ProSoundWeb | The New Bumper Crop of Large Diaphragm Condenser Mics

The New Bumper Crop of Large Diaphragm Condenser Mics
By Ty Ford

SELF-NOISE

Self-noise is the electronic noise made by the circuitry of condenser mics. Self-noise usually sounds like Pfffffft. You'll see its figures as "self-noise" or "equivalent noise level". Specs usually show the figure in dB A, or "A weighted." A weighted (dB-A) means an low end rolloff EQ curve has been applied which gives the mic a more favorable (lower) figure. If you’re recording very quiet instruments or sounds to a digital medium, using mics with low self-noise is very important. If your source is a Marshall guitar stack with half a dozen pedals, the rig itself is probably making so much noise that you’ll never hear the mic self-noise. I try to stick to mics with 12dB-A self-noise figures and lower when recording quiet sources to digital media.

SENSITIVITY

Sensitivity is usually measured in millivolts per Pascal seen in specifications as mV/Pa. The more sensitive a mic is, the more signal it generates. Generally, using mics with lower self-noise and higher sensitivity results in better recordings. I say generally because mics with higher sensitivity sometimes have less headroom. That means you can’t use them with extremely loud sources (known as high SPL - Sound Pressure Level) because the mic will distort. Padding at the console, or even on the mic itself won’t help if the capsule is being overdriven. A pad in between the capsule and the mic electronics will keep the electronics from overloading. A pad after the mic electronics won’t be of that much help, but many cheap mics are designed that way.

DISTORTION

Almost every mic I’ve listened to colors the sound by its unique frequency response. Distortion, on the other hand, is an edginess: a scratchy sound. Many, but not all, of the new low cost condenser mics have this problem. It’s a problem because, unlike coloration which can be changed with mic placement and EQ, you can’t get rid of distortion. If you want clear, deep recordings you can listen way down into, you can’t use you can’t use edgy mics because the edges create unnecessary aural boundaries. Like looking into a cracked mirror, those edges prevent the image from being seamless and deep.

OFF-AXIS SOUND QUALITY

The mark of a truly well-designed mic is what it does to sounds that arrive from the sides. In most cases, that applies to any angle more than 45 degrees off center. If the frequency response changes radically for off-axis sounds, that means any sound bouncing around your studio and coming in from the side will be affected by that change frequency response. This can be a subtle but destructive problem when using multiple mics aimed at different sources. Then you have sounds from one source getting into another mic from an off-axis position. The more gnarly the off-axis response, the more gnarly your mix.

PATTERN SHAPE

Omni, Cardioid, Hypercardioid, Figure of Eight. I wish it were that simple. Some cardioids are wider than others. Some have weird lobes in strange places that hear sounds you don’t want and twist those sounds so they’re even worse. If you’re trying to keep the room sounds or other instruments out of your recordings, a mic with a tight pattern is important. Omnis, NOT as the name implies, are often directional at high frequencies. Not all figure of eights have the same high frequency response on the back capsule as they do on the front capsule. Stay away from them.

FET vs TUBE MICS

We’ve come a long way with tube technology in the past five years. The new tube condenser mics are not necessarily noisier and thicker sounding than FET (Field Effect Transistor) mics. In fact, a good new tube mic can sound quieter and less distorted than a new FET mic. The Audio Technica AT 4060, Soundelux U 95 and Rode NTK are good examples of quiet new tube mics.

Among the quiet ones: AT 4060

Tubes also offer the possible advantage of absorbing transients more gracefully than FET mics. I use “The Dreaded Key Jangle Test” to check how well a mic handles transients. Grab one key on a ring full of keys so the rest of the keys dangle and touch each other. Shake the ring at about four inches from the mic. This is a brutal test of how well the mic will handle transients.

With most mics, you’ll hear obvious distortion in the form of a splatting sound. As you move the keys away from the mic, you’ll hear less splatting. Good tube mics will let you get a lot closer before they break up because the tube absorbs the excess transient energy and rounds off some of the hard edges.

NEW & USED

Unfortunately, buying some of the new low cost condenser mics is no guarantee that they’ll work. Given the lapse in QC on some of these mic companies, I strongly suggest you listen to the actual mic you’re buying before you walk out the door. If you’re buying by telephone from a catalog, get the return policy. Some dealers don’t accept mic returns. They’ll tell you it’s because of “Health Reasons.” Having inquired specifically about that policy at one corporate headquarters, I never got an answer and my follow up calls were never returned.

Were I to hazard a guess, it would be that many a dealers’ good faith has been abused by buyers who “buy” on Friday night, record or play out on the weekend and return the mics on Monday for a refund. Business works best with good relationships. Having a good relationship with a store manager is a very good investment. That’s usually hard to do with someone at a catalog outlet. On the other hand, the better catalog/internet outfits counter with good prices, convenience and an open return policy--including mic returns!

What about used mics? They can be a bargain, but you really have to know your stuff. If you’re unsure, never pay more than you can afford to lose.

That’s it for now. You comments are, as usual, expected and taken as they are presented. Next time I’ll be peeking under the hood of some mic preamps and trying to get to the bottom of some of those secrets. Got questions for me? Hit the boards here at ProSoundWeb or at http/www.jagunet.com/~tford.

For a proven technique for comparing the performance of two microphones (and avoiding disillusionment), click here.

For an enlightening (and provocative?) conversation with Schoeps microphone designer Joerg Wuttke, click here.