From: John Woodgate
Subject: Re: audio line specifications
Date: Sun, 8 Dec 2002 05:38:19 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Sun, 8 Dec 2002 06:29:36 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Ben Bradley wrote (in <firstname.lastname@example.org
>) about 'audio line specifications', on Sat, 7 Dec 2002:
> FWIW, I have Sony MDR-7506 headphones (I have no doubt these are
>moving-coil - they're definitely not electrostatic) and the frequency
>response most definitely IS affected by source impedance.
I'm sure Sony would be fascinated to hear that. It was an expert on
headphones from Sony who agreed that IEC 61938 should call for a 120 ohm
feed impedance for headphones, so that different headphone impedances
can be accommodated with as little difference in apparent sensitivity as
I've also done the experiment, switching source impedance **without
changing signal level**, and no change can be detected. I haven't tested
the MDR-7506. People with good hearing decided whether there was any
change or not.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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