Quick and Dirty 5 minute DIY mod for Chinese dual ribbon mics
A number of clients and forum members have commented on the "phasey" and "hollow" sound they hear in the popular dual ribbon Chinese mics. Here's a quick and dirty mod to clean up those problems - and its reversible. Get out the blow torch, Sawzall and welding mask. Let's get started!
There are several challenges impeding best sound in this ribbon mic design. While the dual ribbon design does offer some increased output over single a single ribbon design (assuming same-size magnets and ribbons), it also introduces phase and tuning issues between ribbons. And the parallel grille design found in some of these mics encourages back-and-forth standing wave comb filtering. You can address the dual-ribbon and parallel grille challenges very easily.
Simply pry off the covers off the mic (press in toward the center slightly and pry away from the frame simultaneously). Running the mic without the grille covers will eliminate nasty back-and-forth standing wave stuff. Ribbon mics are very low impedance circuits so you can run the mic without the grilles and only pick up a little extra hum - just orient the mic for minimum hum pick up when in use.
Dual ribbon Chinese mic ready for operation
Of course the other caveat concerns ribbon damage - its very easy to damage the ribbon when its exposed as I'm suggesting (but I did call this a quick and dirty mod right?) so use a pop filter. More elegant solutions are possible and I'll be offering them in the future.
Next, place the mic so you can see the PC board ribbon connections as shown in the picture here. Loosen the nut closest to the PC board that holds the ribbon motor to the frame. Unsolder the lower ribbon wire and move it up so that it is underneath the ribbon motor mounting washer you previously loosened. Tighten the nut.
What have we done? We've used the frame to complete the ribbon circuit using only one ribbon! This will eliminate all phase problems and tuning discrepancies between the ribbons. Output level drops a little but this mod provides enough level for guitar cab recording or loud vocals.
Now these mods don't address the long acoustic front-to-back path challenge that compromises high frequency response, but solving this and making an improved grille to both protect the ribbon and eliminate standing waves requires some serious re-design and machining work.
But this 5 minute DIY deal makes for a much more pleasant-sounding and useful mic. Enjoy!
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