Micro Precision Z-Studio Z-ST 4c 4-Channel Amplifier

       The Micro Precision Z-Studio Z-ST 4c 4-Channel Amplifier is a product of meticulous design and engineering, starting its journey in 2013 under the project name “Verstärker 1.” This exceptional amplifier, crafted to stand out from current standards, is the result of a collaborative effort led by a dedicated team following the unfortunate passing of the initial developer, Detlef, in 2018.

Micro Precision Z-Studio Z-ST 4c Team Composition:

Thomas: Overall Concept

Roberto: Development & Production

Colpo: Development & Production

Licio: Administration

Cemil: Morale and Advice

Z-ST 4c Design Philosophy:

. “Form follows function.”

. Designed for repairability even after 20 years.

. Avoidance of SMD components to facilitate easier repairs.

. Recognition of the significant influence of an amplifier as a necessary technical construction.

. Not an ideological lifestyle product.

Z-ST 4c Power Supply:

. Three 30 Ampere primary fuses (90A).

. Eight 80 Ampere switching transistors (2x240A).

. Eight high-speed switching diodes to minimize switching noise.

. Two high-current filter chokes to reduce disturbances from switching frequencies.

. Four primary 22,000 uF storage capacitors from the MUNDORF range.

. Eight secondary 4,700uF storage capacitors from the MUNDORF range.

. Various necessary voltages generated by the power supply.

Z-ST 4c System Voltages:

.  +5 Volts for the microcontroller and reference for regulation.

.  +12 Volts for relay switching.

Z-ST 4c Audio Voltages:

. +/- 15 Volts level control.

. +/- 67 Volts bias.

. +/- 47 Volts pre-stage / driver stage.

. +/- 40 Volts power amplifier.

Z-ST 4c Driver Stage:

. High-voltage technology in discrete circuitry.

. No operational amplifiers (IC) in the signal path.

. Only high-impedance FET-transistor built OP amplifiers.

. Bias adjustable via precision potentiometer.

. AUDIONOTE KAISEI coupling capacitors.

Z-ST 4c Power Amplifier:

. Sanken transistors, four pieces at 160 Watts per channel.

. CADDOCK 1% precision emitter resistors, 16 pieces.

. PANASONIC high-current relays for speaker on/off.

. High-quality speaker screw terminals with 4mm banana through cable optimally connected to the board. No losses on conductor tracks.

Z-ST 4c Input Circuitry:

. Bridgeable from 4-channel to 2-channel.

. Bridgeable from 4-channel to 2+1 channel.

. LED control indicator for sequential bridging operation.

. Input level adjustable via programmable resistance matrix in 0.5 dB steps.

. No problematic potentiometers in the signal path.

. No filter functions in this amplifier. Linear phase & amplitude.

. High-impedance FET transistor input stage to minimize unnecessary load on the signal source.

. 20.0 kOhm constant input resistance regardless of level control.

. Input capacitance 5pF.

. Input stage coupling capacitors: AUDIONOTE KAISEI & MUNDORF MCAP EVO.

. Optional amplifier without resistance network for a “direct input” without level control.

Z-ST 4c Microcontroller Display:

. Displays operating voltage (min. 9.0V – max. 16.0 Volt) and working temperature.

. Displays channel-related level reduction (channels 1-4).

Z-ST 4c Protection Circuits:

. Overheating: Programmable 85 degrees via microcontroller.

. Overload; Short circuit.

. Undervoltage: Shutdown at 10V, which can be disabled via the controller.

. Temperature: Around 45 Celsius in normal operation with passive cooling. No fan needed due to large heatsink and side panels. Shutdown at 85 degrees Celsius.

Z-ST 4c Dimensions:

. 325 x 550 x 90mm.

Z-ST 4c Idle Current:

. Total: 5 Amperes = 4 channels at 1.25 Amperes each.

. The idle current depends on the bias pre-setting, affecting harmonic (K2) or unharmonic (K3) distortion. The bias influences sound, idle current, and operating temperature.

Z-ST 4c Performance Metrics:

. Self-noise: A-weighted -90dBV.

. Frequency response: 5 – 250,000 Hz at -1dBV, 5 – 420,000 Hz at -3dBV.

. Power at 4 Ohm load: 160 Watts at 1% THD+N.

. Power at 2 Ohm load: 280 Watts at 1% THD+N.

. Power at 4 Ohm BR: 580 Watts at 1% THD+N.

. Power at 2 Ohm BR: Not permissible.

. Damping factor at 10W: 2700.

. DC Offset