There have been several threads on this subject throughout time here at R.O. and I feel that it is an important subject as many are using or attempting to use multiple mics on single sources or in some cases, for example, a singer songwriter performance where you have two sources effecting two or more mics at a time. A lot is said about the phase relationship of the mics being used though not a lot of clarity on why this needs to be addressed. Certainly pattern size and strength is a primary reason for phase anomalies between two transducers and within this alone, there is a reason to truly understand what a particular mic is capable of before applying it to a source that already has a mic on it. There's lots and lots of pictures on the net of sessions with guitar amps (in particular) being mic'd with all sorts of transducers in order to capture some 'special' sound being produced but the question looms, "Is this really necessary to achieve a quality reproduction of a guitar sound?" I will share with you some pictures of multiple micing being used in sessions and will discuss the whys if there is interest in this subject. I encourage all the engineers and producers here to add their own pics and experiences as well as join in to the discussions. I think that a lot of the time these techniques are employed without much forethought about the 'why' of it and I hear a lot of homemade recordings that suffer in fidelity and size due to some of this. Here are some of my depictions of the use of multiple mics in sessions....... 1. First is a simple two mic wide technique for an acoustic guitar that is not only loud but very full range. The U87 is actually out about 2' and aimed more at the lower bout than the picture shows and the SDC (AT4041) is closer to the 12th fret than it looks like. The clarity comes from the SDC while the size and roominess as well as the stroke is captured by the 87. Since these are not really close to each other the effect you might get from phase is very minimum. I think people miss out on great sounding acoustic guitars by micing them too close and not allowing the sound to develop. 2. Next is a multiple micing of a Bari Sax. You need a good sized car to tote this thing around! Theres a Royer ribbon above the bell simply to capture the 'wind'. It gives (imho) a certain rushy sound to the Bari and lets it sit in the mix better. Only what I like....not a law LOL......Then theres the SM7 down in the brassy part of the bell. We found a resonant spot that really had this instrument's voice nailed. He was pretty still during the take so it worked well. There is also (not pictured) an LDC set up three feet or so above. This gives the 'size' thing I always look for. I use that technique a lot on different instruments. Sometimes its just the thing. Other times its a muted track. 3. I consider this a 'standard' micing of a single speaker combo amp. Royer ribbon and an old SM57. I try and get the capsules aligned as possible but with the ribbon theres not a lot phase problems with other mics as long as they have some space behind them. Yes, for you gear sluts, it is an old Deluxe Reverb. Not an R.I. 4. Another common micing of a combo amp. This one has 2-10's . If you make sure and keep the caps level with each other when you're using similar mics at this spacing the phase problems are minimal. In this case it is (once again) my fave....Royer and 57...There is (not shown) an LDC perched over the top and out for room sound. U87 if I recall. 5. Finally a two mic vocal set-up. This really works on some voices. You have to be very conscious of the position of the capsules to each other as even a slight change in angle can make of break the attempt. This is one of my rebuilt and highly modded ADK TT's (the M249 circuit with CK47 cap) and the Cathedral Pipes U67 clone with a Neumann KK67 cap and Charles' incredible talent as a mic builder. This setup requires strict attention to phase. A Little labs IBP across one of the circuits is a great way to make this really happen. (LOL as a side note I notice that when I took this picture I had NOT set the mics as they were eventually set....) Enjoy and I hope others will participate.