Questions about Mono, Stereo and Correlation?
When producing house music, should leads be mono to make it sound loud and clear? and have a second layered lead that has reverb on it so the sound is spread out? I find that if you have no mono lead the sound gets lost and isn’t as loud. It sounds muffled. Do you check the correlation while composing music? Do you aim for 1+ or not at all? When using reverb what do you aim for?
I never use a correlation meter when working on music, no need to overthink it IMO. If it sounds good run with it. 
You can make your lead more ‘mono’ with Mid/Side EQ by hi passing Sides to 200-300 hz (or whatever sounds good).
There are also loads of plugins for controlling ‘stereo’ signal, for example PSP StereoPack
Brainworx also has a free stereo width plugin, bx solo.
And to answer your question, as far as I know, leads tend to be stereo.
However it’s also important that your track is ‘mono’ compatible, witch basically means that it sounds roughly the same when summed to mono as it does in stereo and no element ‘disappears’ from the mix.
Correlation meter will give you an idea of that, you don’t need +1 (that’s basically mono) but most pro tracks tend to float somewhere between 0.5±1+
An easy way to bring in a bit more of the mono signal, is to use something like Voxengo’s MSED plug-in. Just turn the mid channel up a few tenths of a dB, and turn down the side channels by the same amount.
One of the biggest issues I see in mastering is people having center images that are too weak, everything’s is pushed to the sides. More than just the kick and bass need to be in mono, so it’s good you’re being concerned.
Think of your stereo image like a tree.
At the bottom is your sub bass - mono.
Working up a bit we have your kick drum and mid bass - mono
Going a bit higher up the tree we’re coming into some mid rand sounds - starting to get a bit wider, but only a bit.
Right at the top of the tree the stereo field is super wide.
Checking mono compatibility whilst you’re producing is always a good idea - just keep checking to make sure your lead is as present with the mix in mono as in stereo. If you don’t have a monitor controller with a mono button, just use a utility plugin on your master buss to toggle back and forth between mono and stereo.
I wouldn’t advise having your entire lead in mono, as it won’t sound as big, but the lower frequencies should certainly be mono (maybe unto 350hz), then spreading out more as you move up.
Go easy on the reverb, as this could be what’s making your mix muddy. A stereo spreader or chorus may work better for you.
Try this: on a send channel put a high pass filter to around 1500hz, followed by a chorus. Then do the same thing but this time high passed to around 6000hz. You can now accurately control how “wide” your sound is at different frequencies by changing the send levels. Send a little bit to the first send, and a lot to the second.
Good luck!
Yup! That was the problem. The sound was lost.
Thanks for all the replies and advice!