The View Up Here

Random scribblings about kites, photography, machining, and anything else

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!

Tom

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4 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:

      http://www.thingiverse.com/thing:2036552

      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:

      https://www.shapeways.com/product/PEWRFKNHA/alice-tsb-2555b-capsule-saddle?optionId=61697185&key=677364a04326bc04389a3c0944522563&li=shop-inventory

      (Sorry for the awful URL…)

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

      https://microphone-parts.com/products/tsb-2555-electret-capsule

      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:

      https://microphone-parts.co.uk/products/tsb-2555b-electret-capsule

      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!

      Cheers,

      Tom

      • 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…. http://www.thingiverse.com/thing:2036508 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.

        Cheers!

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