Jeff Rowland Coherence One Preamplifier

 Rowland Research is pleaesd to introduce a preamplifier which combines technical innovation with unmatched beauty and ergonomics. Advances in field effect transistor technology and research into low-level signal recognition and resolution have positioned the Coherence One preamplifier as a standard by which other units will be compared.

The Coherence One is powered by a companion power supply which eliminates the possibility of hum field contamination  in the low level circuitry. In addition, extra care was spent on overall power supply design due to the understanding that an audio amplifier is simply a modulated power supply.

 Features

No negative feedback in all circuit location

Direct coupled design from input to output

Accepts both moving coil or moving magnet cartridge inputs

Optional strain-gauge cartridge inputs available

Passive RIAA Equalization

All signal switching accomplished with mil, spec, hermetically sealed, gold contact relays.

Continuously adjustable loading for moving coil cartridges

All FET in voltage amplification stages

Precision stepped attenuator for volume control

Muted outputs during power outages.

 An amplification system must recognize and respond to all information presented to it. The composite of this information, with all its subtleties and nuances, can be defined as Musical Truth. Once recognized, this truth must be absolutely maintained during the amplification process.

Recognition of Musical Truth has been a shortcoming of most, if not all, amplification systems. While few designers recognize and rigorously pursue the ideal, even fewer approach the realization. Amplifying incompleteness will always be unsatisfying to the music lover.

Maintenance of Musical Truth during the amplification process has often led to novel and ingenious design methods that produce spectacular specifications yet miss the ideal altogether. Although technical measurements have their place, the experienced ear must be the final arbiter of Musical truth

 Rowland Research has made a commitment to the ideal. This dedication is combined with an intimate knowledge of electronic principles and components and a thorough understanding of past and present techniques and accomplishments.

Specifications

Phono Section

RIAA Deviation:  20 Hz - 20 kHz ±0,15 dB

Input Impedance:  0 to 100 Ω, user adj. 47 k Ω for MM

Equiv. Input Noise:  less that 1 nanovolt per square root Hz

Gain:  40 dB MM at 1 kHz, 60 dB MC at 1 kHz

Line Section

Frequency Response:  0,2 Hz to 500 kHz -3 dB

Input Impedance:  10 k Ω

Output Impedance:  100 Ω

Gain:  20 dB

Distortion:  less that 0,05% THD or IM below rated output

Signal-to-Noise ratio:  greater than 92 dB A reffered to rated output

Rated Output:  5 volts RMS

Power Supply

Transformer:  30 VA encapsulated torodial

Capacity:  10,000 microfarads total

Voltage:  ±48 volts DC

Output Noise:  less than 100 microvolts

Dimensions (W x H x D):  483 x 318 x 95 mm (19" x 12,5" x 3,75")

Weight:  13 kg (29 lbs)