A-428A
| Brand | Altec |
| Manufacturer | Altec Lansing Corporation |
| Function | Amplifier, Pre |
| Produced | 1957 |
| Country | United States |
| Form Factor | Part |
| Signal Path | Analog Hardware |
| Dimensions | 4.1 × 10.8 × 22.9 cm (W × H × D) |
| Power | 6.3VAC 0.75A, 250VDC 12mA |
| Frequency Response | 20Hz-20kHz ±1dB |
| Gain | 40dB |
| Gain (Special Connections) | 34dB |
| Source Impedance | 30/150/250/600Ω |
| Load Impedance | 75/150/300/450/600Ω |
| Output Level | +20dBm |
| THD (50Hz-15kHz) | 0.5% |
| Noise Level | -124dBm |
| Tube Complement | 5879 (x2), 6AQ5 |
| Links | Altec 250A Console |
| Notes | 250A Console plug-in module. Available separately for custom installations. |