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Occasional posts on subjects including field recording, London history and literature, other websites worth looking at, articles in the press, and news of sound-related events.

09 December 2014

Down with noise: first impressions of Sennheiser MKH 8020 mics

DURING THE SUMMER I blew . . . I mean, wisely invested a pile of money in a pair of Sennheiser MKH 8020 mics. They’re low-noise (10dBA), high-quality mics and at just three inches long are ideal for headworn use as well placing on each side of a homemade acoustic baffle like the Block.

The DPA 2006C mics I’d been using proved too noisy, even at 16dBA, for very quiet environments such as moorland, marshland, and the insides of buildings when not a lot’s going on.

Scholarly discussions on forums such as Gearslutz concluded that the MKH 8020s are equalised for the free sound field, meaning a hypothetical environment where there’s no sound reflection, but which I understood to approach something like ‘outdoors’, especially those challenging moors and marshes.

The mics are also known to be resilient to humidity and that’s possibly why they’re favoured by some nature recordists, for example the Australian Vicki Powys, and recordings like this one of a thunderstorm in New South Wales helped swing it:


Coldhams Common is a flat expanse in Cambridge consisting of sports pitches and rough patches of grassland. It’s bounded by busy roads on two sides, a railway line to the west and housing to the north. Cambridge’s diminutive airport is to the north-east. This morning I went to the Common and set up the Block baffle with the 8020s clamped to it, each one inside a mic foam and Rycote furry windjammer. Here’s a panoramic view of the recording spot with the middle facing east:

Panoramic view of Coldhams Common, Cambridge


The recording is pretty mundane stuff and no roll-off or other equalising has been applied:

 


The compression used by Soundcloud’s streaming format reduces the dynamic range of what you can hear. With the original 24-bit, 96kHz WAV file the relative loudness of the rumbling traffic is striking. This, of course, is often the case with recordings made using omnidirectional mics. Perhaps it’s also to do with hearing such sounds outside their original context. When we’re in situ our brains may screen out much of the intensity of traffic noise because we’ve become so habituated to it. But the MKH 8020s do seem to have a very powerful low end. There’s some nice detail with the fainter, higher-frequency sounds.

If the mics are equalised for the free field, how might they get on in a diffuse field full of reflecting surfaces? Someone told me that the reverberation times inside Earls Court Exhibition Centre are so long that you can still hear Bob Monkhouse’s voice if you listen carefully enough.

This time the MKH 8020s went on each side of the Block using a stereo bar, the mic clamps that were supplied with them, and a couple of wooden risers made from dowling:

Composite picture showing Sennheiser MKH 8020 mics in use inside Earls Court Exhibition Centre


This recording was made early in the day and you can hear a few different activities going on in the main hall, as well as tube trains passing below the Exhibition Centre:

 


I’m quite happy with that. As with the Coldhams Common recording, the mics could maybe do with being moved forward an inch or two relative to the Block to avoid the sense of something lacking in the middle. But the mics have plenty of oomph and wonderful detail with no really noticeable noise. So far so good.

The question remains as to whether it’s worth spending all that money just to save 6dB of noise over the DPA 2006Cs, which are otherwise very good mics. Perhaps the overall gain should be set lower to begin with and then the mic noise won’t be noticeable. Or, perhaps listeners should be trusted to show some tolerance for a certain (i.e. unknown) level of hissy broadband noise.

The matter of gain or volume levels I first heard raised by the recordist Jez riley French at a talk in Soho a couple of years ago. He made the point that fledgling recordists often produce work where the levels are too high, rather than expecting listeners to adapt to lower volumes. This is a mistake I make from time to time and it’s a good principle to be reminded of: let quiet sounds be quiet.

However, when you disseminate work via the internet the listener has instant control over volume levels, and I bet no other playback context encourages restless fiddling as much as surfing the web does. If something sounds too quiet, even momentarily, the listener can compensate for that with the slightest effort.

Broadband noise is similar to something many older listeners (including me) grew up with: analogue tape hiss. We might tolerate it, although few are probably nostalgic for it. Meanwhile, an ever-growing cohort of listeners have had their expectations raised by digital recording methods.

The relict formats which intrigue them have lower signal-to-noise ratios than modern technology but they also produce warm-sounding forms of distortion which have become signifiers of authenticity or, as with radio futz, immediacy. Broadband noise doesn’t convey either of those qualities and for that reason I prefer to reduce it where I can.