Avantone CV12 Mods
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 mod and upgrade options for this microphone, plus free tips for circuit mods you can do on your own.
#1: Capsule Replacement
As is true of all inexpensive Chinese tube microphones, the CV-12's capsule is a common 32mm K67 type. It is a harsh-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 CV-12 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
Our C12-style grille for the CV-12 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.
Note: the new grille does not have markings for the switch positions. If you rely on those markings, you would either need to manually mark the new grille, or not upgrade the grille.
#3: Tube Replacement
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.
#4: DIY Circuit Mod
The common circuit design found in the CV-12 (and the Apex 460 and all its clones) incorporates two capacitors for EMI/RFI suppression. But they're sized incorrectly, and they actually add an unwanted and inappropriate high-frequency boost to the circuit.
The capacitors in question are C9 and C10. (See the black arrows in the photo at right.) Desolder both from the circuit. Retain them in case you ever want to revert the mic to its stock condition.
Just because everybody asks: no, your goal is not to replace them. Just remove them. They are not needed. They do more harm than good.
Coming soon: full circuit replacement
We are in the late prototyping stage of a full circuit replacement for the CV-12. The new circuit is a virtual clone of the Telefunken ElaM 251 circuit: a single-triode design with a T14 transformer. It retains the operation of the pad and filter features in the CV-12. Subscribe to the mailing list for early access to introductory special pricing; watch for an announcement in July, 2017.