Philosophy
A preamplifier should only attenuate the music signal but not change it in any way while meeting highest technical specifications. No distortion, no humm or noise at the same time providing best cross talk and large bandwith performance!
Layout
The unbalanced design ensures the least amount of compnents in teh signal path. Physical separation of the left and right channel provides optimal separation and cross talk performance. High quality relais switch between the inputs, the music signal gets buffered directly at the input. Therefore the preamplifier is an uncritical load for any source component.
An audio grade coupling capacitor prrtects the preamplifier as well as the subsequent amplifier and loudspeakers from potential DC components in the music signal.
Volume control
For the volume control which also controls the balance of the preamplifier, we use only high-precision, low-noise metal foil resistors. To block out switching peaks during the volume control process which may be hazardous to power amps, the 520 preamp is equipped with a second volume control with PGA (Programmable Gain Amplifier), which is only active during the volume control process.
Similar to a potentiometer, the volume can be adjusted without clicking noises. As soon as the new desired level value has been fixed, the unit will simply return to the control via the precision resistors.
Output stage
The output stage is supposed to drive also long cables lossfree. For this reason it was more than sufficiently dimensioned. The multi-stage signal amplification is similar to that of the 720 preamplifier. Thereby we achieve a very fast, ultra wideband (1MHz/-3dB) amplification.
Phono-MC-Preamplifier
Similar to the reference preamplifier 720 the phono preamp of the 520 is also based on a multi-stage amplification concept using highest grade components.
Operation
The 520 preamplifier is operated via its front-panel buttons and rotary control. Quite a number of additional functions allow an optimisation of the entire hifi system and an ideal set-up of the individual components.
Connectors
Analogue Inputs:
2x balanced input (XLR)
2 x unbalanced input (RCA)
1x phono
Analogue Outputs:
1 x balanced (XLR)
1 x unbalanced (RCA)
LINK-System
Input (IN 1 ... IN 5)
Impedance
balanced (IN 1... IN2) 10kΩ
unbalanced (IN 3...IN4) 47kΩ
Phono (IN 5) adjust..
Output
Gain
balanced -83...+16dB
unbalanced -89...+10dB
Frequency response DC-800kHz
THD+N <0.001%
Signal-to-Noise Ratio >120dB
Crosstalk <120dB
Impedance
balanced 10Ω
unbalanced 10Ω
