Altec Lansing 1268
Three and a half inches of rack space, sixty watts a side, and a protection circuit that thinks faster than the music.
Overview
The 1268 is not a hi-fi amplifier, and Altec never pretended otherwise. It is a two-channel basic power amplifier in a rack-mount chassis with heavy-duty front handles, 3½ inches tall, 19 inches wide, and 10 inches deep, finished in black. Altec's own service documentation talks about contractors, warranty stations, and qualified service representatives. This is a box meant to live in a rack and stay there.
The headline numbers look modest on paper. Altec rates the 1268 at 60 watts per channel into 8 ohms, both channels driven from 20 Hz to 20 kHz at less than 0.03% THD. The manual also notes that the amp typically delivers greater than 75 watts per channel into 8 ohms at 1 kHz at under 0.01% THD. So the published figure is a conservative floor, not a ceiling.
The bridge mode is the surprise. Strapped for mono, the 1268 is specified at typically greater than 200 watts into 8 ohms from 20 Hz to 20 kHz at less than 0.05% THD. Altec's own preliminary literature calls it "200+ watts of controlled power in the bridge mode."
The monitoring circuitry is what separates the 1268 from a generic pro amp of its era. A peak/error computer compares each channel's input and output signals. It lights an indicator when it detects excessive voltage, excessive current, excessive slew rate, or any other significant input/output differential. Altec's documentation specifies the response time at one microsecond with a 25-millisecond hold, and notes the indicator will show when THD exceeds 1% or when transient errors occur. It is a diagnostic tool, not a clipping lamp.
Protection comes in layers. The amplifier output is continuously monitored, with an instantaneous VI limiter restricting output to 100 VA at ±45° phase shift. A temperature sensor disconnects the load via relay if the heatsink runs too hot, and the amp resumes operation automatically once temperatures fall back to safe range. On the load side, an output relay delays turn-on by three seconds and drops the load instantly on shutdown, loss of power, or DC at the output. The operating temperature range is specified up to +55°C (131°F) ambient.
The rest of the spec sheet is thorough. Power gain is 46.5 dB balanced bridging a 600-ohm line with an 8-ohm load, or 52.5 dB in bridge mode. Voltage gain is 29.0 dB unbalanced, with input sensitivity of 0.775V rms for rated output. Input impedance is 15,000 ohms nominal across all inputs. Frequency response from the direct input is ±0.25 dB at 1W into 8 ohms from 20 Hz to 20 kHz, extending +0 dB / -3 dB from 5 Hz to 100 kHz. Output impedance is under 0.1 ohm in dual mode at 1 kHz and under 0.2 ohms bridged. Signal-to-noise is greater than 100 dB unweighted with a 600-ohm source and the volume at maximum. Channel separation exceeds 70 dB at 1 kHz. Slew rate is 18 V/µsec. Load impedance must be 4 ohms or greater per channel, or 8 ohms or greater in bridge mode.
Around the back, the 1268 uses Cannon-type input receptacles, four 5-way binding post output jacks, and two phone jack multiple receptacles for daisy-chaining additional amplifiers. The front panel carries two stepped attenuators, a MODE switch for mono or dual operation, the AC power switch and LED, two peak/error LEDs, and a protection LED. The primary fuse is a 5A 3AG on the rear. Domestic units are strapped for 120V. Export units require restrapping the power transformer primary for 100V, 200V, 220V, or 240V operation, all at 50/60 Hz. Power draw is listed at 50W at zero signal, 150W at one-third rated output, and 225W at rated output with both channels driven at 1 kHz.
The documentation does not give a production year. Studio-Sound (November 1987, p.41) surveyed contemporary power amplifiers such as the BGW 250D & E, rated at 100 W/channel into 8 ohms and 300 W bridged into 8 ohms, which gives some context for the 1268's own power ratings. The service manual carries an SI-112 revision 3 code with a "1184-1M" litho date that suggests a mid-1980s printing. That is a printing date on a service document, not a production date for the amplifier, and it should not be read as one. The preliminary literature describes the 1268 as part of a second generation of "super amplifiers" answering rising system demands. That is Altec's framing, in Altec's words. No original price, no production run, and no market history are documented here.
In practical terms, the 1268 is a rack amp with real headroom in bridge mode, unusual self-diagnostics, and a service setup that assumed authorized dealers rather than end users. The manual is explicit that repair by anyone other than an Altec-qualified representative voids the warranty, and the unit carries no user-serviceable parts inside. That was normal for the period. A 1268 in unknown condition wants a technician.
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