| QEI | FM Transmitter Tube Amplifiers |
| QRO | Datas of Amateur Radio Tubes |
| Quad - The home of hi-fi | Tube Amplifiers, Speakers, |
| Quad - The spiritual home of hi-fi | USA site |
| Quad Francophone | Collections, Associations |
| Quad II Modification | DIY Tube Amplifiers |
| Quad Musik | Refurbished Quad gear |
| Quad World | History of Quad Amplifiers |
| Qualtek Electronics | AC Wire, Plugs & Sockets |
| Quantum Cable | Cables |
| Quarterwave | High Power Traveling Wave Tube Amplifiers |
| Quicksilver Audio | Tube Amplifiers |
| Quicksilver Review | Review |