House of Stereo · Conrad-Johnson
Room for the music to grow.
Some evenings call for a solo voice. Others call for the whole orchestra. The Classic 120 gives a separates system more output headroom while keeping the familiar Conrad-Johnson emphasis on tube amplification and carefully chosen parts.
Inside the design
Purposeful engineering.
The standard Classic 120 uses eight EL34 output tubes. Its separately listed SE sibling uses KT120s and upgraded passive components. KT120 substitution requires circuit changes; it is not an owner tube swap.
Build the right system
The details that matter before it arrives.
Connect a preamplifier or suitably volume-controlled source to the RCA inputs. The manual specifies at least four inches of clearance above and three inches at the sides, with the shelf open front and back. Built-in indicators assist output-tube bias adjustment. Follow the manual when replacing tubes.
The numbers
Classic 120 Stereo Power Amplifier specifications
| Rated power | 125 W/channel into 4 ohms; both channels driven, 30 Hz–15 kHz, ≤1.5% THD |
|---|---|
| Input sensitivity | 0.9 V RMS for rated power |
| Frequency response at 10 W | 20 Hz–20 kHz, ±0.3 dB |
| Hum and noise | 96 dB below rated power |
| Input impedance | 100 kohms |
| Tubes | 3 × 6922; 8 × EL34 |
| Dimensions (W × H × D) | 19 × 7.63 × 18.88 inches |
| Net weight | 75 lb |
Keep the useful stuff
Documentation & further reading
Manufacturer resources
Official product information · Download the owner’s manual (PDF)
