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Marshall Electronics MXL 990 Upgrade Manual

Marshall Electronics MXL 990 Upgrade Manual

Ribbon
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Ribbon Microphone Upgrade for MXL 990
Microphone
TL;DR – 3D printed ribbon bracket, 3D printed transformer bracket for MXL 990
Mic, along with a Ribbon alignment jig for a
www.diyribbonmic.com/parts
ribbon
element.
My Journey
I've been a long time audio buff and musician, who has a little recording studio in my basement. It's always fascinated
me how expensive "good" ribbon microphones were, yet their construction was terribly simple. If you traverse the web,
you'll see I'm certainly not the first to go down this path of homemade Ribbon Mics. There are a number of good
resources out there on the series of tubes. But of course, I'd like to think I'm a little different, and you can be the judge
of that. My approach has been to use cheap microphone bodies and upgrade, rather than making a body from scratch.
This has some limitations with respect to the dimensions of the body, but I think it gives a much more professional look.
At the same time, you now have to convince someone that the guts in that MXL is a whole lot better than they might
think. But once they listen to it, I think they will be able to make that judgement themselves. In addition, with my new
3-D printer, I figured I could design and print anything I might need to help the process, and it seemed some tools and
jigs were missing from all of the other posts I had seen.
Starting with a Kit
What started this journey for me was running into Rick at
www.diyribbonmic.com/parts
(sadly, it was more than a year
before I could finally get the time to finish this project). I saw he had everything you need to make a Ribbon mic
element (motor), transformers and even a complete mic, along with an excellent set of instructions and videos. He was

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Summary of Contents for Marshall Electronics MXL 990

  • Page 1 Ribbon Microphone Upgrade for MXL 990 Microphone TL;DR – 3D printed ribbon bracket, 3D printed transformer bracket for MXL 990 Mic, along with a Ribbon alignment jig for a www.diyribbonmic.com/parts ribbon element. My Journey I’ve been a long time audio buff and musician, who has a little recording studio in my basement. It’s always fascinated me how expensive “good”...
  • Page 2 OTA transformer. You will need an MXL 990 mic, and the 3-D printer files on thingiverse. Why MXL Mics In a word, they’re cheap, easy to find, and many folks buy them as part of their 1 studio equipment, to then end up tossing them in the back of the closet somewhere as they move on to get better quality gear.
  • Page 3  Paper Ribbon Carrier – Again, a simple set of parallel lines 20mm apart to cut some parchment paper, to allow you to fold it in half, and gently tuck your ribbon into it so you can corrugate it. Once you cut your ribbon, you need some place to gently stow it, before you corrugate it.
  • Page 4  Glass – Since I have a 3D printer, I always print on glass, and found it so much easier to cut the ribbon on glass. tape down your ribbon cutting guide, then some parchment paper, then lay the foil on the parchment, and top off with another layer of parchment paper.
  • Page 5  Ribbon Corrugator – In traversing the web, I learned that corrugations of 20 or so per inch were optimal. I tried to 3D print some gears to that specification, but the teeth are just too fine for my 3D printer (a friend’s got an SLA, I might hit him up).
  • Page 6: Part List

    You can get them from Rick as part of his kit (PLA, .02mm, 100% infill) or print them yourselves, getting them from Thingiverse below.  MXL 990 Upgrade - http://www.thingiverse.com/thing:1271932  Just the Austin Ribbon Mic Alignment Jig - http://www.thingiverse.com/thing:1271926...
  • Page 7  Non-metallic tweezers – I love these and they are cheap. Very helpful in really being able to handle the ribbon delicately. You can’t use your fingers, as the ribbon will stick to them. http://www.amazon.com/gp/product/B00HGAKMMI?psc=1&redirect=true&ref_=oh_aui_detailpage_o0 7_s00  2 Brass nuts for the ribbon alignment jig ...
  • Page 8: Putting It Together

    7. Grille – OK, this is a little bit of work. The grille on the Mic has 3 layers. Now on one hand you can just leave it alone, but it does impact the frequency response of the mic. Therefore, I suggest you remove the inner 2 layers. This is a little tough, as the layers are soldered in a number of places.
  • Page 9 2. Using a film of silicone seal on the bottom of each bracket, secure the brackets to the metal plate. I would suggest screws going through the ribbon element bracket, with the nuts on the transformer side. See that little Intent in the bottom there? See the little grooves in the back of the bracket? Those grooves are for the plus (+) wires to sit into.
  • Page 10 Wiring it Up 3. Before you wire up the OTA transformer, you should test fit the transformer into the bracket, to make sure it’s not TOO tight. You may need to use an Xacto blade to shave it a bit. But you do want it very snug. 4.
  • Page 11 12. Next loosen the side screws on one of the metal arms on the bottom mic bracket, and slide the metal plate into place. Twist the transformer wires a bit as you go. Then install the 2 screws to hold the metal plate in place, and tighten up the side arm screws.
  • Page 12 13. Now the black wire will be soldered to the bottom center of the ribbon element. What I did was pull the wire back out, and trimmed, stripped and tinned it. The red wires will go up the channels on each side of the bracket, and to the center top of the ribbon element.
  • Page 13 c. Then tape a layer of parchment paper on top of this. Keep a spare layer of parchment trimmed to fit on top, as you will want to put another layer on top of the foil before you cut it. d.
  • Page 14 Take the folded parchment pocket, and open it slightly, and slide/float the ribbon into the pocket using the tweezers. Be very careful you don’t fold the ribbon, or catch an edge and tear it on the paper. Tuck it into the pocket, and once in, tap the folded edge of the pocket on your desk, to have the ribbon be straight along the folded edge.
  • Page 15 19. Mounting the Ribbon a. Have the Ribbon Alignment jig already printed. b. Cut 4 pieces of 3m double back foam tape into squares about 5mm and put in the indentations of the ribbon alignment jig. This holes the screws in place while you tighten them. c.
  • Page 16 combination of the tweezers and some toothpicks, center the ribbon in the opening of the motor. Use a brass nut to hold one end of the ribbon in place. I found using the toothpick as a means to gently move the brass nut around, to help center the ribbon.
  • Page 17 25. Then press the red plus (+) leads into the channels, and solder both to the top of the element. 26. My element stayed put just fine. But if you are worried about vibration noise, you can use a little dab of silicone seal on the top corners or a rubber band across the top to hold it in place.
  • Page 18 Overall, I’ve been really impressed with the purity of the sound. It sounds great. I like that this let’s me quickly and easily re-ribbon when needed, and the alignment jig really makes installing a new ribbon a snap. I hope you have as much fun with this as I did.