Preamplifiers and Power Amplifiers
By Knirsch - Borbely
The Borbely Audio Interview.
click here
at BORBELY AUDIO Site
Excell II e
Millennium
By Knirsch, a
company already renowned in the audio market due to its famous energy
conditioners powerline and AC extension strips Spiritline,
AC power cords AC-15, and signal cables TOP Wonder Plus,
developing also acoustic and electrical projects, presents the modern
Millennium power amplifiers and the Excell II
preamplifier to the market. Such designs come from the famous American
designer Erno Borbely (
www.borbelyaudio.com ), who as Hafler’s engineering director in
the late 70’s, developed the DH101 preamplifier and the DH200
amplifier, the first ones to make use of FET technology. Since 1982
Erno Borbely develops High End audio projects acclaimed by
audiophiles worldwide.
The Project was created in
Germany and it is custom-built, unit by unit, right here in Brazil by
someone who really loves High End audio and understands what
audiophiles want from electronic reproduction equipment. These
amplifiers’ sound quality gets as close as possible to live
reproduction, bringing to you high dynamics and an extremely flat tonal
balance at extremely low harmonic distortion figures.
Both designs are entirely
executed with discrete components, and integrated circuits are not used.
All transistors make use of J-FET and MOS-FET technologies operating in
pure Class “A”, which eliminates transistors’ “turn-on – turn-off”
time, considerably increasing dynamics. Another characteristic of Class
“A” operation is the naturalness of midranges and highs, with controlled
bass, bringing live reproduction to you. The passive and active
components used are the best ones available in the market. The
technologies used in electronic circuit topologies are the most advanced
ones currently in existence. Power supplies employ over-scaled
transformers, ultra-fast diodes, and over-scaled capacitors as well.
Voltage regulators also make use of discrete components of only the
highest quality as well as the amplification circuitry.
The Excell II
preamplifier has got balanced circuitry and totally independent
amplification for each phase of the signal in each channel, totaling 4
independent amplification and power supply circuits. Transformers and
rectifiers are mounted on separate boxes in order to eliminate
electromagnetic interferences from transformers and the AC line.
Regulators are “shunt” types, what allows for better regulation,
more available energy and lower “ripple” noise than any other
regulator type.
The volume control, instead
of using various resistors in series with the signal, adds just one
resistor in series and varies resistors in parallel, lowering the
interference of having several resistors in the signal path caused by
other attenuator types.
The Excell II
preamplifier can supply pure Class A signals at very low impedances,
from 20 Ohms upwards. The amplification circuit is wholly
made up of discrete transistors, and from this we obtain, as well as
impressive linearity up to 1MHz, also “rise times” below 200ns,
which yields impressive dynamics to the preamp. It’s got active DC
control for the signal under control and keeps DC levels below 1mV, in
order to protect the amplifiers and avoid the use of decoupling
capacitors. As it can be seen it’s a very advanced technology, and this
can be appreciated and tested at our Laboratory of Acoustics and
Audio. The Millennium power amplifier is made up of two
mono-blocks built from thick, solid aluminum plates in order to lower
the transmission of external vibrations into the casing. It’s got
balanced signal inputs and a 75W, pure Class A output through 8 power
MOSFET’s transistor pairs in parallel and 4 large heat dissipaters per
channel in order to control discharged heat.
It’s got independent power
supplies for the signal output and input stages with ultra fast diodes,
and over-scaled inductors and capacitors, in order to guarantee the
needed currents and filtering. The transformers have electrostatic
shielding in order to avoid noise intake into the audio circuits from
the AC line. Capacitors with high filtering capacity, jointly with
transformers, supply the needed energy for excellent dynamics. The input
stage circuit is totally made up of discrete and matched transistors,
and it doesn’t use integrated circuits in the amplification path, and
therefore presents impressive linearity up to 1MHz, and “rise time”
below 200nS. It’s got active DC control for the signal which controls
and keeps DC levels below 1mV, in order to protect loudspeakers’
tweeters.
Millennium
power amps provide you unforgettable listening pleasure, merging the
dynamics and speed of the best transistor amplifiers with the smoothness
and warmth of mids and highs, which is present in the best tube-amps
only. See all kits at
www.borbelyaudio.com
Come visit them
at our
Laboratory of Acoustics and Audio.
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