Hi Mike,
>Sorry but no, you have it backwards, Bruce. Years ago, most speakers were 8
>ohms, and headphones were designed to be driven by the same amp circuit that
>fed the speakers without anything getting overloaded (the speakers, the
>headphones, or most importantly the amp itself, usually tube-driven in those
>days). To do this they had to have a very high impedance, 600 to 2000 ohms, so
>they could be strapped across the amplifier with the speakers without
>affecting the amp load much.
No, the Koss headphones that I used in '71-73 were definitely 8 ohms. I worked for Radio Shack all through college, and nearly every headphone we ever sold in those days said "8 ohms" on the box. Back then, most stereo manufacturers powered the headphone jack by putting a 100-500 ohm resistor in series with each side of the main outs, to both prevent the cans from loading down the main speakers, and to prevent the headphones from taking the full brunt of the amplifier. My trusty Sennheiser HD414's, OTOH, were about 2,000 ohms, and so were relatively easy to fry by turning the levels up; that 150 ohm resistor didn't help at all. :^(
None of this changes the fact that some headphones are much more efficient than others, particularly when driven by the AN1x -- whether the impedance is too high, or too low. I can get a satisfactory sound from my HD580's for late-night tweaking, but I've never tried them in a recording environment. I'd probably be disappointed.
Regards,
-BW
--
Bruce Wahler
Ashby Solutions™
http://music.ashbysolutions.com978.386.7389 voice/fax
bruce@...