Karltone are a U.K based company offering great prices and a friendly service on guitar and amplifier accessories.

All our valves are premium tested by us on precision digital and analogue equipment.

Our power-amp valves go through our in-house 'platinum & matching testing' procedure which entails a 30-40 hour burn-in before testing and matching. The reason we do this is to get rid of any faulty or weak valves and as a pre-grading process to allow the plate/grid mechanism to relax into it's rest position. Tiny differences in construction make for enormous differences in electrical characteristics, and thus if a tube is graded after it's been burned in then the measured characteristics hold true over its lifespan to a greater extent. This seems simple but it's amazing how many vendors ignore it. It's the reason so many people complain about poorly graded valves.

If you have any queries please contact us via the contact us page.