A-428B
| Brand | Altec |
| Manufacturer | Altec Lansing Corporation |
| Function | Amplifier, Pre |
| Produced | 195? |
| Country | United States |
| Form Factor | Part |
| Signal Path | Analog Hardware |
| Dimensions | 3.8 × 12.1 × 25.4 cm (W × H × D) |
| Power | 6.3VAC 0.6A, 260VDC 10mA |
| Frequency Response | 20Hz-20kHz ±1dB |
| Gain | 40dB |
| Gain (Special Connections) | 34dB |
| Source Impedance | 50/150/300/600Ω |
| Load Impedance | 50/150/300/600Ω |
| Output Level | +20dBm |
| THD (50Hz-15kHz) | 0.5% |
| THD (30Hz-15kHz) | 1% |
| IMD (40Hz, 2kHz, 4:1) | 2% |
| Noise Level | -120dBm |
| Tube Complement | 12AY7 (x2) |
| Links | Altec 250A Console |
| Notes | 250A Console plug-in module. Available separately for custom installations. |