Features
| Brand | Mobile Fidelity |
|---|
Tech Specs
- Inputs (MM/MC): Voltage or current
- RIAA Accuracy: ±0.05db
- Frequency Response: 10Hz–50KHz ±0.20db
- Gain: 40db, 50db, 60db and 70db
- Cartridge loading: Ten choices plus custom
- S/N Ratio (A-weighted):
- 93dB for MM
- 85dB for MC
- Remote; input selection, gain adjustment, mute, mono operation, meter operation and subsonic filter.
- Dimensions (wxhxd): 17×3.5×15.75”/43.2×8.9x40cm
- Weight: 15lbs./6.8Kg.
Product Description
The Mobile Fidelity MasterPhono phono stage is a top-of-the-line phono stage with many adjustments. It has four gain settings as well as ten impedance settings. This enables virtually any type of cartridge to be matched precisely. The preamp has a dual mono configuration using discreet FET input and output stages. The circuit is balanced, DC coupled, and has a wide bandwidth. Moreover, the RIAA equalization is passive. Unusually there are current mode and voltage mode inputs to better match low-impedance cartridges. There is good connectivity with both balanced and RCA connectors available as inputs and outputs. Finally, a remote control is supplied.
Discrete FET amplifier
The Mobile Fidelity MasterPhono phono stage uses FET transistors for both the input and output. FETS are voltage-controlled devices, like a valve, and inherently have a high input impedance. The dual mono design also enables the preamp to use balanced XLR inputs. Balanced amplifiers have lower noise, especially with long cable runs or low signal levels, such as that obtained from a moving coil cartridge. Additionally, moving magnet cartridges have a fairly consistent impedance of 47K ohms and an output of around 5 mV. However, moving coil cartridge impedance and output can vary widely. The output can be below 1mV. Hence the Mobile Fidelity MasterPhono phono stage has four gain settings and ten impedance settings.
Isolated power supply
With high-gain circuits, it is important that the power supply is well isolated to prevent noise pickup. As a result, the Mobile Fidelity MasterPhono phono amplifier has a fully galvanically isolated and well-regulated supply. In fact, each channel has its own supply. Galvanically isolated means that there is no physical connection between the power supply and amplifier circuits. Power is transferred via a transformer.
Connectivity
The Connectivity, with the Mobile Fidelity MasterPhono phono stage, is remarkable with individual inputs for both voltage and current-driven sources. There are also custom-loading RCA inputs. Each input also has balanced XLR sockets. Additionally, The outputs can use either RCA or XLR connectors. Lastly, two VU meters are present on the front panel. These indicate the signal level as well as assisting with cartridge setup. There is also a subsonic filter and a mono switch.
What are current and voltage mode inputs?
Amplifier devices such as transistors can be either voltage or current-operated. Bipolar transistors are current operated. In that a change in input current results in a change in the output voltage. These are usually low-impedance amplifiers that put a relatively high load on the connected device. Such as a phono cartridge. Moving Coil cartridges only have a tiny output voltage and this would be lost with a low impedance input. However, devices such as FETS and valves are voltage operated and have a high input impedance. They are more suitable where the input voltage is less than 1 mV. Hence the Mobile Fidelity MasterPhono phono stage has both types of input for different cartridge types.
