Building Microphones

It wasn’t that long ago that the idea of building your own microphones was fine for a science fair project, but the end result wasn’t anything with a practical use. There are a few old articles about building microphones floating about the web. Take a look at The Bantam Velocity Microphone by L.J. Anderson and L.M. Wiginton, (Thanks to New York Dave at Prodigy Pro for posting this) Make This Ribbon Mic by M.H.O. Hoddinot, A Professional Condenser Microphone by R.Williamson,( originally published in AUDIO magazine, July, 1963)  A Stereo Condenser by Debenham, Robbinson, and Stebbings (image HERE) but the information is generally sparse, and it requires precision machining facilities. One person has even built his own gold vapor vacuum deposition chamber for gold-sputtering diaphragms. But with the rise of Chinese manufacturing and the resulting flood of Chinese-built microphones on the market, building a useable microphone is now a more realistic proposition. We can let the Chinese factories take care of the specialized machining, while we provide quality electronics, tuning, and care in assembly to end up with… possibly… a superior microphone, or at least one that’s custom-tailored.

Now, I don’t normally advocate buying Chinese audio gear. Quality control is often lacking, raw materials are questionable to poor, and the lifespan can be short as cheap components fail. And I dislike the idea of buying a look-alike product– i.e., a Chinese copy of a Schoeps or Neumann microphone. But there’s an opportunity here, if one looks at an inexpensive import mic as a source of raw materials. Others have realized this, and built successful small businesses by sourcing Chinese components, then tweaking the parts to yield some really nice results.

Don’t think for a moment that any mic that you or I will build will sound as good as, say, a mic by Neumann, Schoeps, DPA, etc. These mics will never replace those pieces of gear, and when you compare them side-by-side, the deficiencies of a lower-cost product will stand out like a sore thumb. But these mics are still useful, and depending on the situation, can even be a better choice than a top-grade mic. (For example, in an environment where a mic might get destroyed… wild flailing drummers, motocross races, mud wrestling, monsoon rainforests, etc.)

I’ve always been fascinated by the engineering that goes into microphones. It’s a combination of machining to almost unbelievable precision coupled with electronics circuitry that is, to my simple mind at least, almost magic that it works at all. Then when you get to hear the results of a REALLY  nice mic (say, a DPA or Neumann) in front of a good musician… the experience is unforgettable.

The only problem is the price, which is also unforgettable.  The pair of DPA 4016s I heard at the first Nashville AES Recording Workshop sounded absolutely beautiful… a truly AMAZING sound. The list price for the pair is over $3,800. In Brian Gilbert dollars, that price may as well be 38 million… in other words, until I can directly make $4k with that particular piece of gear, it’s an extravagant expense, no matter how much I love the sound. I’ve got a family to feed, after all.

So until I can afford a selection of really classic mics, I can experiment with making or modifying cheaper versions. While I’ll never expect to duplicate the sonic ability of a mic costing $1,900, perhaps there are some things I can do with a less expensive mic that can improve the sound a little.  And it turns out that I’m not alone. The MicBuilders forum (micbuilders@yahoogroups.com) has a lot of people who are interested in the same sort of experimentation. I don’t often contribute, as most of the folks there are far more advanced than I am. But the people there are very generous with their time and willingness to help others learn. Similar audio experimenters can be found at ProdigyPro.

Generally, mic builders have two options: A) buy a readily-available mic and modify, or B) source the parts and build from scratch.

The Neumann MA-200 mic capsule

Some parts, such as the capsule, can be hard to find, but they are out there. Capsules can be found on e-bay, or they are available from Peluso. Microphone bodies require precision machine-shop work if they’re going to look at all professional.

There is a third option that I recently discovered. A company called Aurycle sells condenser mic kits, along with a few completed mics. The prices for Aurycle kits are very affordable… lower than the sum of the parts if you bought them individually. I have built three of their microphones… two large-diaphragm FET mics, and a large-diaphram tube mic. Overall, I’m quite pleased with their products and the results, but like everything in life, there are pros and cons. Let’s start with the PROS:

• The prices are affordable… downright cheap in fact.
  

  The Aurycle A460 FET mic frame and body

• Entire kit is less than the cost of the parts alone.
• Easy to substitute different components to see how they sound.
• Modifications are easier, since it comes disassembled.
• Transformer-based design lets you try a transformerless circuit easier than the other way around.
• The low cost encourages experimentation. If I screw the pooch, I won’t loose too much sleep over it.
  

  Aurycle A5500 Tube mic kit as supplied. The high-voltage power supply comes assembled.

• While these ARE NOT good first projects, they are great learning tools for teaching yourself about microphone electronics and developing skills.
• The machining is pretty good, with all-brass bodies that are suitably heavy.

Now the CONS:

The completed 5500 tube mic.

• The end result of the stock build is very typical of, and in some cases identical to, other low-cost Chinese mics.
• Documentation is not nearly as good as it should be. In some cases, it’s incomplete… you’ll need to do some internet research in order to complete the microphone.
• Electronic components are adequate, but rather low in quality… typical Chinese stuff. This is an easy upgrade, though.
• The brightly-polished brasswork as supplied has a slightly cheesy look to it, and the brass itself seems pretty low grade. Again, fairly easy (though potentially expensive) to change if you want.
• These don’t come with any sort of clips, suspension mounts or cases, which you’ll need. Clips don’t always fit… I bought some that won’t work because the threads are too short.

Microphone building certainly isn’t for everyone, but it is an option for those who want to dig a little deeper into microphones and how they work. The sonic character of these isn’t likely to change your life… just another crayon for your box… but it’s certainly fun to use a mic that you built yourself. Otherwise, contact me… I have several custom-built mics for sale.