Topic: capsule choices: subcards/hypers/omni

[daze]

If all goes well, I'm hoping to run 2 mics/bboxes through my dr2d for an upcoming show.  I'll be in front row lower balcony.  I'm planning on using my trustworthy sp-cmc-4 cards for one of the setups, and am wondering what would be best for the wildcard 2nd set (if I decide to go this route). I have subcards, omni, and hyper capsules (for another sp-cmc-4).  Thanks in advance for any tips/advice.

[DavidPuddy]

You can't go wrong with subcards IMO

[daze]

You can't go wrong with subcards IMO

Thank you. That was my gut instinct but I figured I'd ask the experts.

[Gutbucket]

How's the room acoustics?

If decent, go with the subcards, wider-spaced than your cardioids.
If challenging, go with the super/hypers.

Either way, consider running them in PAS, spaced apart based on this-



That will make for a good comparison between the two.

[Gutbucket]

Or.. If your intention is to play around with mixing the two together afterward:
1) Run one pair spaced around 24" apart, angled +/- 45 degrees (90 degrees total).
2) Run the other pair X/Y in the middle, spaced a bit forward of the first pair.

That configuration tends to work better when the two pairs will be combined.

[daze]

Or.. If your intention is to play around with mixing the two together afterward:
1) Run one pair spaced around 24" apart, angled +/- 45 degrees (90 degrees total).
2) Run the other pair X/Y in the middle, spaced a bit forward of the first pair.

That configuration tends to work better when the two pairs will be combined.

Thanks for the helpful information.  I'll be in stealth mode so will be severely limited (but figure if I have the capacity to plug in 2 sets of mics, why not).

[Gutbucket]

Have at it.

Retaining your regular setup while running another and comparing the two afterward is the best way I know of to really figure out what works best and where.

Try them all over time, and you'll really get to know what each can do. I'd probably gravitate to the subcards first.

[EmRR]

Stealth, then I’d consider a ‘Strauss Paket’ approach, make 2 virtual mics by mounting 2 diff types as close as possible with the capsules aligned, and mix them later for best pattern. I’d go with sub and hyper probably, or sub and card.  Good luck!

[rocksuitcase]

what EMRR said. I'd also go card/subcard if close, maybe card/hyper if farther away

[Gutbucket]

^ Fun stuff, and I'll add some details about it in a following post..  But tread with caution.  In a number of ways this is one of the more complex arrangements you are likely to come up with using four channels, subject to a few potential problems.

The good-

• If it works out right, you can extend low frequency response of the cardioids or super/hypers
• If it works out right, mixing the two will produce a variable virtual polar pattern that ranges between the two used, adjustable afterward
• You can do things to create polar patterns that vary with frequency
• You can still compare between the two separate pairs, and use just one stereo pair or the other if that works out best

The bad-

• Its more complicated
• In practice, its not as clear cut as described in theoretical terms - there are various interactions all working at the same time
• It can be difficult to determine if its really doing what you think its doing

The ugly-

• If it doesn't work out right - say the the phase response match between of the two pairs differs, and/or the capsules are not closely aligned so as to be nearly coincident, you can get unwanted constructive/destructive interference, which might manifest as a roll off in high frequency sensitivity, a weird peaky response, or a ragged polar response
• With power comes responsibility - you sort of need to commit to listening closely with fresh ears for problems that typically won't arise from just using one pair or the other (or from two pairs arranged so that they can be mixed with less potential problems to begin with, as suggested in my second post).. and to doing the post processing mixing work

[Gutbucket]

The theory behind it-
(you may already know this!)

Fundamentally, all first order directional polar patterns are created by the combination of pressure (omnidirectional) and velocity (bi-directional or fig-8) components. 

A cardoid pattern results from a 50/50 combination of pressure and velocity (which is to say, 50% omni + 50% fig-8).  A subcard results from more omni, less fig-8, a super/hyper from less omni, more fig-8.  In most of the microphones we use, this combination is determined by the construction of the microphone, and is fixed.  But in microphones that feature mechanically or electrically switchable patterns, this is what is actually being changed to affect a change of pickup pattern.

If you mount an omni and a figure-8 so as to be as coincident as possible and record their outputs as two to separate channels, when you mix those channels together later, you get a polar pattern that can be varied depending on the level difference between the two.  Cool, huh?

Practicalities-

• If possible, use two microphones of the same model with different polar pattern capsules (as they are more likely to have close phase and frequency responses)
• Make sure the polarity of all channels is the same.  If polarity of one channel of the packet is reversed, whatever virtual pattern is produced will face backwards (and in most cases will not be the same forward-facing pattern you would've gotten with the two in the same polarity)
• To do it right, tape or otherwise mount a microphone of each pair together so that both are parallel and the diaphragms as close together as possible, one directly above the other in the vertical plane.  Do not allow either microphone of the "packet" to shift at all in relation to the other (you also don't want the two "packets" to shift relative to each other, in the same way that you don't want two microphones of a stereo pair to shift relative to each other, but it is more critical in this case)
• If it gets weird or sounds odd, you can always revert to using just one pair or the other..
• ..or you can try implementing a cross-over between the two.  This will keep the two from interacting outside of the cross-over range.  So if using say an omni and supercard together, you can have omni response below the cross-over point, supercardioid response above that point, and a morph through cardioid in the crossover region
• A simple version of that is low-pass filtering the omni wherever the supercardioid begins to naturally roll-off, and leaving the supercardioid unfiltered.  You then get extended omni bass at the very bottom, cardioid through the rolloff region and supercardioid response through most of the supercard's frequency range.
  
• Shaping frequency response of the two channels differently using complementary EQ (one cutting where the other is boosting) is a more subtle way of morphing polar pattern than a hard cross-over, but requires good interaction between the two.
• You'll get the greatest range of adjustability by combining patterns that differ most.  If you don't have a fig-8, that means omni + hypercardioid (hypercardioid is mostly bi-directional with a little omni thrown in)..
• ..but unless you've already determined that it's working well for you, it will be safer to use the two patterns you think will be most appropriate to the situation on their own.  This will reduce the total range of adjustability, but either on its own is more likely to make a good recording.

[daze]

Thanks for all of the information (both the plain-language summaries and the theory/technical stuff behind it, are very helpful).  Lots of food for thought.