Rostec Engineering Administration: Christianehøj 43, 2860 Søborg, Denmark - Email - Phone +45 3967 6438
ROSTEC LMA2 Preamplifier 2 channel High Performance Microphone and Line Preamplifier
Rostec LMA2 is a truly high performance microphone and line preamplifier in a rugged half size 19”magnetically shielded metal enclosure. It features High-End true class A analog input circuits with the same beautiful and musical transfer characteristics as vacuum tubes. At the same time it maintains ultra low noise, ultra low distortion and huge dynamic range by using cutting edge advanced technology. LMA2 has plenty of inputs and outputs for a professional studio set-up: High gain microphone inputs with +48V phantom power, high impedance line inputs for instruments, direct analog outputs, analog insert points, USB class-compliant interface, AES3 transformer balanced output and unbalanced consumer SPDIF output. The built-in state of the art Analog to Digital Converter boasts impressive specifications and exquisite sonic performance. It connects directly to your favourite DAW via the bit-perfect USB interface, and to broadcast, studio and hi-fi equipment via the AES3/SPDIF interface. The user interface is straight forward and intuitive with a clean “What You See Is What You Get” look. The fast true peak meter provides for efficient control of analog output levels and input levels to the digital section.
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General description: With its carefully designed true class A analog circuitry, Rostec LMA2 represents a sound quality that is far above what you will find in the standard digital interfaces flooding the market today. LMA2 is constructed with a throughout balanced analog architecture, meaning that audio signals are routed internally as balanced signals, and all analog signal switching is performed by hermetically sealed relays with gold contacts. There is no digital analog switching, no digital level adjustments, and there is no digital processing, except from the AD conversion and the USB/AES/SPDIF format conversion The analog circuits feature balanced floating industrial output buffers, which support balanced as well as unbalanced configurations. The analog circuits have, throughout the unit, a 10 dB higher headroom than the digital converter circuits, which means that analog clipping cannot be heard, simply because when the analog clipping point is reached, the digital circuit is already in severe clipping. Also, the power supply is pure analog for a quiet and noise-free environment. We want none of that ugly digital noise pollution from switch mode power supplies, thank you! This highly sophisticated design gives LMA2 a large dynamic range, huge headroom, ultra low noise and ultra low distortion, and the result is a beautifully relaxed, open, warm and natural sound, with an impressive amount of details and an astonishing depth and perspective. LMA2 is a highly efficient tool for the professional Sound Engineers and Artists, who wish to record program material with true fidelity. The natural clear and open sound from LMA2 helps create a satisfying working situation for musicians, producers and engineers, in their search for the quality sound, that often eludes them when they use standard digital preamplifiers and digital interfaces with their typical flat, ugly and lifeless sound. Readings for audio enthusiasts: In the design of LMA2, special care and attention has been paid to maintain the linearity of the dynamic range, all the way down to the level where the signal drowns out in the circuit noise. Maintaining the absolute linearity at the low end of the dynamic range is essential for allowing the human ear to correctly detect the environmental information of program material reproduced through the LMA2. Back in the stone age humans were depending on their hearing to detect precisely from which direction the attack of the tiger came, and this information is mostly found in the low level parts of the sound. Although many years have passed, evolution has not changed this ability much. We still use it when we listen to music and pin-point the position of the musical instrument and performers. Maintaining the low level linearity in the electronics, both in the analog circuits as well as in the digital circuits, is mandatory for getting the full experience of the music. In most digital audio interfaces, the lower portion of the audio signal is polluted with digital noise and non-harmonic ground based noise from switch mode power supplies and various digital processing. The human ear detects this part of the signal as sound garbage with no clear relationship to the program material, which as a consequence confuses the ear and impairs the listeners perception of depth and dimension. Although a substantial part of this digital noise is found outside the hearing range, the audio circuits still have to cope with this. The sharp digital pulses have the ability to repeatedly force the electronics into Slew Rate Mode, dramatically reducing the circuits ability the respond to subtle changes in the low level part of the audio signal. The result is, that the environmental information is degraded or partly lost, and the listener loses portions of the depth and perspective details, giving music and human voices a flat, mechanical and dimensionless expression. The LMA2 does not suffer from these ailments. The dynamic linearity is outstanding, and there are no internal digital pollution from switch mode power supplies or free running digital processes. The audio circuits can function freely without being bogged down, which is one of many reasons for the relaxed and open sound of this preamp.
Features * 2 balanced microphone inputs at the back panel, D-SUB 25 female, TASCAM STANDARD. * 2 High-Z instrument inputs at the front panel, 1/4" Jack * 2 balanced high level analog line outputs at the back panel * 2 balanced insert points at the back panel, insert between pre-amp and AD converter (USB/AES/SPDIF outputs) * Insert points are switchable using hermetically sealed relays with gold contacts * Full wave true peak meter, range 40 dB, attack 0.2 msec, release 5 sec * Full balanced internal analog architecture * Built-in +48 Volts Phantom Power * Smooth gain adjustment from +10 dB to + 70 dB by potentiometer, one turn - no clicks * Class-compliant USB 2.0 Digital interface, TYPE B connector. * Transformer balanced AES3, unbalanced SPDIF at the back panel, D-SUB 9, YAMAHA STANDARD. * AD Resolution: 24 bits @ 44.1k, 48k, 88.2k, 96k, 176.4k, 192k. * USB latency: down to 1.5 msec. This is highly dependent on the host computer speed and sampling frequency * AES latency: down to 0.05 msec, depending on sampling frequency * Analog input noise -134 dBu (A weighted)) * +30 dBu input headroom (!) explained in the manual * +30 dBu max analog output level (measured at 1% distortion threshold) * Analog outputs and Insert points nominal level is +18 dBu at digital full scale (EBU standard) * Analog frequency response 5 Hz - 200 kHz +/- 0.1 dB * Analog crosstalk -120 dB, @ 1 kHz, input terminated by 150 ohm * Digital crosstalk -110 dB, @ 1 kHz * THD+N: 0.00035 %, THD: 0.00014 % (see detailed distortion analysis in the manual) * Linear Low Noise Power Supply * Hum residue from analog power supply, 1st, 2nd, 3rd and 4th harmonic: less than -136 dB referenced to 0dBFS. * Mains voltage: Nominal 230 VAC, range 180 - 264 VAC 50-60 Hz (115 VAC version available by request). * Power consumption: 8 Watts. * All digital outputs are ESD protected to 23 kV 15 A surge (IEC61000-4-2 and IEC61000-4-5). * All analog outputs are ESD protected to 2000V, human body model. * Sturdy steel casing, magnetically and electrically screened • Affordable price. High value for money.
Fits nicely with other Rostec units on the 19” rack shelf
The Inputs The microphone inputs are available on the 25 pin D-SUB female connector on the back panel. The gain is set by a potentiometer on the front panel from +10 dB to +70 dB in one turn (no clicks!). The +48V Phantom Power is switched on/off on the front panel. The 1/4" Jack line inputs on the front panel are High-Z instrument inputs intended for electric guitars, bass etc., but are equally well suited for line level equipments, such as keyboards, synts and the like. They are direct inputs to the preamplifier circuit, and follows the gain setting on the front panel. Plugging in a Jack connector automatically enables the line input and switches off the microphone input on the back panel. The Insert return point can be used as a direct line input to the AD converter. When the insert point is enabled on the front panel, the analog and digital sections are separated, and the insert return point becomes available as an AD converter input. The clock input is available on the BNC connector on the back panel. This input is used for digital synchronization, and it features auto detect of the frequency of the incoming clock. However, when the LMA2 is connected to a DAW via USB, the DAW takes over the control of the sampling frequency, and the clock input is only used for synchronization info from other digital equipment.
The Outputs The direct analog outputs are available on the 25 pin D-SUB female connector on the back panel. The analog outputs feature high performance balanced floating industrial buffers, able to handle any impedance from 600 ohm to infinite. The buffers accept balanced as well as unbalanced configurations. The Insert send outputs are identical to the direct analog outputs, and can be used as extra analog outputs or as insert send to external analog equipment. The USB output is a fully Class-Compliant USB 2.0 interface, available on a type B connector on the back panel. It connects directly to a MAC running OS X 10.6.8 or later. A driver for Windows systems is available for download in the Support Section. The USB interface features a Bit- Perfect transfer protocol and runs at 44.1 to 192 kHz @ 24-bit. The AES output is available on the 9 pin D-SUB female connector on the back panel. The output is transformer balanced 110 ohm and adheres to the AES-3 professional format recommendations by The Audio Engineering Society, The SPDIF output is available on the same 9-pin D-SUB connector. The output is unbalanced 75 ohm, and is a downscaled version of the AES output, making it a PRO (professional) format. However, for measurements or tests on the lab table, the format can be changed to CON (consumer) by connecting two pins of the 9 pin connector. The Clock output is available on the BNC connector on the back panel. It is used for synchronization of other digital equipment, and the clock frequency follows the indication on the front panel. The output is 75 ohm TTL compatible and features impressive jitter specifications and a grade-2 accuracy. It works excellently as a master clock reference in small/medium studio set-ups. For larger studio or broadcast set-ups, the high performance ROSTEC ASD24 Reference Generator is recommended.
The Insert Points The Insert points are available on the 25 pin D-SUB female connector on the back panel. When the insert point is enabled on the front panel, the analog and digital sections becomes separated. Various analog equipment, like equalizer, compressors etc., can then be connected to create an external signal bridge between the analog and the digital sections. The insert points are balanced in and out, but accept unbalanced connections as well.
The Meter The meter is a true peak meter with fast attack and slow release, having a correct professional ballistics profile (not like the rubbery and sloppy meters on a typical DAW). The switch on the front panel selects two measuring points: SEND measures the insert point send level (same as analog out), and RTN measures the insert point return level. Note that the meter is only a measurement device, it does not route any signals. The meter provides the user with a trustworthy indication of levels and clipping of the digital converters, microphone amplifiers and the inserted analog equipment.
About cables The 25 pin D-SUB female connector on the back panel is configured as TASCAM pin out, but in a TASCAM digital connector configuration. This means that the connector has 4 outputs and 4 inputs. i.e. D-SUB 25 pin MALE to 4 XLR MALE and 4 XLR FEMALE. This cable is readily available on the market, but is labelled as a digital cable. Do not let that deter you! Digital cables are usually of much higher quality than analog cables. A warning: Some manufacturers of digital cables provide cables without screen, only as a twisted pair configuration with one ground wire. These cables cannot be used with analog signals. The 9 pin D-SUB female connector for the AES/SPDIF outputs is wired to a pseudo Yamaha standard. It is easy enough to make the cable for anyone who can use a soldering iron. A cable can be supplied by Rostec.