How to set the levels of Subs and Tops to achieve balanced sound and safe operation in 6 easy steps

1) Set up your mixer and speakers with all power and signal cables appropriately connected. (OK, this is the hardest step.)  

2) Power the speakers on and turn their levels to minimum. (All the way down.)

3) Pick a very loud song or set of songs to play and start the first one on your player. Check the input level on your mixer to ensure it's not being overdriven. Whenever possible, keep the input signal below clipping, below any distortion.

Boss Tip: Listen for distortion in the tops speakers with their inputs at a very low level. This requires turning up the outputs of the mixer all the way, turning up the speakers until you can barely hear them, then adjusting the input level up until you hear distortion, then down until you hear no distortion. This is informative because if there is any audible distortion with the speaker's inputs at low levels, the distortion is being created before it's reaching the speakers. Obviously any distortion indicates something is being driven too hard and that situation will need to be addressed, usually by adjusting the input levels on a preceding device or within a software application.

If you connect more than one mixer, as in a DJ controller and a secondary mixer, it's critical to follow this same procedure for both and follow the same rule: Keep the inputs from distorting! Overdriving or clipping inputs on secondary mixers is the most common cause of distortion and can cause damage to loudspeakers. It's a common mistake to run line-level outputs from DJ controllers into mic inputs on secondary mixing boards, with the result being the overdriving (aka clipping) of the mic-level inputs. In short, line-outputs should be connected to line-inputs, and sometimes adapters (XLR to 1/4" TRS) or attenuators (aka pads) or new mixers, are called for. Whatever the case, keep it clean!  

4) Now that you have verified there is no distortion on the inputs, with one of the test songs playing, turn the output of the mixer* up until the output meters read at the top of the range where you'll be using it. The specific labeling may vary between mixers. It's recommended to pick a level at which the color of the indicator LEDs changes and to have the higher level indicator just occasionally flashing. The level indicated by the color change will permit the operator to easily recognize when the limit is reached.

*In case there is more than one, the "mixer" in this step refers to the device connected directly to the speakers; however it's necessary to complete all the previous steps on all the devices ahead of the final mixer first.

5) Turn up the input level of the first speaker until the "limit" LED illuminates. (This will be loud, so step 4A might be to warn the neighbors.) When using BASSBOSS gear exclusively, we recommend starting with the subs. If you don't have subs, or if you're using a different brand of subs, starting with a top is appropriate. Repeat with the remaining subs, if any, for one side of your system. Next, if possible, rotate the balance to the opposite side. If you don't have a balance control, disconnect the signal from the first side. Repeat for the second side.

With this step completed, the mixer's output indicators are correlated to the speaker's output limits. In other words, when the mixer indicates signal above your chosen maximum, the system will be at its uncompressed limits. Pushing the mixer above that maximum will indicate that the system is being pushed above the level at which it begins to compress. That's the point at which sound quality begins to deteriorate. It may still get somewhat louder but it won't get better.

(When using tops without subs, follow the procedure to Step 5.)

6) If you started with subs, with the sub(s) of one side on at the previously determined level, turn up the top on the same side until the sound is balanced to your liking. (If you started with tops, bring up the first sub to suit your taste.) Repeat this process for the other side. (Yes, your subs should be in stereo.)

When using tops with one sub or small subs, most often the system will sound balanced when the tops are below the level at which the limit light would come on. This isn't certain because the relative level will vary according to tastes. The selected preset will also affect the level at which the limit light comes on. The more subs in use, the higher the tops level will need to be. In other words, it's possible to use more than one sub with each top, so to realize the full potential of your tops may require using more than one sub with each. When that's the case, the procedure is the same: Set the maximum level on the subs and then add level to the top cabinet until you get the balance you want. If the subs and tops reach their limits at the same time, the maximum output capacity of the system is matched to your tastes.

Following this procedure, the levels should be left where they are. There should be no reason to change them unless a different mixer is used or a different combination of speakers is used.

There is no reason to turn the levels down before disconnecting power from the speakers. It's always best to power the speakers off before powering off mixers and other audio equipment in the signal chain. It's also recommended to connect and power on all other audio equipment before powering on anything with an amplifier.

Here's a handy PDF reference you can download and save to your device for when you are out in the field and need to set your BASSBOSS gear up: