Intro: Ribbon Microphone Upgrade for MXL R144
2nd in a Series
Hello, this is my second in a series of DIY ribbon mic upgrades. In this instructable, we will re-ribbon an MXL R144 mic, and replace the stock transformer with and upgraded transformer. Again, I’m relying on my friend Rick at www.diyribbonmic.com/parts for his OTA-1 transformer in this example.
I have also designed a Ribbon Alignment Jig for this RIbbon Truss (motor, element, or whatever you choose to call it), along with some additional enhancements we'll discuss as we go.
Rather than make this an abbreviated Instructable, I am going to cut and paste a good portion from my previous 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.
The MXL R144 Mic
I like this mic, as it has a nice big full metal framed ribbon motor element, and also has the transformer placed in a metal can, which I assume is mu-metal, and is shield for hum. This makes this mic perfect for with the Austin OTA-1 or Lundahl transformer upgrade.
Step 1: 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. For this mic, for me, a 4mm ribbon seemed to be the right width.
- Paper Ribbon Carrier – Again, a simple set of parallel lines 20mm apart to cut some 22lb 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. What I've learned here is that I initially started with Parchment paper, but found that 22lb copier paper worked better to put more pronounced corrugations in the ribbon. Also, when trying to fold the carrier by hand and crease it, it actually put a curve in the paper, which also tended to curve the ribbon, not making it straight. So now I use a straight edge ruler to help fold it over.
- Ribbon Sheet cutting Guide – Just a couple of lines, so you can trim down the ribbon material to fit the ribbon cutting guide. 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 motor on your desk, and try to do everything free hand. This help keep the ribbon truss oriented and stable. This jig allows you to place the Ribbon Motor in it, then drape the ribbon element across it to more easily align it, and put tension on it. I initially used brass nuts, but have now switched to brass tubes/rods, to hold the ribbon in place. As using the tube/rod allows you to twist them to help center the ribbon. I still used a trusty toothpick to slide them (the brass tubes) around to align and tension the ribbon. 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, 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 R144 ribbon mic element. What I am hoping to do is 2 things. 1st create a catalog of simple ribbon alignment jigs for this modular ribbon motors. 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 aggressive, but I think I have a good 20 years left.
- Yes, it takes time, patience and some experience to get the ribbon in place and of the proper tension. My goal here was to provide some tools to help you and to take some of the black magic mystery out of the process. I'm still working on the jig, as I really want to improve how you can manipulate the ribbon ends to align things.
- 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. 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. Also, some little wire guides that clip right onto the truss to keep the wires in place.
- 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. 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.
- I've got 1 more instructable coming for the R80 mic, and after that, I intend to whip out the CAD software and design a better Ribbon Corrugator. I might even have a motor drive it, so it runs at the same speed. We’ll see. This will be next on the list.
Step 2: 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. 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.
- Lebow also can supply ribbon material of different thicknesses - http://www.lebowcompany.com/foils_list.htm#ALUMIN...
- MXL R144 Ribbon Mic Alignment Jig
- MXL R144 Ribbon Mounts – More on these later
- MXL R144 Wire Guides
- All are also found here: http://www.thingiverse.com/thing:1289373
Step 3: MXL Mic Disassembly
As can be expected, I was too excited, and tore down the mic before I took any pictures. You can refer to the finished mic pictures to get the idea, in addition to the picture here of the parts laid out. Basically, you just want to strip it down to where you only have the case, XLR connector and basket. The mic basket has 2 layers of grille material. You really want to remove the one interior layer.
- Unscrew the blue base at the bottom of the mic.
- Once that has been removed, the blue main body can slide out.
- Now loosen the two screws, which are holding the basket on, this will expose the ribbon element.
- Cut the wires going to the ribbon element underneath the plate it is attached to.
- Remove the screws holding the base plate to the 2 frame arms. The plate that the ribbon element is attached to, along with the ribbon element will drop off.
- Remove the screws holding 1 of the arms to the bottom of the mic. Put the arm off to the side.
- Unsolder all of the wires from the circuit board on top of the transformer can. If it’s like mine, there’s about a ½ pound of solder on it.
- Remove the screw on the other side, which is holding the transformer can in place.
- Remove the transformer, while it is still in the can.
- Unscrew the XLR connector, and let it drop out the bottom. Then desolder the + and – leads.
- Getting back to the Ribbon element, remove the screws that are going through the little rubber gaskets, and holding the element to the metal plate.
- Remove the ribbon element from the plate.You can go ahead and remove the fine mesh grill taped to each side of the ribbon element.
- Grille – OK, this is a little bit of work. The grille on this Mic has 2 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 layer of the main body. You can pretty much leave the inner layer on the top portion of the grille alone.
- This is a little tough, as the layers are soldered in a number of places. I used long nosed plyers and some long necked wire cutters. But if you are patient, you can completely remove the inner layer
Step 4: Print the Parts and Test Fit
Please print the RIbbon element parts, Brackets, covers, wire guides and Jig and test fit everything. You want everything test fitted before you have an actual ribbon in the thing.
Step 5: Wiring It Up
Let’s first get the Mic body prepped for the new ribbon motor (element)
- Put some 1/16” heat shrink on the mic input leads of the transformer. Then just tack solder a couple of wires to these inputs. You’ll use these to help guide the leads through the hole in the can shortly.
- When you remove the old transformer from the can, you will see a chunk of double sided foam tape. Remove it from the can, and clean it up a bit. You will also see the screw holding the tiny PCB poking through. Replace this with 2 layers of the ½” wide 3m double sided foam tape. Then take a layer of the ½” wide double sided foam tape and line the inside wall with it.
- Now take some electrical tape and wrap the transformer, to cover the exposed metal. I did a double layer around the ends, tucking the tape up against the metal of the transformer, and then a double layer around the coils to hold it all together.
- OK, here’s where I got ahead of myself. Run a wire through the one hole in the can, to use for chassis ground. You’ll hook it up to the XLR in a moment.
- Now use the 2 wires you tacked on to the input leads and run them through the other hole in the can. Now press fit the transformer into the can. The mic input leads should line up with the one hole, gently pulling the input leads through as you press it in. The transformer will be perpendicular to the strip the held the old transformer in.
- For some odd reason, MXL originally wired both the XLR and transformer leads to the little circuit board. But we’re just going to wire the transformer outputs directly to the XLR pins, this way we keep the leads shorter.
- Cut a 1 inch piece of the 1” wide 3m double sided foam tape and apply it to the bottom of the transformer in the can. Run the transformer output wires through the base. And place the can in its proper place, ensuring the transformer output wires are clear. As you still have the one arm installed, go ahead and install the one screw to hold the can in place.
- OK, my dad always told me, never cut the wires on a transformer. You never know when you will need to reuse it someplace else. So of course, I trimmed the transformer output wires. (I'm a bad son, I never listen) You can see how much wire you need to hook up the output wires to the XLR. You can choose to trim them or not. Put some 3/32” heat shrink on the leads, 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. 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.
Step 6: Getting Ready to Cut a Ribbon
OK, before I start, yes, there is some skill and patience required to do this well. Take your time. Once you cut the ribbon, check to make sure the edges are smooth and straight, and that the entire main body of the ribbon looks good. The ends can be a little ragged, as you will only be using them to adjust the ribbon, and they will get disposed of, once you tighten up the clamps.
- Ribbon Pocket Carriers - Simply print the ribbon pocket carrier page, and cut on the solid lines, and fold on the dashed lines. Tape the cutting guide onto the piece of glass, and then tape the 22Lb copier paper onto the glass on one edge, and using a steel rule (cork side up if it has it), using a brand new exacto or razor blade, cut them into strips. These will give you 20mm wide strips, which are around 145mm long. Then fold them in half long ways. Rather than trying to fold and crease them by hand, user the straight edge of a ruler to fold them. When you do them by hand, I've found that the paper curves along the fold, and this puts a curve in the ribbon, which makes it hard to straighten out in the truss. 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. For the MXL R144, I used a 4mm wide ribbon. The closer the ribbon is to the magnets the better, but you don’t want the ribbon to actually touch the magnets. But if too close, it is really hard to get it set up. I'm finding about 1/2 of a mm on each side is easy for me to do, and I'll probably get better over time. I’ve found that using the ribbon alignment jig, I was easily able to keep the ribbon centered, and get it tensioned. 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 7: Cutting the Ribbon
Here too, there is some finesse in cutting a good ribbon. I've seen that Rode uses a laser cutter. You need to be gentle with the sheet. You don't want folds or creases. You need to make sure you have a nice set of parallel lines. The edges of the ribbon shouldn't be ragged, but nice cuts. You need to hold the ruler firmly on the ribbon, to ensure no part of the ribbon shifts while you make your cut. I found that I wasn't holding the ruler down well, and a part of the ribbon would shift, making it skinny for a little section. Maybe a thicker piece of metal would be better to hold it down. That's why it's always a good idea to cut multiple ribbons at one time.
Also - Practice. You can use some standard kitchen foil (thinner in this case is actually better), and you can try cutting ribbons of different widths, so you can sort out which size makes sense for you to use.
- Turn off all the fans, close the heater vent, put the dog outside, kill the cat (Geesh, OK, I like cats) close the door. The slightest breeze will send the foil flying.
- Put the surgical mask on.
- OK Branch in process
- If you are using Rick’s foil material, you can leave it in the thin parchment paper, as it cuts OK. If you are using the foil from Lebow, I have found that when you cut the foil in the parchment they provide, it sticks on the edges, and can tear the ribbon. So if you are using Lebow foil, I suggest removing the foil from their parchment, and use kitchen parchment paper.
- 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 a peice of foil into a section that 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.
- Again, for the MXL R144, I found that a 4mm wide ribbon works well.
- 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, you should be only rotating the gears and let the gears do the work of pushing the carrier and ribbon through them.
- You want to try and do this in a single smooth manner as every time you stop and start, this will leave a minor impression on the ribbon. This is being a perfectionist here. If you stop and start, the ribbon will work, it just won't be "perfect"
Step 8: Prepping the Truss for the New Ribbon
First, I should make you aware of some changes I made to the
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.
- 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.
- Use some scotch tape and pick up any metal fragments that might have been picked up by the magnets.
- Take some acetone or alcohol and clean up the truss. Mine had residue from the tape on it.
- Place the clamps into the truss, place the truss in the Ribbon Alignment Jig, and adjust the clamps as necessary.
- 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 9: Installing the RIbbon
First, the ribbons in the pictures don't have enough tension. Later pictures you will find that I subsequently replaced it. This is an example, of straight, but still not enough tension on the corrugations.
In addition, 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.
- 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. 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 10: 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. You can totally trash a ribbon by blowing on it.
- Have the two wire guides already printed.
- Gently remove the Ribbon Element from the alignment 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
- Check the orientation of the metal mounting plate. the protrusion on the plate is the front.
- Wiring for ground. Here if you didn't make my mistake, you should have a ground wire coming from your XLR connector, use one of the original ribbon solder tabs, and solder the ground wire to the tab, and put one of the ribbon mount screws in it. It should be ground solder tab, metal washer, rubber washer, through the metal plate and then the other rubber washer.
- For me, I made a little jumper, which connected to the one truss screw and then to metal arm.
- Put the the other screw in the metal plate, metal washer, rubber washer, through the metal plate and then the other rubber washer.
- Now when you bring the ribbon truss to the metal plate, it will be drawn to it. The metal plate is magnetic. So be careful. You want the solder points on the truss to be facing the back, (yeah, my pictures are backwards)
- Screw the truss to the metal plate.
- Now screw the metal plate to the two arms. What I found to make this easy, because the screws are also magnetic, was to place the screw in the hole using a pair of hemostats. Then screw with a jewelers screwdriver.
- Solder the black minus (-) wire to the solder point on the bottom of the truss.
- Now grab the two wire guides, and they shold press fit right onto the sides of the truss. I used a little bit of silicone seal on the inside of them (just a dab) to make sure they stayed in place.
- You can wait for the silicone to dry, or press on. I just kept working, as they were a snug fit already.
- Trim the plus (+) leads to length, strip, tin and solder to the top solder point of the the ribbon.
- Press the wires into the channel on the wire guides.
- Grab the grille, and carefully insert the ribbon motor into it, align the notch for front, and use the 2 screws to hold in place.
- Grab the body, install, and then use the bottom screw to hold everything in place.
- You're done.
Step 11: 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
a. Rick’s Ribbon Mic Preamp from www.diyribbonmic.com/parts
b. Cloudlifter CL-1 - http://cloudmicrophones.com/products/cloudlifter-cl-1/
c. Triton Audio FETHEAD - http://tritonaudio.com/index.php?sectionid=4&option=com_content&task=category&id=17&Itemid=33
i. 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've one more Ribbon mic project, which I plan to knock out in the next two weeks, which is an MXL R80 mic. Again, I'll re-ribbon, make the ribbon floating, and install Rick's OTA transformer. But I also changed the entire mounting of the element, using 3D printed suspension mounts using flex filament. Stay tuned.
Once I get the R80 project complete, I'll record some samples using all three and a condenser mic for comparison.