Tape Op Review: Avantone’s BV-1 MkII Tube Mic
Avantone began making microphones close to 20 years ago, and has recently updated their BV-1 large-diaphragm tube condenser microphone to the BV-1 mkII. First off, this upgrade comes as a significant design change. The original BV-1 was in the form of a large lollypop, whereas the mkII looks more like a standard large tube condenser. The color of the mkII’s mic body is similar to a vintage Telefunken ELA M 251 yet slightly more yellowish. Its shiny chrome basket houses a hand-selected, edge-terminated “34 mm CK12-style capsule.” Specs list its frequency response at 25 Hz to 20 kHz, with a S/N ratio of 78 dB, and a max SPL of 134 dB. There are two switches directly under the chrome band (between the basket and the mic's body): One for a 10 dB pad, and the other for an 80 kHz high-pass filter. The included power supply shares the same paint color and finish as the microphone body and connects via a custom 7-pin Sommer-made cable, which utilizes thicker gauge conductors for the valve heater and heater ground that "ensures the vacuum tube is always being provided the best current." The power supply also allows the mic to operate with a continuously variable polar pattern between omnidirectional, cardioid, and figure-eight. The mkII uses carefully chosen and individually sourced capacitors and incorporates a custom-made Cinemag transformer. The BV-1 mkII (and the included wood box that safeguards the mic), power supply, cabling, and spider-type shock mount are all housed in a “hardshell briefcase.” It's a complete package with protection should you ever need to travel with thismic.
As I initially set the BV-1 mkII up, I noticed five open vents at the rear of the mic that allow the internal tube to be slightly visible and let the heat from the tube disperse out of the microphone instead of building up internally. "We did extensive testing on thermal venting with this design and found that allowing heat to vent resulted in more consistent results from the microphone as heat no longer built up on the surrounding components and values no longer drifted as heat built up inside the shell." I did struggle with the thin-wired clip mechanisms of the shock mount. The clips felt flimsy, and it took a bit of pressure to get them to lock fully. I was careful not to push them too hard for fear they might break. In addition, I could never get the included microphone cable to click into place when inserting it at the base of the BV-1 mkII. So, I crossed my fingers that it stayed put and powered it up – ready to hear what this mic could do.
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