A main distinction of the L2.1 is its almost inaudible sonic signature


Model L2.1 Reference represents top of the line in LAMM hybrid and solid-state audio equipment. It is one of the best creations of its designer’s professional career – a result of years of intensive research directed at attaining the most accurate reproduction of recorded music. Unique topology and application of the most advanced technological resources and processes bring the L2.1 near the threshold of excellence in sound reproduction.

design elements


A main distinction of the L2.1 from any other comparable type of preamplifiers is its almost inaudible sonic signature. When connected to an appropriate type of power amplifiers, and especially LAMM amplifiers, it assures the extraordinary transparency of perceived sound and recreation of a three-dimensional soundstage in the home, recording studio, etc., without boundaries and limitations.

The L2.1 features a topology that brings out the most natural sound performance in the audio path, as well as graceful and sophisticated design. Its unique circuitry utilizing specially selected super-linear high voltage MOS-FET transistors ensures a class A operation from input to output, with no overall feedback at any stage. All stages, including high current output buffers, are single-ended. A unique electronic protection circuit enables manual muting of the outputs until the preamplifier has stabilized after a turn-on; it also enables functioning of the preamplifier in a “muting” mode during operation and automatic switching to muting in case the AC line voltage drops or is interrupted.

Other features include 3 inputs; 1 tape loop; output signal phase switch; balanced and single-ended outputs; and built-in remote on/off for LAMM power amplifiers.

The L2.1 has a separate power supply that utilizes a choke contained filter, vacuum tube rectifier and voltage regulator.

components


Special care was taken in designing a high voltage (+350V) high speed vacuum tube voltage regulator. Using this voltage regulator, in conjunction with other technical aspects, enables the reproduction of tiniest nuances and three-dimensional subtleties in the music palette (provided that such details had not been lost in a recording process). A somewhat unusual combination of high voltage vacuum tube power supply and superlinear high voltage MOS-FETs allows to attain an enormously large output swing while retaining practically constant harmonic contents of the signal with an absolute dominance of the second harmonic.

In designing the L2.1 special attention was directed toward optimization of the output impedance of the preamplifier with an aim of attaining practically full independence of the output impedance from frequency, as well as to allow the preamplifier to drive (without audible sonic degradation) significant capacitive loads created by many modern interconnect cables.

Each preamplifier is carefully hand-crafted with matched components of the highest quality, some of which include military graded low noise DALE metal film resistors; unique TKD stepped potentiometers (41 detents); PRC wire wound resistors; ELECTROCUBE and ROEDERSTEIN film capacitors; high frequency switching grade CORNELL DUBILIER electrolytic capacitors; specially selected long life vacuum tubes; high quality heavy duty gold-plated RCA connectors; and gold-plated NEUTRIC XLR connectors. The preamplifier power supply features a custom-designed super-low noise toroidal power transformer. AC voltage is filtered by special RFI power line filter.

Summing up the above, we take the liberty in stating that we have been able to create a preamplifier with practically no sonic signature, of course, taking into consideration the fundamental limitations inherent in reproduction of live music by electronic means.

The L2.1 works on all world AC line voltages (100/120/220/230/240V).

audio critic reviews coming soon


Measurement


Rated Output Voltage
From 20Hz-20KHz into instrument load: 0.75 Volts RMS.
From 20Hz-20KHz into IHF load: 0.75 Volts RMS.
Voltage Gain
5.54 + 2% or 14.87 + 0.2dB.
Frequency Response
From 1-60 Volts RMS into instrument load: -0.2dB) 20 Hz, 20 KHz, (-3dB) 5 Hz, 140 KHz.
From 1-30 Volts RMS into IHF load: (-0.2dB) 20 Hz, 20 KHz, (-3dB) 5 Hz, 120 KHz.
Slew Rate
Vout=36 Volts peak-to-peak of square-wave signal, F=10KHz: 30 Volts per microsecond.
Rise Time
Vout=36 Volts peak-to-peak of square-wave signal, F=10KHz: 1 microseconds.
Total Harmonic Distortion from 20 Hz – 20 KHz
Vout=2 Volt RMS into instrument load: no more than 0.03%
Vout=60 Volts RMS in to instrument load: no more than 1%
Vout=2 Volt RMS into IHF load: no more than 0.03%
Vout=30 Volts RMS into IHF load: no more than 1%
IM Distortion
Vout=2 Volt RMS into instrument load: no more than 0.03%
Vout=60 Volts RMS in to instrument load: no more than 1%
Vout=2 Volt RMS into IHF load: no more than 0.03%
Vout=30 Volts RMS into IHF load: no more than 1%
Inputs
Unbalanced gold plated single-ended RCA connectors.
Input Sensitivity
Vout = 0.75 Volts RMS into instrument load: 0.135 Volts RMS ± 2%.
Vout = 0.75 Volts RMS into IHF load: 0.135 Volts RMS ± 2%.
Input Impedance
51 KOhms.
Outputs
Unbalanced: gold plated single-ended RCA connectors.
Balanced: 3-pin gold plated XLR connectors.
Balanced pin assignment: pin 1 = signal ground; pin 2 = non-inverting input (+); pin 3 = inverting input (-).
Corrected Output Impedance
Typically 130 KOhms.
Noise
Signal-to-noise ratio, below 2 Volts RMS output, unweighted: typically 82 dB.
Operating Temperature
-4 to +104 degrees Fahrenheit (-20 to +40 degrees Celsius) ambient.
Power Supply
Nominal line voltage: 100-240 Volts 50/60Hz. Input voltage range: ±10%.
One power transformer, two vacuum tube rectifiers, one filter choke, one high-speed vacuum tube voltage regulator, one solid-state analog non-switching voltage regulator.
AC voltage intensively filtered by special RFI power line filter.
Front Panel Controls: Preamplifier
OUTPUT LEVEL controls (separate for left and right channels).
SELECTOR switches (separate for left and right channels).
MONITOR switches (separate for left and right channels).
MUTING switch.
ABSOLUTE PHASE switch
Rear Panel Connectors & Controls: Preamplifier
Four pairs of INPUT CONNECTORS RCA for line inputs and TAPE (play).
One pair OUTPUT CONNECTOR RCA for TAPE (record).
One pair of OUTPUT CONNECTORS RCA (single-ended outputs).
One pair of gold-plated XLR CONNECTORS (balanced outputs).
One XLR CONNECTOR (6 pins, gold-plated) for connecting the power supply cable.
Front Panel Controls: Preamplifier Power Supply
POWER switch.
OUTLETS switch.
REMOTE 1 turn-on/off switch for LAMM power amplifiers.
REMOTE 2 turn-on/off switch for LAMM power amplifiers.
Four LED controls.
Rear Panel Connectors & Controls: Power Supply
IEC 320 POWER INLET (3 lug).
Two AC OUTLETS, switched.
One XLR CONNECTOR (6 pins, gold-plated) for connecting the power supply cable.
Two REMOTE CONTROL plugs.
EARTHING POST (gold plated).
Features
Pure class A fully balanced MOS-FET zero feedback design. Power supply utilizes vacuum tube rectifier, choke contained filter and high speed vacuum tube voltage regulator.
High-current drive capability, in combination with unique single-ended class A circuitry, assure the preamplifier’s capability to drive any cable and any real world load, while maintaining its practically inaudible sonic signature.
This design is unique to LAMM INDUSTRIES, INC.
AC voltage selector:
100/120/220/230/240 Volts, internally switchable.

Remote Control:

Special built-in circuit enables the remote turn on/off of LAMM power amplifiers.
Available remote link cable coordinates the remote functions of two or more amplifiers.
Safety:
Unique electronic protection circuit enables muting of the outputs until the preamplifier is stabilized after a turn-on, as well as functioning of the preamplifier in a “muting” mode during operation, and automatic switching to muting in case the AC line drops or is interrupted.

Vacuum tube voltage regulator overload protection: 0.125 Amps slo-blo fuse, internally mounted.
AC voltage fuses: 2 Amps slo-blo for 100/120 Volts. 1 Amp slo-blo for 220/230/240 Volts
.

General
Power Consumption: Typically 95 Watts.
 Burn-in Time at Factory: Minimum 72 hours.
Recommended Burn-in Time in End-user’s System: Minimum 200 hours.
Warm-up time: Minimum 45 minutes.
Unit dimensions: 4.5 inches high x 19 inches wide x 13.875 deep + 1.375 inches for front handles.
Crate dimensions: 23″ x 19″ x 10″ (58.42cm x 48.26cm x 25.4cm).
Unit weight preamplifier: 15.42 Lbs (7 Kg).
Unit weight power supply: 19 Lbs (8.63 Kg).
Shipping weight preamplifier: 34.6 Lbs (15.7 Kg).
Shipping weight power supply: 39 Lbs (17.71 Kg).
Tube Complement Power Supply:
one12AX7/ECC83, voltage regulator tube;
one 6C19P, voltage regulator tube;
one 5651A, voltage reference tube;
two 12AX3, rectifier tubes.