DESIGNED AND HAND CRAFTED BY MR LABS

BASED ON SWISS PRECISION ENGINEERING

VERA 10 Phono Preamplifier - Product Details

The VERA 10 is a three stage design, comprising

  • Active Input Stage
  • Passive Equalization Network
  • Amplifier Stage

The active input stage is designed as a floating balanced complementary current amplifier/voltage converter. In this design, a current flowing between the positive and the negative input terminal is amplified and converted into an proportional output voltage. Specifically, a current in the region of 20µA to 60µA@1khz, as it is typically supplied by a moving coil cartridge connected to the input terminals of the input stage, results in a voltage at the output of the input stage of typically 60 to 180mV@1khz.

Following the input stage, a passive frequency equalization network is provided, yielding the three time constants 3180µs, 318µs and 75µs as required for proper equalization of the RIAA recording curve. It is understood that only the highest quality components are used for this passive network, particularly WIMA film-foil polypropylene capacitors and Vishay CMF precision metal film resistors with excellent high frequency characteristics, exceptionally low noise and low temperature coefficient. Each set of capacitors and resistors of each channel of the VERA 10 phono preamplifier is individually matched to ensure that the specified accuracy of RIAA equalization is met or exceeded.

The equalized signal is fed to the input of the amplifier stage. It has the topology of a discrete fully complementary operational amplifier operated in pure class A, having an open loop gain of around 70db, a unity gain frequency response of >1MHz and an output impedance of <2Ω. The closed loop gain of this stage is user-selectable in five steps. Due to the use of highest grade components and careful manual matching of parts, the behavior of this stage comes very close to an ideal operational amplifier.