The new (4000 EUR) MLP-1(Marohei Line Preamplifier) is an universal tube based line level preamp. The main goals in it’s design were…
* Shortest and simplest signal path: To achieve this, the amplification circuit is tube based, using two triodes per channel, and the component placing is optimized for the least length of the signal path, including input selection and attenuation using high quality sealed relays right next to the input connectors.
* Stability and longevity: Semiconductor circuits have shown to be excellent in insuring almost ideal operating conditions for tube circuits. To this end the preamp uses independent filtered and regulated power supplies for the main circuit, tube heating and control circuits. The control circuits additionally pre-heat the tube circuit before switching on the main power supply. The operating points of the tubes are chosen for best quality amplification without compromising tube longevity.
* Amplification without inverting the absolute phase and compromising the natural harmonic structure: A specially developed circuit is used to compensate for the attenuation of even order harmonics which happens in circuits that do not invert the absolute phase of the signal, thus preserving the more natural SE triode harmonic structure.
* Flexibility in choice of source and power amplifier hookups: The input selector and attenuator have been designed to present a constant standard input impedance to the source, regardless of the attenuation level chosen. The output stage can drive quite low impedances, so it is far less flexible regarding the choice of interconnect cables.
* Precision volume attenuator with fixed steps: The attenuator has 64 steps, 1.5dB each, with a step to step and channel to channel precision better than 0.1dB at any setting.
* Maximally simplified controls: simple selection of input and attenuation, with OLED display indicator. The indication operates only when the controls are operated (either on the front panel or by remote control) and fades out after a short time-out, not to be intrusive. All controls are available both through the front panel and remote control.
Specifications:
- Inputs: 4, standard RCA connectors, input impedance 47k ohms, selection through relays.
- Gain (at 1kHz and 0dB attenuation): 6, 9.5 ili 12dB (internally configurable).
- Attenuator: precision, relay based, 64 steps, 1.5dB each, constant input impedance regardless of attenuation level chosen.
- Output impedance: 150 ohms (at 2Veff and 1kHz)
- Frequency range: 3.5Hz-300kHz (+0, -3dB), 20Hz-20kHz (+-0.1dB) at 2Veff into 10k ohms.
- Maximum output: guaranteed minimum 10Veff into 10k ohms, at less than 1% distortion.
- Tube complement: ECC88/6DJ8/E88CC/6922/PCC88 family (internal selection between 6.3 and 7V DC heater voltage), one tube per channel.
- Remote control: standard Philips RC5 code compatible
