Andre Jute wrote:
>
> On Mar 23, 2:03 pm, John Byrns <byr...@[EMAIL PROTECTED]
> wrote:
> > In article <47E5E768.28256...@[EMAIL PROTECTED]
>,
> > Patrick Turner <i...@[EMAIL PROTECTED]
> wrote:
> >
> >
> >
> > > John Byrns wrote:
> >
> > > > In article <47E4A1B3.B6709...@[EMAIL PROTECTED]
>,
> > > > Patrick Turner <i...@[EMAIL PROTECTED]
> wrote:
> >
> > > > > There are NO other brands other than Quad *I know* of who now
use 10%
> > > > > CFB,
> > > > > and none at all in the 1950s and 60s, except Lincoln-Walsh, who
may have
> > > > > made amps with CFB BEFORE Quad made their famous type II power
amps.
> > > > > I invite someone to name other makers who they think did use
CFB.
> >
> > > > It probably wasn't 10%, but Bogen used CFB in many of their
amplifiers,
> > > > see this link for an example:
> >
> > > >http://www.schematicheaven.com/hifiamps/bogen_db20df.pdf
> >
> > > > Regards,
> >
> > > > John Byrns
> >
> > > You are quite right John.
> >
> > > Most amplifiers manufactured in the US were not im****ted to Oz
> > > in the 1959s and 60s.
> >
> > > Hell, they all needed 120V mains and we only had 240V.
> > > And we had quaint tariff laws, and US proces for any darn thing
> > > were high, and when folks dreamed of nice amps,
> > > they thought of Quads, Leaks, Radfords, and other Bitishalia.
> >
> > > The Bogen is quite sophisticated in its FB arrangements and
elsewhere.
> >
> > > There sure is local NFB in the output stage from OPT to OP tube
> > > cathodes.
> > > I dunno how much. 6L6 like KT66 will need at least 10% to do much
good.
> >
> > > It has a substantial conventional global NFB to one 12AT7 cathode.
> > > Then there is variable current FB from speaker return current path
of
> > > 0.27 ohms and 0.47 ohms.
> > > The pot makes the current FB either positive or negative, and
> > > drastically changes
> > > the amp Rout between very low and quite high respectively.
> > > The 4uF below the 68 ohms at V1 reduce the current FB at HF,
> > > lest the current FB spoil stability.
> >
> > > This is the classic way positive current FB could be applied to
> > > better bass performance.
> >
> > > They also use the 12AT7 filament as a resistance to get -12.6Vdc
grid
> > > "back" bias
> > > for the output 6L6.
> > > This looks quite silly to me, but for them it worked.
> >
> > It's not silly at all, it pleases the bean counters
>
> Damned right too. It is high time we gave the bean counters some
> credit on RAT. Without the bean counters we wouldn't have had the
> great benefits of the transistor, especially outside audio. Even in
> tube audio we would not have had the pleasure of the company of
> Kroogie, Pinkostinko, Poopie and others of similar persuasion.
>
> I don't actually fancy a tube computer on my desk...
>
> Andre Jute
> Do accountants not bleed when you backstab them?
Definately not.
All their blood is devoted to life preservation purposes,
and there's not a drop to spare for such luxuries as bleeding,
even after a kerfuffle such as a company going broke, where
not a skerrick of funds can be ever be found to give ashen faced
shareholders
or the teams of happless little people who were so foolish to invest.
If you front stab them, or pound them in their already flattned nose
with a clenched fist,
it makes utterly no difference, since not only do they seem to lack
a blood circulation network, but they are incapable of any emotions.
They say money is the root of all evil, and money
sure has completely rooted the bean counter species.
Patrick Turner.
>
> > by saving the cost
> > of an extra winding on the power transformer, a selenium bridge
> > rectifier, several electrolytic capacitors, and a resistor or two that
> > are otherwise necessary to provide DC current to the heater of the
phono
> > preamp tube.
> >
> > Regards,
> >
> > John Byrns
> >
> > --
> > Surf my web pages at, http://fmamradios.com/
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