Cambridge 540P

Cambridge 540P - MM phono pre-amplifier

The entry-level 540P is a high quality Moving Magnet design featuring single-ended "Class A" gain stages and a discrete transistor input stage instead of the more common integrated circuits. The 540P employs a highly accurate active RIAA equalisation system. The rear panel benefits from gold plated input connectors to minimise signal path interference and reduce surface degradation. An external 12 volt power supply comes as standard.

This unit feature the now customary Azur steel chassis and a robust anodised aluminium front plate.

Specifications

Max Power Consumption:  5 W

Gain at 1 kHz :  39 dB

Nominal Output :  300 mV

Sensitivity for Nominal Output:  3,35 mV

Total Harmonic Distortion:  less than 0,009% (20 - 20,000 Hz)

RIAA Curve Accuracy:  less than ±0,65 dB (25 -20,000 Hz)

Signal-to-Noise Ratio:  better than 85 dB (using Audio Precision RIAA-1 with grounded inputs)

Crosstalk at 20 kHz :  better than 76 dB

Dimensions (H x W x D):  46 x 215 x 133 mm (1,8" x 8,5" x 5,2")

Weight:  0,8 kg (1,8 lbs)

I like 

Luxman CX-1

Ultimate Fidelity Sound Reproduction by Means of DC Configuration

Lux's unique philosophy of ''real time proces'' is taken into account in addition to through study of conventional distortion shown by continuous signals. To avoid large capacitor harmful to tonal quality pure DC amplifier circuit is employed.

Perfect Muting Circuit

In the case of a head amp which deals with the lowest level signals, even the slightest thump noises at On/Off switching time cause a serious problem. With this unit, a muting circuit is provided that short-circuits the output by means of realy for about 10 seconds after the power is turned on or off, which completely removes this nuisance.

Necessary and Sufficient Noise Ratio

At the 30 dB position, the input-equivalent noise is -150 dB/V, input shorted, based upon IHF A-curve. Generally speaking, with a head amp whose 1st stage is composed of transistors, the S/N ratio is excellent when a low-impedance cartridge is used, but it is audibly deteriorated at the time of use of high-impedance cartridge. With this unit, FET's are employed at the 1st stage, and the S/N ratio is immune to fluctuation of impedance. At the 20 dB position the noise level is -148 dB/V.

Amplitude Selector

Most MC cartridges are classified into 2, one with an extremely mall output voltage and the other with a relatively large output voltage. To handle both types, the amplitude selector is abile to select either 20 dB or 30 dB gain. Also, the ''Bypass'' position is useful when an MM cartridge is used. needless to say, appropriate counter-measures are taken against shock noises at the time of switching.

Perfect Elimination of External Inductance Noise

The inside is shielded by quality silicon steel plate so as to minimize the noises caused by the inductance of transformer of amp or phono-motor of turntable, and also the input terminal is directly wired to the printed circuit board with the optimum earth point, which ensures virtually perfect elimination of external inductance noise.

High-Quality Power Supply Section

Ripple ingredients are suppressed by means of a ripple filter, and at the high sensitivity constant voltage power supply circuitry effective counter-measures are taken to prevent power source noises. In addiction, a decoupling circuit of large capacitance is used.

Other Features

Contact resistance increases as time goes by. To ensure ultra low contact resistance and to prevent its possible deterioration with the lapse of time, gold-plated pin-jack terminals are employed. naturally, specially selected components are used, and the best-quality metalic film resistors, precision potentiometers, and metalized film capacitors, are placed at optimum points.

Specifications

Voltage Gain:

20 dB (MC cartridges of middle output type)

30 dB (MC cartridges of low output type)

Frequency Response: 5 Hz - 500,000 Hz (-1 dB)

Total Harmonic Distortion:

no more than 0,003% (20 dB position, output 300 mV, 20 -20,000 Hz)

no more than 0,005% )30 dB position, output 300 mV, 20 - 20,000 Hz)

Input Equivalent NOise:

-150 dBV (30 dB position, iput short-circuited, RIAA, IHF-A weighted)

-148 dBV (20 dB position,input short-circuited, RIAA, IHF-A weighted)

Input Overloaded Voltage: no less than 90 dB (1 kHz); no less than 80 dB (20 kHz)

Input Impedance: 100 ohms

Output Impedance: 100 ohms

Power Consumption: 5 W

Dimensions (W x H x D): 138 x 77 x 305 mm (5-7/16'' x 12'' x 3-1/32'')

Weight: 2,7 kg (5,9 lbs) net

Graaf GM 70 Phono Preamplifier

The philosophy of GM 7O phono stage design, is the most typical for GRAAF, followed for its whole production. It regards mainly the insertion of the active elements in an environment that is able to let them express their complete potential. The same importance is given to the full exploitation of each component own characteristics, so to avoid the use of additional circuits, which could interfere on the musicality of the performance. Therefore, RF filtering is obtained by the inner characteristics of active components used, and not with the recourse to a passive network. In the same way, in order to obtain the correct input sensitivity for MC cartridges, there is not any additional gain stage. Instead, a variable gain Implement has been chosen, because it has a simpler lay out and is more transparent to music.

RIAA eq is made by a completely passive network, placed after the gain stage. Its components have been calibrated with the greatest care to maximize the response precision and the purity of the musical signal, with the help of critical listening tests as well. Power supply implements the same transformers section of GM 13.5 B II, quite huge, followed by independent filtering for gain and RIAA stage, and for output stage.

The correct electric interface between cartridge and phono stage has been carefully regarded. The knob on the back side of the unit is for the selection of six different impedance loads. Wishing to have a custom load, it is possible to use the upper RCA plugs to connect a resistance of the proper value.

The input stage is based on two pairs of PC 9OO tubes. Gain stage and output buffer stage use a pair of 6922 tubes each, chosen for their linearity, low noise and musical characteristics. The active components used by GM 7O and the whole GRAAF production are subject to a very hard selection, that guarantee the full correspondence of each unit to the reference specifications.

Built manually one by one, with components selected with the greatest care, tested by a severe burn in procedure that go on no stop for several days, each one presented to the definitive approval of the designer in person, given only after a careful listening test, GRAAF electronics have all the qualities to fulfil the most discerning of the listeners, first of all for purity of sound and luminousness of timbre.

 SPECIFICATIONS

Frequency Response:  20 Hz - 20 kHz

50 KHz Attenuation:  28 dB.

100 kHz Attenuation:  34,8 dB

Input Impedance:  38, 56, 100, 500, 1000, 4700 Ω

High Gain:  56 dB

Signal-to-Noise Ratio:  73 dB

Separation:  60 dB

Low Gain:  46 dB

Signal-to-Noise Ratio:  82 dB

Separation:  70 dB

AUDIO RESEARCH MCP-2 (1982)

AUDIO RESEARCH MCP-2

Pre-pramplifier is a stereo preamplifier designed to provide the additional gain required (with low noise) to alloe the use of low output moving coil phono pickup cartridges with existing stereo preamplifiers.
It is intended for use in the highest quality systems.

Analog Modules™ (type 3) are used to proide the voltage amplification with low noise. No efort has been made to design a unit with theoretical minium noise. Since "trade-offs" are involved in design for linearity vs. noise, primary emphasis has been placed on providing a unit with the intrinsic linearity to offer
state-of-the-art sound reproduction, while keeping noise to an acceptable and reasonable level.

Since a pre-preamplifier must amplify very small signals up to the level of the normal preamplifier's low level inputs, any instabilities or power supply weaknesses will result in significant degrading of system performance. Because of this, the MCP-2 contains a very sophisticated two-stage electronic regulation system to assure stability and power line isolation. This feature becomes especially important when using wide-band high power amplifiers at live music sound pressure levels.

SPECIFICATION

Frequency Response:  ± 25dB from 20 Hz to 20 kHz  -3dB points, 5 Hz and 100 kHz

Harmonic Distortion:  less than 0.005% at rated output, IHF load.

Intermodulation Distortion:  less than 0.005% at rated output, IHF load

Noise & Hum:  less than 50nV equivalent noise with 10 Ω input (RIAA weighted)

Gain: s witch selectable, 10, 16, 22, 28, 34 dB.

Imput Impedance:  switch selectable, 10, 30, 100 Ω and special (can be any value from 3 Ω to 1 k Ω ).

Output Impedance:  50 Ω

Maximum Inputs:  50 mV RMS

Rated Outputs:  25 V RMS

Power Requirements:  105-120/210-240 V AC,  50/60 Hz

Weight:  5.5kg (with cartoon 7.3kg)