User manual HUGHES & KETTNER PURETONE HEAD COMBO

[. . . ] In a nutshell, a world of killer tone is right there at your fingertips. The PURETONE gives you exactly what guitarists all over the world want: freedom of expression. Next to its exceptional sound quality, the hallmarks of the PURETONE are reliability and stage-worthiness. Every amp of the Custom Tube Series is equipped with tubes that live up to the highest standards for quality and thus guarantee maximum dependability under even the most demanding conditions. [. . . ] Ensure the amp's voltage rating matches your local AC voltage rating before you plug the cord into the wall socket. The mains fuse bracket is located next to this socket. When replacing blown fuses, make sure you use specified replacement fuses only (see Technical Specifications). aNODE FUSE: This is the holder for the power tubes' anode fuses. Here too, make sure you use specified replacement fuses only when replacing blown fuses. If a replacement fuse blows after just a short while in operation, you should definitely have the power tubes checked for defects. oUTPUT: On the PURETONE head , the OUTPUT POWER switch is located on the rear panel. (For more info, check out the description above. ) SPEAKERS: The PURETONE features two speaker outputs for connecting speakers with an overall minimum impedance of 8 ohms. This means that you can connect either an 8-ohm cabinet or two 4-ohm cabs to the PURETONE head. on the combo version , the output is factory-connected to the internal 16-ohm speaker. You'll find the connector for an external cabinet behind the rear panel next to the connector for the internal speaker. Bear in mind that if you want to connect additional speakers, you can only connect a 16-ohm cabinet. However, if you first disconnect the internal speaker, you can connect an 8-ohm cab. Once they've been burned in (initial continuous operation under a load), these undergo an in-depth selection process where their electrical values and mechanical status (microphonics) are checked. Beyond that, they're installed in a finished amp and their sound is auditioned in a listening benchtest. One of the most important steps is power tube matching, a process whereby tubes with the same characteristics are selected and combined to make matched sets. The golden rule: Replacing tubes is a job best left to qualified professionals. Accordingly, these guidelines are addressed to reputable technicians who earn their living with a screwdriver: Pull the mains plug of the PURETONE and allow for a discharge time of at least two minutes before removing the sheet metal panel on the rear of the amp. Once the panel is off, you can cautiously ease the tubes out of their sockets. A single power tube may only be replaced if the replacement tube is precisely matched to the original, in other words, it has the same characteristics. As a rule, if you are replacing power tubes, use matched sets only. [. . . ] - Ensure plenty of air can circulate around the amp's ventilation slots at all times your PURETONE's life depends on it. Be very careful about the kind of peripheral devices you connect to your amp and always check out their specs before you plug them in. Never connect speaker cabinets with an impedance (ohm) rating lower than the PURETONE is designed to handle. Under no circumstances should you connect devices with high output signal levels (e. [. . . ]