Altec Lansing 724A (1970)

At 27 pounds, it arrives like a promise kept — dense, deliberate, and wired for war against noise and distortion.

Overview

The Altec Lansing 724A isn't a tuner that whispers; it’s one that means business. Released in 1970, this FM/AM tuner preamplifier was engineered with a clear directive: extract every ounce of fidelity from broadcast signals and deliver them to the next stage with surgical precision. Marketed at $119.95 as a kit, it catered to the serious hobbyist — someone who didn’t just want to listen, but to understand, tweak, and optimize. Its all-transistor configuration was standard for the era, but the implementation was far from generic. The use of FETs in the tuner section gave it high sensitivity and stability, critical for pulling in weak stations without succumbing to drift or interference. This wasn’t a consumer-grade tuner built for casual Sunday mornings — it was a tool for the technically inclined, designed to anchor a high-performance system.

Owners report that the 724A was never intended to stand alone. Its design purpose was explicitly tied to synergy with the Altec 770A electronic crossover bi-amplifier, suggesting it was conceived as part of a larger, modular strategy. The plug-in modular circuit design reinforces that idea — faults could be isolated, modules swapped, and upgrades potentially field-installed. That kind of serviceability was rare in mass-market gear, and it speaks to Altec Lansing’s roots in professional audio. The preamplifier section, with a frequency response of 20 Hz to 20 kHz ± 0.5 dB and a harmonic distortion factor of 0.05% or less at 1 Vrms, was exceptionally clean for its time. The phono input, requiring only 2.0mV, was well-matched to moving magnet cartridges common in the early 1970s, though the hum and noise level of -60dB or less at phono suggests that careful grounding and layout were essential in practice.

The FM tuner section was competitive on paper, with a 1.3dB capture ratio and 40dB or more stereo separation at 1 kHz — solid numbers in 1970, though not class-leading. The image ratio of 90dB indicates strong rejection of off-frequency signals, a hallmark of good front-end design. Frequency response extended to 15 kHz ± 1 dB, which was typical but not exceptional; some contemporaries reached 18 or 20 kHz. AM performance was respectable, with a 15 μV input sensitivity at 20 dB S/N and a signal-to-noise ratio of 48 dB at 1 mV — adequate for local stations, but likely noisy on weaker ones. The inclusion of high and low filters (12dB/octave at 6 kHz and 50 Hz respectively) offered useful room correction or system protection, and the ±16 dB tone controls at 20 Hz and 20 kHz provided aggressive shaping when needed, though purists would have bypassed them entirely.

Specifications

Key Features

FET-Based Tuner Section for Stability

The use of field-effect transistors in the tuner section was a deliberate move toward higher input impedance and lower noise — critical for weak signal reception. FETs were still relatively novel in consumer gear in 1970, and their inclusion here suggests Altec Lansing prioritized front-end integrity over cost-cutting. The result was a tuner with high sensitivity and improved stability, reducing drift during long listening sessions. Capture ratio of 1.3dB indicates it could lock onto the stronger of two close signals effectively, though real-world performance would depend on local RF conditions.

Plug-In Modular Circuit Design

Few tuners of this era offered true modularity, but the 724A did. Plug-in circuit boards meant that servicing wasn’t a matter of tracing cold solder joints across a rat’s nest of point-to-point wiring — a failed stage could be swapped out. This design philosophy points to professional influence, possibly borrowed from Altec’s broadcast and cinema equipment lines. For restorers today, it’s a blessing: modules can be tested, recapped, or replaced without desoldering entire sections.

Preamplifier Section with Low Distortion

With a harmonic distortion factor of 0.05% or less at 1 Vrms, the preamplifier section was exceptionally clean. That figure, combined with a flat 20 Hz – 20 kHz ±0.5 dB frequency response, suggests a neutral, transparent character. The -90dB hum and noise level on auxiliary and tape inputs indicates a well-suppressed power supply and careful grounding layout. Even the phono stage, while noisier at -60dB, was competitive for a discrete transistor design of the period.

High and Low Filters with 12dB/Octave Slope

The inclusion of both high and low filters — each at 12dB/octave — was unusual for a tuner preamp. The high filter (6 kHz or more) could tame sibilance or tape hiss; the low filter (50 Hz or less) likely served to block rumble or subsonic noise from records or weak AM signals. These weren’t just tone controls — they were system-shaping tools, possibly intended to work in tandem with the bi-amped setup the 724A was designed for.

Optimized for Use with Altec 770A Bi-Amplifier

The 724A wasn’t a standalone statement. It was engineered to feed the Altec 770A electronic crossover bi-amplifier, suggesting a complete high-end signal chain. This pairing would have allowed separate amplification for highs and lows, with the 724A handling source selection, preamp duties, and filtering. The synergy likely delivered a level of control and clarity rare in home systems of the time — assuming the user had the speakers and amplifiers to match.

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