The AKG D 40 is a unidirectional dynamic cardioid microphone designed for drums, guitars, and wind instruments. The mic element, which utilizes the patented AKG Varimotion Laminate Diaphragm technology as used on the D5 vocal mic, is protected by a shock mount and steel-mesh grille to prevent damage to the element itself.
According to AKG, it has a relative flat frequency response down to 125 Hz, where it drops off with a high pass. It also has a boost of approximately 6 dB in the 3 to 4 kHz range. Similar in size and shape to the Shure Beta 56, the D 40 comes with an H 440 drum rim clamp and a zippered nylon pouch.
Upon opening the D 40 package, the mic impressed me with its "bulletproof" look. I first thought it might have a weak point at the two screws that hold it onto its mount (and, admittedly, I am a bit weary of the rim clamp concept). The rim clamp appeared to be flimsy; I was concerned about whether it would be able to hold the substantial weight of the mic, which is heavy for its size. I also noticed a cool feature about the D 40 stand mount; AKG integrated both thread sizes, so there is no need to find an adapter in order to screw the mic onto a rim clamp.
I used the D 40 in a large array of applications. On its first show, it was used as a second mic on a lead electric guitar cabinet. The first microphone was a Sennheiser 421 (series one) microphone. The engineer on the show said the D 40 was "the perfect complement" — he ended up using both microphones, adding a high pass on the D 40 channel and a low pass on the 421 channel to create a "bi-miked" situation and was very happy with it. The engineer said the D 40 had properties that made it great for the guitar, particularly in the high mids, which accentuated the instrument and naturally brought it out in the mix.
The next application for the D 40 was as a tom mic. This gig had three toms: the D 40 was used on the first and floor toms, while the second tom was miked using a Sennheiser e604 cardioid drum microphone. I liked the sound of the D 40 on the first tom; it had a nice frequency response with the drum, and its highmid boost accentuated the character of the tonal qualities of the drum. In comparison, the e604 offered more low end, a flatter overall response, and sounded slightly smoother throughout the spectrum. On the floor tom I was neither happy nor unhappy with the sound of the D 40. On one hand, I was pleased with the sound; the mid-high boost accentuated the sound of the stick, rim, and head, but I wish it picked up the sub-low qualities that the drum's tuning offered. On that note, the D 40 would definitely work well for drum kits where you don't want a lot of low end from the toms. With this in mind, I wish I had tried the D 40 on snare, as I have a feeling this would have been the perfect place for it.
My final test with the D 40 was on saxophone and trumpet via a band with a small horn section. I double-miked the sax for an accurate A-B test; the other mic was a Sennheiser 421. In this instance, I much preferred the Sennheiser to the D 40; in comparison, the 421 had nicer lows and a smoother, much clearer quality to it. The D 40 sounded not as "full-bodied" as the 421. For trumpet, I double-miked using the D 40 and a Shure SM57. Here, the D 40 won hands down; its high mid boost and natural roll-off simply made the trumpet sound better. With the D 40, this trumpet cut through the mix without much labor.
After all field-testing was complete, I felt that it was time to settle my doubts about the durability of the microphone's mount. The mount looked suspiciously like the D 40's Achilles Heel; the rim clamp looked even weaker. So I did what any live sound guy with too much curiosity would do: I smacked it with a hammer in a few different ways to simulate a just bit of typical road abuse. In doing so, there were two things I found out: one, the mic still works like it did out of the box, and two, the mic is still attached to its plastic mount and rim clamp. I then clipped the rim clamp to the rim of an old beat-up snare drum. I took a drumstick and smacked the mic several different ways, managing to break a stick over it, yet the D 40 held on while working like a charm. Note that the rim clamp is very low-profile, which keeps the mic close to the drum, forcing it to be at a set angle to the head.
The AKG D 40 proved to be a great utility microphone for many uses. Its high-mid boost and low cutoff make it a good choice for drums, horns, and lead guitars — places where you want that "cut through the mix" sound. Finally, the D 40's test-proven durability make it ideal for a truly roadworthy microphone collection.
Karl Bader is a lead audio engineer for Entertainment Sound Production and can be reached firstname.lastname@example.org