Introduction: Ribbon Microphone Upgrade for MXL R80
3rd in a Series
Hello, this is my third in a series in of DIY ribbon mic upgrades. In this particular Instructable, in addition to simply re-ribboning an MXL R80 mic truss (using a trusty 3-D printed ribbon alignment jig), I will present a couple of other options as well. Regardless, in all cases, we will replace the stock transformer with an upgraded transformer. Again, I’m relying on my friend Rick at www.diyribbonmic.com/parts for his OTA-1 transformer in this example.
1) First, you can reuse the stock MXL printed circuit board frame, make a couple of improvements to it, replace the transformer and remount the ribbon truss as originally supplied.
2) Next, you can 3-D print a replacement for the printed circuit board, and use Rick’s ribbon truss for the ribbon element. This allows the ribbon truss to be suspended in the center of the mic body using some 3-D printed flex corner supports. Rick’s ribbon is about twice the length of the stock R80 ribbon.
3) In the third approach, I again created a replacement 3-D printable frame to suspend the MXL R80 truss using the same version of the flex filament corner suspensions. I will take you through all the steps in this third approach, but the first two approaches are essentially interchangeable.
If you are worried about using plastic for the ribbon motor truss frame, you can always use it as a template to cut out your own printed circuit board. However, I did make it as thick as possible while still fitting in the slot and it seems plenty sturdy to me.
Again, to make this a complete and standalone Instructable, I am going to cut and paste a good portion from my 1st Instructable (MXL 990 Ribbon upgrade) here, particularly with respect to prepping for the ribbon material, and cutting the ribbon itself. I will make adjustments as necessary.
Step 1: What's Coming Up Next
- One more Mic - Just to let you all know what’s coming up next, I have one more MXL ribbon microphone that I’ll be working on. What I’m trying to do is get a collection of ribbon alignment jigs made for various Ribbon trusses of different shapes and sizes. My intention is to make a series of Ribbon Carriers for a ribbon tuner I intend to make over the summer.
- After that, I’m going to take a little bit of time and design a 3-D printable ribbon corrugator, which will have nice little input and output trays for the ribbon to lay in, and most likely a little motor to be able to drive the ribbon through in one pass. As I’m finding that if you stop and start corrugating the ribbon by hand, you can see those places where you stop and start in the ribbon. I’m thinking of something with a little foot switch, so you would have both hands free to guide the ribbon. I will also be looking at trying to find a source for gears with a different range of teeth per inch, so I can experiment with a number of corrugations per inch as well.
- And this last task is going to be fairly substantial one. What I am wanting to do is create an automated ribbon tuner. I’m going to take all of the little ribbon alignment jigs that I’ve created over time and standardize them so they are interchangeable in this ribbon tuner. My thoughts on this are to center and affix one end of the ribbon in the truss leaving the other end loose in the ribbon alignment jig. You place this in the tuner. You hook it up to a little Arduino, set the resonant frequency, and it measures the circuit until resonance is achieved. As what’s happening, is that the Arduino is moving a stepper motor in and out to put tension on the loose end of the ribbon. I’m hoping this will be my summertime project.
- In the middle of all of this, I’m also looking to pick up an inexpensive laser cutter/engraver, slap a little vacuum table on it, and use it for laser cutting ribbons. That should be fun.
Between the ribbon tuner, the ribbon corrugator and the alignment jigs should take a lot of mystery and black magic out of ribbon microphones.
Step 2: The MXL R80 Mic
The construction of this mic is novel, as it uses a printed circuit board that slides up through the center of the microphone body (which has slots in it) to suspend the ribbon element and also to mount the transformer. There are 4 screws, which hold the printed circuit board in place. However, the ribbon element is not symmetrical to the body, as they mounted it on one side of the printed circuit board. In addition, they are using these cheesy little rubber gaskets with some screws to hold it only at the top of the ribbon element, which lets the other end of the ribbon truss just flop around. In addition, the printed circuit board completely bisects the microphone opening. As a result, the only place for air to go is directly through the ribbon element or around the outside of the microphone body. There’s really not great airflow. But it has a decent metal grill, although they use foam inserts to protect the ribbon. And as I have found with the R144 mic, they do tie the one end of the ribbon to the metal ribbon truss, and also tie the ribbon truss to chassis ground. So I change that up and make the ribbon fully floating.
But as you can see in looking at the picture of the original ribbon truss, the ribbon in it is so loose, that it's flopping. And this was a brand new mic right out of the box. I pity the poor guy who gets one of these, in this shape, who doesn't know how to check the ribbon. Boy, will they be unhappy.
In this case, I’m going to go ahead and use the stock MXL ribbon truss, as I’m curious to see how the microphone will sound using a smaller ribbon element than the other microphones that I have. It's obvious that it is in urgent need of a new ribbon. But, since this microphone is going to be so easy to change (because all I have to do is slide out the printed circuit board), I will probably try Rick’s ribbon element in it as well.
Step 3: 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.
Paper Ribbon Carrier – Again, a simple set of parallel lines 20mm apart to cut some copier 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. All you need to do here is print out my cutting guides and cut the page on the solid lines. Then you fold on the dotted lines. Rather than trying to fold it in half and crease it by hand, I suggest using straight edge ruler and fold it over the ruler. This gives you a much straighter crease.
Ribbon Sheet cutting Guide – Just a couple of lines, so you can trim down the ribbon material to fit the ribbon cutting guide. Basically, you need a ribbon is about 4 inches tall, to be able to spend the entire ribbon truss as well as give you some loose ends to overhang the alignment jig so you can straighten things out and then put proper tension on the ribbon. That should help you end up with less waste.
Plastic Tweezers – So much easier than toothpicks to move the ribbon around, although, you will still love to use those toothpicks in some places
Glass –Since I have a 3D printer, I always print on glass, and found it so much easier to cut the ribbon on glass. 1st 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. I also just used some picture frame glass.
Ribbon Alignment Jig – This 3D Printed part is probably the single most important thing I made. Getting the ribbon properly aligned and tensioned in the motor is really tough when you just lay the ribbon truss on your desk, and try to do everything free hand. This jig allows you to place the Ribbon Truss in it, then drape the ribbon element across it to more easily align it, and put tension on it. Initially I used brass nuts to hold the ribbon in place on each end, and used a toothpick to slide them (the brass nuts) around to align and tension the ribbon. But I later learned that the brass acorn nuts were too hard to pick up in addition to fitting too snugly in the jig (I actually did that on purpose, but learned that I really need to be able to twist these little holddown weights to help align the ribbon more easily). I ended up using instead some brass tube, and will likely try to use a piece of brass rod. This lets you twist the rod to help you center the ribbon as well. The ribbon really needs something to help keep it aligned. This really did the trick. Then tighten up the clamps to hold the ribbon in place (one end 1st, make final adjustments, and then the other end). If there was any one thing that I was happy about, it was this jig. I literally was able to use my very 1st ribbon and got it done in like 5 minutes. I attribute it to this tool. This version is customized for the R80 ribbon mic element. What I am hoping to do is 2 things. 1st create a catalog of simple ribbon alignment jigs for a number of different ribbon trusses. Next is to adapt these jigs to have them all fit into a resonant tuner. Get the ribbon laid in, clamped on one end, dial in a resonant freq, and then an Arduino, Raspberry Pi or similar automatically adjusts a stepper to tune it up. A bit of an aggressive project, but I think I have a good 20 years of life left. So we’ll see how it goes.
Ribbon Clamps and wire guides - I found that one of the problems with the MXL ribbon trusses, were that the existing clamps, covers, what have you, were too narrow, and when you tried to tighten up the screws, they would twist and throw everything to heck. If you glued the bottoms to the truss, you still had the same problem with the covers. So I just printed some thin replacements, which are wide enough for a snug fit, and don't twist when tightening. What you really need is 1mm thick PCB material, but I couldn't find any. I also changed the grounding on the truss, so there are clamps for both ends.
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). And again hitting the Internet and various Ribbon Mic sites, I came across a very simple arts and craft corrugator, which works perfectly. This has 48 gears on 1 inch diameter (or Pi circumference) gear. So that works out to about 15 corrugations per inch. So little bit low, but still pretty reasonable. I’m still pretty new at this, and am learning all the time. And after doing a handful of ribbons, I realize that I should really come up with a 3D printed stand for this. As I am finding that it is important to corrugate the entire ribbon in one smooth motion. As you can see in the ribbon, where you stop and start. Might even have a motor drive it, so it runs at the same speed. We’ll see. This is next on the list, ahead of the resonant tuner.
Step 4: Parts List
This is the list of parts used and where to get them
- Ribbon material and OTA (or Lundahl) transformer from Rick.
- A word on ribbon material. 1.8 micron is a whole lot better than what comes on many Ribbon mics. You will get a little High Frequency roll off with this, material, but it is still a damn site better than any stock MXL. Even though MXL called their ribbons 1.8 micron, they seem to coat the ribbons with a thin film. You can also get the 0.8 micron material. But be prepared to be a little frustrated. It is very thin, and can be difficult to work with. But with all of the tools and guides I’m providing, you should do fine. But you might want to start with the 1.8 micron, until you get handy at it. But over time, I’ve gotten pretty good with .8 µm material as well.
- Lebow also can supply ribbon material of different thicknesses
- 3D printable ribbon fixture jig, ribbon mounts
- Option 1:
- MXL R80 Ribbon Mic Alignment Jig
- I used 30% infill in PLA
- MXL R80 Flex Ribbon Mounts
- I did 100% infill with Ninjaflex flex filament (I tried another flex filament, and the Ninjaflex came out way better)
- MXL R80 replacement PCB
- I used 100% infill
- MXL R80 Ribbon mount points and covers
- I used 100% infill
- All also available at Thingiverse: http://www.thingiverse.com/thing:1357979
- Once again, the little MXL thin PCB’s which they use to hold the ribbon to the truss, are not wide enough, and twist, when you try to screw them down. So I again have these little thin pieces of plastic to print, which are snug fits, and don’t twist. You just need some copper tape, and to be quick with the soldering iron, as to not melt the plastic too much.
- MXL R80 Ribbon Mic Alignment Jig
- Option 1:
- Austin Ribbon Mic Alignment Jig
- I used 30% infill in PLA
- Existing MXL R80 PCB
Step 5: MXL Mic Disassembly
Yeah, I did it again.
I was too excited, and tore down the mic and didn’t take any pictures along the way.
1. Unscrew the two screws at the bottom of the mic, and the XLR connector will drop off. Just cut the wires.
2. Cap and Grille Removal - This is a little tricky. So let me explain before you get started. The little metal bar that goes across the top of the microphone is held in by two little plastic pins, one on each side. However, there is also a little groove on the sides of the cap, for the top of each side of the grill to fit into. So what you need to do is take a jeweler's screwdriver and gently pry up each side of the little metal cap while also helping the grill up on both sides slide up. After a while you be able to get underneath the bottom of both grills to help push them up. There will also be some black foam inserts that will slide up with it all together.
3. Go ahead and completely remove all of the grills and foam inserts.
4. This will leave you with the little printed circuit board that has the ribbon element and transformer mounted to.
5. You will see that there are four little straight head jeweler’s screws on the inside of the mic body frame, which you need to loosen to allow the circuit board to slide out. Go ahead and remove the circuit board.
6. There are two screws holding the top of the ribbon element to the printed circuit board, go ahead and remove those and cut the wires to the ribbon element so you can completely remove.
7. The Transformer is just held in with a little bit of glue. So go ahead and just pop it out and cut the wires off from the PCB.
8. There are some metals mesh screen taped to the front and back of the ribbon element and you can go ahead and remove those too.
9. Unscrew the XLR connector, and let it drop out the bottom. Then desolder the + and – leads.
Step 6: Putting It Together
Let’s first get the Mic body prepped for the new ribbon motor (element)
Wiring it Up
Option 1: Use existing PCB with some minor improvements
Here, all I did was drill some holes in the PCB around the perimeter of the ribbon truss to allow for some air flow through the microphone body. I also filed the printed circuit board to allow the transformer to sit in it. Please note, you should file the circuit board to allow the microphone input leads for the transformer to face upwards towards the ribbon truss. You will find a picture of this as I did in option three. I will recommend you do the same modifications to the ribbon truss to also isolate the ribbon which is also demonstrated in option three. Then go ahead and mount the ribbon truss using the little angle bracket to the printed circuit board. I recommend that you separately ground the printed circuit board and ribbon truss to chassis ground. Also, make sure that mount the transformer such that the transformer body is on the fiberglass side and not the copper side to ensure that the transformer does not short the ground.
Option 2: Rick’s Austin DIY Ribbon Mic Truss, 3-D printed PCB replacement, flex corner ribbon truss mounts and replacement transformer.
This is essentially the same thing as option three. However, in this case, rather than use the stock small MXL ribbon truss, you use Rick’s ribbon truss from his website, in addition to his OTA transformer. Therefore, you can simply follow option three, and use the Austin 3-D print files and ribbon truss in place of the MXL 3-D print files and the stock smaller MXL ribbon truss. Rick’s Ribbon Truss is about twice as long as the stock MXL ribbon truss.
Option 3: Stock MXL Ribbon Truss, 3-D printed PCB replacement, flex corner ribbon truss mounts and replacement transformer.
1. Remember to test fit everything ahead of time. Make sure the 3-D printed ribbon motor frame will slide into the microphone body, and that the transformer will fit into the frame as well. You will want to check the length of the plus and minus wire, trim them to length, strip and tin them now. The Minus wire is short and at the bottom, and there are 2 plus wires, that go to the top of the truss.
2. Cut a section of black wire, and solder it to the minus wire on the input side of the transformer. A piece of 1/16” heat shrink will suffice. Then cut two lengths of red wire, and solder the ends to the plus side of the mic input side of the transformer. A small piece of 3/16” heat shrink will do here.
3. Slide the transformer into the opening of the 3-D printed PCB replacement as shown, such that the microphone input wires go through the printed circuit board and up the back towards the ribbon truss. Please note, I used dab of silicone seal on the transformer, in addition to the tie wrap.
4. Okay, this is the part that kinda sucks. I wanted to find a way to keep the wires out of the way. In the last two mic mods, I was able to put a little wire channel on the side of the 3-D printed bracket, but I couldn’t make one fit here. I wanted to make a channel in the flex corner brackets, but they wouldn’t print well, as I didn’t want to make it a dual head print with PVA. So I made a ledge, and then planned on using some silicone seal to hold the wire in place. But it was a pain. This is what I would suggest after I learned from my mistakes.
5. First, using a little dab of silicone seal, install each corner bracket. Then temporarily install the ribbon truss. You don’t need the ribbon in it. You’re just using the truss to hold the four flex corner cushions in place while the silicone seal dries.
6. Then grab a piece of wax paper. Use some silicone seal to hold the red wire in place on each side, lay the wax paper on top, and then lay the body of the microphone across the ribbon. Then tape the whole thing together. What I found was the diameter of the microphone body did a nice job of holding the wire in place. I let that sit for a day, and then carefully removed the paper (in my case I had you scotch tape). But as the silicone seal was partially covered it probably won’t fully cure. But it had cured enough to hold the wire in place. I then put a little bit more silicone seal on each point. Let this dry overnight.
7. Once dry, carefully remove the ribbon truss.
Step 7: Getting Ready to Cut the Ribbon
Prep for dealing with the Ribbon using the cutting guide PDF
- Print the ribbon pocket guide page of the PDF, and then using either a paper cutter or straight edge and razor cut yourself a bunch of strips. Cut on the solid line, and fold on the dotted line. Rather than trying to crease them by hand, I suggest that you use a straight edge to help fold them. If you try to increase them by hand, you will find that the paper curves. The ribbon is going to end up following the curve in the crease, and when you corrugate it, you’ll end up with a curve ribbon to. See want this foil to be nice and straight. These strips will be the width of the page. You’ll want to cut them down to about 4 to 5 inches. Any longer they get a little unwieldy. You will use these as pockets to place the recently cut ribbons into them.
- Select and cut the ribbon cutting guide. There are several difference sizes to choose from. The closer the ribbon is to the magnets the better, but you don’t want the ribbon to actually touch the magnets. In the case of the R80 ribbon, the gap is 5.25mm, so you really should be trying a 4.25mm wide or so ribbon. I managed to get a 4.5 mm ribbon to work just fine. So pick the ribbon cutting guide you want to try, and tape this to the glass.
- 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.
- Take a second piece of glass, and tape the ribbon sheet cutting guide to it, then tape a piece of parchment paper. Have another piece of parchment paper ready. You will use this piece of glass to trim up the big sheet of ribbon foil to a smaller size.
Step 8: Cutting the Ribbon
- Turn off all the fans, close the heater vent, put the dog outside, kill the cat, and close the door. The slightest breeze will send the foil flying.
- Put the surgical mask on.
- OK Branch in process
- Bring the ribbon foil over the top of this 2nd piece of glass, with only the parchment paper. You will essentially want to gently and carefully use one 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 fold either. Nice and smooth.
- COVER IT WITH ANOTHER LAYER OF PARCHMENT
- What I suggest is roughly cutting it into a section or RIbbon Material that is 110mm tall (the length of the motor element and some extra length for the ribbon alignment jig), by 55mm, which is a little wider than my cutting guides.
- Using a fresh razor or Xacto and steel ruler (cork side up), cut the ribbon material.
- Take the extra ribbon material and put it back into its parchment and store.
- Now take this glass, and bring it over to the other piece of glass with the cutting guide, and gently float the foil you just cut onto the cutting guide, roughly aligning it with the cutting lines.
- Tape a fresh piece of parchment paper on top of the foil.
- Again using the steel rule cork side up, line up on the guide and cut several ribbons. While you might not need them all, cutting multiple now, will save you material, as you will have to trim off that 1st edge the next time you need it. So might as well cut some extras.
- Using the cutting guides to cut your ribbon. Again, I found that a 4.25mm to 4.5mm wide ribbon works well.
- 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. This is important, as when you go to crimp the ribbon, this will help it stay straight, and easier to align in the motor.
Step 9: Corrugating the Ribbon
- Take the ribbon, in the carrier, and in a nice steady motion, while applying decent pressure on the two gears, corrugate the ribbon.
- Don’t pull on the paper, rotate the gears and let the gears do the work of pushing the carrier and ribbon through them. Drive you can to do the entire ribbon in one motion.
Step 10: Preparing the Ribbon Truss
First, I should make you aware of some changes I made.
Second, I forgot to take pictures of the R80 truss in the ribbon alignment jig, so I am including pictures of the R144 truss. The mechanics are the same.
The Ribbon Element and Truss itself. For some odd reason, MXL tied the minus (-) side of the ribbon directly to the truss, and then (kinda of half-assed) tied the truss to chassis ground. However, everything I’ve seen shows that the ribbon element is floating (not tied to ground), while the truss itself might be tied to chassis ground. Therefore, I removed the metal bracket on the one end of the truss, to allow me to have that end be floating.
The other issue I found was that the little ribbon clamps used to hold the Ribbon in place would shift and move, when you would tighten up the screws to affix the ribbon in place. This was driving me nuts, as the ribbon would twist, putting it off center, put more tension than I wanted or have the ribbon go slack. Therefore, I designed and 3D printed replacement ribbon clamps. The bottom clamps need to hold some copper tape to allow you to solder the wire in place. The covers, just need to be the right size and thickness to hold the ribbon in place. Please note, the bottom clamps are 2 different sizes. The shorter one is for the narrow end of the truss.
Granted this isn’t perfect, as the plastic can melt when you solder to it, but I’ve been able to be quick, and it works fine. If anyone can source me some 1mm thick PCB material, I’d appreciate it.
- Print 1 of each of the bottom clamps, and two of the covers.
- Check to make sure you have clearance for the screws, the covers should be snug, where the bottom clamp should let the screw more freely pass through.
- You may need to use an Xacto to trim the outside edges for them to fit in the truss.
- You should also smooth or round the edge, where the ribbon will meet both the clamp and cover.I print on glass, so for me, the surface that printed against the glass is the surface that will touch the ribbon.
- Tap the screws into the covers, so they are being held in the cover and poking through the bottom of the cover. This will help you install them later.
- Next, you will need a piece of copper tape. However, the copper tape that I had was to wide and could potentially touch the screws when putting the cover on. Therefore, you will need to trim the with of the copper tape.
- Now take a piece of copper tape and center it on the clamp, and trim. You might want to tin the end where the wire will later be installed.
- You might want to cut a strip of paper, which you can place on top of the truss, for when you install the screws to protect the ribbon.
Step 11: Installing the RIbbon
Yes, there is some finesse in properly installing, centering and tensioning a ribbon. You will get better at this the more you do. Which is is why I make the cutting guides and Jig, so it is easier to replace a ribbon, whenever you want. This way you can also try different tensions, and see how each one sounds.
I also initially started out using Brass Nuts to hold the ribbon down, and help center and put tension in the ribbon. However, I'm now using a brass tube (a piece of 1/4" brass coupler with the nut removed). I will probably try to find a piece of brass rod. I've also found that the top of the Alignment Jig isn't as smooth as I would like. What you want to have happen is to have the ribbon stick to the brass rod, and slide on the plastic. Sometimes the opposite happens. I'm thinking if I switch to a brass rod, and even just making it moist will help. I'm still trying to improve the process.
Please note, the thin end of the truss, where the faux brass piece was glued in, is the minus side and will be at the bottom.
- Have the Ribbon Alignment Jig already printed
- Put your mask back on.
- Take the now corrugated ribbon carrier, and pry it open with your tweezers, so the ribbon can be easily slid out. Bring it over top of the motor and alignment jig, and slide it out over the middle. Using a combination of the tweezers and some toothpicks, center the ribbon in the opening of the motor. (Here, you do not want the ribbon to twist, crease or fold) Use a piece of brass rod to hold one end of the ribbon in place. I found using a toothpick as a means to gently move the brass nut around, to help center the ribbon. Then using the tweezers, center the ribbon on the other end. Put a piece of brass rod on top of that end and using the toothpicks, just ensure that the ribbon is primarily centered. Then place the cover on one end, gently press it down. NOTE: On the minus side, you will want to install the little wire tab to allow you to later ground the truss. See picture.
- Begin to screw both screws down taking turns. If the ribbon shifts, you should still be able to adjust the ribbon, until you actually make contact. And even if you have made contact, you can loosen it, and use a toothpick to try and shift the ribbon off of the cover. However, once it's tightened up, the ribbon will stick to the mount and cover, and there will be no way to remove the cover, without tearing the ribbon (another reason to have a couple cut and prepped)
- (here’s where I put that strip of paper on top of the motor, to protect the ribbon if the cover falls)
- Now you have one end clamped in.
- 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 too much tension, to where you are completely stretching out the corrugations. (Making the ribbon look flat). You want to see the corrugations. But you do want the corrugations to have some tension on them, so they will be slightly stretched.
- Put the cover on the other end, and install and tighten up the screw.
Step 12: Finishing Up
First, everything you do from this point is slow and gentle. You don’t want to trash the ribbon element you just installed. I’d still keep the surgical mask on, to keep you from breathing directly on the ribbon.
Also, you are going to do some soldering. Resist the common urge to blow on your recent solder joint to cool it. I swear to you, I drafted this Instructable ahead of time, and promptly blew out my ribbon. You can totally trash a ribbon by blowing on it.
Next, is you have to think about phase. The front of the truss is where the head of the screws are. However, the original construction had the one end of the ribbon grounded to the truss. This should be the minus side. Therefore, to get the phase correct, you should actually mount the truss upside down. So the part of the Ribbon Truss, where the metal is narrower (where you removed the faux brass piece) is minus or the bottom.
- Gently remove the ribbon truss from the jig. You can pull off the excess ribbon from the ends.Make sure you don't have any random bits of metal or tools laying around your work area
- Gently insert the Ribbon Truss first into the bottom 2 flex corner brackets, and then into one of the top corners. Then flex the frame and press the top corner into the last one.
- Solder the Minus wire to the bottom of the truss
- Solder a piece of wire to the ground tab on the truss,
- Now solder the two plus wires to the top of the truss.
- Tie wrap the wires to the frame
- Slide the fixture into the mic body. You can leave the bottom hang out a bit to help you have some length to work with in soldering the XLR.
- Pull the transformer output wires though the metal base.
- Put some 3/32” heat shrink on the output leads of the transformer, and solder the red (+) to pin 2, and the black to pin 3 (-). Slide the heat shrink back over the pins, and shrink’em on up. Twist the wires some. Then solder up the ground lead while you are at it as well.
- Slide the XLR back into the body, gently twisting the transformer leads while you are at it. Tighten up the XLR in place.
- OK, Here's where I screwed up. I forgot to take into account the little plastic pins that help hold on the little top piece of metal. You have a choice, don't bother with them (the grilles hold it in just fine), or trim the pins about half the length. If you are using the pins, slide the frame up the body to where they hit the bottom of the pins, and tighten up the 4 screws to hold it in place.
- Grab the little piece of black plastic and slide it in the bottom, and then screw on the bottom cover with the 2 screws, and then screw the base on.
- Next grab the 2 grilles (I didn't use the foam), and get them in place, and then get the metal top and align the slots to the grilles and then slide everything doen into place.
- You're done.
Step 13: Final Thoughts
Grab a cable, hook it up to your preamp, 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 before it gets to the mixer. A phantom powered in line preamp is perfect, because you can plug it right into the bottom of the mic. I suggest that you get one of the following:
Rick’s Ribbon Mic Preamp from www.diyribbonmic.com/parts
Cloudlifter CL-1 - http://cloudmicrophones.com/products/cloudlifter-...
Triton Audio FETHEAD - http://tritonaudio.com/index.php?sectionid=4&opti...
This is what I’m going to get for the short run, until I can get an in mic body phantom powered preamp
Again, I'm really pleased with the sound of the mic. I haven't spent enough time yet to listen to noise, and to see if the ground wire situation helps or not. I'll probably take the grille basket off, and try tying the one end of the ribbon to ground and see what difference it makes.
I'll try to record some samples using all three of these mics in addition to a condenser mic for comparison soon.