw should be just enough to destroy your ears with most headphones.
From that I came up with the following.
With a 25 ohm headphone you need about 0.85 volts and .34 amps.
With a 300 ohm headphone you need about 3 volts and .01 amps.
With a 600 ohm headphone you need about 4.25 volts and .007 amps.
Three AA batteries could supply this much or even two batteries if you value your hearing. Assuming 30mw is very loud on something like a AKG 240M (88dbl/mw), three AA batteries is enough even for those headphones.
So why in the world are there headphone amps with 12volt, 15volts, 24 volts supplies, etc?
Is it simply a matter of headroom?