Korby Audio Technology FET Condenser Mic

By Barry Rudolph

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Korby Audio Technology FET Condenser Mic

The Korby Audio Technology FET condenser microphone is an updated version of their FET cardioid-only model and is offered in two versions: the Studio version (tested here) with its single-backplate design and the Broadcast version with a dual backplate capsule. The studio version produces an extra 10dB output over the Broadcast model by using a custom-wound Cinemag output transformer. The two versions are identified with either a red (Studio) or black (Broadcast) painted dot marker at the XLR connector to indicate which model.

The Korby FET studio microphone uses a newly designed 1-inch diameter Mylar gold-sputtered 3-micron diaphragm. All Korby mics use their own handmade and ear-tuned capsules, and the company does its own in-house sputtering. Said to "lean towards" the sound of a Microtech-Gefell M7 capsule, the Korby has a center-terminated front diaphragm (active side of the mic) and a rim-connected backplate.

The capsule itself is encased in a white colored Teflon "collar," and there are two vertical rubber straps that straddle the capsule's active surface area on the left and right sides. These straps also wrap around over the back of the capsule in the same fashion. Said to protect the capsule from severe damage if the mic was ever dropped, this entire system is mounted on a pedestal machined from nearly invisible acrylic that rides on two rubber shock absorber standoffs attached to the top of the amplifier compartment below. With the update, this capsule can handle higher SPL--up to 140dB SPL--due to its new design. Designer Tracy Korby remarked that the capsule's output level can exceed his head amp's input capability--I found this when I got a little too close to the front head of a kick drum.

The FET head amp uses 0.8-mA of phantom power current and is point-to-point, hand-hand wired using individually selected and tested premium components. The entire capsule and head amp assembly fits into the mic's stainless steel case with a finely weaved stainless steel mesh windscreen that is internally attached to the case with an adhesive. There are no attenuator or roll-off switches--only the Korby logo indicating the front of the mic.

The updated Korby FET retains the gimbal U-shaped mounting system but adds isolating rubber bushings on both sides of the microphone's body that shock-absorb vibrations transmitted up the mic stand. Overall, this new version is more rugged than before with accidental changes in the mic body's tilt in the gimbal less likely.

On The Job

The Korby weighs about 380 grams and its demure size makes for a less intrusive setup than larger studio mics for placement in front of acoustic guitar players.

The first of two different acoustic guitar recordings was of an Ovation Celebrity--a bright sounding, steel string acoustic that the Korby FET captured brilliantly. I used the studio's API 1608 console mic pre with minimal mic gain and no pad. As soon as I raised the console's fader, my guitarist (who was playing on mic) immediately commented that the guitar's sound in his headphone mix was huge! I had the mic out about 4-inches over the 12th fret and aimed towards the sound hole. For loud strumming or to get more "body" into the recording from this thin-sounding instrument, I liked the mic directly over the sound hole and close in.

I found a new favorite microphone for nylon-stringed guitar at a project studio where I used the mic pre in an old Digidesign 002 interface. The new Korby FET sounds like a small diaphragm microphone with good transient reproduction for a clear, thick and tonally balanced sound as if EQ'd. Every nuance of this instrument (including fret squeak noise) was easily heard along with the reverberant qualities of the room my musician and I were sitting in.

The cardioid front lobe of the pickup pattern is wide in the low frequencies and small changes in the mic's aim are hearable and I never felt the need to do any corrective equalization--I would just move the mic around and try different distances, aiming and/or tilting the mic down from above the instrument.

Next was as a mono drum overhead where the Korby FET's bright sound worked well. The hi-hat sounded clear with good "chick" presence, and the ride cymbal was captured with excellent stick definition. At about three feet above the rack toms, there was plenty of low frequency heard coming from the snare, toms and kick--all I can say is I wish I had a pair of them to try for overheads!

The Loud And Close

The Korby Audio FET is rated at max SPL: 140 dB THD @ .5% with a self-noise of 17 dB A-weighted and a total dynamic range to the head amp is 122dB.

For the rest of my testing of loud sources and close lead vocals, I used a Pete's Place Blast Filter between the mic and source. Like any thin diaphragm capsule, without this protection you risk the diaphragm "bottoming out" against the backplate with any significant wind plosive from close-by vocalists, air pumping out of kick drums, loud guitar and bass cabs--whatever is moving air around the studio. Tracy Korby redesigned the mic's pressure plate and says it: "aids in reducing the pressure of the leading wave and serves as additional shock protection."

I think a good addition to the kit for any thin-diaphragm condenser mic like the Korby FET would be a form-fitting plastic sleeve for covering the windscreen section (and capsule) when storing, moving it or setting it up.

I tried the Korby FET about 18 to 24-inches out in front of a 22-inch kick drum fitted with a DW KickPort. I used it exactly how I would use a Neumann U47 FET in a covered bass drum tunnel. The microphone pre-amp gain setting in the ML530 Analog Mic-Line Preamp in the studio's Euphonix S5 Fusion was at minimum and more than enough beater attack and low frequency content from the front head was captured without any EQ. When time-slipped in Pro Tools, the Korby FET track and the AKG D12 VR placed in the KickPort added up to great kick drum sound.

Next I tried the Korby on a Fender Blues Junior amp in all the same mic positions I normally placed a Shure SM57 dynamic. It sounded great although none of the SM57's "compressed" qualities and not as much "nose"--mid-range honk. I liked it for a more transparent sound that suited my player's clean lead playing style. For overdriven sounds, I used the proximity effect to dial in the low frequency content level required--at a foot away from the amp I got a cabinet sound where the Korby FET pulled in the ambient room sound along with the amp's sound.


I recorded lead vocals with my male singer using a BAE 1073 channel strip. I used minimal gain--20 to 30dB gain and the 1,200 ohm input impedance position and no EQ. (the Korby has a 500-ohm output impedance). My singer had been using the studio's Neumann U87Ai that sounded good but the Korby had a more open and airy sound with less of low mid-range thickness. When singing close, the sound of the 87 is much more proximity-dependent than the Korby. Output levels of the two mics to the BAE were about the same and we tried to keep a consistent 4-6-inch mic distance and the same windscreen.

Particularly for vocal recordings, I do wish the gimbal mount assembly could be completely removed from the mic's body for conventional shock mount usage. If you wanted to set up the mic vertically like a stage vocal mic stand, the mic's cable rubs the bottom of U-mount and sometimes limits final position tweaking.

Good Investment

The new Korby Audio Technologies FET Studio condenser makes a good workhorse and is great for capturing any source. It excellent for drum overheads, acoustic guitars, and certain vocalists who would benefit from the way it captures sound in a bright and detailed manner without need of EQ.

 Try This! 
One of the studios I tried the Korby FET on electric guitar cabs has a terrazzo tile floor that's very hard and reflective. Instead of aiming the mic directly at the speaker cab I went for a bounce off the floor in front of the amp. So after tilting the amp at the floor and moving the mic and adjusting its angle, I arrived at just the right comb filtering sound--a 50/50 mix of both the direct and reflected sound off the floor that worked unbelievably well for funky rhythm part. I put gobos all around this setup to reduce additional reflections off the studio walls--I was looking for only the mix of the direct and bounce off the floor in front of the amp.

Barry Rudolph
 Barry Rudolph 
Barry Rudolph is a recording engineer/mixer who has worked on over 30 RIAA certified gold and platinum award-winning records and three Grammy Award winners. He has recorded and/or mixed: Lynyrd Skynyrd, Hall & Oates, Pat Benatar, Rod Stewart, the Corrs and Robbie Nevil among others.

Barry has his own futuristic music mixing facility called Tones 4 $ Studios; and also teaches audio engineering at: Musician's Institute, Hollywood, CA.


 Korby Audio Technology 
Web Site: www.korbyaudio.com

Price: $1,800 (includes velvet carrying bag)
optional flight case: $175

Pros: Excelemt transient response
For a very detailed sound.

Cons: Sensitive to plosives and requires
a windscreen most of the time.

Barry Rudolph is an L.A.-based recording engineer. Visit his Web site at: WWW.BARRYRUDOLPH.COM

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