Tech Tip:When The Sound Sounds Wrong

By Dennis Kambury

Occasionally I get calls from friends wondering why their gear doesn't sound quite like they expected. They may describe the sound as hollow or metallic, or perhaps lacking in depth. However described, it is usually the result of some form of delay.

For example, one guy complained that his multi-effects unit sounded cheap and tinny - a big surprise to him, as he had done his homework before purchasing the unit and was impressed by the rave reviews from other users.

Through a little troubleshooting, we determined that both the dry and effect signals were being output in equal amounts - the ideal setup for in-line effects (like you might find going from guitar to stomp box to amp). My friend, however, was feeding the effects unit from an auxiliary bus on his mixer. Because the effects unit digitized the dry signal before passing it through to the output, that signal was delayed by a few milliseconds. Mixing that delayed signal with the original signal resulted in metallic, robotic-sounding audio. (Note: if the delay time were varied continuously, the result would be that pleasing effect known as "flanging"!)

By editing the effects unit's Mix parameter, we removed the dry signal from the output, eliminating the metallic effect. My friend finally heard the sound he had been expecting!

The same problem can occur with MIDI sequencers. If your DAW has a MIDI echo (or pass-through) option, you could inadvertently feed the output of your keyboard back to its own input. Because it takes several milliseconds to make the round trip, the same comb-filtering effect described above takes place, with equally thin sound as a result. By disabling the MIDI echo option, your sound will be as full-bodied as a cup of Colombian coffee!