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The Reference Preamplifier is the culmination of over two years' research and development. Our goal has been to produce a preamplifier which not only sounds excellent, but is also inherently reliable. Early on in the research we found that simple designs sound best. They have an immediate and natural quality; in short, more like listening to real music and less like listening to electronics. Simple designs have other benefits. Since there are fewer components, we have been able to select the very best available - many of which have not previously been used outside military and aerospace application. Top quality components not only sound better, but since they are manufactured to a higher standard, offer far better long term stability and reliability. In many cases, the components are manufactured exclusively for Matisse to our specification. If you would like to find out more about the Matisse design, read the Technical Discussion. But what really counts is how it sounds - and for that, all you need to do is connect it to your system!
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| GAIN CONTROLS | The preamplifier features twin precision attenuators, one for each
channel. They Comprise multi-way switches together with a resistor
network. The switches are designed to have a positive detent which
allows you to easily “dial in” the same number of clicks for each channel.
The “feel” of these switches is quite different from the more usual potentiometer. (in fact the click stops on conventional volume controls are meant to emulate the feel of the switched attenuators!) The switches give 26 Positions, and used in conjunction with the gain selector on the mute switch provide 52 different gain settings. Separate Left and Right channel controls are employed to ensure the greatest Possible channel separation.
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| TECHNICAL
DISCUSSION |
When we started the development program, we built a number of development
prototypes. To our surprise, the differences between the various
circuits were far less than the differences between different grades of
components used in their construction.
The simpler the circuit, the more we were able to hear improvements arising from build quality. We therefore decided to adopt the simplest circuit which met our technical aims, and to concentrate our research effort on component quality. Instead of technical innovation for its own sake, we have adopted well-proven "building blocks". some of which are over 20 years' old! The preamplifier uses components which are unprecedented in audio construction, being more in keeping with military or instrumentation grade construction.
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| VACUUM TUBES | Our search for simplicity led us to the vacuum tube (or thermionic
valve). The tube is inherently more linear than solid state devices,
and it is possible to build high gain circuits with as few as four tubes
- as we have done.
With correct voltage management, the operating life of the tubes is very long. Our first prototype is still within specification on the original set of tubes after 3 years continuous operation! The preamplifier uses selected high-grade tubes, type ECC83 and 12AT7WA. Replacements are easily obtainable, and a supply is assured into the forseeable future. We have spent many hours listening to different brands of tubes. Each brand tends to have its own sonic "signature". We have selected tubes which offer the best overall balance and the minimum signature of their own when used in the Matisse circuit. Substituting different brands of tubes will significantly affect the sound of the preamplifier.
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| THE AUDIO BOARD | We use construction methods which ensure that the signal suffers least
degradation.
Our custom audio board comprises a double sided ground plane, which helps to minimise radio frequency interference (RFI) and also minimises stray capacitance effects. Cadmium-loaded solder is used throughout. (This is more conductive than silver solder.)
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| VALVE HOLDERS | The tubes are all mounted in ceramic holders with gold plated contacts. These are far more stable than the more usual moulded Plastic types, and offer the best possible electrical contact with the tubes. | |
| RESISTORS | The preamplifier uses non-inductive wire-wound resistors in all the
audio stages. These are much more satisfactory than the more usual
metal film types, albeit at a price.
(These components cost twenty times more than an equivalent "audiophile" resistor.) They have virtually no thermal noise (an important consideration in
tube circuits) and they are completely stable over time. Not only
is the amplifier quiet, but the resistors maintain their precise value
over the entire life span of the equipment.
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| CAPACITORS | The coupling capacitors in tube circuits can have a major effect on
sound quality. After evaluating the available “audiophile” components,
we selected a capacitor designed for high frequency pulse operation.
Sonically. it is extremely neutral, uncoloured and does not restrict the dynamics of the preamplifier.
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| MOVING COIL
TRANSFORMERS |
The preamplifieris unusual in that it uses on-board transformers to
provide the initial gain necessary for low-output moving coil cartridges.
Active MC stages are certainly cheaper to make than transformers. But transformers are inherently noise-free. so they do not "mask" the output from the cartridge. Our transformers have a flat frequency response up to 100KHz together with a completely accurate phase response. The transformer can be switched out for high output MC or MM cartridges, with an internal switch. It has become fashionable in some quarters to run MC cartridges into MM inputs. We do not subscribe to this view. It leads to a reduction of dynamics, and could only be justified with an inadequate MC stage! The impedance and gain of the transformer has been selected to suit the vast majority of high-quality cartridges. However, some cartridges, such as the Audionote range and certain Ortophon models have an unusually low output. In these instances, you should defeat the internal transformer and use an external step-up designed specifically for your cartridge. If in doubt, consult your dealer.
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| GAIN CONTROL | After experimenting with conventional volume and balance potentiometers,
we found that they significantly degraded the sound quality.
For a solution, we turned to a proper switched attenuator as used in instrumentation. (The "click stops" found on many volume controls are intended to mimic the operation of the switch!). Instead of a potentiometer built from conductive plastic or similar resistive material, the switched attenuator uses a high quality switch. to select combinations of discrete resistors. This allows precision matching of the channels, maintained even at low levels. Switched attenuators have been used before, but they have more commonly the series-attenuator type, which is simpler to build, but as the disadvantage that all the resistors are in the signal path, along with all the solder joints The step-ladder attenuators used in your preamplifier are more complex to build, but have only two resistors in circuit at any time. The Matisse attenuator is a 26-position switch with hard gold contacts with precision resistors used throughout. We feel that the performance more than justifies the extra effort required to build them.
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| INTERNAL CABLING | The internal cable used in the preamplifier is made specially for Matisse
and comprises a high purity silver-clad coper conductor with p.t.f.e. insulation.
It is derived from cable used in aerospace applications.
Incidentally, this cable is also available (and recommended!) as an inter-connecting cable.
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| DE-COUPLING | The entire audio board is mechanically de-coupled from the chassis
to minimise the danger of damaging the tubes in transit.
Nevertheless, you should always disconnect the amplifier from the mains and allow the tubes to cool fully before moving the preamplifier.
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| POWER SUPPLY | The power supply is an integral part of the Line Stage design.
It has been built with the same attention to detail as the audio section.
Not only has the supply to provide a stable and noise free voltage to audio
sections, it must also isolate each tube to prevent the different stages
from interacting, it must have a low impedance so that the amplifier can
draw current at all operating frequencies, it must ensure that the voltages
supplied to the tubes are managed so as to maximize their life span.
We have used conventional solid-state regulators through-out for maximum reliability consistent with performance. As in the audio section, we found that high quality components significantly improved the sound of the preamplifier. The Power Supply has two modes: Standby and Operate. Mains in supplied to the PSU at all times, provided that the PSU is plugged into the mains outlets! In Standby Mode, a small small secondary transformer is in circuit. This provides 6 Volts AC to the tube heater circult, keeping the tubes at a constant temperature. This reduces the stresses on the tubes when the unit is switched on, and dramatically extends the operating life of the tubes. (The tubes glow faintly when in Standby mode.) You should leave your preamplifier connected to the mains at all times, unless you wish to move or store it. In Operate Mode, the heater AC is disconnected, and the tubes led from a seperate 12.6 Volt DC regulated supply. The high voltage supply comprises a separate regulator for each tube. The regulators for the phone section are cascaded to provide maximum inter-stage and inter-channel isolation. The PSU uses selected components throughout, using the latest generation of solid-state regulator IC’s, to produce a stable, low impedance, low noise supply. The supply is massively over-specified, so that the tubes draw only a fraction of the power available.
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| SPECIFICATIONS | HIGH LEVEL STAGE
Stage Gain:
30 dB
PHONO STAGE Stage Gain:
28 dB MM
TUBE COMPLEMENT The preamplifier uses four tubes:
The tubes supplied by Matisse are premium-grade tubes which are carefully selected for optimum performance. For emergency use, you may substitute the following tubes, which are electronically equivalent: Type: ECC83 12A7'T WA Equivalent: 12AX7WA ECC81
Although these tubes are electronically equivalent, they differ appeciably in internal construction and production methods. As a consequence, they produce quite different sonic results. Also, different brands of the same tube differ sonically! For best results use only Matisse authorized tubes!
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