Re: 3 dB bandwidth

Guy Macon wrote:

> Joerg wrote:
> >
> >Hello Larry,
> >
> > >... So it is readily calculated by hand,
> > > (as things were when that standard arose).
> >
> >Hey, they still are. I have one calculator in my drawer (HP11C) but
> >several slide rule calculators. No abacus though.
>
> Addiators work better for addition and subtraction, and are still
> 100% mechanical. There are usually a few on eBay cheap because
> many were made and few people collect them. (Always contact the
> seller and confirm that the slides move freely and that the numbers
> are still readable).
>
> >Thing is, if the power goes out I can keep going. A long time ago they
> >pestered me about it at a client's lab and one of the engineers bragged
> >about a new calculator with "continuous memory" that didn't fail when
> >the battery died. I told him my slide rule had continuous memory as
> >well. The slider...
> >
> >Then one day a company came out with a slide rule calculator that had an
> >LCD and buttons. That almost made me sick.
>
> I remember that one. The calc only added and subtracted. There was a
> sliderule with an addiator on the back too.
>
> Back to the topic, 3DB is also the amount of drop you get when you
> have the output impedence and the input impedence matched, which was
> common in the days of transformer-balanced audio lines.

Nooooo ! That's a 6dB drop.

Thank God we got rid of so-called 'matched impedance working' and went for
'voltage matching' in audio a long long time ago.

I can recall seeing 600 ohm variable attenuators though in an antique studio
when I was a young 'un. I expect they'd cost around £1000 to make today. Just
to control the 'volume'. Wow !

Graham


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