Full Product Overview & Specification
The Fusion HB70i is designed to offer exceptional realism
in a Hi-Fi system without having to use vacuum tubes in
the output power stage.
Combining modern features with classic analogue design
principles the HB70i achieves remarkable results by featuring
our own proprietary circuit design called T-ODE-FET. This is
essentially a hybrid design, combining Mosfets with a vacuum
tube input stage in a novel circuit configuration, allowing
the unit to offer good output power levels in a compact space
saving contemporary design. Our experience in designing tube
amplifiers has enabled us to offer similar levels of performance
usually only found in our pure tube designs. This amplifier
design is not a compromise but an exciting breakthrough
in what can be achieved by combining technologies.
The unique T-ODE-FET circuit developed at TT is different to
many other hybrid amplifiers which have recently entered the
Hi-Fi market-place. The overall circuit topology features
a single rail power supply for the output stage whilst the
double triode input stage remains part of the whole feedback
loop, emphasizing the sonic character of introducing a tube.
This also ensures a very natural musical character and
minimises odd order harmonic distortion components.
The separate class A preamplifier circuit utilizes a
high voltage FET with low impedance output. Output from
the preamplifier is directly connected to the input of the
amplifier through a hard wired high quality interconnect
cable. All inputs are switched through high grade audio
relays and minimum track routing for all signal paths.
The highest-grade milspec 6922 vacuum tube is used in
the front end input stage of the amplifier which is powered
from a dedicated supply including a constant current
source, minimising tube drift over time.
The output devices were selected after exhaustive listening
tests to many types of Mosfets. The final devices selected
offer high current transfer and excellent audio characteristics.
The response curve is very similar to a power triode. A very
stiff power supply has been designed to give the amplifier
very controlled detailed performance whilst delivering full
power over an increased audio spectrum of 5Hz to 65 kHz.
Careful attention has been taken to ensure that all the 'lifestyle'
features such as full microprocessor control featuring the easy
to use rotary encoder volume control, remote functions and
vacuum fluorescent display does not detract from the HB70i
being a high-end audiophile component. The volume control
features our own custom designed solution which enables
the use of a traditional high quality potentiometer with
an optical disc recognition system, all power supplies for
the VFD (Vacuum Fluorescent Display) and remote functions
operate on a separate floating power supply, therefore not
interfering with any of the audio circuitry.
As part of the Fusion range the HB70i is housed in the same
family case work, maintaining a high standard of build
Sonically the Fusion HB70i is a very clean and open sounding
amplifier. Excellent bass drive and detail together with a full
tangible mid-band, an area that tube amplifiers excel in and
its solid-state counterparts struggle with. In it's price range
the Fusion HB70i offers an unbeatable introduction into the
world of audiophile amplifier performance at a fraction of
The Fusion HB70i comes complete with full remote control
facilities offering six inputs and 70 Watts per channel.