OceanAudio Signature Three Owner's Manual - Product Description
Signature Three - Owner’s Manual - Revision 1 - page 4
Product Description
The
Signature Three equaliser consists of two identical channels of discrete transistor - inductor based
equalisation. Silicon transistors as opposed to integrated circuits (op-amps) provide a much simpler
dedicated signal path, thereby providing a much cleaner signal path. Silicon transistors can also be run
at much higher voltages than integrated circuits which vastly increases the headroom capability.
Inductor based circuits are the ‘holy grail’ of equaliser designs. These were used for example in the
much favoured Pultec equaliser design, which dates back to the late 1950‘s. Owing to their unique
electro-mechanical properties, inductors impart a character all their own which is very distinctive.
Because of their cost and large size, inductors are rarely used in the low frequency ranges of other
currently available equalisers . Often the extreme low and high ranges utilise non inductive ‘shelving’
circuits that do not give the precise control provided by inductors.
The
Signature Three uses inductors in each of the four sections (bands) giving precise control and the
distinctive inductor sound on each range.
Each range provides switch selection of any of six carefully selected frequencies chosen at musically
pleasing intervals. Each range is also provided with a continuously variable cut and boost control
allowing a maximum of plus or minus 15 dB. A centre detent offers instant return to the ‘neutral’ position.
An illuminated in/out switch makes it possible to compare the treated and untreated signal.
As mentioned above, the Signature Three uses inductors in each of the four sections and as a
consequence provides a ‘peaking’ characteristic. This provides much tighter control of the frequency
selected and the inductor values and components have been carefully chosen and matched to provide
an extremely musical sound. One example of this is the Signature Three’s ability to enhance bass
frequency signals without introducing the unwanted 'boom' so often found in many modern equaliser
designs.
A feature of the design made possible by the use of individual transistors is the ability to handle high
signal levels with very low distortion. The
Signature Three
is capable of providing output signal levels in
excess of +28dBm which could quite easily overload the equipment that is connected to the output. To
provide a visual indication when the output signal is approaching a level that could cause problems, a
large LED illuminates when the signal at the output exceeds +15dBm.
Because the
Signature Three only uses individual silicon transistors, the noise and frequency response
of the unit is to a very high specification. With the equaliser section bypassed, the noise in the bandwidth
20Hz to 20kHz is below –85dBm. With the equaliser in circuit and all boost/cut controls in their centre
position, the noise in the bandwidth 20Hz to 20kHz is below –80dBm.
The precision components used in the design and manufacture of the unit guarantee close matching
between the two channels. This means that
The Signature Three can be used as a mastering device
when accuracy between the two channels is extremely important.
When the equaliser is switched out of circuit (‘IN’ button depressed), the equaliser circuitry is completely
bypassed thereby ensuring the best possible signal to noise ratio and a minimum of electronic circuitry in
the signal path.
The
Signature Three combines the very best of classic equaliser design with modern day technology and
components.