5
1. INTRODUCTION
1.2 DESCRIPTION OF THE JUBILEE PREAMPLIFIER
Circuit design
OCTAVE has designed its reference amplifier – the Jubilee preamp – as a
two-stage hybrid amplifier
.
Tube circuitry manages the high precision
balanced stage
and amplifies the signal. The
high output
current
requirements are satisfied by an output impedance converter implemented with semiconduc-
tors. The unique combination of tubes and transistors allows the Jubilee to do without overall negative
feedback and thus deliver the undeniable sonic benefits of a
zero feedback design.
However, any
amplifier that dispenses with negative feedback also dispenses with the corrective mechanism pro-
vided by negative feedback circuitry. In the Jubilee preamplifier, we solve this problem through the
extremely high specification of the output stages and power supply section, creating virtually perfect
conditions for achieving
perfectly accurate amplification
– without the need for corrective mechanisms.
Whether the source equipment is connected via the RCA / CINCH phono or XLR inputs, the Jubilee
tube preamp always produces a
perfectly balanced output signal
and delivers an optimum sonic per-
formance independent of the source type. The XLR inputs are fitted with step-up transformers that
have no sonic signature of their own. Because they introduce no noise or phase shifts, step-up trans-
formers are the technology of choice for this application in professional recording studios. In addition,
they also perform the function of a ground lift circuit, eliminating the risk of interference and hum, which
is particularly critical when it comes to complex multi-amp combinations connected via balanced inputs.
The
low impedance output
is yet another feature designed to enhance the sound quality and versatility
of the Jubilee preamplifier Only a semiconductor-based output stage is able to cope with long cable
runs and integrate perfectly with low impedance power amplifiers It would be impossible to implement
such an uncritical output using tubes alone without sacrificing accuracy in the low bass and extreme
high frequencies.
Outboard power supply
The outboard power supply, which was developed exclusively for the Jubilee preamplifier, substantially
enhances the sound quality of the preamp by separating the preamplifier from the mains (simulated
battery operation). The
separate power supply
stops mains noise from entering the preamp's signal
processing circuitry. It also provides highly accurate and stable electronic voltage regulation, which is
one of the ways we ensure this product's consistent performance over time.
Power management system
The Jubilee's sophisticated power management system guarantees a long and reliable life and incor-
porates highly refined soft-start technologies that help the tubes achieve their theoretical maximum
service life of up to 10,000 hours.
Build quality
The volume control with its precision ball bearings is centrally placed within a polished Labrador natural
stone slab, flanked by two, three-centimeter thick, solid aluminum panels. The extremely stable, low
resonance, all-aluminum casing eliminates any possibility of magnetic distortion. Before leaving the fac-
tory, each hand-built Jubilee preamplifier is thoroughly inspected and subjected to a 48- hour endurance
test
