12-251 Microphone Kit
The 12-251 is one of two DIY tube microphone kits we make that are based on the Telefunken ElaM 251. It contains all the parts needed to build a phenomenal tube microphone that is suitable for a wide variety of sources, from vocals to drum kit to guitars, basses, and strings.
We revised and improved the 12-251 circuit in January, 2022, to incorporate four upgraded capacitors, notably including the tube cathode capacitor. The board layout and build process were refined, along with the documentation.
The 12-251 microphone kit includes:
- C12-style tube microphone body (in either of two finishes)
- Elastic shockmount, foam windscreen, 7-pin XLR cable
- Power supply (complete and US-tested) with 9-position polar pattern switch and US power cord
- Complete custom circuit kit, based on the ElaM 251: circuit boards, premium components, tube, transformer, best-in-class assembly instructions
- Our CK-12 style, edge-terminated large diaphragm capsule, called the RK-12
- Custom, locking flightcase with die-cut foam
This kit includes everything needed to build a C12/ElaM 251 style tube microphone -- just add solder and a few hours' time.
The second 251-style tube mic kit we make is called the V-251; you might wish to read about that one before you decide which kit best meets your needs.
Drummer, engineer, and microphone aficionado Don Gunn reviewed the 12-251 kit for Tape Op magazine. Click the cover image at right for the full text.
Testing [a DIY microphone] build is always a bit nerve-wracking, as you hope for the best but always expect the worst, so I was overjoyed when the first thing I heard when I spoke into the mic with headphones on was my voice sounding big, resonant, and clear. It reminded me of what I like about my Soundelux E47 - a really pricey mic with a richness of tone that's just lush and "expensive" sounding...
I placed the 12-251, my Soundelux E47, and my Neumann U 89 capsules as close to each other as I could and recorded Lacey Brown playing her guitar... The consensus was unanimous that the 12-251 was the vastly superior mic on the acoustic guitar tracks - it provided the perfect balance of string attack/airiness and body from the guitar. I would be happy to have that acoustic guitar sound forever more.
The microphone body is made of heavy brass. The black version has a matte finish. The front of the mic is indicated by the Micparts vintage diamond logo badge.
We have a limited supply of silver powdercoated mic bodies. Please be aware that the powdercoating process occasionally leaves tiny imperfections in the surface finish.
Power supply options
This kit includes a fully functional power supply (not a kit), which we QC extensively prior to shipping. Part of the microphone build process requires swapping two components in the power supply to optimize its voltage output.
Alternatively, you could upgrade this microphone kit to use our premium, MOSFET-regulated "VPS" power supply. This is a modern design with very low noise, rock-solid regulation (no voltage drift), and excellent filtering. There are two ways to do this: buy the PSU circuit kit, or buy a built/tested PSU.
To build the premium power supply yourself, add the VPS1 Circuit Kit to your cart. Instead of sending you the standard PSU that normally comes with this kit, we'll ship you the empty PSU chassis and case (flat black painted finish), Neutrik XLR jacks, power transformer, custom PCB, components, and our excellent DIY instruction manual. This option will give you everything you need to build the complete VPS power supply.
If you want the benefits of the VPS power supply but do not wish to build it yourself, order our prebuilt premium tube mic power supply. These are handbuilt in California and extensively tested. You would not need to build or modify this power supply; it is complete and ready to plug in. Order it here and choose the "upgrade bundle" option for discounted pricing. We would ship the built VPS1, with a silver powdercoat finish, and (for US domestic customers only) a premium AudioQuest IEC power cable in place of the standard supply that normally comes with this kit. Note: the upgrade bundle pricing is only available if the PSU is ordered in the same shopping cart as the 12-251 kit.
XLR cable options
The 12-251 kit includes a 7-pin XLR cable. We recommend upgrading it to our premium tube mic cable, made with Gotham GAC-7 and Neutrik connectors.
International power cords
Kits shipped within the US and Canada include an IEC power cord. We do not stock IEC power cords for European, Asian, or Australian power outlets, and therefore cannot include IEC power cords for export orders other than Canada.
The included PSU will work fine in all countries; it has a 115/230V switch on the rear panel.
The headbasket is our C12 grille recreation, with 2-layer metal mesh grille, in a chrome finish.
The 7-pin XLR insert is included. We also provide color-coded, pre-cut and tinned silver/Teflon wiring, as well at heat-shrink insulation.
The circuit kit provides a modernized version of the ElaM 251 circuit. It is a 2-stage topology, where the second triode of the tube is used to lower impedance. We include a custom-wound (US made) transformer that was designed specifically for this circuit, and a Russian 6072 tube (tested for low noise and low microphonics).
This is an advanced kit. Populating the two small circuit boards is easy, but the wiring task is complex. Our documentation is excellent (and includes an innovative full-color wiring map), but you must be able to form good solder joints reliably, and follow written instructions accurately, if you wish to build this kit.
The non-DIY option (we build it for you)
If you want this mic but don't have the confidence, tools, or experience to build it, we can build it for you. See the V12 Tube Microphone.