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[EMAIL PROTECTED] wrote:
>
> On Thu, 23 Mar 2000, Ralph Smeets wrote:
>
> Hi!
>
> > than a year...) The only portable that won't break and that is Sony is my
> > CMC-Z1+ portable GSM phone... (of which most consumer magazines write you
> > that the flip-down microphone will break very quickly...)
>
> BTW, I don't see http://home.worldonline.dk/~isl366/md/md.htm
> listed on the construction projects section on minidisc.org (although I'd
> swear I got that link from somewhere related to minidisc.org.
>
> It's a pretty good idea: recycle old GSM phones mics, have done something
> similar and it actually perform great for speech recordings!
>
> > > The only unexpected mis-feature I have found is the headphones
> > > sound; even when people said sharps sound greatly, i found the headphones
> > > to have a very harsh and unpleasant sound. Mids are unsanely boosted, and
> > > I (I know that is a very subjective area) don't like that at all. Is the
> > > only drawback I found on the sharp. I hate earbuds commonly found on other
> > > portables, so I don't mind too much, sony's would be worse.
> >
> > I tossed them away after 1 day. I replaced them with the 888's of Sony.
>
> Are they sold as a separate product? My impression is that Sony
> isn't very good with transducers...
>
> > > Here's were my question comes: Sharp headphones are 32 Ohm, I have
> > > an old walkman Aiwa headphones whose sound I like too much (in fact i
> > > tried lots of walkmans back then to find the better sounding ones). But
> > > they're 200 Ohm.
> > >
> > > My electronic knowledge have some dust on top, and I was wondering
> > > if the battery life will be shorter. My mind says that as impedance is
> > > higher, AC current *voltage* will actually be higher, and battery life
> > > will be shorter. Higher impedance: higher energy loss also...
>
> > 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...
>
> 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...
Off course you NEED higher power to drive high quality headphones. Why?
Higher quality headphones (like speakers) tend to be less efficient with
the energy put into them. Ie, to get the same sound-level out of them as
with normal headphones, you need to drive them with more power.
However, if you connect these headphones to a portable player, you'll
notice that the sound isn't as loud as a normal headphone. A 5mW amp can't
put out more than 5mW!
Cheers,
Ralph
--
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Ralph Smeets Functional Verification Centre Of Competence - CMG
Voice: (+33) (0)4 76 58 44 46 STMicroelectronics
Fax: (+33) (0)4 76 58 40 11 5, chem de la Dhuy
Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN
E-Mail: [EMAIL PROTECTED] FRANCE
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"For many years, mankind lived just like the animals. And then
something happened that unleashed the powers of our imagination:
We learned to talk."
-- Stephen Hawking, later used by Pink Floyd --
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