An Unforgetable Front Stage Audition
An analysis on the electron tube front stage amplifier

A front stage amplifier is the core of a stereo system and a dispensible component of an advanced one. It has a great influence on the quality of sound reproduction, especially on the improvement of the quality of bass and dynamics. However, as there will be possible dyeing and nonmusical properties added into the music being played, high demands are imposed on the circuit design, producing craft and components selection of a front stage amplifie. Hence the high price of a high quality front stage amplifier. Nevertheless, for some front stage amplifier, the price does not indicate its sound reproducing performance. Therefore, it takes effort to buy an authentic high-performance front stage at a reasonable price,which is the constant pursuit of many high demanding stereo enthusiasts.
The common defect for a front stage amplifier is that although it could present various musical details, the descant is overbrilliant, the alts a bit too acuate and stiff. After a long time listening, you¡¯ll easily get tired. In another case, although the musical sensation is rich, the details are vague, lacking in transparency, and the sound field indistinct. There are two types of front stage amplifier namely, electron tube and transistor front stage amplifiers. Most higher performance front stage amplifiers adopt electron tube for amplifying. As the laser phonographs are now commonly adopted as signal source, the electrical level output is relatively high, therefore low magnitude ratio(5 to 10 times) is enough for the front stage amplifier. Music Space Time integrated electron tube amplifier has gained wide recognition with its fine appearance and craft and excellent sound quality. After several modifications, the same model has improved considerably in terms of analytic ability, vitality, controlling force. It has distinguished itself in domestic power amplifiers, yet its model name and price remain as the same, from which we.could see the company¡¯s earnest pursuit for product perfection. That in turn brings blessing for all the enthusiasts for electron tube amplifiers. To meet the demand of stereo fans for high-level music, this time Music Space Time has specially developped MUSICIAN-P1MK electron tube front stage amplifier.
With a simple yet elegant appearance, MUSICIAN-P1MK electron tube front stage amplifier has a solid machine case and a concise and rigid circuit. The machine consists of a pentode converted through triode connection as a common cathode amplifier and a 1/2 double triode cathode follower. Adopting direct output coupled mode, it has a wide frequency response and good phase characteristics. As loop negative feedback is parellel feedback, which will not incur common mode error, it is able to present exquisite and open music with good dynamics and little distortion. The output impedace from the cathode follower is as low as 500¦¸£¬which enhances the loading ability and the adaptive ability for back stage power amplifier while reduces the influence of outside electromagnet field at the same time. Mains voltage high and low alike are supplied by a voltage regulator circuit.
The main features of MUSICIAN-P1MK electron tube front stage amplifier are as follows:
1. optimal selection of components, such as imported high-quality volume potentiometer MOBLE, DALE resistance, high-speed electrolytic capacitors like nichicon, jrmicon,KMG, specially designed import coupling capacitor, double C mode and double screen power transformer reeled with special craft, all of which are decided upon through repeated selection.
2. Based on actual effect, manually developped print circuit is a 70um thickened gilded copper foil double sided one, which diminishes the infuence of copper foil on properties to a maximal extent. Power and amplifier are seperated independently.
3. EMI/RFI wave filters and phase selection are set with the power incoming line, avoiding various interferences as a result of electrified wire netting introduction while getting users to the correct phase conveniently and swiftly. High voltage power is supplied by a high-speed electron tube voltage regulator circuit, low voltage power a three terminal integration voltage regulator circuit, which not only assures the machine of stable performance but also improves the SNR.
4. Solid machine case and specially crafted undercarriage put the mechanical resonance under effective control, providing stable working circumstances. Both power transformer and choke are installed with antirattlers to reduce the mechanical noise. The antirattler on the amplification circuit is able to prevent rheomicrophone effect.
5. The interior of a complete machine is composed of two seperated sections of power supply and amplification with a full screening in between, which eliminating mutual electromagnet interferences, well comparable with seperated power supply.
6. Full screening is applied to the input signal groupware and a radio frequency filtering circuit is set at the signal input terminal to prevent radio interference. Anti hum loop measure has been taken as an independent earth wire is laid to prevent noise from grounding.
To test the sound performance of MUSICIAN-P1MK electron tube front amplifier, we¡¯ve organized several auditions with audience of different ages and appreciation habits. Matching several types of floor sound box and the transistor back stage amplifier, we¡¯ve conducted auditions of various pieces of music over and over again. Generally speaking, the sound is balanced and realistic, gentle and elegant, soft and stretching. Also it is transparent and open, lively and fresh with good extention and control force, properly delicate with rich details. Having wide sound field, appropriate imaging plus adequate dynamics and strength, the sound is of excellent sense of reality, comfortably pleasing to the ears. Due to its powerful musical expressive ability, the machine is quite suitable for reproducing various musical genres and human voice, of which its performance is outstanding.
MUSICIAN-P1MK is a low gain front stage amplifier, particularly suitable for an audio system with laser phonograph as its main signal source. Complete with back stage power amplifier and sound boxes of fair quality, you will get unbelievable musical reproductive effect at such a reasonable price. Besides, the higher quality the back stage power amplifier and the sound boxes have, the better the potential of the machine will come into exertion. Perhaps, you first feeling upon audition is unforgetable and its performance- price ratio is another real surprise! It is indeed worth of recommendation.
MUSICIAN-P1MK electron tube front stage amplifier is considerately designed for use and operation in that the phase indicator at the back panel of the machine case could help users get the accurate power phase with convenience and dual output links also promotes convenience for the dual power amplifier drive.

Main technical parameters:
Input sensitivity/input impedance: 200MV/ 70K¦¸
Output electrical level/output impedance: 1VRMS/ 500¦¸ maxium value:15VRMS
Total harmonic wave distortion coefficient: £¼0.1%
Frequency response: 16Hz-25000Hz¡À0dB
Size: 430¡Á100¡Á340mm
Weight: 13kg

Extracted from¡¶Hi-Fi Audio¡·Hongkong 2005.11 author: Tang Daoji