Ribbon Mic Test

Here’s a look at my latest… a ribbon mic motor under test on my bench. Right now, it sounds pretty good. In fact, I’m tempted to just toss it into the case and call it done as it is, but I’m going to wait a bit. I can see some tiny problems with this one that I’d like to correct first. I’m not sure if you can tell in this photo, but the ribbon has a very slight curve… it’s closer to the magnet on the middle on one side, and the edges on the other. This is probably due to the way I corrugated the ribbon, using a fluted dowel pin and rolling it on a mousepad. This method works, but it is hard to get an even amount of pressure, and I probably pressed down a hair more on one side than I should have.

A completed ribbon motor of my own design

Still, it sounds quite nice. It has a fair amount of output, though I might like to squeeze out a bit more signal. A more accurate assessment will have to wait for a new ribbon… I’ve bought a “Paplin Crimper” on ebay for $15, which should be adaptable into a better ribbon corrugator. It’ll at least be an improvement on my current method.

I’m especially pleased with the transformer on this mic. I managed to get a pair of these from Les Watts. He has them wound for use in his microphones, and they have specifications that rival some of the best ribbon transformers available. Of course, it’s hard for me to tell what is due to the transformer and what’s the result of my ribbon motor design. Hopefully I’ll be able to source some cheap Chinese ribbon transformers soon so that I can compare the two.

A “Paplin Crimper Tool.” These are readily available on eBay for about $15, and I’m told they make good ribbon corrugators… we’ll see shortly!

Remaining work on this microphone is a new ribbon and adding some ground connections, but apart from replacing the ribbon, it’s just a matter of wiring it up and screwing it closed. The shell will certainly affect the sound to a degree, but I don’t think it will be too detrimental… the EM shielding that a mic shell provides will likely be an improvement, though I’m not hearing much in terms of self noise as it is.

Here’s a voice test MP3 of this mic just as it appears in the photo above. This isn’t a critical test, just a check to hear if it’s working. It’s on my workbench, not the perfect place for this… I hear reflections from the rear, and the fan noise from the laptop is audible. The cable being used to connect the mic was quite prone to noise depending on it’s position… I just placed everything where the noise was lowest. The mic is connected directly into an M-Audio Duo interface, sample rate was 44.1. Have a listen… comments and opinions are most welcome.

RibbonTestRevA

6 responses to “Ribbon Mic Test

  1. What size ribbon on this one? I’m using the stuff with Ricks kit (0.6-0.8 micron) and as my wife says “why did you pay $300 just to make yourself super frustrated?” I’m teaching my little boys a lot of bad words when I work with that stuff!

    • bgilbertsound

      I used 2.5 micron ribbon material. It was/is a huge pain in the ass, but it’s WAY better than signwriters leaf, which is something like 0.2. I’d buy some extra foil from Lebow company, it costs about $25 per 14cm x 14cm sheet, and you can re-sell the surplus on eBay. Rick’s kit is an excellent starting point, and will give you a very nice mic when you’re done. But there are LOTS of ways you can improve it… mainly a narrower ribbon, a tighter gap between the ribbon and the magnet, and using a steel frame rather than a plastic one. Gluing some silk to the magnets will also improve things. Experiment on your design for mic #2. Good luck, BG

  2. Do you find a difference in tone from the really thin stuff to the 2.5 micron?

  3. Hard to say exactly, since I don’t have Ricks ribbon anymore. It was donated as a door prize at Welcome To 1979 in Nashville. My new one had a number of design changes, so it wouldn’t be a fair comparison of the ribbon thickness. According to my friend Les Watts, (mic designer & engineer, ex Shure and EV) you don’t see any improvement below about 1.2 microns. Sadly, the glue let go on one of the magnets, so this one is history & I’ve been too busy to finish another, but it’s still in the planning stages. I’ve got three shells ready, but I’ve got to finish setting up my basement lab- we had to move a few months ago, and everything is still a shambles.

  4. bgilbertsound

    That sounds about right… it was a couple years back, and I’m not sure where the invoice is. I’ve got enough to last for a long time yet, if I can remember where I put it.

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