BadAax T11A Mods

BadAax T11-A tube microphone

The BadAax T11-A is a dirt-cheap version of the Alctron T11-A, better known as the Apex 460. It is one of the best tube mic mod platforms on the market. We have multiple mod options for this mic, enabling you to turn your T11-A into a virtual clone of the AKG C12 (or ElaM 251).

#1: Capsule Replacement

RK-12 capsule

The T11-A's capsule is a common 32mm K67 type, found in nearly every inexpensive large-diaphragm condenser ever made. It is not a great-sounding capsule, due to its uncorrected high-frequency peak. And it's the wrong capsule for this circuit, in any case.

Our favorite (and best-selling) capsule for T11A mods is the RK-12, which is our version of the capsule in the famous C12 and ElaM 251. The RK-47 is another perfectly viable choice, if you're going for a U47 vibe.

See all of our large-diaphragm microphone capsules.

#2: Grille / Headbasket Replacement

C12 Grille for Apex 460

Our C12-style grille for the BadAax T11-A provides an easy cosmetic and sonic upgrade. The chrome grille not only looks sharp, but is more acoustically transparent than the stock grille, giving the mic a more open sound.

Click for more info on our C12-style grille for the BadAax T11-A.

#3: Circuit Replacement

Fox 460 Mod Kit

We make two distinct circuit replacements for the BadAax T11A. Both offer user-controllable high-frequency EQ, so that you can adjust the high frequency response at build time. Both include custom circuit boards, best-in-class components, and custom transformers.

The Fox 460 circuit mod kit is a cathode follower, dual triode design; it offers low noise and high output. The transformer is custom-wound in the US specifically for this circuit, with a 6.5:1 turns ratio. We have sold hundreds of these kits, with many positive reviews.

V-251 Circuit Kit

The new V-251 circuit kit is a single-stage triode design, more closely modeled on the original Telefunken ElaM 251. It uses a US-made T/14 transformer (11.5:1 ratio). It has approximately 6dB lower output than the Fox 460 circuit, but at least 6dB more headroom. It also offers an internal high-pass filter switch, and your choice of HPF behavior (rumble filter vs. high pass).

Both circuits offer excellent performance. When combined with our RK-series capsules, both will allow your BadAax T11-A to compete with, if not beat, commercial tube microphones in the $1500-$2500 range.

The Fox 460 has higher output, which means you'll have less preamp noise in your vocal tracks. It benefits from 3 years' worth of refinements and hundreds of customer installations. The V-251 has more headroom, switchable HPF, socketed high-frequency EQ cap, is easier to build, and has a nicer output capacitor, but it costs more, and it needs more preamp gain on quiet sources.

Both these circuits will significantly outperform "capacitor swap" and "tube swap" and "transformer swap" DIY upgrades. Only by designing the entire circuit, end to end, can the performance of any microphone be truly optimized.