What is a Sovtek 6H30,6C45, and a KR Audio T-100?
In short, they are vacuum tubes. There are
three stages to Opus 2. They are: the voltage amplifier, the driver, and the power
stage. The 6H30 and 6C45
tubes are very linear. For Opus 2, this eliminates the need
for corrective circuitry. The result is accurate, simple, and
pure sound. The power stage requires a different type of tube, one which can
handle a lot of power. The T-100 is brain child of Dr Kron, founder of KR Audio in Czech Republic. Sadly, he did not live
long enough to see this tube to fruition. Since his passing,
his wife (also Dr. Kron) has taken over the business and continued the tradition. The T-100 is unique in many ways .
It is built with Pyrex glass and the insides are completely hand assembled and tested in very small batches. The KR Audio lead engineer, Mr. Marek Gencev
does "engineering control" to ensure consistency. This means that each T-100 is essentially matched to every other T-100.
These tubes have an life span of almost 10000 hours and are only available from KR-Audio.
What are Class A and Push-Pull?
Class A and Push-Pull describe
the architecture of the amplifier. A class A amplifier is the least
amplifier because the electronics are always working their little
out; however, it produces one of the least distorted most true sounds
available. Push-Pull amplifiers use two tubes working together to get
and to cancel out certain aspects of noise that can be created by
the electronics. A Push-Pull amplifier works alot like a slinky. The
transformer is energized by two tubes operating exactly out of phase. Courtesy of the T-100 and our special toroid transformers,
the Opus 2 has a power bandwidth that extends from 17Hz to over 124000Hz.
Why tubes? Why Transistors?
These questions are
enough to make the hair stand up on the back of any audiophile's neck!
It is a debate that continues on with a theological zeal. Technically,
there are only two ways to amplify signals. Voltage swing can be
increased or Current swing can be increased. There is a
analogy. When you run water through the kitchen sink and shut it off
the pipes bang with the inertia of the water passing through them. The
of the water is dramatically changed through this process. This is much
like current flowing through a wire. Voltage swing is like having the
water in the pipe, but having a balloon at one end and a piston at the
other. Very little movement of the water will make large size changes
in the balloon. Tubes work like the piston and the balloon. Transistors
work like the kitchen
sink. In truth, each has their strengths and weaknesses. We opted for
tubes because, in general, there are fewer components required to make
tube amplifier work well. As such, the possibility of the sound being
by a component is reduced. This keeps us in line with our original
of simplicity and purity of sound.
What is Negative Feedback?
Negative feeback is a method
of circulating a small piece of the output signal back through the
to gain better control of the natural hysteresis of the output
Negative feedback can also be used to flatten the frequency response of
The reality is that it can slow the response of the
amplifier and dull the sound of the finished product.
We are proud to print that the Opus 2 requires no feedback of any
kind to alter the signal.