Good quality ribbon microphones cost a lot, mainly because they're difficult to produce in large numbers in extremely high quality. That being said, it's surprising to many to learn that ribbon microphones are extremely simple electronically.
It takes a steady hand and some knowledge of electronic repair to modify your RSM-4, but the basic modifications aren't too complex. And I guarantee you'll be happy with the results!
Now, for the disclaimer: I can't be held responsible if you destroy your RSM-4 in the process, nor will Nady repair your mic if you ruin it. I can't take responsibility if the modifications don't work out for you, whether due to human error or a difference in the materials inside your RSM-4. Remember, these microphones are mass-produced in China, and variances in workmanship and materials quality are common, although uniform quality is much more common today than it was even five years ago.
Understanding Ribbon Mics
Before we dig in to modifying your mic, let's take a look at how ribbon microphones actually work. This is a necessary step before starting your mods!A ribbon microphone is extremely simple. The element that picks up sound is a small ribbon -- typically of pure aluminum or an aluminum composite -- suspended between two magnetic elements. The vibrations of the ribbon against the tension created by the magnets turns the sound wave into electrical signals. The ribbon is tied to a a transformer, which is then wired directly to your outputs. It's that simple -- no fancy electronics!
Step One: Physical Modifications
The first step of modifying your RSM-4 is to remove some mesh inside the microphone capsule. Removing these layers will open up your sound quite a bit -- especially in the high end. There's a layer of fine mesh immediately on top of both sides of the ribbon element. Also, the grills on either side of the microphone element (the large round part) consist of two separate meshes. Unscrew the small screws around the mesh basket.On the large circular part, you'll want to remove the first layer of mesh, leaving the outside basket part intact. This is a little more difficult than the mesh on the elements themselves; you'll need to pry them a little bit (in my case, I resorted to cutting it away once I got an edge pried out). Once these are removed on both sides, it's time to remove the mesh close to the elements.
Using a pair of tweezers, gently edge up the back tape holding the mesh over the element in place. Remove it carefully, making sure you don't puncture the ribbon itself. This would be catastrophic, so make sure you don't damage the element! Once these are both removed and you've reassembled the circular basket, it's time to move on to the next part: the transformer.
Step Two: Replace The Transformer
The next step in modifying your RSM-4 is to replace the transformer. The transformer replacement is the most complicated part of the procedure -- it requires some patience and soldering knowledge -- and it'll add to the cost of your microphone substantially.The new transformer will change the sound of your microphone quite a bit; your lows will be lower, the mids will be firmer and more detailed, and your highs will sparkle -- even more than the original!
First, you'll need to purchase the transformer. For ribbon microphone modifications, I prefer a Lundahl 2912 transformer. (Note: on the first draft of this mod, I mistakingly mentioned a Lundahl 2913 transformer; this was a typo on my part, as the 2913 won't fit in the casing of the RSM-4. My deepest apologies to anyone who tried the larger transformer -- this was an accidental typo. Sorry!) These aren't easy to find, and will run you around $65-75. I recommend K&K Audio for these, but a little shopping around should find you more retailers to choose from.
Remove the screws around the body of the microphone, and you can remove the body to expose the transformer. Simply unsolder the existing transformer (remembering which leads go where), and re-solder the new transformer in it's place. You can even buy a small PC board to make this process simpler -- just remember which leads go where, and you're all set.
Now reassemble and enjoy your even-better-than-new microphone!
Still unsure? Let a professional do it!
While modifying your RSM-4 is extremely simple, if you're not so convinced about your ability to keep a steady hand, there's a few professionals out there willing to do your modification for you.While I can't speak for the quality of workmanship (although reviews have been glowing around the Internet), Michael Joly at OktavaMod.com is widely regarded as the microphone mod expert; for $219, he'll modify your RSM-4 in ways similar to what I mentioned above.
Whether you do the work yourself or pay a professional, the RSM-4 is an incredible value, especially when modified to perform better!
