🚀 go-pugleaf

kludge@grissom.larc.nasa.gov ( Scott Dorsey) writes:
: 
: How are you measuring distortion?  I gather that you are talking about a
: THD rating, but a system that has a poor slew rate may have excellent THD
: and still sound poor because it doesn't follow transients well.

I don't understand.  How is having a 'poor slew rate' any difference from
high-frequency dropoff in response?  Intuitively, they seem to be
two ways of describing the same thing, though "poor slew rate" provides
a bit more physical intuition.

Or perhaps "poor slew rate" is a code word for "distortion at high
frequencies"?

: 
: Therefore, you basically need to find what particular rating is required
: to account for a particular type of audible distortion.
: 
: This basically comes down to the argument as to whether people can hear
: differences in CD players.  I can definitely hear them.  More than that,
: I can measure them.  The group delay that is produced by the filters on
: some CD players is really shocking.

This is 'dispersion', right?  (I presume you mean frequency dependent)

: By the way, when people say something sounds "muddy" it generally translates
: as excessive IMD.  I am starting to get better at guessing what is wrong with
: systems ased upon very vague and subjective commentary.  Of course, it takes
: an objective measurement to be sure.

Why doesn't some scientist build a circuit with controllable & measureable
amounts of various types of distortion, and then ask people to choose
from a list of favorite 'audiophile-adjectives', and see what most
reliably goes with what.    

Hmm...I bet somebody's already done this and us kibbutzers just aren't
paying attention...


Flash! Just coming in on the wire.....

6. PAILLARD B; MABILLEAU P; MORISSETTE S; SOUMAGNE J.
     PERCEVAL - PERCEPTUAL EVALUATION OF THE QUALITY OF AUDIO SIGNALS.
     JOURNAL OF THE AUDIO ENGINEERING SOCIETY, 1992 JAN-FEB, V40 N1-2:21-31.

45. ZWICKER E; ZWICKER UT.
      AUDIO ENGINEERING AND PSYCHOACOUSTICS - MATCHING SIGNALS TO THE FINAL
    RECEIVER, THE HUMAN AUDITORY SYSTEM.
      JOURNAL OF THE AUDIO ENGINEERING SOCIETY, 1991 MAR, V39 N3:115-126.


And remember that thread about digital amplifiers?
31. GOLDBERG JM; SANDLER MB.
      NOISE SHAPING AND PULSE-WIDTH MODULATION FOR AN ALL-DIGITAL AUDIO POWER
    AMPLIFIER.
      JOURNAL OF THE AUDIO ENGINEERING SOCIETY, 1991 JUN, V39 N6:449-460.

And objectively evaluating amplifier quality?
39. WOODFORD TW.
      NEW TEST FOR AUDIO AMPLIFIERS.
      Pub type:  Letter.
      ELECTRONICS WORLD & WIRELESS WORLD, 1991 MAY, V97 N1663:406-406.


Amazing what computers can do these days....

: --scott

Matt Kennel
mbk@inls1.ucsd.edu