"SST" wrote in message
et

Did you go to the various websites and see the specifications for
yourself?

Yes, in many cases there were no numbers whatsoever. And as I show below,
the numbers provided are incomplete and/or unbelievable.

I cited my sources specifically which you obviously did not do.

Obviously not. I didn't make them up, only reprinted them.

You didn't cite your sources specifically, so who's to know. However, just
because someone prints a spec doesn't mean its right or even reasonable.
Furthermore, I checked www.nomadworld.com and it provides a completely
different number for the NJB3's power output than you did (see below).

I checked out two of your numbers and found that they are terribly bogus.

The Apple iPod site http://www.apple.com/ipod/specs.html says that the iPod
puts out 30 mW per channel, but as I showed in my previous post, independent
measurements say that's impossible. My source says that the iPod only
delivers out 80 millivolts into a 32 ohm load. It would have to deliver 3/8
of an amp to a load to deliver 30 mW at 80 millivolts. It takes 12 volts to
deliver 3/8 of an amp to a 32 ohm load! Apple's specs appear to violate the
laws of physics given the (independently) measured performance of the iPod.

Coming around from another angle, it takes about a volt of output to deliver
30 milliwatts to a 32 ohm load. Frankly, the iPod should have no
difficulties delivering about a volt of audio from a 3.6 volt Lithium Ion
battery. That's essentially what the NJB3 does, and that's essentially what
the RS 330-1109 3-Way Headphone Volume Booster does with 2 AA Alkaline cells
(2.8 volts). However, it's well known that the iPod has perceptibly lower
output than the NJB3, and the independent measurements posted at
http://members.brabant.chello.nl/~m....surements.html
support that perception, to say the least.

But look again at the fact that a device delivering a volt can only deliver
about 30 milliwatts to a 32 ohm load. How does that fit with your claim that
the NJB3 delivers 900 milliwatts? It doesn't!

http://www.nomadworld.com/products/jukebox3/specs.asp says that the NJB3
delivers 100 milliwatts, which probably means 50 milliwatts per channel.
They don't say what impedance load, but we already know for sure that this
is impossible with typical 32 ohm headphones. But, at least it's the right
order of magnitude.

Show my numbers to an EE. He'll explain Ohm's law to you.