Nady RSM-5 Review and Modification
Want an inexpensive ribbon microphone with a Royer-like feature? The RSM-5 (wooden box version) has a ribbon motor similar to a Royer R121 but needs some help to live up to its potential in my opinion.
In the RSM-5s I've seen, the ribbon material is thicker than specified and causes sub-optimal performance. This mic is spec'd as having a 2 micron ribbon. But upon inspection I found the ribbon to be made from the same heavier 6 micron material used in the RSM-4. So the first step in getting an RSM-5 to be a top-shelf performer is to replace the stock ribbon with a lighter and more responsive 1.8 micron ribbon.
This is Michael Joly writing, the guy behind OktavaMod. You're invited to contact me directly to discuss your mic needs and discover if the Premium modification for your RSM-5 ribbon is right for you.
Not only was the ribbon thicker than spec'd - it had "foot bridge" sag.
Stock Ribbon Sag
About 50% of the eight hundred or so Chinese-manufactured ribbon mics I've seen have come from the overseas manufacturer with improperly tensioned ribbons - often with 80% of the ribbon length sagging out of the magnetic gap. While the specimen below had ribbon sag, it was not as bad as some that I've seen.
Notice the ribbon sagging in a "foot bridge" fashion. Ribbon sag causes low output, "clanging" noise, infrasonic rumble pick up and high distortion - all of which can be eliminated with proper ribbon tension.
You can check your RSM-5 (or any other ribbon mic) for ribbon sag very easily. Listen to the mic in headphones, gently tip the mic back and forth so first the front face, then the back face comes to rest parallel to the floor. If you hear a sudden "clang" or "clunk" this indicates a severely under tensioned ribbon flopping about in the magnet gap. Not good. When I modify these mics the new 1.8 micron ribbon is properly tensioned for best low frequency response and minimal footfall vibration pick up.
Video: Superior sensitivity of new 1.8 micron ribbon vs. stock 6 micron ribbon
By the way, the ribbon motor used in the "wooden box version" RSM-5 mimics the patented Royer technique of offset ribbon placement in the magnetic gap. In the Royer mics, the ribbon is placed closer to the front of the magnetic ribbon gap. This allows the ribbon to move further into the gap at high SPL and still remain in the magnetic field.
But to get around an obvious patent infringement, the RSM-5 has the ribbon located asymmetrically toward the back of the mic when addressed from the front! Simply use the back side of the RSM-5 and you'll get similar high SPL handling as offered by the front side of a Royer R121.
While asymmetrical ribbon placement is not ideal for M-S or Blumlein usage were a symmetrical figure 8 pattern is desired, the offset does offer the advantage of slightly different frequency response between front and back. In the case of the "wooden box version" RSM-5, the front is brighter than the back.
11/30/07 NOTE: Now, the RSM-5 is shipping in a cardboard box, no velvet bag, no shock mount. The ribbon clamps have been re-designed to hold the ribbon in the center of the magnetic field. This appears to be a redesign intended to move away from the patented "Royer offset ribbon" technique. The sound of the modified RSM-5 is still great - it simply has a symmetrical frequency response front and back.
Ribbon mics are simple devices, but a big part of their sound is the output transformer. The OktavaMod Premium modification swaps in my custom designed, made in America transformer for better time and frequency domain performance across the audio spectrum.
In addition to the new transformer installation, the inner headbasket screen is removed to reduce standing wave reflections and smooth frequency response.
Once modified, this medium length 35mm ribbon mic offers a musically useful low frequency resonance without accentuating unwanted LF rumble. Plus the high frequency response sounds like a high quality ribbon mic should - righteous.
Click "Add to Cart" to purchase the Premium mod for your RSM-5 ribbon - you'll get an immediate confirmation email of your order. By the close of the next business day you'll receive a personal email with your scheduled modification and return ship dates. Questions? Just click "Contact Me" - best, Michael
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