Audible Illusions Modulus L3A Line Stage preamplifier

Audible Illusions Modulus L3A Line Stage preamplifier

"The L3A line preamp distills the best attributes of modern tube sound: swift transients, a detailed presentation, and natural yet non-euphonic textures. It is its insistence on the sonic truth that defines it as a true reference line preamp. The L3A's ability to retrieve the music's rhythmic drive and drama make it one of the most sonically persuasive line preamps on the market and one of the best I've auditioned over the years at any price. If your goal is to conjure up audible illusions on a grand scale, this is your preamp!"1


Audible Illusions Modulus L3A Line Stage preamplifier


Product Info

- The audio control center second to none.

Many audiophiles remember how the introduction of the original Modulus preamplifier excited the audio industry. For the first time a full-function, reliable vacuum tube preamp with true high-end sound was available at an affordable price. It's rare for a company to capture one's imagination and loyalty even once in such a manner. With the L3A Line Stage, the legend continues.

As many audiophiles migrated to CD and digital media for their main source, Audible Illusions began producing the Modulus line stage series. These preamps were specifically designed to optimize digital playback and other line-level equipment. While the L3A retains the physical characteristics of its predecessors, it's not a rehashing of old ideas. The preamp is on the leading edge of audio technology. The L3A makes elegant use of engineering approaches to circuit board design that improves signal flow and reduce interference and vibration. A Class A, zero feedback, single-ended design built on the proven tube design philosophy that "simpler is better." Additional improvements include dedicated relay signal switching and Teflon coupling capacitors which result in outstanding resolution. The L3A also features a dedicated external power supply which isolates AC fields from the main chassis and prohibits common-mode noise from interfering with the musical waveform.

In terms of features, the L3A is an audio control center second to none. It has inputs and switching designed for CD, DVD, Tuner, External Phono Stage, Video, Aux and Tape. Volume and Muting functions are operated from the front panel or with Remote Control. The L-R Balance Controls are precision stepped attenuators.

For Home Theater use the L3A includes complete input and output switching facilities for surround sound processors. Another feature incorporates special active buffer circuitry for optimum matching of components which prevents signal degradation and impedance mismatches.

As with the previous Modulus preamplifiers, the L3A is next step in the evolution of their famous single-ended designs—the heart of fine audio and video systems for years to come.

Control Functions: Master Stereo Volume, L&R Stepped Attenuator Balance Controls, Source-Tape, External S/S Processor, Mute and Power

Remote Selection: Stereo Volume Up-Down, Muting

Output Selection: Main (2) Tape, External S/S Processor

Optional: Mirror-polished nickel-silver faceplates available as a special order

L3A Technical Features:
- Circuit design is dual-mono, Pure Class A, single-ended triode.
- To prevent unwanted AC-induced distortions, the L3A features an external power supply housing three separate supplies and a large-shielded, custom-wound transformer.
- In the main chassis, four-separate, fully-regulated FET power supplies drive the audio circuitry in addition to separate filament supplies.
- Audio circuit has no cathode followers or buffers.
- Automatic-timed muting with tri-color LED indicator.
- Low-light illumination for selector switch and master volume control knobs.
- Standby Mode avoids cold starts and prolongs tube life and circuit components.
- Active tape output and external S/S output buffers are FET regulated, set for unity-gain.
- All circuit boards are hand-soldered using the finest silver solder available. All polypropylene and polystyrene film capacitors used are proprietary designs of Audible Illusions. Resistors are precision 1% Holco and Roederstein.
- All circuit boards are hand-soldered with silver-bearing solder.
- Proprietary gold-plated RCA Jacks with Teflon insulators.
- Master stereo volume is laser-trimmed Alps. Balance controls are precision stepped attenuators.
- Completely handcrafted in USA.

Footnote 1: See full context of The Absolute Sound review by Dick Olsher at Audible Illusions L3A Line Preamplifier, An All-Time Classic Still Going Strong.

L3A Technical Specifications

- Gain: 30dB, Tape & S/S processor 0db
- Distortion: .10% at 1.5V rms, 20-20kHz, into 50kOhm. Less than .12% at 1V out 20-20kHz into IHF load
- Frequency Response: Within ± 1dB 2Hz to 100kHz measured w 1-1 probe/50 kOhms,100pf
- Signal to Noise: 90dB below 1.5V rms output wideband
- Max Input: 9V rms
- Signal Phase: Main Out-Inverting, Tape and S/S Processor-Non Inverting
- Input Impedance: 50kOhm - all
- Output Impedance: Main-1.2 kOhms Tape, S/S Processor-150 Ohms
- Muting: 45 second warm-up and automatic brown-out protection
- Tube Compliment: 2-6H23EB twin-triodes, graded & matched
- Power Requirements: 115-125VAC, 60Hz 45 watt maximum. 6 foot IEC Line Cord-Supplied. Optional 100, 220, 230, 240 50-60Hz transformers.
- Dimensions: 19″W × 3.5″H standard rack mount; Chassis is 17″W × 11″D × 3″H; Power Supply, 6″W × 10″D × 5″H
- Weight: 19.5 lbs, 24 lbs (shipping wt.)

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