Sennheiser MKH 8090 for mid-side: the Goldilocks mid mic for field recording?!

Introduction

It’s funny how reluctant some are to try an omni as the mid mic in a mid-side pair (seemingly afraid that this will make for a mono recording) despite it often being the best tool for the job. But I have had many queries now about whether a wide cardioid will strike a sweet spot between an omni and a cardioid when paired up with an MKH 8030 for mid-side recording. Normally, I swap between omni, cardioid and supercardioid mid mics, but recently, thanks to the good folks at Sennheiser, I have extended my available mid-mic options to include the wide cardioid MKH 8090. And so has begun my exploration as to whether – and this is said only partly tongue-in-cheek – it is something of a Goldilocks mic, hitting the perfect balance between omni (MKH 8020) and cardioid (MKH 8040) options, or, alternatively, whether – in practical use – for many it represents too fine a mid-point between these polar patterns, if, indeed, it can be described as a ‘mid-point’.

These things are personal, of course, reflecting both taste and subject matter, but in this blog post I will focus on a series of recordings made with the different mid-side pairs at the same time, so hopefully it will be of some use to a few readers – especially those who cannot try the different polar patterns before buying. And, although I have demonstrated the supercardioid (MKH 8050) mid-mic options previously, in comparison to the MKH 8020 and MKH 8040, I have included it again here for completeness. I have omitted the Sennheiser shotgun mid-mic options (MKH 8060 and MKH 8070) for three good reasons: first, mid-side recording with an interference tube mid mic is a very different beast and usually, though not always, for very different purposes than field recording or music recording; second, it is very hard to think of a set-up that could adequately cope with simultaneous recordings or such differently sized mid mics (well, not one that doesn’t involve at least four fig 8s); and, third and most conclusively, I don’t have either! Likewise, it would be rather tricky to include a fig 8 as the mid mic in a typical windshield, given the required orientation of the mic.

The specs

I don’t want to repeat what can be read in detail on Sennheiser’s website, but, nonetheless, a quick comparison of the polar and frequency response charts is a useful starting point, not least as they are rarely seen grouped together for these four mics.

The most obvious feature of the polar pattern of a wide cardioid such as the MKH 8090 is the absence of a null, with the pattern looking rather that of an omni, albeit consistently reduced at the rear by around 7dB.

In contrast to the situation with polar plots, the frequency response graphs see the MKH 8090 wide cardioid look much more like its cardioid sibling than the omni. The two most noticeable differences from the cardioid are the earlier high-frequency peak and the slightly flatter curve below 100Hz: this is still a long way from the MKH 8020 omni with its almost flat response down to 10Hz.

Test rig

Even rigging four alternative mid mics is no doddle, especially for outdoor field recording, so I have done some thinking and, inevitably, a bit of 3d printing to make a suitable mount. Although, as readers of this blog will know, I am not overly concerned about the often rather theoretical (or at least often imperceptible) issues of shadowing, even I think a cluster of four mics around a single fig 8 seems a bit too congested, so I split the mics into two pairs each with its own MKH 8030 side mic, spacing the two groups of mics 170mm apart on a 3d-printed bar I made up, and mounted within my roomy Mega-Blimp. It is not perfect, of course, but each MS pair can’t occupy exactly the same space at the same time and be free of other mics nearby, so its is a reasonable compromise, and one, I feel, that doesn’t obscure or misrepresent the differences between the various pairs.

Village street

Although the garden has changed dramatically here over recent months (much of the reason why blog posts have been a little thin on the ground of late!), the nominally quiet village street – used as a frequent test bed for me – seems as noisy as ever, with a ripe mixture of sounds. In the recordings below, you can hear the curious thumps from inside a Waitrose van delivering to a neighbour, followed by its departure, along with passing vehicles and birdsong.

First up, we have MS with the omni MKH 8020 mid mic:

Second, we have MS with the wide cardioid MKH 8090 mid mic:

Third, we have MS with the cardioid MKH 8040 mid mic:

And finally we have MS with the supercardioid MKH 8050 mid mic:

Down at the station

Risking large crowds on a bank holiday Monday, I tootled off to Holt station on the North Norfolk Railway, which is another familiar haunt of mine for mic tests, positioning myself a little way from the platforms, opposite the signal box and right next to a signal (I do like the double clunk the latter makes). Funnily enough, it was unexpectedly quiet in terms of people, although the distant hum of traffic and the more disturbing near continuous thunder of aeroplanes overhead were ever present. Here is a snippet, with the signal changing and then a small 0-6-0ST saddle tank setting off, pulling a short train of three Victorian carriages and leaving another train (pulled by an xxxx) hissing steam at the platform:

Following the same sequence as before, first up we have MS with the omni MKH 8020 mid mic:

Second, we have MS with the wide cardioid MKH 8090 mid mic:

Third, we have MS with the cardioid MKH 8040 mid mic:

And finally we have MS with the supercardioid MKH 8050 mid mic:

Conclusions

In the strict sense there are no universal conclusions to be drawn from these tests, with their purpose being simply to illustrate the differences in the polar patterns of the MKH 8090 and its MKH 8020, MKH 8040 and MKH 8050 siblings when used as the mid mic in a mid-side pair. Inevitably, to some these tests will serve to show how the less directional MKH 8090 and MKH 8020 mid mics work well and are viable alternatives to the more commonly used cardioid and supercardioid mid mics. To others, these tests will show how radically different the four mid mics are. Such is the nature of listening tests even without confirmation bias rearing its ugly head. From a personal view, and drawing on wider use than the few test clips presented here, I have been very impressed by the stereo image presented in mid-side with the MKH 8090 mic. Unless more rear rejection is needed from the null of a cardioid or the deeper bass response of an omni is required (and often the bottom end of the MKH 8020 needs rolling off in field recordings), the MKH 8090 is a compelling option, and one I have been using increasingly in my field recordings. In short I am so glad to have it in my arsenal of mics. Now making such finely gradated choices between polar patterns can be hard when field recording compared, say, to setting up mics for an acoustic music recording in a more controlled indoor space, due to the fact that outdoors sound sources can be unpredictable and constantly swapping mics can become impractical, so, in that sense, having an option between a cardioid and an omni can just make life more complex. But, equally, field recording can involve frequent recordings of the same sound source, or similar sound sources, in familiar or similar locations, and for many an experienced recordist having more finally gradated choices in polar patterns can be useful. And if you are just kicking off with mid-side recording and are uncertain as to which initial mid-mic polar pattern to choose, then, just possibly, this post might provide some food for thought.