I don't have a ton of experience with this mic, but from what I've gathered most of it mirrors what John above me posted. I whole-heartedly agree about the crappy mic clip. I don't know why they designed it that way, you'd think they could have been a little more practical about it. The clips have a tendency to 'not be trusted' but a bead of polyurethane fixed it in place, and that thing isn't going anywhere. heh So aside from the inconvenience of the lame clip, which is a relatively minor issue, the mic really does a great job for it's purpose. The bass roll off options are a nice feature to have if you like to process on the way in.

This mic shines in all the places an sm57 does, except when you want a little more beef, a bit more clarity/detail, and an overall 'fuller' tone. Though, the issues it has that a 57 doesn't so much, is as John stated in the pick-up pattern and bleed/ leakage concerns. Things can get a bit messy with this mic, more so with multiples of it and it can be a pain on drums, but it isn't so bad with proper arrangement - also it's tonality just seems to fit so very well on toms and drums, guitars, and I'd suppose most anything focused from the low-mid to the high-mid range of the spectrum, most typically in a close-mic'd situation. It serves as a nice dynamic compliment to the sm57 in that it's reach seems to extend a bit further out from the very mid-oriented 57, being a little more open in the lows and highs, and when combined in the mix can have a very full sound, especially on electric guitars for example.

Pricewise, I think this mic is a good value at roughly $300, but really I'd find the price more reasonable around $200, partly because you typically want more than one of them Overall, I find it to be an essential piece of gear and that it certainly fills a part in the big studio picture.

The Sennheiser MD421 comes in a softish hardbox. It comes with a clip mount that attaches to the mic by sliding in a groove on the bottom of the mic. There can be problems when adjusting the positioning of the mic, because the clip will easily un-attach when handled.

The MD421 dynamic microphone. It is fairly large in size which sometimes makes it a bit hard to get in the right position - for instance, one of my favourite applications for this mic, close micing a snare drum. The most conveinient place to do that is usually just underneath the hi hat to obtain as little hi hat bleed as possible, but the size often makes this hard.
The same goes for toms, where it also is a great mic!
It will also work quite well paired with a SM57 for guitar cabs - adding the body that the SM57 often badly needs. It is also good for micing bass cabs. Many engineers, especially live engineers, use it as default for saxophones and trumpets, but I personally reach for ribbon mics for these applications.

As stated before it really often is the perfect mic for a full sounding snare drums and toms, but I was not recording drums I really could live happy ever after without MD421's. I can find better sounding alternatives in allmost every other application.

The price is kinda high, but it's like a studio standard, so I guess you should have a t least a pair or 4 of these. I don't care if it's the old grey ones or the newer black ones. They all do the drum trick ;-)

Many people will say that I rated this mic WAY too high for overall sound quality, but for the application I use it for it's near perfect. I've used this mic mainly to record classical woodwinds for which it has been outstanding. The one complaint that I have is that it IS made for sources with high SPLs, so using it as a spot mic on a clarinet requires a little extra gain on the mic pre. If you're not careful, this can lead to noise issues. Overall though, the sound is warm and well rounded, the slow transient response is ideal for leaving out key clicks on noisy instruments. I've found the bass roll-off ideal when recording in the same room as percussion too. I've also seen this mic used on a cello pointed directly down onto the bridge- sounded fantastic there as well.

As far as ease of use goes, I agree with what everyone has already said about the clip- it's a piece of crap. The bass roll of is easy to apply though, by turning the dial on the base, and the nice little box it comes in keeps it protected.

I think the mic is a little pricey overall though. I wish you could find these in the $200-250 range new. Now that I already own one, I suppose the damage has already been done.

I have used the md 421 for a variety of different applications and only rarely does it not fit the job. The applications that I find it best suited for are for lower frequencies such as floor toms of bass cabs. They offer great low end response, and don't require much equalization depending on the gear you are mic-ing. I have used these on guitar cabs as well, and they sound decent enough. The price is a little high on these, but I do think that they are worth it. The clip is a piece of crap and I wish it fit in a more universal clip. I currently have mine taped to a stand.

I picked up a NOS 1962 421 from Madooma a few years ago. Not the least expensive 421 I could find, but couldn't beat the quality of the piece. Mine doesn't have a rolloff filter.

It absolutely kills on floor toms, just point and go. Good off axis rejection, and the bleed somehow compliments the track without gating. Very natural and forward sounding.

Haven't used it on anything other than floor tom.

Agree with other reviews about the lame mic clip. I bought a chinese LDC shock mount for a 1 1/4" mic and it works great.

I'll try to make this short and sweet, i've owned this microphone, the mkII version, for about 2 years now. Sound quality wise, it's probably one of the best mic's i own, but the whole mic clip issue is why i don't use it as often as i would like to. You'll notice that i still gave it a relatively high score for features, i've done this because the multistage rolloff is actually pretty useful. After experimenting with the rolloff a bit, i found i could get similar results to a 57 with a tighter bottom end, and work from there, so when mic'ing a snare drum or guitar cab, i would use the roll off to one click and the rumble would be mostly gone. When mic'ing a hihat, i would use the roll off the whole way and the hihat would need no further EQ.

Where this mic really shine's is on male vocals. Paired with my UA710, i was able to get big smooth sounding vocals from guy's with voices that were slightly on the harsher side. Once in my DAW, it took to EQ very well.

Overall, it's a pity that the mic clip thing is an issue. When using it for vocal's it never get's in the way, but try to use it on tom's or kick drum, and you gotta be really careful not to knock it off the clip when adjusting, which sucks because it sounds great on these sources. Other than that, i've had pretty a pretty positive experience with it, i just wish it were a little cheaper in Australia like the Heil PR30.

One of the best-known microphones for both live and studio use, the 421 has a boxy, mid-hyped frequency response that helps sources cut through the mix, especially when the source itself lacks mid-presence.

High frequencies are a little dull, but are present enough that they can be boosted with eq. The mic has a lot of boomy proximity effect, which can be tamed with the 5 position low-frequency roll off switch.

My theory for why this mic is so popular for guitar amps and drums is that those instruments are frequently set up by musicians to lack mids, so the mid-boost of this mic corrects a problem at the source.

The mic is also good for instruments that you might not want to sound natural, but instead want to sit in the background while still being heard at low levels in the mix. For example, it's a pretty good choice for a horn section that you don't want front-and-center of the mix. The highs don't interfere with other things you'd want to stand out more, and the mids are a little sloppy and slow, like adding a nice maple syrup with a bit of butter.

For me, the 421 absolutely shines on guitar amps where the player has oodles of low and high end, as this mic will roll those frequencies off and bring up the midrange so it sounds like a guitar again. I have used it on snare in the past with good results, as it can help the ringing tone chime through.

For the money, and for the certain applications where it shines, it's a great value. It's not a good general-purpose mic, but it's far more than a one-trick pony, and I wouldn't want to give up my pair.
Lee

...i really hated this microphone. Everybody wants it on toms, and i found it really sterile. Until i had to record my own band...

I tried, km84's, akg 414's, sm57's and even U67's on toms!!! i could not hear that "tom" sound i was used to...and then i tried the MD421's and there it was...the sound i was looking for. Everything else failed. So i guess it's always good to have at least a pair at any studio.

You can use them for percussion, electric guitars, and even vocals (why not)

It's just one of those microphones that does not sound good on its own. But who cares, you'll appreciate it during the mix.

I bought my first 421 because I needed a good kick mic and I really like the sound of it. I use it a lot as an inside kick mic to get a lot of beater sound and I normally add an LDC as an outside kick mic to compliment and get a more full kick sound.
Now I have 2 of these and they get used a lot for a lot of different things. I like the 421 on toms and that’s probably the most common source for this mic to be used on. Great bass response and the hyped highs help a lot to bring out the attack.

I like trying this mic on just about everything and sometimes it works great but sometimes it can really suck. But it really depends on what you’re looking for in that particular production. It can work great as a vocal mic but I have found that it’s not uncommon to end up with a little too much sibilance. The singer also better not be moving too much because the tone changes a lot if he or she alters the distance to the mic. It’s easy to get a lot of proximity effect for good or worse and the off axis response is not great.
I do however enjoy using it on guitar amps. I tried the proven method of pairing it with a SM57 and yeah – it was certainly a great match where the 57 added a lot of “missing” mid freq of the 421. You really have to play around with the angle of the mic(s) though.

This mic is hated by a lot of people due to the really bad clip-design. It would not surprise me if the MD421 is the most dropped mic in studio history. You barely need to touch the release button to make the mic slide off the clip. Best idea is probably to just to secure it with tape. Luckely this mic can take a few beatings before it breaks.
Overall, a good and useful microphone.

I've been using the Sennheiser MD 421 II for several years and am very pleased with its sound, performance and durability.

Yes the clip is a poor design, get over it. The MD 421 II's performance outweigh it's poor clip design by a long shot.

I mic tenor and soprano sax live and have used it on a kick drum as well. Very high SPL and indestructible!!!!! Keep in mind this is a very bright sounding mic. A sound tech can warm that up a bit for you as your taste requires.

They are all over and widely used for a reason. (see Lenny Pickett back in the day, though I usually saw Brecker with an EV RE-20 I think)

As a last resort alternative, I actually prefer the SM58 over the SM57 with what else is in the sound man's bag.

I first noticed this mic back in 1970/71 at a Band concert (the band that called themselves the Band)... They used it on EVERYTHING. To this day I can't say I've been more impressed with the sound quality of a live concert.

I bought my first one in 1982 when I bought a Tascam 4 track reel-to-reel. I was pretty impressed with that one. Nice on vocals and pretty much everything else. The years went by and I loaned it out and never saw it again...

This year I decided to try a couple of new ones. I bought two from SoundPure.

My initial thoughts on these two new ones:
...not crazy about them on vocals. Looking at the frequency response chart there's a pretty steep rise at about 5K and it reflects on vocals. They're a bit too shrill sounding for me. This, of course, could be tamed with some eq.
...I've come to LOVE them on acoustic guitar! Big, fat, in-ya-face! Not a lot of eq needed!
...on sax, not bad at all. Point it right above the bell and it seems to work nicely.
...toms are great and everyone seems to agree.

Overall, I'm just slightly disappointed (mostly as a vocal mic) but it's mostly because I remember the one from '82 being a bit warmer. Yeah, it was tape so... They're absolutely staying though. An SM7 on vocals and a MD421 on acoustic is a sweet combo in today's world!