Nady RSM-5 Review and Modification

Want an inexpensive ribbon microphone with a Royer-like feature? The Nady RSM-5 has a ribbon motor similar to a Royer R121 but needs some help to live up to its potential.

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. 

And, about 30%-50% of the 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.  

So the first step to get 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.

The ribbon motor used in this mic 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.

To avoid an obvious patent infringement, the RSM-5 has the ribbon located asymmetrically toward the back of the mic when it is addressed from the front! Simply use the back side of the RSM-5 and you'll get the same "offset ribbon / high SPL" benefit offered by the front side of a Royer ribbon. The offset ribbon placement has the additional benefit of providing different front and back frequency response curves - almost like two mics in one.

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 response between front and back.

Ribbon mics are simple devices, but a big part of their sound is the output transformer. Installation of a premium Lundahl ribbon microphone transformer will reduce midrange ringing distortion and really extend the low end of the RSM-5.

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.