Avantone CV12 Mods

Avantone CV-12 tube microphone

Although the CV-12 is billed as having a "warm, pleasing sonic character," neither the mic's peaky K67 capsule nor the artifically boosted top end due to a mistake in the circuit are delivering such a sound.

We have several upgrade options for this microphone, including a full capsule/circuit replacement that will allow the CV-12 to rival $2000+ microphones.

#1: Capsule Replacement

RK-12 capsule

As is true of all inexpensive Chinese tube microphones, the CV-12 uses a common 32mm K67 type capsule. It is a harsh-sounding capsule, due to its uncorrected high-frequency peak. It's not only the wrong capsule for a mic that seems to be pretending to be a C12 recreation, it is also the wrong capsule for this circuit design.

Our favorite (and best-selling) upgrade capsule for CV-12 mods is the RK-12, which is our version of the capsule in the famous AKG C12 and Telefunken ElaM 251.

Alternatively, the RK-47 capsule is another perfectly viable choice, if you're going for a Neumann U47 vibe.

Replacing the capsule in the CV-12 will immediately re-voice the microphone. Because the capsule determines the mic's frequency response, a capsule upgrade is an easy way to change the mic's sound, giving it a smoother top end and fuller bass response.

See all of our large-diaphragm microphone capsules.

#2: ElaM 251 Circuit

V-251 Circuit Kit

We have developed a drop-in circuit upgrade for the CV-12, based on the circuit of one of the most  famous vintage tube mics in history, the Telefunken ElaM 251.

The circuit topology is a true single triode design. We use a hand-selected 6072 tube and a US-made T/14 transformer, as well as audiophile-grade components throughout the audio signal path.

Because the CV-12 offers two switches, we have added a pad feature and a high-pass filter feature to the 251 circuit design. This circuit kit includes two filter capacitor values so that you can personalize the mic's high-pass filter behavior.

The new circuit is rich in harmonics and low in self-noise. It makes a fantastic mic for vocals, acoustic strings, guitars, and bass.

Read more about the V-251 Circuit Kit.

#3: Tube Replacement

EHX 6072a tube

Older CV-12s came with a Russian 6072a tube, but we have seen newer mics with Chinese 12AX7 tubes.

If your CV-12 has a 12AX7 tube, or if your mic's tube (whatever the model) has become noisy, the easiest and most cost-effective upgrade is to change the tube.

Our 6072a's are made in Russia, and hand-tested in the US. We select only the best tubes, with matched triodes, low noise, and low microphonics.

Fewer than 30% of tubes pass our selection criteria.

Note - the V251 circuit kit listed above includes this upgraded tube; there is no need to purchase a tube separately if you are buying the V-251 circuit kit. We sell these tubes separately for customers who lack the budget to do the full circuit replacement.

#4: Cable Upgrade

Gotham GAC-7 Cable

The XLR7 cable included with the CV-12 is functional but compromised. We offer genuine Gotham GAC-7 cable, imported from Switzerland, hand-terminated in California with Neutrik connectors. The GAC-7 cable has two heavier conductors, which we use for the sensitive tube heater circuit, to minimize losses that would affect the operation of the tube and the sound of the mic.