A10 Line Integrated Amplifier
The A10 is a new, small line integrated amplifier from puresound. Operating
in Class A and delivering 10 Watts per channel it is intended for users of high sensitivity loudspeakers or for
those seeking high performance with small speakers perhaps in a bedroom or study. The A10 accepts two line level inputs
and may be switched to drive 4 or 8 ohm loudspeakers. The circuit is based around the sweet sounding 6P14 a modern equivalent
to the EL84/6BQ5 family.
The A10 has earned Best Buy awards
in the UK and Russia and has just won a 'Golden Ear' award for best amplifier in Germany's 'Audio'
A30 Line Integrated Amplifier
The puresound 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,
NB. The factory
that makes the A30 also makes a 60 Watt Class B amplifier with different output transformers, a different mains transformer,
reduced bias current, a different feedback circuit and several different types of component. All puresound
products are specifically made to suit our particular requirements.
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 puresound 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.
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.
Class A operation
3 Line level inputs
Watts per Channel Output
4 and 8 ohm output taps
Twin valve rectifiers
Carbon film resistors (for better sound
ElectroHarmonix (Russia) 6550 output tubesVery
substantial construction including cast metal transformer shrouds.
2A3 Line Integrated Amplifier
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 puresound
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 puresound 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 puresound 2A3 is no exception in this regard.
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.
output can be configured for use with 4 or 8 ohm loudspeakers.
The puresound 2A3
may also be used as a very high quality stereo power amplifier if the volume control is turned up fully.