LM-845IA Vacuum Tube Integrated Amplifier
- Amplifier Type: Vacuum Tube Integrated Amplifier
- Circuit Design: Single‑Ended Class A
- Power Output: 22 W + 22 W
- Tube Complement: 2 × 6P3P, 2 × 12AX7, 1 × 5AR4, 2 × 845
- Output Transformer: Custom‑Wound Output Transformer
- Analog Inputs & Outputs: 1 × Pre‑In (RCA, L/R), 3 × Line‑In (RCA, L/R)
- Speaker Outputs: 2‑Channel Stereo (L/R), 5‑Way Binding Posts
- Taps Per Channel: 0 Ω (Common/GND), 4 Ω, 8 Ω, 16 Ω
- Operation & Control: Remote Controllable
LM-845IA Vacuum Tube Integrated Amplifier
Lush Sonic Texture, Natural Musical Resonance
Featuring the iconic 845 power triode, the LM‑845IA delivers 22W per channel pure Class‑A single‑ended power. With three‑stage amplification, premium transformers and adjustable tuning, it reproduces rich, immersive tube sonics with remarkable depth and musical realism.
Electronic Specifications
- Power Output: 22 W + 22 W
- Frequency Response: 20 Hz – 50 kHz (-1.5 dB)
- THD: 1% (1 kHz)
- S/N Ratio: 87 dB
- Input Sensitivity: Line: 300mV Pre in: 1000mV
- Input Impedance: 100 kΩ
- Output Impedance: 4 Ω, 8 Ω, 16 Ω
- Power Requirements: ~ 115 V/120 V/220 V/230 V/240 V ±5% (50 Hz / 60 Hz)
- Tube Complement: 2 × 6P3P, 2 × 12AX7, 1 × 5AR4, 2 × 845
- Power Consumption: 320 W
- Working Conditions: Temperature: 0 ℃ – 40 ℃; Moisture: 20% – 80%
- Storage Conditions: Temperature: -20 ℃ – 70 ℃; Moisture: 20% – 90%
Weights & Dimensions
- Dimensions (W × D × H): 430 mm × 255 mm × 365 mm (17.31" × 10.04" × 14.37")
- Net Weight: 33 kg (72.75 lb)
Application
- Daily leisure: Vinyl records, Hi‑Fi music appreciation, background listening
- Home audio: High‑fidelity home listening room, dedicated audio corner
- Audiophile session: Music appreciation gatherings, record sharing parties
- Work & creation: Music production evaluation, audio tone reference
- Relaxation time: Late‑night listening, quiet immersive music enjoyment
Design
- Type: Vacuum‑tube integrated amplifier
- Chassis: Sturdy metal chassis, classic retro layout
- Transformer: Hand‑wound EI output & power transformers
- Tube complement: Swappable vacuum tube sockets
- Construction: Point‑to‑point hand‑wired build
- Finish: Brushed metal
Analog Inputs & Outputs
- 1 × Pre‑in (RCA, L/R)
- 3 × Line‑in (RCA, L/R)
Speaker Outputs
- 2‑channel stereo (Left / Right), 5‑way binding posts
- Taps per channel: 0Ω (Common/GND), 4 Ω, 8 Ω, 16 Ω
One‑year warranty for the complete unit, and six‑month warranty for vacuum tubes.
Products purchased online or from authorized local dealers and still within the warranty period are eligible for warranty service upon presentation of a valid purchase receipt.Purchases made from unauthorized dealers are NOT eligible for warranty service.
Call us: (+852) 8480 1098
Email : info@lm-audio.com
22W Pure Class A Single-Ended 845 Amplification Topology
At its core, the amplifier utilises a true Class‑A single‑ended topology built around 845 output triodes — celebrated among audiophiles for lush midrange density, solid low‑end weight and organic harmonic texture. Its three‑stage audio signal path uses 12AX7 and 6P3P to drive the 845 output tubes, providing clean linear gain and ample driving power to realise the full sonic potential of these iconic triodes. Power supply rectification is handled by a 5AR4 rectifier tube for smooth, gentle high‑voltage delivery.
Isolated Premium Transformer System
Underpinning the amplifier’s performance is a custom‑built transformer set engineered for ultra‑low noise and extended frequency response.
A Z11‑core toroidal power transformer provides clean, stable power delivery with minimal magnetic flux leakage, sustaining rock‑solid performance through high‑demand musical transients.
Two audiophile‑grade wide‑bandwidth EI output transformers are precision‑wound to perfectly match the 845 triode output characteristics, faithfully preserving full dynamic range and tonal integrity.
All transformers and chokes feature individual encapsulation and segregated mounting layout to suppress mutual electromagnetic interference. This yields a dead‑silent noise floor and exceptional micro‑detail retrieval.
Hand‑Selected & Precision‑Matched Tube Complement
Every tube within the audio signal path originates from trusted audiophile‑grade sources and passes rigorous quality screening before assembly. Pre‑amp tubes and power tubes are hand‑picked and precision‑matched for closely‑aligned electrical parameters between the left and right channels. This strict matching procedure delivers consistent channel balance, precise sound‑stage imaging and maximised overall sonic performance.
Dual User‑Adjustable Tuning with Front Monitoring Meter
Engineered for audiophile‑grade calibration and routine tube maintenance, the unit integrates hum‑balance and bias‑adjustment functions. Operated via the top‑panel selector and the dedicated front‑panel VU meter, it allows users to fine‑tune relevant parameters while offering clear visual monitoring of power‑tube bias conditions.
Comprehensive Connectivity & Dual‑Mode Flexibility
The rear‑panel hosts a full complement of connection terminals to support versatile hi‑fi system configurations:
- Three pairs of RCA line‑level inputs for multiple source components
- One pair of Pre‑in terminals
- Robust speaker binding posts compatible with 4 Ω, 8 Ω and 16 Ω loudspeaker loads
Thanks to the dedicated Pre‑in input, the LM‑845IA can function as a standalone power amplifier when driven by an external preamplifier. This delivers outstanding flexibility for system upgrades and custom audio setups.
High‑Power Single‑Ended Amplifier: Expansive Dynamics & Refined Finesse
It inherits the smooth, natural sonic character of single‑ended topology, paired with excellent dynamic headroom and authoritative, solid low‑frequency performance. Rich, dense mid‑range delivers solid body and texture for vocals. Bass extends well with firm control and ample energy. The sound‑stage is wide horizontally with clear depth layering, offering fine instrumental separation for large‑scale musical pieces. Boasting an ultra‑quiet noise floor, it renders subtle musical details exceptionally well. Its three‑stage amplifier delivers robust drive and snappy transient response, handling grand orchestral works with ease while rendering expressive vocals delicately. A premium single‑ended unit balancing driving power and musical beauty.