The MINI AMP, originally
designed by Erno Borbely, is a very
high quality discrete operational
amplifier (op-amp). Why design a
discrete op-amp? While state of the art
op-amps are very good quality and many
boast great specifications, they still
possess both technical and sonic
limitations due to their monolithic
nature. A discrete op-amp allows the
designer to hand pick each and every
component for both performance and
sonic enhancements. Transistors can be
selected for low noise, low capacitance
and quick response time. High quality
film caps can be applied as well as
super low noise resistors. Higher
voltage rails can be incorporated
allowing for greater voltage swings and
beefier output devices, able to
withstand heat, can be selected to
operate in full class-A mode providing
both excellent linearity and high
current drive.
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The MINI AMP has very good open-loop
linearity at high frequencies, is
extremely stable and boasts some very
impressive specs like; an input noise
voltage below 1uV, a slew rate greater
than 100V/usec and a THD figure
that’s so low most test
equipment can’t measure it! S/N
ratio greater than 110dB and a
frequency response of 5Hz to 110khz
+/-0.5dB. But most importantly, this is
the BEST op-amp you’ll ever
hear, with loads of low level detail,
impressive bass, a nice neutral but
warm midrange and rounded out with a
very smooth and extended top
end.
Did we say
this is an op-amp? Yes, we did.... and
therefore you can use the MINI AMP like
you would any other audio op-amp. For
example; it can be configured for
inverted or non-inverted outputs;
balanced or single-ended operation;
balanced to singled-ended converter; it
can be set up for unity gain (gain of
1), gain of 10, 20, etc. The MINI AMP
can be used as a simple but great
sounding linestage, a buffer amp, an
I/V converter in your DAC, a summing
amplifier for a mixer and in active
crossover filters. It's even
quiet enough that you could drop an
RIAA filter in between a pair of these
amps and create great sounding
phonostage.
Our MINI AMP
features a JFET input circuit
incorporating matched devices and a
bipolar output stage operating in full
class-A mode. Its input impedance is
approximately 1 Mohm and its output
impedance is less than 100 ohms. It
requires a power supply capable of
providing + 24 and - 24 volts DC @ 0.5
amperes.
We have
packaged the MINI AMP as a mono
amplifier, i.e. two boards are required
for stereo operation and four boards
are required for balanced stereo
operation. The MINI AMP is packaged on
a silkscreened 4-layer printed circuit
board measuring a very petit 3"(76mm)
by 3"(76(mm). This 4-layer board
features a dual ground-plane design
providing a very low impedance return
path and superior shielding for added
immunity from noise. Each unit also
includes on-board voltage regulation
circuitry. These regulators can be
bypassed if using a power supply with a
more elaborate regulation scheme.
The kit includes all components
necessary for proper operation and all
components are individually packaged in
plastic bags and marked with their
reference designators. A few
options are available and these
include: with or without the
on-board voltage regulators, kit or
assembled, plus an upgrade option to
the low noise Linear Technology voltage
regulators (LT is phasing out these
parts so this option will be available
while supplies last).
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