MXL 3000 Mods
The MXL 3000 is yet-another variation on the MXL 2001 / V67 theme: a 2-stage FET circuit coupled to a low-ratio transformer. But this incarnation contains several upgrades not found in the 2001 and V67: a direct coupled input circuit (no input capacitor) and a large output capacitor. These two changes would be near the top of the list for any DIY circuit upgrade.
The one component that most significantly limits the performance of this microphone is the capsule. It is MXL's common 32mm K67, which tends to deliver an uneven and somewhat hyped high-frequency response, usually with thin bass response. It is prone to harshness on any source with high-frequency energy (cymbals, voices, strings).
We recommend changing the capsule to our RK-12. This will give the microphone fuller bass and a smoother high-frequency response.
The RK-47 is also an option, but see the notes below on circuit EQ.
Our top capsule recommendation for the MXL 3000 is the RK-12. It has a rich, full low end, and a broad but low-amplitude boost in the high frequencies that adds excitement without hype or sibilance.
This capsule is based on the design of the AKG CK-12, which was used in the AKG C12 and Telefunken ElaM 251.
All RK series capsules include all necessary mounting hardware for installation into the MXL 3000.
The MXL 2001/V67/3000 circuit provides some high-frequency corrective EQ -- approximately 1.3dB around 10kHz, in the sample 3000 we tested. This EQ curve will work well with the RK-12.
If after installing the new capsule, you find the result too bright for your applications, you can increase the level of correction by changing capacitor C3 from 220pF to a higher value, between 330pF and about 820pF. (The same trick is not so effective on the stock capsule, because the stock capsule has frequency anomalies that are not easily corrected by circuit mods, such as thin bass and a sharp HF peak around 12kHz.)
You can optionally disable the EQ circuit within the mic by removing capacitor C5. This will raise the mic's output level slightly, and raise the high-frequency response slightly. This trick will open up the top end of the RK-12 and RK-47 (neither of which has an exaggerated HF response).
To be clear, no circuit mods are necessary if you install the RK-12 capsule. If you install the RK-87 capsule, you might be happy with that sound, or you might wish to increase the value of C3 (and/or increase the value of R2) to create slightly greater HF attenuation. If you install the RK-47, you might be happy with the sound, or you could remove C5 to restore the mic's upper-mid and high frequency response.
MXL 3000 Circuit Upgrade Kit
We have adapted our best-selling T-84 circuit kit to fit the MXL 3000. This circuit works beautifully with both the RK-12 and RK-47 capsules. Read more here.