Originally posted by CFS:
So I am wondering what happens to the pickup patter of a figure 8 mic if you 1. Lets say seal or duct tape the rear port
A quicker, less destructive way to test this would be to simply cup your hand around the back of the mic. Results will depend on the specific mic used and the exact position of your hand. Are you trying to get a cardioid pattern out of a figure 8 mic? Simply positioning the mic differently (further away) might give you the results you're looking for.

or 2. you spilt the mic like you do for M/S but make it so you reverse the phase on the rear lobe so they now both have positive phase?
I don't get this one at all. If you reverse the polarity of the back plate, you will drastically change the properties of the mic, possibly making it unusable for m/s (or maybe anything else for that matter).

Do you have something specific in mind? Or are you just tinkering to see what happens?

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So I am wondering what happens to the pickup patter of a figure 8 mic if you 1. Lets say seal or duct tape the rear port or 2. you spilt the mic like you do for M/S but make it so you reverse the phase on the rear lobe so they now both have positive phase?

On 1. RCA did this on the 77dx when they built an acoustic labryinth to close off the back of the ribbon on a figure 8 It became more directional but sounded like crap.

On 2. You will end up with an omnidirectional microphone pattern.

I am just trying to get more results out of my mic collection essentially. So now the question becomes if the figure 8 would be come omnie how could i wire an adapter to do that so i dont need to use up two mic pres/tracks to do it? Any ideas?

You didn't say what figure 8 you were using. If it is a condensor, It is really two cardioids back to back and that is the system that I was referring to when I said that the system could become omni. This needs to be done within the microphone as you will not have seperate wire sets coming from each capsule.

If it is a ribbon, them you won't be able to get the result as the pattern is developed at the ribbon and the electrical signals cannot be changed. Any signal from the side hits both sides of the ribbon at the same time and the ribbon doesn't move, so there is no signal generated.

I have a Neumann UM 57 that uses an external power supply that I had modified to give continuously variable patterns from omni to hypercardioid to figure 8 and sub cardioid and everything in between. In any case, this isn't a really cheap way to make the most of one microphone.

I'll say it again, like the real estate motto...

Position, position, position!

Instead of worrying about what pickup patterns you don't have, use the mic's you do have to your advantage. I never let the lack of an omni mic stop the session. I use what I have in front of me to the best of my ability. Sometimes I use it in a way that wasn't originally intended, but somehow get it to work for the track. Limitations can be an excellent tool for experimentation and creativity.

Tell us some of the situations where you found yourself needing a different mic pattern. Maybe there are some non-invasive solutions for them.

I have every pattern and plenty of mics available to me, this was all just insomnia curiousity thinking and not being able to sleep. The mic I am gonna try it with is a royer.