Mic modding



Pictured above are the BM800 microphone (left) and one of the Zramo microphones.

In the long-run, I’ve never saved any money with my DIY electronics hobby because of the investment in tools and in component inventory. If one finds a way to save money on a particular project, though, the tool and component costs don’t matter. Those are sunk costs – you can’t get that money back.

Such an opportunity presented itself recently in the world of microphone modding. I’d read about mid modding from time to time, but never gave it a shot until recently. The key was finding an Instructables article by Jules Ryckebusch that showed how to take an inexpensive Chinese-made microphone and turn it into a microphone with excellent performance.

I’ve read many DIY electronics articles by Mr. Ryckebush over the years. He’s an excellent writer. His writing is easily understandable. Also, the projects he writes about work very well.

The Instructables approach was to buy an inexpensive Chinese condenser microphone solely for its metal case. Most DIY’ers don’t have the ability to make a metal microphone case. With inexpensive cases already available, why try?

The BM700 and BM800 microphones were recommended. These are all over eBay under many different brand names. In the course of the project, the circuit board and capsule would be replaced, basically making it a new microphone.

The capsule is the component that receives sound and converts it to an electronic signal. The circuit board does the work of amplifying that signal, sending it into the cable, and then off to the mixer board or whatever fate awaits the signal. (For an explanation of how condenser microphones work, see the Instructables article.)

The microphone’s electronics are replaced by a new circuit board. The circuit is based on the “Alice” microphone developed by Scott Helmke. His web site about the Alice mic can be found here. If you don’t want to build an Alice microphone, you can buy one off of his web site. The circuit in the Instructables story is a modified version of that circuit called the “Pimped Alice.”

So, I bought a BM800 microphone on ebay for about $23 (you likely will be able to find one for less). I also bought the replacement capsule, TSB-2555BXZ3-GP here.

My DIY electronic building skills were rusty – or at least that’s my excuse for my failed attempts to produce a working circuit board. After a few misfires, I learned about an Alice circuit board available on eBay. To find it, search eBay for “Pimped Alice V.40 microphone PCB.”

Essential information about building the circuit using that board may be found at this link. There also are other useful links in the eBay listing.

I bought a board and ultimately built a working circuit. One of the nice features of the board is that it allows you to build different versions of the Alice circuit. You can do a “minimum” circuit with a low parts count. Or, you could add lots of bells and whistles and make a very versatile, even better-sounding microphone.

My first successful board was the minimum parts version. I figured the fewer the parts, the less opportunity to make mistakes!

That board didn’t make it into the BM800 body. During this time, I discovered a low-price microphone that was much better for modding than the BM800. It’s a Zramo large-condenser microphone described in this article.  At the time of this writing, it was selling for $13.90 on Amazon. So far, I’ve bought two of them.

I like the Zramo microphone because I don’t feel like I have to replace the capsule. The Zramo has a CM012 capsule. The author of the e-mail quoted in the article says the CM012 is comparable to a TSB-2555 capsule. So, I did the math: BM800 plus TSB-2555 equals 36 dollars, plus shipping. The Zramo mic is $13.50 plus shipping, with no replacement capsule to buy.

With the three microphones – one BM800 and two Zramos – I did three different mods. For the first Zramo, I modified the circuitry as described in this article. I didn’t replace the capsule and I performed two of the three circuit board mods.

zramo mic

The Zramo microphone with the Alice circuit board is shown above.

My first successful circuit board went into the other Zramo. I didn’t change the capsule.


This is the BM800 with the original Alice circuit.

The BM800 received an original Alice circuit that I managed to build on perfboard. I previously had installed the TSB2555 capsule in the BM800. The original Alice schematic calls for a different capsule, but the TSB2555 worked.

Component note: I replaced the 2N4416 transistor on the original Alice schematic with a PF5102. Some Pimped Alice schematics call for a J305 transistor. I substituted the less-expensive PF5102.

So, how do they sound? Disclaimer: I am not qualified to evaluate sound. I’ve never owned a condenser microphone that cost more than $100. I have hearing loss and wear hearing aids. I am a home recording hobbyist, not a trained audio engineer.

With that said, the Zramo with the Alice board sounded better than any condenser microphone I’ve owned. The BM800 with the original Alice circuit also sounded quite good.

I succeeded in improving my microphone collection without spending a lot of money. The Zramo with the Alice circuit board probably cost me no more than $35, plus time. The BM800 mod cost more, at around $50, but it still sounds better than a $50 condenser microphone that I once owned.

Eventually, I will put an Alice board in the other Zramo. Eventually, I would like to have four of the Alice-inspired microphones. I’m also interested in doing a mod with a larger capsule. That will take some research.

So, fire up that soldering iron and upgrade your mic locker!

If you’re interested in learning more about mic modding, consider joining mic modders Yahoo Groups.

Electronic component sources were Mouser, Digi-Key and Randolph-Williams Electronics, an electronics store in Columbia, Tennessee, where I live.




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