".Bill" wrote:

Jon Noring wrote:


Now the question is how accurate are the simulations of circuits
which include factors for real-world (e.g. non-linear) performance?
Patrick keeps saying to get out the soldering gun and see how things
turn out, which I find perplexing since I assume the circuit
simulation codes that exist today are quite powerful. It would not
surprise me if many commercial electronic circuits are first
designed entirely by computer using simulation and optimization
techniques, then prototypes built for final tweaking and testing.

Jon Noring

My opinion is that the simulated circuits generally do just fine unless
there is one parameter that we might be looking for that isn't included.
Quantifying or averaging human hearing is the classic example.

Thats where you get into the fuzzy areas of things like which sounds
better (or different)...11.5 kHz components at 6.5db down or 11.5 kc
components at 12.3 db down. One guy may immediately note the
difference, the next segment of the population wouldn't notice if it
were 6.5db up. (I'm thinking of the 10kc wide AM radio here)

But FM radio surely sounds better than AM radio.

So we should aim for wide audio bandwidth.




Then the designer is faced with a real-world decision of whether of not
this is an issue and what other implications might it have further down
the chain with increased distortions, etc. The simulation can provide
the data but with the 'wrong' criteria it can equally as efficiently
spit out a worthless design. It would be nice to say "I want maximum
bandwidth, flatness and minimum distortion" but at the end of the day a
knowledgeable human being has to decide which of the results are what HE
is looking for.

Getting out the soldering iron quite often is the proof of the pudding.
You may know all the parameters of the circuit down to three decimal
points but does it sound the way you expect or want it to? (Again, the
10kc wide AM radio is a good example) And less importantly, will anyone
else concur?

Well quite a few would, and there have been quite a few designs for
a least technically excellent AM radio receivers over the last 30 years
which make what preceeded them look like a POS, if the Kreisler type of
radiogram
is anything to go by.
99% of the public bought what worked, and was cheap,
and that excluded the finer gear made by so very few makers.

The modern radios didn't look very nice though,
they were very bland, and the real charm was in the radios
of the time when radio was all there was.
Huge resonant wooden enclosures were used, and then elaborate dial glasses,
neither of which improved what was heard one bit. More value was in the
pretentious appearence than in the electronics.
Part of putting on the agony and putting on the style.
People were very fussy and even snobbish about their prized radios they
owned,
and those who had their youth in that time are now very nostalgic about the
symbols
of that time.

I doubt I will ever be nostagic about my CD player.
Its black, and reminds me of a funeral, and I need a torch to read the many
horid buttons,
and sounds worse than vinyl when vinyl is good, and if something goes wrong,

I damn well can't fix it.
Modern junk.

Patrick Turner.


-BM