Microphones, part 1

 

Recording sessions all start with and are dependent upon microphones.  It's where the sound is captured, and everything about that step is critical.

That said, microphones are an odd thing.

Mics are a very personal choice.  Each one sounds different, each are intended for different purposes, and they all have their place.  It's not too different from photographers using different lenses or paint artists using different brushes.  Well-stocked studios have dozens of microphones; all for different applications and aesthetics.

With rare exception (like antique carbon telephone microphones), all microphones fall into one of the following categories:

• Dynamic
• Ribbon
• Large-diaphragm condensor (LDC)
• Small-diaphragm condensor (SDC)

For mic'ing instruments in mono, I really like the slightly wider image provided by LDCs.  However, I mic instruments in stereo, and in my experience, I've found that SDCs provide a highly improved stereo image, which is very important to me.  I also prefer the better transient response of SDCs.  Hence, I almost always use SDCs on my instruments when in a recording studio.

My current favorite SDC for my instruments is the venerable Shure SM-81.  It's detailed without being harsh or brittle.  And the details are well-balanced; they're not too crisp or too out front.  The 81's frequency response is pretty flat across its range, and has a very usable proximity effect that is not muddy and still retains good definition in the bass registers.  That is a trick that not many cardioid-pattern microphones can pull off.

Other microphones that I really like:

• Shure KSM-32.  A cardioid medium-diaphragm microphone.  Clarity and detail; flat at 20kHz.  Due to that extended top end response, it resolves details better than many other microphones.
• Shure KSM-141. In omni, this is my favorite mic for classical guitar.
• AKG C-460-B with either the CK-61 (cardioid) or CK-62 (omni) capsule.  AKG no longer makes these, and the ones I have are well over 30 years old.  A very accurate and linear capture without adding much of anything.  The CK-61 capsules have a usable proximity effect, but it's not quite as clear as the SM-81 and loses a bit of definition in the bass registers.  The top end is a tiny bit brighter than the SM-81, but never harsh.

Last week, I put up the AKG-460 in a side-by-side mic comparison with the SM-81.  For this comparison, I used both the CK-61 and CK-62 capsules.  I like both equally, but for this setting, the CK-61 brought more of what I wanted to hear.  It was a very difficult choice.  The midrange on the 460 sounded more natural and had a measure more clarity and detail than the 81.  The bass registers were very close, but I preferred the 81, as the proximity effect had more resolution.  The 460's proximity effect was very full, but almost muddy compared to the 81 with less definition and clarity.  The upper registers were very interesting.  The 81 captures upper registers very accurately without adding much of anything.  Many microphones have an enhanced or exaggerated upper register making them sound very bright.  Sometimes that's good.   But it's not what I want, as a brighter mic can place too much emphasis on artifacts that you don't want emphasized; for example, finger noise or string squeak.  The 460's upper registers had great clarity and provided more note separation in complex harmonic situations.  The 81 didn't quite articulate this as well.  However, additional clarity in the upper registers also brings forward unwanted artifacts. It was a tough decision as it's all about balance and trade-offs.  The 460 sounded truly great.  But due to the 460 placing a bit more emphasis on unwanted artifacts and having less articulation in the bass registers, the 81 won out.

Regarding spatial pickup, the 460 proved to have a somewhat wider cardioid pattern, and picked up more of the room sound.  The 81 had a more conventional cardioid pattern, which again I preferred in this comparison.

I'm pretty happy with the 81, but it would be ideal to have the added resolution and definition of the 460's top end without placing undue focus on unwanted artifacts.  

I sometimes wonder if the quest for microphone improvement ever ends.

-kk