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Building the MS Alice Microphone – Part 2

Posted by Tom Benedict on 23/11/2016

This is the second half of a two-part article describing my build of the mid-side Alice microphone, following the Instructable written by Jules Ryckenbusch: Build the MS Alice Stereo Microphone. In Part 1 of this article I ran through how I was planning to build it (mostly following the same steps I used in another two-part series I wrote about another of Jules’s Instructables, Modify a Cheap LDC Condenser Microphone, namely: BM-800 Microphone Conversion Part 1 and Part 2.) I also covered my design for the saddle and post that holds the three capsules in the particular orientations required for Jules’s MS microphone build. (Jules used a different method, using PVC pipe, which you’ll see in his Instructable if you decide to build one of your own.)

Since writing Part 1 all the bits and pieces came in. I was eager to see how the 3D printed saddle and post turned out, and how well the TSB-165A capsules fit.

M-S Alice Capsule Saddle and Post - Unpopulated

I designed the cavities for the capsules at-size, meaning I didn’t leave any slop for fit. The plastic Shapeways uses to make their least expensive printed parts is described as “strong and flexible”. I took them up on that, figuring the part would flex enough to allow the capsules to snap into place. It worked like a charm.

M-S Alice Capsule Saddle and Post - Populated

The fit is snug, but not snug enough to hold the capsules in use. As with my first Alice, I glued the capsules into the saddle with E-6000 adhesive.

I’m a little disappointed with the handling noise on my first Alice mic. I chalk some of that up to the metal saddle and post, but some of it I chalk up to the relatively stiff wire I used to connect the capsule to the PCB. It was stiff enough that manipulating the wire wound up breaking off one of the ground tabs from the TSB-2555B capsule I used on that mic. Rather than repeat that experience, and in an effort to reduce conduction paths for handling noise, I gutted some of the Mogami cable I use for all my microphone projects and used the wires to connect the capsules. (NOTE: It didn’t actually affect handling noise that much. After thumping various bits of the mic, I’ve come to the conclusion the dominant frequency of the handling noise is driven by the resonant frequency of the mesh in the headbasket.)

I already had two Pimped Alice PCBs built, tuned, and ready to go for this project. The remaining steps were to screw one board onto each side of the mic frame, solder the capsule wires to the boards, solder the four 0.022uF capacitors between the ground pin (pin 1) and the remaining pins of the XLR connector (2, 3, 4, and 5), and to solder wires between the XLR and the PCBs.

M-S Alice Internals

Since I oriented the two capsules of the figure-eight mic side-by-side, they won’t fit inside the headbasket with the foam liner in place. So I stripped the foam out before closing up the mic.

The very last step was to build the 5-pin XLR to dual 3-pin XLR splitter cable. There are a number of ways I could’ve done this, but I followed (mostly) Jules’s build on the cable as well, using separate Mogami lavalier cables for each channel. This is a wonderfully floppy wire, and does an excellent job of reducing handling noise transmitted through the cable.

The one change I made to Jules’s design was to jacket the central eight feet of cable in a woven sleeve to keep it from tangling.

M-S Alice Patch Cord

I left the last foot and a half at each end loose, though, to take advantage of the wire’s floppiness. (Hey, that’s actually a word spellcheck recognizes!)

And at long long last I’m able to play with mid-side recording and compare it against my EM-172 based SASS.

SASS vs. M-S Comparison

Big big thanks to the following for making this all possible:

  • Jules Ryckenbusch – for writing the two Instructables that got me going on these microphones
  • Homero Leal – for coming up with the PCB layout for the Alice boards used in Jules’s Instructables
  • Scott Helmke – for designing the Alice circuit in the first place
  • Ricardo Lee and all of the above – for their endless patience with all of my questions and what-ifs
  • Dr. Ing – for designing the Schoeps CMC-5 in the first place, without which none of this would exist

For my own contribution, here’s the link to the MS Alice capsule saddle and post on Shapeways. I’ve listed these at-cost, with no mark up (meaning I don’t see a dime of the 5.35 USD price tag at the time of this writing – labor of love).

Have fun recording!


16 Responses to “Building the MS Alice Microphone – Part 2”

  1. Nick Allen-Rowlandson said

    Hi, I am in the UK and wish to build the Alice mic. Is the file for the 3D printed capsule holder available? Also does anyone stock any of the mic capsules as the shipping costs from JLI are offputting for just three!!!!

    • Tom Benedict said

      The file for the 3D printed capsule holder is up on Thingiverse:

      If you don’t have access to a 3D printer, it’s also up on Shapeways. I list stuff there at cost with no mark-up:

      (Sorry for the awful URL…)

      The only sources I know of for the capsules are JLI and Microphone Parts:

      But I’m pretty sure Microphone Parts is a US company, so the shipping may still be high.

      I understand your frustration with shipping. I get my Primo capsules from FEL Communications in the UK. I hate looking at the shipping and thinking, “How many more capsules would that buy?” It hurts. But for the Primo capsules I really don’t know any other way to get them.

      Ah! It looks like Microphone Parts may have a UK presence, too:

      It’s listed there for 36 Euros. Not sure how that compares to the price from JLI plus shipping, but it’s an option.

      Have fun building the microphone!



      • Nick Allen-Rowlandson said

        Thanks Tom for such a quick response!!! Also loved your photos! I will explore the options and I will most likely design a PCB to suit two Pimped Alice circuits that will fit into the BM800 body. If enthusiasm still exists, I may do a surface mount version too. When I do that, I could make them available to anyone else interested. Has anyone got surface mount alternatives for the FET???? Everything else I can find.
        I have the BM-800 body and just about to get a Zoom H4N Pro which has MS decoder built in. I record my local community choir most weeks and concerts. If you let me have an e-mail address I can send a file or two.

        This was what I was looking for…. I found from your links….thanks again

        Regards…………. Nick.

      • Tom Benedict said

        Oops! I pointed you toward the wrong post! Glad you found the one for the MS Alice.

        I haven’t found an SMT option for the FET, which I was looking for when I was designing the PCB for the Behringer mics. But since I was planning to air-solder the high-Z part of the circuit on those as well, I didn’t get too heartbroken. Sorry I can’t help you there.

        Back when I built my first Alice I asked a similar question to the one you’re asking: making boards available. Homero Leal rightly cautioned me that since it’s not my circuit, that might be stepping on toes. A better person to ask would be Jules Ryckenbusch, whose Instructable I used for the build.

        I’ll email you so you’ve got my address.


  2. John said

    Where can i get the pcb and bom for this?

    • Tom Benedict said

      Send me an email at tnbenedict at gmail dot com.

      • Nick Allen-Rowlandson said

        I do have some PCBs available for a small fee. You are welcome to forward my e-mail address. I really must finish that project…life has been silly hectic recently…..oh well!

  3. […] a stereo microphone, and since I’d already built an XLR-5 to twin XLR-3 splitter cable for my MS Alice microphone, I used an XLR-5 connector for this mic as well. While not the most elegant setup for this […]

  4. Benjamin said

    Hi again Tom,
    In your first pimped Alice (TSB-2555B), it seems you follow Jules circuit to the letter by skipping the 10uF polarized cap on the other side of the 6.8K resistor (I did the same). But on this build you seem to have put it in there, do you now what it does?
    I have also seen it has been replaced by a second 47uF on a more recent build.

    Thanks for all your posts,

    • Benjamin said

      Actually your 47uF seems to have shrunk on this build so I’m not sure what’s going on here 🙂

      • Tom Benedict said

        The filter caps have been my Achilles heel on these. The original layout I used (the one Homero Leal did that was in Jules’s article) didn’t entirely fit inside the BM-700 / BM-800 body tube unless you mounted the board so the component side of the board faced into the frame rather than into the body tube. (If that makes any sense.)

        My next go ’round I measured the voltages actually present at each of the filter caps, and got capacitors sized for the voltages present. That’s why some of them shrank.

        The set I built with TSB-25AX capsules used capacitors scaled to the actual voltages present, but one of the ones I got was still too tall to use on the front side of the board, so I soldered it to the back. This helped things fit into the body tube better.

        My most recent build, the one with the 34mm LCD capsule, uses a newer version of Homero’s board in which he re-arranged everything so the filter caps are positioned as close to the centerline of the board as possible. I really like this layout for a number of reasons, the biggest of which is that all the components fit on one side of the board while using 50V or 60V filter capacitors.

        That’s the whole long spiel about the filter capacitors on these mics. Except for the most recent build, every single one has involved at least one head-scratching session while I say to myself, “How am I going to make this fit?” In each case it was possible. It just wasn’t always satisfying.

      • Benjamin said

        Oh ok that explains it. Thankfully I don’t have any boards left, so I will have to build the MS with Homero’s last version… Life is simple for me!
        I just noticed on Jules instructables that he excluded that 10uF cap in between it’s Oct and Dec 2015 build… I am still very curious about that so I dropped him a question. I am slowly understanding how this circuit works but it stills very foreign to me! I wish all were as simple as Ricardo Lee’s SimpleP48!

        Thanks again, and all our prayers to all of you in Hawaii

  5. suicufnoc said

    How do you think the 165A capsule compares to the 2555B Capsule? I’m considering building one of these, but using a 2555B for the mid capsule. Would have to tweak the holder a bit (which I have no idea how to do, guess I need to learn some 3D modeling…)

    • Tom Benedict said

      The 2555B has a remarkably flat response. Henry Spragens’s measurements of Homero Leal’s Alice gives you a good idea of what it looks like. If you skip down to the frequency response graphs at the end (after Henry removed the foam liner from the head basket), you can see what its response is:

      I don’t have any measurements of the 165A, but just listening to the two it’s got a more pronounced presence peak out around 10k. Nothing you couldn’t take out with EQ, but the two do sound different.

      Something else to look at. A while back I picked up another mic body that I haven’t put into service yet:

      It’s more solid than a BM-800 body, has a better finish on the head basket, and comes without logos or any labeling of any sort. It’s also bigger. Same diameter, but the body is considerably longer and the head basket is taller as well. I still haven’t measured mine to put into CAD, but I need to in the not too distant future. I bought the thing for a vocal mic project using an edge-terminated 34mm diameter capsule, but…

      Just looking at it, I’d be willing to bet there’s room to build an MS Alice mic using three TSB-2555B capsules. Fitting the two capsules for the Fig-8 would be a bit of a dicey job, but there’s room for them.

      If you decide to pursue this, let me know. Depending on where I am with other projects, I might be interested in doing the 3D design for the saddle and post to hold the three capsules.


      • suicufnoc said

        Thanks for the input. I have a BM800 sitting here already that I want to use for something, so I’ll probably stick with using the 165As for the sides and just ugrade to the 2555B for the mid mic. Most mid side micing isn’t done with identical mics, so I don’t think its really a problem. The 10k peak should be a little less impactful I think on the side mics than the mid too, as it should translate into more width at that frequency rather than just a volume peak.

        I suppose you could put two 2555B capsules back to back with some space between them for the side mics and probably fit the whole thing in a BM800. hmm…

        I downloaded blender last night and got about halfway through recreating your mount with the top enlarged to fit the 2555B, so I think I’ll be okay on that part. I haven’t found eagle/gerber files yet for the version of the circuit with the BM800 mounting holes. Shouldn’t be hard to add them in Eagle to the original version, but I’m a kicad guy and never learned Eagle at all…

      • Tom Benedict said

        Yup! That’s one of the things I like about mid-side. You can EQ the two channels independently. To be honest I hadn’t really thought about what the presence peak would do on the mid channel with respect to the stereo imaging. Now I have something else to play with! (YAY!)

        The toughest part about fitting two 2555B capsules back to back and fitting them in the head basket of the BM-800 is that baseplate at the bottom. The hole to get stuff into it is a little restrictive. It’s possible to machine away a good bit of the plate, but it’s not ideal. Still, I’ve been able to fit a surprising amount of stuff up into them. (I need to do a write-up of the quad capsule mic I built a while back!)

        Let me know if you run into issues adding the holes in Eagle. I just did a re-spin of the board layout for that other mic body, so it’s still pretty fresh in my mind.


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