The Sennheiser MD 421 is one of a handful of microphones that has rightfully earned iconic status, having maintained a continuous presence in the audio industry since it was introduced in 1960. While it was originally developed for use on vocals in television, radio and public address applications, studio engineers had other plans, putting the microphone in place for capturing drums (kick and toms in particular), bass amp, horns and guitar amplifiers.

The MD 421 Series II debuted in 1998 and found its place in a variety of applications, but engineers have long expressed two major gripes about the design. First, the body is rather large, making it difficult to place in tight quarters (such as staying out of the way of cymbals when miking toms); and second, there’s that pesky slide-on clip that, no matter how you handle the microphone, inevitably unlatches from the mic when you attempt to pivot the body, sometimes sending it crashing down on an unsuspecting tom or, worse, to the floor.

Then, in late 2024, Sennheiser introduced the MD 421 Kompakt, which remedies both of these issues in a single glorious revision, swapping out the slide-in clip for a captive mount while reducing the size of the body by almost 40 percent. The MD 421-II measures 8.4 inches (215 mm) long, while the MD 421 Kompakt measures 4.8 inches (122 mm) in length.

The MD 421 Kompakt ships with a padded drawstring bag; the “+ Drum Clamp” version also includes the MZH drum clamp for mounting the mic onto the rim of a drum.

A LOOK INSIDE/OUTSIDE

The MD 421 Kompakt features the same moving-coil cardioid capsule used in the MD 421-II, with sensitivity of 2mV/Pa and frequency response stated as 30 Hz to 17 kHz. Experienced engineers will notice that the MD 421 Kompakt lacks the high-pass filter switch that surrounds the XLR connector of the MD 421-II, but one could argue that the HPF is superfluous these days when most mic preamps and DAWs provide their own. The frequency response plot for the 421 Kompakt appears identical to that of the MD 421-II when the latter’s high-pass filter is set to the “M” position. The polar response patterns also appear to be identical.

At first glance, the 421 Kompakt seems to simply be a cut-off MD 421-II, but the head grille of the Kompakt is slightly smaller than that of the 421-II. This reduction in size, combined with the captive stand mount, makes the Kompakt much easier to place while providing an effective solution for mounting the mic onto a drum. While the MZH doesn’t provide a myriad of placement options, it gets the mic in the spot where you’d probably want it anyway: poking over the rim of the drum, an inch or two off the head. You can back it off from there if desired.

The MZH securely held position without unwanted movement and easily fit most of the drum rims I tried—though there were one or two instances where an unusually thick rim made it difficult to snap the MZH into place. The MZH can also clamp to a microphone stand, but the effectiveness of this approach will require the diameter of the stand to be just the right size for the clip.

STARTING WITH DRUMS

I used the MD 421 Kompakt on a wide variety of sources, including kick, snare, toms, acoustic guitar, electric guitar, vocal and voiceover, at times A/B’ing the Kompakt with an MD 421-II. As I expected, the 421 Kompakt excelled on toms, producing thunderous sound from floor toms, and rack toms that practically exploded.

The top end has enough attack to help poke through a mix, but doesn’t get pointy or too snappy-sounding, and the bottom end was full and round. I didn’t feel the need to add much, if any, EQ to achieve a “finished” tom sound. Compared to the MD 421-II on toms, the Kompakt has more mojo in the lower midrange and produces a more rounded sound, while the original is slightly more forward in the upper mids. I felt that the 421 Kompakt had the edge in the bottom end and produced a fuller sound, especially apparent on floor tom.

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Leakage from cymbals was very well-controlled. Ride cymbal leaking into the floor tom mic was down better than 20 dB, and I couldn’t hear much leakage in the rack tom mic from a nearby crash cymbal. Sennheiser really nailed the voicing for the 421 Kompakt on toms: if your toms don’t sound good under the MD 421 Kompakt don’t blame the microphone.

Kick drum was up next, and you’re either going to love the sound of these microphones on kick or hate it. I never much cared for the sound of the original MD 421 (or -II) on kick, and the Kompakt isn’t changing my mind. They both sound too 1970s for my taste—too much in the midrange around 400 to 500 Hz (the Kompakt somewhat less so), not as much snap as I’d like in the top end, and a little bit of that “speaker cone breakup” sound. The MD 421-II had a bit more in the bottom end, but the two microphones sounded very close in this application.

Snare drum was one of the sources where it was easy to hear a difference between the two mics, with the Kompakt sounding darker, almost rolled off in the highs compared to the MD 421- II. This was a bit of a head-game. Does the 421 Kompakt produce more low-mids or does the original 421-II produce more top end? Tough to say, but the audible differences were clear in this instance.

VOCALS AND GUITAR

When used on vocals and voiceover, the 421 Kompakt produced a subtle proximity effect within four to five inches from the source. Moving the mic beyond that distance delivered a very clear and natural sound, proving why Sennheiser engineers designed this mic for voice reproduction in the first place. The MD 421 Kompakt has some of the presence and air that you’d expect from a condenser mic without being overly bright, and seems a bit smoother in the upper-midrange when compared to the MD 421-II.

On a lead vocal for a rock track, the Kompakt did a nice job of capturing the growl from the singer and easily handled the SPL when the singer screamed, which was quite a bit. Popping P’s and B’s can be an issue when a singer gets within a few inches of the mic, so I’d suggest using an external pop filter.

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Recording an acoustic guitar using the MD 421 Kompakt was a pleasant surprise. I generally reach for small-or large-diaphragm condenser mics for this application, but the Kompakt captured a good balance between the resonance of the guitar body and the strumming of the pick on the strings. I placed it in my go-to location: aimed at the area where the neck of the guitar meets the body, about 10 inches away and pointing slightly toward the sound hole. In comparison, the 421-II produced more “honk” in the midrange, but some of that could be due to positioning, as it can be tough to simultaneously place two large microphones in the optimum position.

I also tried the 421 Kompakt on electric guitar, where it captured a lot of detail (there’s that word again) but didn’t sound harsh. Compared to the MD 421-II, the Kompakt is a little more open in the upper-mids around 3 kHz; and adding a few dB of EQ in this area to the 421-II made the microphones sound almost identical.

COMPARE AND CONTRAST

When comparing the mics head-to-head, recorded levels were virtually identical for the same preamp gain settings (Focusrite ISA 828 Mk II, Great River MP-2NV, and Grace 201), and off-axis rejection was about the same for both mics. Employing the same capsule in the MD 421 Kompakt as the one used in the MD 421-II was a smart move on the part of Sennheiser—no need to reinvent the wheel here.

There are two perspectives from which to evaluate the MD 421 Kompakt: on its own merit as an effective dynamic instrument microphone, and in the inevitable comparison to the original MD 421-II. Sennheiser succeeds on both fronts.

The MD 421 Kompakt is easier to place than the MD 421-II, it eliminates the problematic microphone clip found on the original, and provides a secure solution for mounting the mic on the rim of a tom. The MD 421 Kompakt sounds virtually identical to the MD 421-II on most sources, and the sonic differences I heard could be due to the fact that we’re comparing new MD 421 Kompakts to MD 421-IIs that have considerable mileage on them and may have changed over time.

As is the case with the MD 421-II, I expect that the MD 421 Kompakt will become a go-to microphone for toms. In a rare instance of newer being better, Sennheiser has produced a revision that improves upon the original without compromising its sonic signature. Buy a three-pack; you won’t regret it.