Re: Negative Feedback and the Criminal Assets Recovery Bureau


"Patrick Turner" <info@xxxxxxxxxxxxxxxxxx> wrote in message
news:44C5F4D1.EA43F22A@xxxxxxxxxxxxxxxxxxxxx
Modern transistors are more linear than even the best Triodes.

You have said this misleading statement before.

**It's not misleading. It's fact.


Unfortunately for your arguments this is not the case with regard to
voltage
gain.
Transistors need only a small range of turn on voltage applied between
their
base and emitter,
and their gm varies enormously between being on the threshold of turn on
of
collector-emitter current and saturation.

**Transistors are controlled by CURRENT, not Voltage. The CURRENT gain of
modern transistors is extremely linear, over a wide range of Collector
currents and Voltages.


Only enormous amounts of externally applied NFB corrects the inherent
voltage
non-linearity
of all BJTs where there is substantial current change as in the case of
all
power transistors.

**Transistors (BJTs) are CURRENT amplification devices.


Try setting up any bjt in common emitter mode without any emitter resistor
and
apply
a voltage from a very low impedance to the base. The bjt is disgustingly
non
linear
compared to a triode using no external applied NFB.

**Transistors (BJTs) are CURRENT amplification devices. Apply a current to
the Base and measure the change in Collector current. Get back to me when
you've done this.


Even most pentodes which do not have internal electrostatic NFB like a
triode
can easily
out perform a bjt.

**Not even close. Pentodes are vastly less linear than even average BJTs.
Triodes, at least, are reasonably linear.


I am not here to discuss whether the bjt amp can sound well, or measure
well.
Both are known to be possible so it is believed by most folks.

**Me either. I'm here to correct Jute's lies.


Without external loops of NFB including the emitter follower connection
which is a high amount of applied series voltage NFB, the BJT is a
hopeless
voltage amp


**Transistors (BJTs) are CURRENT amplification devices.

unless we try to restrict the current change in the device, and then the
gain is

enormous and subject to the perils of the high collector resistance and
circuit slowness due to capacitances, and the non linear input resistances
of
other
devices in the signal path.

A class A single bjt voltage amp stage with a single MJE340 with another
for a
constant current source
collector load can have a gain of maybe 1,000, or like a pentode with a
CCS load
in its anode circuit.
If external loops of shunt NFB are applied around either device, then the
linearity can be quite good for
either device, because for a gain reduction of 100, from 1,000 to 10, the
thd is
also reduced about
100 fold.

The linearity is dependant on the NFB applied, and not on the basic
VOLTAGE
linearity
of the device without NFB, which for a bjt is relatively poor, and poorest
when
considerable
current change occurs in the device.

**Transistors (BJTs) are CURRENT amplification devices.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

.

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