The Rode NTK & K2 have classic build styles reminiscent of European classics of the golden era of sound. Unfortunately this is where the similarities end as the sound is lacking in low frequencies and the tops are grainy and overly bright. most of these issues can be traced back to the capsule.
Enter the NTK OPR Ck12 MOD
It's important to point out that the capsule and it's housing or "head basket" is the ultimate dictator of the sound of any microphone, imparting the all important sonic fingerprint or DNA if you will, other components matter too but but not nearly as much.
With that said going straight to the source and replacing the capsule with a quality unit is the best coarse of action. I use my hand made OPR ck12 which is an accurate replica of AKG's original brass Ck12 the capsule that made AKG famous the world over and the capsules used in venerable AKG C12 and Telefunken ELA M251 microphones which are now fetching $10,000- $30,000 USD. on the pro audio market.
The mod raises the NTK into a completely different league with a smooth yet open sound, airy highs, huge low end and glorious proximity effect that the classics are known for. To add icing to the cake the signal path is opened up sonically to allow the capture of every nuance and detail of the source.
If your tired of wrestling with your NTK maybe it's time?
With the O.P.R CK12 MOD the NTK just go a whole lot better!