Polyribbon tests completed

I’ve just completed testing of the Polyribbon that Les sent me, and it’s ready to go. This is easily the finest sounding ribbon microphone that I’ve ever heard. The older RCA77 series suffered from a lack of high end, but this design corrects that deficiency with a response well past 18k. Low output voltage was also a problem, requiring lots of preamp gain (and increasing the preamp self-noise.) This mic comes in at a little hotter than an SM57.

The pattern selector switch is what makes this mic truly unique. This mic can be set to fig 8 like a traditional ribbon, supercardioid, or omni. In figure 8, the side rejection nulls are extremely deep… the mic only hears reflections from the room walls. Try vocals in supercardioid, the side rejection is good, though not as deep as fig 8. A small back lobe lets in some room reflections for a very natural sound. The omni setting has some high-frequency attenuation in the back side of the mic due to the shadow effect of the headbasket.

Proximity effect can be considerable with ribbon mics, and it varies with the pattern on this mic. A two position low cut inductor is provided to help with the equalization. At the max cut position (full clockwise), the filter is calibrated for a flat response at 300mm. The supercardioid setting exhibits moderate proximity effect, there’s a less aggressive filter setting for this. Omni exhibits no proximity effect.

I haven’t gotten this in front of some talent yet… I can’t wait to get to Nashville. Upright bass through this thing should be a signal to die for, as well as vocals. Sax would probably be pretty nuts as well.


The first production Watts Polyribbon in its case.

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