Capsule Installation Instructions

Never do this!

The wires from the new capsule must be soldered to the microphone’s circuit. Never unscrew wires from the new capsule.

Also, never touch the capsule diaphragms! Hold the capsule by the edge only.

Unbox the new capsule

First, clear your workspace to ensure that you have a clean surface to lay the capsule on.

RK7, K67LE, RK-67

The RK7, RK-67, and K67LE can be easily lifted from their cases.

RK-47, RK-87, RK-12

These three models are wedged into their plastic cases with a short length of transparent plastic tube. This prevents the capsules from rattling around during shipping, but makes it trickier to unbox the capsule. To safely extract the RK-47, RK-87, and RK-12 from their cases:

  1. Remove the case lid.
  2. Carefully invert the box, being prepared to catch the capsule (by its edges only) if, against all odds, it is loose.
  3. Assuming the capsule is wedged in its case, rap one edge of the box against the table a few times, open end down (toward the table). The weight of the capsule will push the capsule out of the case partway. You need not slam the case against the table until the capsule flies out completely; rather, tap the case against the table just enough that you can then remove the capsule with your fingers.

Prying the capsule out of the box with a screwdriver is not recommended.

Open the microphone

Most imported large-diaphragm microphones open by spinning off the threaded base, near the XLR jack. Then, slide off the tube covering the circuit board.

The microphone grille or “headbasket” must be removed. In most cases it is screwed to the microphone chassis using two small machine screws.

In the case of the MXL 1006 pictured here, a second circuit board (which holds part of the battery-power circuit) had to be detached from the chassis first, to allow access to the screws holding the headbasket in place.

The white arrow marks the location of one of the screws holding the headbasket to the chassis.

Be sure to retain all the screws as you disassemble the microphone.

Make notes as you go

Locate the 2 or 3 wires from the capsule. Take a photo of the microphone to record where these wires attach to the circuit board.

Such a photo is also useful if you accidentally break off another wire or component during handling. It is a critical reference if you end up troubleshooting your installation.

Many Cardioid microphones will have just two wires: one from the front diaphragm (usually from the center, but possibly from the edge), and a second from the side of the capsule.

All Multipattern microphones will have three wires: one from each diaphragm (front and rear), and a third from the side of the capsule.

If the leads from the new capsule are soldered to the wrong points on the circuit board, the microphone will no longer function properly. Be sure you have recorded the location of the wires before you remove the original capsule.

Remove the original capsule

Carefully desolder all capsule wires from the circuit board. Be careful to avoid burning nearby components with the soldering iron; we recommend bringing the iron’s tip in from the outside edge of the microphone, rather than holding it above the circuit board where heat from the iron could damage a component.

Once the diaphragm wires have been desoldered from the circuit board, unscrew the 2-4 screws holding the capsule to the saddle. Set the capsule aside; later, it can be stored in the plastic case that the new capsule came in.

Install new saddle (if necessary)

The “saddle” is the curved plastic piece at the top of the mounting post; it is the thing that the capsule is screwed on to. Hold your new capsule against the microphone’s existing saddle to see if it happens to fit, and, more critically, if the mounting holes drilled in the saddle line up with the holes drilled into the edge of the new capsule. If the new capsule lines up perfectly with the stock saddle, there is no need to install a new saddle.

(If your mic’s capsule mount is a rubber or plastic harness, as in the Rode NT1 or Blue Bluebird, or a one-piece plastic pedestal mount as in the Mojave Audio microphones, you will need to either attach the new capsule to this existing mount, or replace the mount entirely. These options are outside the scope of this document; see the capsule installation photo gallery pages for further ideas.)

Remove the stock saddle from the microphone, replacing it with the saddle included with your new capsule. In this photo, the white saddle came with the microphone. The black saddle, shown here already installed on the stock mounting post, comes with the RK-47 capsule.

Be sure the screw holding the saddle to the post is tight. Consider putting a drop of Loctite or glue on the screw head, to ensure that it does not come loose over the following years. If you use Loctite or any other adhesive, allow it to dry thoroughly before mounting the capsule, so that the fumes from the solvent in the adhesive do not affect the thin Mylar membranes of the capsule.

Saddle Preparation

basic-saddleIf you’re using the saddle pictured here, whether you’ve left it on the supplied mounting post as pictured, or transplanted it onto your microphone’s existing mounting post, you should test-fit the capsule into the saddle to check for fit.

saddle-gap2These saddles are made of a pliable plastic that can contract with temperature variations. If the capsule does not make contact with the center of the saddle, as shown at right, you will need to spread the arms of the saddle by pressing them against a flat surface. This will stretch the arms out, allowing the capsule to sit flush against the saddle. If you skip this step, you will find it difficult to line up the mounting holes in the saddle arms with the holes in the capsule backplate.

Mount new capsule

All capsule types can be attached to all saddle types with two screws: one on each arm of the saddle. These screws are included with your capsule.

The RK-47 capsule needs special treatment, because one of the mounting screws must first go through the metal tab on the enclosed blue termination wire, as pictured at right (click image to zoom in). In some cases, the RK-47 is supplied with screws of two different lengths; the longer one is to be used with the blue termination wire.

See additional installation photos of our “supersaddle” with the RK-47, RK-87, and RK-12 on the supersaddle installation page.

Inspect the capsule alignment to ensure that it faces exactly 0° and 180° with respect to the microphone chassis. In most cases it is possible to gently twist the capsule mount to adjust the capsule position. Do not touch the microphone diaphragms.

Route leads

Be sure you have identified the front of the microphone before routing the capsule’s wires.

If the microphone provides only a Cardioid polar pattern, the wire from the rear diaphragm of the new capsule can either be clipped short or wrapped around the post to keep it out of the way. We recommend leaving the wire long, but wrapped out of the way. Just clip the bare end off first, or wrap it in a small piece of tape so that it can’t cause shorts or other electrical problems.

Route the diaphragm wires through the capsule mount and chassis as the originals had been. Refer to the photo and notes made earlier.

Replace headbasket

Attach the microphone headbasket to the chassis to protect the new capsule.

Optional: some microphone builders recommend removal of the inner layers of metal mesh from the grille. This operation requires no special tools; a pair of strong needle-nose pliers and a wirecutter are sufficient.

We no longer recommend this modification; we have found that a single-layer headbasket offers reduced EMI/RFI protection and reduced blast protection. Further, we have experienced an increase in unwanted resonance effects with a single-layer grille on some microphones. While arguments have been made than an open headbasket can reduce reflections that cause muddy or congested sonics, our test results have been mixed.

Solder capsule wires to circuit

For best results, capsule wires should be trimmed to be as short as possible, leaving only enough slack to reach the circuit board without stressing the wire or joint. Additional wire length leads to an increase in capacitance, which can degrade the signal from the capsule.

If you are experimenting with capsules and expect to be transplanting them across multiple microphones, it is of course best to leave the capsule wires full-length until final decisions about which capsule goes into which mic have been made.

In general, you’ll need to solder at least two wires for Cardioid operation: front diaphragm and backplate. For multipattern operation, you would also need to solder the rear diaphragm wire. Refer to the notes made during the removal of the original capsule; the new capsule should be wired identically.

Wiring notes for RK-87 Customers

The RK-87 has insulated backplates, like Neumann’s K87 capsule from the original U87. There are multiple ways to wire this capsule:

  • For Cardioid-only use: it is unnecessary to attach the rear diaphragm or backplate to the circuit. Connect the front diaphragm’s wire, and use a single blue wire to connect the backplate half nearest the front diaphragm. (Whether to pass polarization voltage to the backplate or diaphragm depends on your mic’s design; if you reverse them, your mic will have reversed polarity with respect to correctly-wired microphones.)
  • Proper wiring and grounding of RK-87.For multipattern use in a 3-wire microphone: connect the two backplate halves together via an external wire, then treat as any other K67 capsule. See photo at right (click on it to zoom in).
  • For multipattern use in a 4-wire microphone (such as the original U87): wire the two backplate halves separately so that they remain insulated from one another.

Inspect the solder joints to ensure that they are sound. Research cold solder joints for tips.

Final assembly and testing

Replace the body sleeve and bottom nut. Gently tip the microphone back and forth to listen for rattles. If a screw, washer, or bit of solder is loose inside the microphone, it could cause problems over time, and should be removed immediately.

The microphone’s headbasket and body sleeve must be reinstalled prior to audio testing. Without these parts in place, the microphone will hum.

Joint hygiene

After the microphone has passed an audio test, the new solder joints should be cleaned and protected. These high-impedance connections are sensitive to contamination, which can degrade the signal quality and level.

Use 99% pure Isopropyl Alcohol (note: this is not the same thing as 72% or even 90% rubbing alcohol), or a commercial flux cleaner. Never spray aerosol solvents near the capsule. If your solvent is in an aerosol can, spray the end of a cotton swab after moving a safe distance away from the microphone. Then use the swab to scrub the high-impedance solder joints.

Remove all the solder flux and any built-up contamination or grime.

For best long-term results, we recommend covering these joints with “conformal coating.” Find specific product recommendations for both flux cleaner and conformal coating here.

Once you are confident the installation work is sound, connect the microphone to your favorite preamp, turn up the gain and enjoy the new microphone!