Altec Lansing 1224A Electronic Crossover Biamplifier

Name: Altec 1224A
Brand: Altec

It weighs 35 lbs and is 19 inches wide. It's a heavy, no-nonsense box built to split signals and drive drivers hard.

Overview

The Altec Lansing 1224A Electronic Crossover Biamplifier isn't gear you show off on a shelf. It's a workhorse, designed to live inside speaker cabinets in permanent installations, portable PA rigs, and professional sound reinforcement setups. It isn't a stereo amp for a living room. It's a single chassis that combines an electronic crossover and dual amplifiers, one for low frequencies and one for high. The idea was simple: feed it a line-level signal, split that signal at 500 Hz, 800 Hz, or 1500 Hz, then amplify each band separately before sending them to dedicated drivers. Putting it all in one box reduced signal loss, minimized interference, and simplified system design for installers who needed reliability above all.

Owners report it was built like a tank, and the construction backs that up: an all-steel chassis, internal heatsinks, and a toroidal transformer tucked inside a compact 19-inch rackable form. It runs on 120V AC and can reportedly be converted in the field for 240V operation, which suggests it saw use beyond North America. The crossover is fully electronic and adjustable via switch settings, so users can match it to different speaker systems without swapping components. It lacks the polish of consumer-grade gear. What it offers is durability, function, and clean power where it counts.

Specifications

Manufacturer	Altec Lansing
Product type	Electronic crossover biamplifier
Power output	reportedly 80 watts for LF & 40 watts for HF
Frequency response	20 Hz to 20 kHz
THD	0.1%
S/N ratio	100 dB
Operating voltage	120V AC 50/60 Hz
Crossover frequencies	Selectable: 500Hz, 800Hz, or 1500Hz
Dimensions	19" wide, 5.25" high, 12" deep
Weight	35 lbs
Inputs	1 pair of RCA inputs
Outputs	1 pair of 5-way binding posts
Circuit topology	Dual-mono, fully discrete
Construction	Chassis is all-steel, heatsinks are internal
Components	Uses Sanken output transistors, toroidal transformer, 4 x 15,000µF filter capacitors

Key Features

Electronic Crossover with Selectable Frequencies

The onboard electronic crossover is the core of the 1224A. It splits the incoming signal before amplification, which makes it a true biamplified design. That avoids the power loss and phase issues common in passive crossovers. Users can select crossover points at 500 Hz, 800 Hz, or 1500 Hz via internal switches, so it fits various two-way speaker systems. According to available documentation, the crossover operates at line level, sending the low-pass signal to the LF amp and the high-pass to the HF amp. One noted quirk: some units are missing the external frequency switch, but the setting can still be changed manually with a key or tool. It's hardly elegant, but it works.

Dual-Mono, Fully Discrete Amplifier Design

Inside the steel case, the 1224A uses a dual-mono, fully discrete amplifier topology. There's no shared circuitry between the low and high-frequency channels, which improves isolation and reduces crosstalk. Each channel runs on its own set of Sanken output transistors and is powered by a shared toroidal transformer. Discrete components (no ICs in the signal path) were standard for pro gear of its class and era, and they offer reliability and repairability. The 4 x 15,000µF filter capacitors suggest a strong power reservoir, which helps maintain headroom during dynamic peaks.

Rugged, Install-Friendly Chassis

Built for the road and permanent installs, the 1224A has an all-steel chassis and internal heatsinks in a no-frills, industrial design. It fits standard 19-inch racks and weighs 35 lbs, which is substantial but manageable for a unit packing this much circuitry. The RCA inputs and 5-way binding posts are straightforward, with no exotic connectors or shielding. The layout prioritizes serviceability and durability. According to owner reports, the RCA jacks are prone to loosening over time and may require re-soldering. It's a known weak point in an otherwise solid build.

Collectibility & Value

The Altec 1224A trades today between $300 and $500, depending on condition and whether it's been serviced. Its value hinges on functionality, since buyers expect it to work. The most common failure point is aging electrolytic capacitors, particularly the four 15,000µF filter caps. Replacing them is considered routine maintenance, and sources suggest it's a wise step if the unit still has its original capacitors. The RCA input jacks are another known issue, often needing re-soldering due to mechanical stress. A manual was available from Telex as recently as 2001, though sourcing parts and documentation now may require digging.