Re: opamp sine wave oscillator

On Feb 8, 9:35 pm, Phil Hobbs <pcdhSpamMeSensel...@xxxxxxxxxxxx>
wrote:
John Larkin wrote:
On Sat, 9 Feb 2008 08:35:54 +1100, "Phil Allison"
<philalli...@xxxxxxxxxx> wrote:

"John Larkin"
"Phil Allison"
The famous Quad ESL63 electrostatic speaker has THD in the order of
0.03% at
97dB SPL.

How can that be measured?

** Huh ?

No idea how THD can be measured ?

No idea of how to measure THD in a sound wave to this sort of
resolution. Are microphones this good? If so, how do people measure
*them*?

One method is to assume that the microphone is time-invariant at small
amplitudes, pick a repetitive signal, and do a lot of signal averaging.
By attenuating the sound with distance, the distortion polynomial
(i.e. the Nth harmonic goes as amplitude**N for small amplitudes) allows
you to distinguish between microphone and speaker distortion.

Not too much fun, but conceptually not too bad.



Do you believe the number?

** No faith required, it ain't religion.

A lot of audio stuff seems to be. It sure ain't science. Do you
believe that you can buy cables that are six-nines pure copper?

I believe that some are _advertised_ to be six nines...of course that's
before they went through the drawing die, not to mention the oxidation
due to using thin strands...even assuming that people who would stoop to
fleecing audiophools have the elementary honesty to _try_ to deliver six
nines wire.

There really was at least one wire maker that really did deliver on
the 6 nines pure claim.

I think they used ceramic or copper in all of the wire pulling
hardware. Unlike the Phelpsdodge wire it didn't have to be pickled
before coating to remove the outer layer.
.

Relevant Pages

  • Re: Capturing EM interference with a microphone
    ... sounds were almost drowned out by the actual normal sound produced by the fans, hard drive, etc. in the computer. ... the microphone was quite adept at recording these sounds. ... loudspeaker) anf that coil picks up all the electromagneic interferance inside your computer. ... wire, perhaps half an inch in diameter, with a hundred turns of wire or so should ...
    (sci.electronics.basics)
  • Re: mobile phone and door entry system
    ... joseph2k wrote: ... mobile phone speaker and microphone to a door entry system speaker and ... I don't suppose that you have heard of wire? ...
    (sci.electronics.design)
  • Re: A little help here
    ... computer to use as a microphone? ... Ya know, a regular house phone. ... Just rip the electret insert out the handset and wire a 2k2 resistor in ...
    (sci.electronics.design)
  • Re: Need Advice on Lighting and Audio Equipment
    ... and the voice-over of the reporter explaining what's happened (this example coming to mind because the news is on TV right now). ... interview is done. ... important to *hide* the microphone. ... same wire between the micropone and the belt ...
    (rec.video.production)