The nature of mixing a wide stereo track and then playing it back on a mono device is that you're bound to deal with instruments disappearing which is why some people advise to mix in mono.

Go listen to your favorite tracks on your phone's speakers. Compare them with your own. What's different?

In FL, there's a knob under each mixer track called 'Stereo Separation' that can be turned clockwise to merge the audio to mono. It's on the Master track as well.

Listening and mixing in mono is a really good habit to get into. If not for making sure sounds aren't vanishing on smaller mono speakers, it's a great way to ensure your most important sounds are up front and taking centre stage, and also for making sure your bass isn't disappearing, or not as solid as it sounds in stereo.

awesome thank you, now is there a way to do this same thing in cool edit for vocals?

You could just set your entire project to mono and adjust from there.

or find a stereo width plug in, and make sure that it has mono capabilities and slap it on w/e instrument/channel you want to check it out on

The best advice ever given to me was to check your mixes in mono. I have a stereo processing effect rack I made that I use on many of my mix busses and the master bus. If you use Ableton you can grab it here:

https://dl.dropboxusercontent.com/u/3817027/FM%20Stereo%20Processor.adg

Here are what the macros do:

• Low X-Over: the crossover frequency for low to mids
• High X-Over: the crossover frequency for mids to highs
• Mid Drive: Adds some analog clip saturation drive to the mids
• High Drive: Adds some analog clip saturation drive to the highs
• Low Width: Lets you make the lows less wide (on big systems, you should be full mono down there)
• Mid Width: Control width of mids
• High Width: Control width of the highs
• Master Width: If you turn this to 0 you will be in full mono.

If you put the master to 0% width you may find something similar to what you are hearing on your mobile phone speakers. (summed mono can be a killer if you don't have all your phasing perfect)

I've found this rack super useful in controlling the low end because any stereo information below around 150hz will rob you of power on a club system because the subs are almost always summed to mono. Just slap this on your bass buss and set the low width to "0". Then tweak the low x-over until it sounds the best.

If you pull the master width to 0 you will here anything with phasing issues cut out and as you open it back up you will here which things you need to "fix"...

Controlling the mid and high width individually can also help diagnose phase problems that may be fixable with EQ.

Enjoy

Ableton's Utility effect has a stereo imager built in - pull it to your master, drag the 100% at the bottom of the effect window to 0% and boom. Instant mono.