Francisco Jose Montilla wrote:
> > Well, U=I*R. U can't change!! So if you increase R, you decrease I.
> > P=U*I, U doesn't change, but I get's smaller. Thus lower power consumption.
>
> Not with variable AC...
Ok, here is the problem.... You are driving the head phone through an
output stage that has an internal resistance.. The battery voltage
comes through the output transistor(s), through the headphones and back
to the battery.
So, if the unit was designed for 32 ohm headphones, and you put 200 ohm
phones on it, you have changed one leg of a voltage divider, and more of
the battery voltage will develop across the headphones .... However, you
have changed the operating point (bias) of the transistor output stage,
and that can lead to clipping and distortion.
You have to remember that you are dealing with a battery voltage of 4.5
to 6 volts or less, not a headphone distribution amp.
>
> Wait! I have remembered someone posted a site devoted to
> headphones (www.headwize.com)! Have just checked it and that's what they
> say (http://headwize.com/articles/hguide_art.htm#imped):
>
> -----------
> Impedance: A measure of headphone load on an amplifier and stated
> in ohms. This factor is less important with solid state amplifiers, which
> can drive most headphone impedances, but can be significant with tube
> amplifiers, which are more sensitive to load impedances. Both consumer and
> professional headphones generally have impedances of less than 100 ohms.
> There are professional models rated at 200 ohms or more to minimize
> loading effects on distribution amplifiers which are often drive a whole
> bank of headphones at one time. Be aware that very high impedance phones
> may require more power - on the order of Watts instead of milliWatts.
> ---------
>
> mine aren't pro's, that's sure. But it seems I was on the right
> direction...
>
> I'd try to contact this guys to see if the can clear it.
>
> *****---(*)---**********************************************---------->
> Francisco J. Montilla System & Network administrator
> [EMAIL PROTECTED] irc: pukka Seville Spain
> INSFLUG (LiNUX) Coordinator: www.insflug.org - ftp.insflug.org
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--
Jim Coon
Not just another pretty mandolin picker.
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