On Mon, 24 Mar 2008 01:05:22 GMT, Patrick Turner
<info@[EMAIL PROTECTED]
> wrote:
>
>
>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,
Another well promulgated distortion.
The admonition is, for the *love* of money is the root of all evil....
and some by longing for it have wandered away from the faith and
pierced themselves with many griefs.
1 Timothy 6:10 (King James)
> 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/
|
