Analogue / Phono Stages / Step-Up Transformers

DESCRIPTION

The Ios is a reference level four stage, entirely symmetrical phono preamplifier. Rega designed the Ios to offer a superior performance without compromise, dedicated to amplifying the very low-level signals that are generated by quality moving coil cartridge models. The Ios is an excellent match with the Apheta 2 MC cartridge from Rega, and has been visually designed to match the aesthetic of the Isis and Osiris flagship components.

Regarding the four symmetrical amplification stages: The first stage uses a to- quality step-up transformer: the SOWTER 8055 (report 1:10). The second comprises discrete components only, using paralleled low noise Hitachi transistors in the input stage. This drives the passive high frequency part of the RIAA equalisation stage. The third stage is also fully symmetrical and is a class A differential amplifier. This is also used as the active amplifier in the low frequency part of the RIAA equalisation stage. The fourth stage is a low noise operational amplifier with a very high bandwidth. The power supply is a symmetrical discrete tracking power supply using fast diodes and a low noise voltage reference. Each stage has its own localised power supply, and LED referenced current generators.

Very high quality, polypropylene capacitors have been used in the signal path. 1% tolerance polypropylene capacitors are used in the RIAA EQ stages and audio grade capacitors are used in the rest of the circuit. The entire unit has been fully rewired with ultra-low capacitance cabling. 

A phono stage with immense dynamics, a deep soundstage, a controlled and tight bass and a strikingly quiet, noise-free background.

Remarks: With aesthetic issues such as scratches and dents. Please ask for pictures.

Specifications: Input sensitivity for 200mV output: 61uV – 70dB gain setting I. 118uV – 64dB gain setting II. Gain input to output: 64dB Minimum and 70dB Maximum. Input load: 50, 100, 150, 300 & 400Ω. DC resistance (Zobel network): 5 to 7.5Ω (6.25Ω nominal), 7.5 to 10 Ω (8.75Ω nominal), 10 to 12.5Ω (11.25 Ω nominal), 12.5 to 15 Ω (13.5Ω nominal). MC Transformer: Sowter 8055. Input overload @ 1KHz: 8.7mV – 64dB gain setting and 4.5mV – 70dB gain setting. Maximum output level: 14.7V RMS. Rated output level: 200mV. Output resistance: 100Ω. Minimum output load resistance: 1KΩ for –3dB point @ 15Hz. RIAA accuracy (Better than): 0.2dB. Frequency Response: 14Hz (-3dB) to 54KHz (-0.5dB). THD (Better than): 0.008% @ 1.5V 20Hz 20KHz. THD bandwidth: 100Hz to 22KHz. Output noise level: -85dBV (64dB gain setting & 15Ω input load). Notch Filter centre frequency: 8.5KHz. Notch Filter maximum depth: -6.5dB. Notch Filter Q: 2.5.(2) Inputs: 1 x balanced (XLR) and 1 x unbalanced (RCA). 1 x unbalanced output (RCA).

SITE: https://www.rega.co.uk/

SERIAL NUMBER: 00085