[R-390] Never heard the real R-390

[Sheldon Daitch]

Maybe I have missed it, isn't 6 per cent distortion
pretty high?  I asked a colleague and his idea on
6 per cent was pretty high, and should be very
audible.  But he also said below about 3 per cent
starts to get into the area where folks stop 
complaining.  Audiophiles want it to be a lot lower,
though, and maybe with good equipment, you can hear
in A-B testing, between 3 per cent and something a 
lot lower.

I believe the old standard for AM broadcast transmitters
was a maximum of 5 per cent, except at the lower audio
frequencies, where the limit was 7.5 per cent.  I guess I
ought to check an old rule book.

Sheldon


Roy Morgan wrote:
> 
> At 08:52 AM 7/26/2004 -0500, you wrote:
> >I suspect that when the RX is tweaked to meet the book specs, which
> >include 1% THD if I recall correctly, the sound from the Diode Load
> >terminals is at least a bit better than "not impressive".
> 
> Mil Spec 13947B says:
> 
> "3.13.41 Audio harmonic distortion.- Harmonic distortion shall be no greater
> than 1- percent with 500 milliwatts outputs at the local audio channel, and no
> greater than 6 percent at the line audio channel. (See 4.41)"
> 
> "4.41 Audio harmonic distortion.- Audio harmonic distortion shall be
> measured with a Distortion Analyzer Hewlett-Packard Company Type 330-B, or
> equal, to determine compliance with the requirements of 3.13.41. Signal input
> shall be 1000 microvolts. The receiver audio outputs shall be loaded with a
> non-inductive resistance of 600 ohms, one Watt rating or larger."
> 
> Roy
> 
>