Classic Four
| Brand | KLH |
| Manufacturer | KLH Research & Development Corp. |
| Series | Research Ten |
| Function | Speaker |
| Produced | 1975 |
| Country | United States |
| Model ID | CL4 |
| Form Factor | Bookshelf / Stand Mounted |
| Signal Path | Passive Hardware |
| Dimensions | 36.2 × 68.1 × 32.8 cm (W × H × D) |
| Weight | 52lbs |
| Frequency Response | 38Hz-15kHz +1/-2dB |
| Treble | 1.9" Paper Cone (x2) |
| Midrange/Bass | 12" Paper Cone |
| Impedance (Nominal) | 8Ω |
| Crossover Frequency | 1.5kHz |
| Recommended Amplifier Power | 25-150W |
| Power Handling | 150W |
| Enclosure Type | Sealed |
| Finish | Walnut |
| MSRP (1976) | $170 |