The luminous efficiency is good. Not quite as 50W halogen but better than 35W halogen (subjective impression). Small drawback: If you want to use this as a reading lamp bulbs near the head, will feel it may interfere with the faint but clearly and listening Schnarr / humming noise. Not very loud, but in the silent room definitely audible. When used as a ceiling or wall lamp that should no longer play a role. Tested with 2 different electronic power supplies, with or without front of it a dimmer. All 3 identical lamps made this noise, so obviously due to their construction.
