Members gubu Posted August 23, 2011 Members Share Posted August 23, 2011 Say if you set them up as a coincident pair but at 180' to one another, one aimed at your source, the other aimed away? Would you need to flip the phase on the 'back' mic? Link to comment Share on other sites More sharing options...
Members Zooey Posted August 23, 2011 Members Share Posted August 23, 2011 I'd say no. It sounds like it would mimic a quasi figure 8. Sounds like something kind of like this: http://www.oktava-shop.com/view_prod.php?id=154 But I don't understand why Oktava says you need a stereo pair of MK-012 to make it work. edit: I think they mean you would need 2 mics, plus this adapter to do M/S recording. Link to comment Share on other sites More sharing options...
Members gubu Posted August 23, 2011 Author Members Share Posted August 23, 2011 Yep that's what I was wondering, what kind of a pattern would you get. Superimposing the response patterns of 2 cardioids suggests that it might be similar to an omni but I wish I'd bought a pattern selectable mic or 2 back when I was rich! Link to comment Share on other sites More sharing options...
Moderators Lee Knight Posted August 23, 2011 Moderators Share Posted August 23, 2011 http://www.tonmeister.ca/main/textbook/node469.html Link to comment Share on other sites More sharing options...
Members gubu Posted August 23, 2011 Author Members Share Posted August 23, 2011 http://www.tonmeister.ca/main/textbook/node469.html Thanks Lee. The math is a little beyond me but it does seem to prove that what you're getting with coincident cardioids at 180' is an omni pattern. This is hugely helpful. A recent post on this forum suggested that omnis are a great mic for acoustic guitar. I remember doing this by accident with 2 cardioids a good few years back and being pleasantly surprised by the results. The mics weren't matched but they were fairly coincident and 180' to one another. I was using a borrowed LDC and mistakenly faced it away from the guitar Summed with the 'direct' mic, it sounded pretty good, much better than the direct mic on its own. Link to comment Share on other sites More sharing options...
Moderators Lee Knight Posted August 23, 2011 Moderators Share Posted August 23, 2011 Yeah, I stopped completely at the math... Link to comment Share on other sites More sharing options...
Members DigitMus Posted August 23, 2011 Members Share Posted August 23, 2011 Although 2 cardioids can be combined to give you an omni (or close enough) pick-up pattern, it WON'T give you a true omni's immunity from proximity effect. Unfortunately, that immunity is one of the major factors that make omnis such a good choice for acoustic instruments. Scott Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 23, 2011 Share Posted August 23, 2011 One of the methods many mikes use to "create" a cardioid directional pattern is to create alternative pathways for the sound to travel to the rear of the diaphragm. If you block those rear ports, the response of many cardioid microphones becomes omnidirectional... BTW, great link Lee -- the author did a good job of covering the subject IMO. Link to comment Share on other sites More sharing options...
Members gubu Posted August 23, 2011 Author Members Share Posted August 23, 2011 Thanks guys. I have some more questions. I hope I can phrase them so they make sense! As many cardioid mics have a roughly omni pattern with respect to bass frequencies, shouldn't proximity effect be cancelled out or reduced when the signals from the 2 mics at 180' are summed? The bass from the 'front mic' should be 180' out of phase with the bass from the 'back' mic, no? Phil, I'm wondering how to do that with a 'barrel' shaped LDC as there is no obvious interference porting anywhere on the chassis? edit:- I just noticed you said you can only do this on some mics. Also, when blocking ports, is this going to affect the frequency response of the mic besides reducing proximity effect? Link to comment Share on other sites More sharing options...
Phil O'Keefe Posted August 24, 2011 Share Posted August 24, 2011 Check this out... Link to comment Share on other sites More sharing options...
Members gubu Posted August 24, 2011 Author Members Share Posted August 24, 2011 Check this out... What about the new questions, above? Link to comment Share on other sites More sharing options...
Members RevRomansky Posted August 24, 2011 Members Share Posted August 24, 2011 I needed a real classic sound on my acoustic, pulled out the SM58 and, voila. I think they used 57's/58's in the heyday more than we know, and they're cardiod, but surely boxed in to the "classical sound" pardigm. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 25, 2011 Members Share Posted August 25, 2011 If you get yourself a reverse phased adaptor cord that you can connect to the mic cord where the + and - leads are reversed you can try some cool things on an acoustic guitar like micing the front and back of the instrument or amp, or record a wall reflection etc and have the waves not cancel each other out. I havent tried it but you may be able to use three dynamic mics to creat a coincident-pair type recording. You would normally use a bi directional mic for the side mics in that case, but with two dynamic mics one reverse phased you may be able to do something very simular. http://www.deltamedia.com/resource/stereo_microphone_techniques.html Link to comment Share on other sites More sharing options...
Members gubu Posted August 27, 2011 Author Members Share Posted August 27, 2011 If you get yourself a reverse phased adaptor cord that you can connect to the mic cord where the + and - leads are reversed you can try some cool things on an acoustic guitar like micing the front and back of the instrument or amp, or record a wall reflection etc and have the waves not cancel each other out. I havent tried it but you may be able to use three dynamic mics to creat a coincident-pair type recording. You would normally use a bi directional mic for the side mics in that case, but with two dynamic mics one reverse phased you may be able to do something very simular.http://www.deltamedia.com/resource/stereo_microphone_techniques.html I haven't had time to check out the link yet but will do. Isn't using a phase reversed cable the same as engaging the phase reverse switch on a mixer or in your DAW? Link to comment Share on other sites More sharing options...
Members gubu Posted October 21, 2011 Author Members Share Posted October 21, 2011 Phil, I tried your suggestion about blocking the ports on one of my SE3's to make it an omni. It certainly does give scope for closer mic positions and a more 'transparent' guitar sound but I'm also getting a phasey low mid hump that is un-eq-able. Pity, because it does have potential. Now to buy a couple more leads so I can run a 2nd mic in my living room Link to comment Share on other sites More sharing options...
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