Noise/Hum
•Check the signal cable between the mixer and the subwoofer. Make sure all connections are secure. These problems usually produce crackling noises or hum.
•If you are using two or more TH-18s powered subwoofers, try plugging them all into the same AC outlet panel or outlet strip. The purpose for this is to connect them all to the same earth ground point and reduce the possibility of creating a ground loop.
•If connecting an unbalanced output to the TH-18s balanced input, make sure the shield is connected to the unbalanced ground and to pin 1 of the XLR.
Repair
For warranty service, refer to the warranty information on page 17.
Non-warranty service for Mackie products is available at a factory-authorized service center. To locate your nearest service center, call our Tech Support department at 1-800-898-3211, Monday-Friday, during normal business hours, Pacific Time, to explain the problem. Tech Support will tell you where the nearest factory-authorized service center is located in your area.