Once in a while a ‘flat’ microphone is the order of the day…
Text: Robin Gist
When I was not long out of college (and naively thought I knew everything I needed to know about engineering), I bought an omnidirectional B&K 4006 condenser microphone. My belief at the time was that microphones should have a flat frequency response; recording mediums and associated electronics should be noiseless and artefact-free; and by the time I was older there would be no more wars!
My audio education really began after I’d spent some time in recording studios and learnt about nicely ‘coloured’ mics (colour of the sonic variety, of course), desirable distortions and the sound of saturated tape. But even with my new perspective on recording, I still found plenty of uses for the B&K in situations where I had to capture an accurate sonic imprint of an instrument in a space. And, at that, the B&K excelled. At the time I bought it, it was the best mic I couldn’t afford. Twenty years later, I’m reviewing a DPA 4090 and 4091, which I probably still can’t afford and, of course, we still have wars!
Danish Pro Audio (DPA) began its life in 1992 when Brüel & Kjær (founded in the late 1940s), decided to separate its specialist pro audio division from its core business (manufacturing precision instrumentation for acoustics and vibration measurement and ultra-flat microphones for frequency response measurement and anechoic chamber testing).
In keeping with the tradition of matched pairs, two former B&K employees, Morten Støve and Ole Brøsted Sørensen, who had designed the B&K Series 4000 microphones, were given the job of running the new company. A year later they moved the service department from Ole’s wife’s sewing room to proper premises in Alleroed and began developing a series of proprietary compact cardioid and omnidirectional condenser microphones, many of which have since become (in some areas) industry standards. It’s two of their latest products that we will now investigate.
The DPA 4090 and the DPA 4091 are 48V phantom-powered omnidirectional condenser microphones, each consisting of a 5.4mm diameter pre-polarised condenser capsule in a tapered body measuring 12cm in length. The models differ only in their sensitivity, with the 4090 handling a maximum of 134dB SPL and the 4091 at 144dB SPL, making it suitable for electric guitar amplifiers, drums and percussion. In all other aspects they are identical. The published on-axis frequency response is 20Hz to 20kHz and the obligatory inspection of the frequency response graph shows slight peaks (less than 1dB) at about 8.5kHz and 12kHz. Bear in mind, though, that response graphs are generated using sine waves, and I don’t know too many people who record sine waves! (As an aside, the closest things to straight sine waves that I’ve recorded were pure quartz crystal ‘singing’ bowls… but that’s a whole other story.) The mics have a gradual high frequency roll-off for the off-axis response with about a 7dB drop at 20kHz at the rear of the capsule. What’s more, these mics can drive up to nearly 300 metres of cable! Surely an advantage on location recordings.
The test recordings I made were of guitar (both steel and nylon stringed), female voice, percussion and drums. My B&K 4006 has always performed exceptionally well on acoustic stringed instruments and the DPAs were no different. The microphones sounded beautifully open, with a clear and delicate top end that was not overly accentuated, harsh or brittle. I found that when I used the 4091 as room mic on a drum kit I was able to position the mic to obtain a naturally ambient and detailed room sound of the top end of the kit. Both mics seem less susceptible to acoustic guitar sound-hole boom than other condensers I’ve used and, by experimenting with positioning, a variety of different tones can be found. The vocal recordings were present, detailed and accurate. The 4090 captured the unaccompanied singer’s voice with an impressive level of depth and realism. The percussion sounded tight and defined once the right mic position was found with the recordings requiring no further equalisation or processing. All in all, I could find nothing negative to comment on with the performance of these microphones.
However, there is one aspect of the mic presentation sadly lacking – and this also true of my 4006 – and that’s the packaging. Microphones of this calibre shouldn’t come in cheap, nasty plastic cases.* Although the cases for the DPAs are a minor improvement on the flimsy ‘shirt box’ that houses my 4006, they are inexcusable. Given that the new crop of mid-priced Chinese microphones mostly come packaged in wooden cases of varying quality, surely DPA could provide a decent case or box to protect the valuable contents.
The DPA 4090 and 4091 really come into their own in situations where you have beautiful sounding instruments in great-sounding spaces that you want to capture accurately. If you expect these mics to have a ‘sound’ you will be disappointed. What you won’t be disappointed by is their clarity, low self noise, flat frequency response, natural open sound, long-term dependability and their ability to be also used for system setup, testing and alignment. At $948 these mics are not the cheapest options around, but if you have a need for an accurate and precise recording tool that will allow you to make pristine recordings, then DPA away! Skol.
*Right of Reply
DPA was keen to point out to readers of AudioTechnology, as we went to press, that the packaging of DPA mics no longer involves the use of timber boxes for environmental reasons.