MK-319 Bottle Mod

A couple of years ago I got really interested in the classic bottle mic design. There's an appealing retro vibe going on, plus the acoustical properties are interesting as well. For my first bottle mod, I started with an MK-319. The head basket was removed and the top rounded portion of the grille was saved along with the inner flat round grille that is normally found above the capsule. A copper disc was cut and installed as a shield and capsule mounting platform at the top of the mic body. On top of this platform is a short copper pipe that is soldered to the horizontal "lollipop" grille. The stock MK-319 capsule with HF resonator discs removed was installed in the round grille.

Although not visible in this photo, the back of the grille is flat, not rounded. This design appeals to me acoustically because the capsule sits fairly far away from the reflective and diffractive surfaces of the body. In fact, the capsule mount platform and post are covered in foam to further absorb and diffuse reflections from the body that would reach the capsule and smear midrange and high end detail. The one down side of this mod is that by placing the capsule farther away from the body acoustically, I've also placed it farther away electrically. The important signal wires from the capsule to the FET head amp end up being a bit longer than my standard MK-319 mod in which I drastically shorten the capsule-to-FET wires to eliminate stray capacitance that reduces high frequency detail. (I've actually gone as far as to move the input coupling cap and FET up into the headbasket in one mic I'm testing).

Hybrid Oktava Capsule / Schoeps Circuit Bottle Mod

The next stop on the bottle mic path was a little different. Here, a large diaphragm Oktava capsule modded to have an omnidirectional pickup pattern is mounted in a home-brew copper lollipop head. A common tin kitchen funnel is the neck, while the body is a budget MXL mic circuit that uses the popular "Schoeps-derived" transistorized head amp and output stage. This beast is remarkably clean, clear and open sounding. No proximity effect is discernable and a wonderfully accurate mid range phase integrity comes from avoiding rear wave cancellation (as is used in most cardioid pattern microphones).

China 32mm Capsule / Oktava MC-012 Body

This hybrid was inspired by the Lomo large diaphragm capsules that are designed to fit onto the Oktava MC-012 bodies. Harvey Gerst of Indian Trail Recording, a frequent and respected contributor to a number of online microphone discussion boards, wrote glowingly of the large diaphragm Lomo M1 capsule and MC-012 combination. I thought I'd try to cook something up that was similar in the lab.

Back in 2002, I used an MXL mic (don't remember which one) with a Chinese-manufactured 32mm capsule sitting in a U67/87 style head basket. I pulled out two layers of grille screen. I converted a stock Oktava MC-012 with 10dB pad into a unity gain coupler and mounted it to the bottom of the MXL head basket. This allowed me to screw on the MC-012 body and head amp. The MC-012 body now contains a 5840 miniature vacuum tube wired in single-ended output cathode follower configuration.

ML-52-02 Ribbon Microphone Mod

This was a real saga that is well documented on USENET newsgroup rec.audio.pro. I experimented with various grille damping methods. The last iteration of these tests is a hand-rolled shield to replace the stock headbasket. Someone said it now looks like the mantel of kerosene lamp he had growing up in Africa in the '50s. This thing now has a Lundahl transformer upgrade and heavier ribbon motor wires. The ridiculous "goal post" wind blast / resonator shield and extra silk screening were removed. Open, airy, takes EQ well and has a meaty midrange with harmonic enhancement from the Lundahl. Note: the mic pictured on the right is one of my experiemental models. The commercial mod I offer for the ML-52 retains the stock headbasket.

Royer 5840 Tube Mod

The action is in the details. See that little red/orange glow at the bottom right of the capsule? That's a subminiature 5840 pentode-wired-as-triode tube laying at the base of capsule mount. The standard Royer mod has the tube installed in the body of the mic. Here it is moved into the headbasket to shorten the distance between the capsule and head amp to minimize high frequency losses due to stray capacitances.

This is actually the backside of the mic (shows the tube glow better). Currently sporting a 34mm Chinese capsule and one layer wire grille. I think the 5840 and 34mm make a great pair. They're happy in there together.

Teac ME-120 / Behringer C2 Mod

The Teac ME-120 is a very highly regarded small diaphragm electret condenser mic that was built by Primo in the 1970s. The mic was also sold as the Nakamichi CM-300. These mics are favorites with the concert taping crowd. I got several of these omni capsule from a colleague who had extras when he purchased a couple dozen of these mics from a live sound firm. My goal was to see if I could take these fine-sounding capsules and replace the stock capsule in the $25 Behringer C2 which I find to be sibilant. The ME-120 capsule is not a direct fit so mods were necessary. Using a Dremel tool with cut-off wheel I cut apart the stock Behringer capsule and saved the lower threaded portion to make an adapter for the ME-120 capsule. The ME-120 capsule is attached to the adapter with some conductive silver epoxy. The Behringer amp body has been upgraded with polypropylene capacitors to get rid of the edginess of the stock ceramic caps. I also removed the little HF resonator disc in the capsule for a smoother and less "spitty" top end.

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