[[email protected]]

On Sun, 23 May 2010 16:20:10 -0700 (PDT), Danny T wrote:


Exactly what specification are you looking at? Can you find
one and either quote it exactly or paste it into a message?
It seems odd that a headphone amplifier should "need at
least 100 ohms."

The one manual I had sitting around reads about the same as I remember
the others to and it does say not to fall below 100 ohms. So if the
Sony's are only 63, that would mean I could not use them according to
their specs, right? On the other hand, if I have that backwards, then
the AKG K240's cant be used because they have 600 ohms printed on the
side of them.

I'm thinking at such a low voltage, like you said, the volume would be
the only real short term thing to think about. The long term affect
would probably be to immaturely age the product.

I never really looked at headphone impedance before but on the casual
accidental noticing of it found that the impedance of must of them are
rather high.

I understand ohm's law but I guess I'm confused about the way they
have the limits based for the amps. If you need at least 100 ohms -
and for instance, the Behringer powerplay has room for three
headphones per each of the amps in the rack, you'd need at least 300
ohms on each headset or you'd drop to low and start burning the thing.
It seems a rather dishonest way of promoting the thing.

Some of the headphone amps I have looked at are simply op-amps driving the
output through a series resistor...

If you place a load that is too low you will simply lose too much signal inside
the amp, and get distortion. I doubt you can burn the headphone amp, they should
be designed to take a short circuit either because of the series resistor or
internal limiting. Some amps have a complementary pair to increase the drive
capacity, and some use a power amp chip. These types usually can go below 100
ohms...

Knowing the circuit you have is the most important consideration here...