I have 3 of these AKG 451E each with different capsules with a different polar pattern.
The capsule choice makes a big difference to the 'voicing'. Capsules I have are cardioid, omni and hypercardioid. They all represent typical traits for their polar pattern.
The mic is a small pencil mic, 15cm by 2cm, with integral xlr. Weighing about 250g without metal screw-on basket, or 100g more with it on. The screw-on basket is an effective pop-shield, but I still use an seperate pop-shield for 'plosifs.
Great mid & top, with just enough lo-mid to capture male voice. but no real low-end bass [due to size of mic/diaphragm]. So recordings sit nicely in the mix without eq'ing.
Medium sensitivity, slightly variable on capsule used.
40-45db gain on the pre-amp before clipping. +48v phantom power.
Nice studio tools. Very different voicing to standard SM57's [smaller too].
Condenser mic with cylindrical format and small capsule.
I have some other mics of the same type, I use this mainly for strings (folk guitar, violin). Compared to the Oktava MK012, it is much more brilliant and it's a mic whose setting is not so critical, it doesn't detune much. An example? The guitar (a Taylor C-414) here was recorded with a C451e - https://fr.audiofanzine.com/folk/compos/a.play,t.13658.html
This mic is the first preamp version of the 451, which was revolutionary in its time!
But despite its technical characteristics (transformerless solid-state preamp, exceptional transients)
Despite all that it has a well-known defect, the famous dropouts after some time (you need to cut the phantom power, turn it on again and then everything's fine).
The next versions (451 EB, 451B) don't have this defect.
It's a reference in terms of sound.
The features have already been mentioned. It's ideal in pairs to record guitar, vocals (CK5 capsule), as drum room mic (CK1 & CK2), or as room mic (CK8 shotgun).
I have been using this AKG C451e pair with different capsules (CK1, CK2, CK5, CK8) for 14 years. I have never had an issue with them, no ugly surprises. I heard about the "dropout" problem after a while. I might be lucky, but I've never had a single problem. I use them mainly together with CK2 capsules for room takes or with the CK5 for vocals. The sound is huge. Neutral and warm at the same time. I use a lot of other mics. These are among the ones I use as reference. Treat yourself to some real sound!