Pure Sound
A30 Line Integrated Amplifier
£1199
The pure sound A30 amplifier was developed to meet the
demand for an affordable Class A amplifier that would be
compatible with all types of loudspeakers. The A30 is
a line level integrated design that allows for the
selection of up to 3 different source components and
control of the volume by a high quality ALPS Blue Velvet
potentiometer. Class A operation was chosen because
it gives lower distortion and a more relaxing, natural
sound.
The amplifier uses the very robust Electro Harmonix 6550
output valves in an Ultra Linear Push Pull
configuration. This arrangement gives a combination
of power and clarity that is difficult to beat. The
amplifier uses an Auto Bias system, which means that
replacement output valves should be fitted as matched
pairs. There will be no need to reset or monitor bias
conditions.
Very high quality components are used throughout including
selected carbon film resistors and SCR polypropylene
capacitors. The power supply makes use of twin valve
rectifiers and choke smoothing.
The output can be configured for use with 4 or 8 ohm
loudspeakers.
The output stage can also be switched to triode-coupled
configuration. This further linearises the operation
of the valves at the expense of some output power. It
may be preferable with higher sensitivity loudspeakers.
The A30 may also be used as a very high quality stereo
power amplifier if the volume control is turned up fully.
When partnered with appropriate ancillary equipment the A30
is capable of very satisfying performance.
Why this amplifier? Why now?
With the recent interest in lower powered Single Ended
triode amplifiers has come the realization that to get the
best from these, the speakers used have to be both
sensitive and quite large to give truly satisfying results.
There are also not that many good, high sensitivity (>97
dB/W) designs available at any price never mind at price
levels the majority of music lovers can afford.
However, there are some very good loudspeakers currently
being made with sensitivities between 88 and 94 dB/W. These
are sufficiently revealing to make the virtues of simple,
high quality amplification readily apparent, although in
most cases the output of a typical single ended amplifier
is insufficient to give the scale and drama many types of
music demand.
A good amplifier with 25 -30 watts of output power is more
than enough to drive this type of loudspeaker to sensible
levels even in quite a large room. For simplicity a valve
amplifier is preferable. Recently, there has been an
increase in the number of relatively affordable valve
amplifiers made in China. Many of these are compromised by
the quality of their transformers, components, layout and
because they operate in Class AB or B to give a higher
power specification. They often also use a lot of negative
feedback in an attempt to compensate for these shortcomings
with a consequential impact on clarity and low frequency
control.
For some 10 years there has been a lack of affordable Class
A valve amplifiers.
The pure sound A30 operates fully in Class A up to its
rated output so it does not change character at any signal
level. There is none of the distortion caused by output
devices switching on and off and therefore no requirement
for excessive feedback to correct for it. The 6550 valves
supplied are the extremely robust Russian Electro-Harmonix
variety and are quite content with dissipating the power
required to maintain Class A operation up to 30 Watts.
The valve rectifiers used keep the high voltage power
supply clear of the noise that can be introduced by silicon
rectifiers. A substantial choke is also incorporated to
keep the power supply impedance low.
The output transformers also give extremely wide bandwidth
allowing very solid low frequency performance as well as
exceptional reproduction of timbre.
These design features combined with the use of high quality
passive components, octal based input and driver triodes
and an elegant but simple internal layout results in an
amplifier which sets a new benchmark for performance, build
quality and value.
Features
- Class A operation
- 3 Line level inputs
- 30 Watts per Channel Output
- 4 and 8 ohm output taps
- Twin valve rectifiers
- Choke smoothing
- ALPS potentiometer
- SCR coupling capacitors
- Carbon film resistors (for better sound quality)
- ElectroHarmonix (Russia) 6550 output tubes
- Very substantial construction including cast metal transformer shrouds.
2A3 Line Integrated Amplifier £1799
The earliest audio amplifiers made use of small, 3 element valves known as directly heated triodes. For many, the simple circuits that can be built around such devices better preserve the structure, colour and feeling within the music than any other circuit topology. One of the best sounding triodes, the 2A3, is in production again and its characteristic linearity has been employed in a novel configuration to create a particularly charming amplifier. The Pure Sound 2A3 is an 18 Watt per channel line level integrated design that allows for the selection of up to 3 different source components and control of the volume by a high quality ALPS Blue Velvet potentiometer.
There are many amplifiers now making use of directly heated triodes but few which adequately address the particularly awkward issues involved in driving these devices properly. The Pure Sound 2A3 amplifier features an unusual choke loaded driver stage which allows the 6SN7 driver valves to deliver the full measure of signal to the push/pull output valves. This rather exotic configuration usually results in a tremendous depth to the tone of instruments and the Pure Sound 2A3 is no exception in this regard.
Very high quality components are used throughout including selected carbon film resistors and SCR polypropylene capacitors. The power supply makes use of twin valve rectifiers and choke smoothing.
The output can be configured for use with 4 or 8 ohm loudspeakers.
The Pure Sound 2A3 may also be used as a very high quality stereo power amplifier if the volume control is turned up fully.
P10
phono amplifier
£449
The P10 phono amplifier is the latest addition to the
highly acclaimed Pure Sound product range. It is intended
to meet the requirements of audio enthusiasts who still
enjoy the distinctive strengths and high quality of
reproduction that can be derived from vinyl records.
It is compatible with moving magnet and high output moving
coil cartridges. Low output moving coil cartridges
will require the use of an additional step-up device or
matching transformer. Full output from the P10 is
sufficient to drive the line level inputs of any integrated
amplifier or pre-amplifier.
The active amplification stages use double triodes in a
simple anode follower configuration. The phono equalisation
is achieved using passive components and can therefore
maintain its accuracy over time without introducing the
unacceptable levels of phase shift found in active
equalisation stages. There is no negative feedback in the
circuit.
The P10 features a particularly elaborate HT power
supply. After the initial rectification and
smoothing, the supply is split and two separate, heavily
decoupled high voltage rails are established. These feed
each half of the output valve while further decoupling of
each rail allows the cleanest and most independent voltage
rails possible to feed each half of the input valve.
The absolute stability of this supply regardless of the
demands made by the audio signal on the circuit, lends the
P10 a stability and poise which allows effortless
reproduction of the most demanding source material.
The valve filaments are also fed by a DC supply thereby
ensuring constant operating conditions for the amplifier.
The circuit makes use of close tolerance metal film
resistors, polypropylene signal coupling capacitors and
selected valves.
The gain of the P10 is 40 dB (x 100).
The P10 phono amplifier meets the very strict performance
criteria required of all Pure Sound products and will give
excellent results with vinyl records provided that it is
used with appropriate ancillary equipment.
