Marshall Electronics MXL 990 Stereo Upgrade Manual Download Page 2

very easy to communicate with, and I had numerous emails with him before I even bought the kit. But to save some time 
and cash, I wanted to upfit an old MXL mic.  

Being an engineer, the first thing I did immediately after ordering my kit, was to look how to improve what was already a 
good thing.  A couple of things immediately struck me.  1

st

 was that no matter what, I knew full well I would need to 

eventually re-ribbon the thing.  And I wanted to make that process as easy as possible. And I wanted to be able assemble 
and disassemble the mic cleanly.  So I started to work on some 3-D Printed parts.  

But before you get started you will need to hit Rick’s site at 

www.diyribbonmic.com/parts

 and buy the ribbon motor kit 

and his 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

st

 studio equipment, to then end up 

tossing them in the back of the closet somewhere as they move on to get better quality gear.  So they are good 
candidates for cannibalizing for upgrades.  While ripping the inner layers of mesh out of the basket is a bit of a pain in 
the butt, you can’t beat them as a nice mic body as a base for an upgrade. And they most often come with a decent 
shock mount.  I often find them used for less than $50 each on craigslist, and found 4 for $25 each.  Sticking a quality 
Ribbon Motor and Transformer into one, quickly turns them into sounding like a mic costing $1,000 or more.  

1

st

 is a Series 

This is in fact the 1

st

 in a series of Instructables, with adjoining 3-D printable files to either upgrade or entirely build a 

Ribbon Microphone.  Since it’s my first, I’m making it fairly detailed. The ones that follow won’t be as long.  

This Instructable is to take a ribbon microphone element (motor) from Rick at 

www.diyribbonmic.com/parts

 along with 

his OTA transformer and upgrade an MXL 990 using some 3-D printed fixtures and tools. 

Over the coming months I will be offering up other Instructables. I have recently completed an upgrade for the MXL 
R144 Ribbon Mic (Ultimately, I plan to build in a phantom powered preamp into this body), and will shortly be working 
on similar upgrades to the MXL R80 Ribbon Mic.  All this will ultimately culminate in an entirely 3-D printable Ribbon 
microphone (active, with a Phantom powered preamp), which I also hope to CNC a metal motor. They will come in time. 

Needing Some Tools 

(Here’s where some CAD skills and a 3D printer helped)

 

When I traversed the web, what seemed to be missing, were some tools that would make things much easier to deal 
with ribbon prep, installation and the final build.  And that’s what I wanted to accomplish in this Instructable.  Some 
things I realized would make things so much easier.  

 

Cutting Guides –

 Terribly simple, but really necessary.  You need to cut the Ribbon straight and of a particular 

width. So I fired up InDesign, and made a very simple cutting guide of parallel lines for different Ribbon Widths.  

 

Summary of Contents for MXL 990 Stereo

Page 1: ...ies 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...

Page 2: ...lity Ribbon Motor and Transformer into one quickly turns them into sounding like a mic costing 1 000 or more 1st is a Series This is in fact the 1st in a series of Instructables with adjoining 3 D pri...

Page 3: ...u 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 Plastic Tweezers So much easier...

Page 4: ...allows you to place the Ribbon Motor in it than drape the ribbon element across it to more easily align it and put tension on it I used brass nuts to hold the ribbon in place and used a toothpick to...

Page 5: ...ame across a very simple arts and craft corrugator which works perfectly I of course wanted to 3D print some fancy contraption for it but the simple device works just fine 3D Printed Ribbon Motor Moun...

Page 6: ...or bracket and transformer bracket o 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...

Page 7: ...you want to go hog wild and buy a sheet of 1 8 micron foil it will set you back 25 plus shipping Not a whole lot of difference but I spent the extra money Hit the site below then email them with what...

Page 8: ...take a screwdriver handle and push up on the inside of the grille to again return the top to where it is curved out You don t want to have the top of the ribbon element touch the grille as it will sh...

Page 9: ...he 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 th...

Page 10: ...e wires through the mic body BEFORE you solder them to the XLR connector Then solder the red lead to the pin which is pin 2 Solder the black lead to the pin which is pin 3 Slide the heat shrink over t...

Page 11: ...e 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 This is actually where I connecte...

Page 12: ...ings easier later 16 Prep for dealing with the Ribbon using the cutting guide PDF a Use the ribbon pocket guide to 1st cut a number of pieces of parchment paper This will create 20mm wide strips First...

Page 13: ...of the tweezers to float the foil out onto the parchment paper But don t manhandle the foil it will tear Carefully remove the ribbon foil and slide it onto the parchment paper You don t want it to fol...

Page 14: ...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 This is important as when you go to crimp the ribbon this will help it s...

Page 15: ...have picked up ii Clean with some alcohol don t use acetone it will loosen the superglue e Put the 4 screws used to hold the ribbon element brackets in Then flip the jig upside down and then put the...

Page 16: ...and center the ribbon while sliding it back to put tension on the ribbon i You want enough tension to where the ribbon looks straight across the motor You don t want it to sag But you also don t want...

Page 17: ...audio interface or mixer and give it a try NO PHANTOM Power You will need to turn the gain up pretty high What I recommend is to put an inline preamp close to the ribbon mic so it has some gain befor...

Page 18: ...ssed 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 a...

Reviews: