Introduction

In my previous blog post on the Nevaton MC59-8 (fig 8) and new MC59 Twin mics, I touched briefly – as an aside – on the question of using the MC59 Twin or, indeed, any similar twin mic (such as the Sennheiser MKH 800 Twin) for mid-side (MS) recording on its own: i.e. without a second mid mic. This means using the combined output of the two (cardioid) capsules with the rear (or right) out of phase to create the fig 8,and simultaneously using the two outputs combined in phase to create the omni. Evidently this allows the single mic to be used for omni MS, although no other variation of MS (i.e. with a different polar pattern for the mid mic) is possible with such usage: only the omni pattern will create a mid mic at 90 degrees to the side (fig 8) mic. Of itself this isn’t a problem since, while many assume a cardioid or, perhaps, a supercardioid mid mic only is necessary for satisfactory results for MS, an omni mid mic is eminently usable, even desirable, in many situations. Indeed, in a previous post I provided (simultaneously recorded) comparisons of MS rigs with different polar patterns – the MKH 8020 (omni), MKH 8090 (wide cardioid), MKH 8040 (cardioid) and MKH 8050 (supercardioid) – so you can hear how they compare. Rather, assuming omni MS is appropriate for the recording, the issue with using a twin mic on its own for MS is to do with the fact that the polar pattern of an omni created by the two diaphragms is imperfect: whereas most SDC omni mics are also imperfect, typically becoming more directional from, say, around 8kHz (I am thinking here of the polar pattern of my MKH 8020 mic), the frequency response on axis remains consistent, while the omni polar pattern of a dual-diaphragm mic is best at the front and rear (i.e. on axis to the individual diaphragms) but sees significant high-frequency fall off at 90 degrees, as illustrated in my previous post. This isn’t a particular issue if using a twin mic as an infinitely variably patterned mid mic in MS in conjunction with a separate fig 8 mic, since the mid mic is facing forward to the assumed focus of the sound source. However, when using a twin mic on its own for MS, the two diaphragms are necessarily facing sidewards for the fig 8, so the omni mic (created from the same two capsules) is aimed poorly for sounds directly in front of the mic. On the positive side, though, the fig 8 and omni mic are truly coincidental, having none of the vertical separation of the two mics in a normal MS pair.

Field testing

The introduction above is just an amplification of my cautionary aside on use of twin mics in their own for omni MS in my previous post. But so much for theory: the point of this short present post is to provide an example of a simultaneous field recording so that others can download and scrutinize the files, compare and analyse short snippets in a DAW etc. as they wish and draw their own conclusions. I have deliberately chosen a field recording since it is hard to imagine anyone would accept the very high-frequency loss in, say, a classical music recording, and it is the most likely scenario – due to compact rigs – where someone might be tempted to make an MS recording with a single twin mic. And I have gone for one of my, perhaps all too frequent, railway loco recordings as it is good to have a varied sound source crossing the stereo field. So here we go with the two sample recordings, one using the MC59 Twin only and one using the MC59 Twin with the omni MC59/O as the mid mic:

Just as with the pinknoise test in my previous post, this field recording reveals the fall off in high frequencies at 90 degrees to the omni mic created from the MC59 Twin, which, in this MS use, becomes on-axis for frontal sound sources. You can see this in the spectrum analyzer visualization below, which is a snapshot of the sound as the steam loco passes directly in front of the mics. Whether or not you can hear a significant difference is another matter as the drop in sensitivity to high frequencies really only kicks off in this example around 15kHz.

Conclusions

The main purpose of this short blog post is to provide an example comparing the all-in-one omni MS recording with a twin mic vs the more normal approach taken with separate mid and side mics. Take from it what you will! From my own perspective, while it sounded better to my ageing ears than I suspected, I can’t really think of circumstances where I would find it helpful to use the MC59 Twin on its own and accept the pay-off of high-frequency loss on axis. I would much rather use the twin more flexibly as the infinitely variable mid mic of an MS pair, along with an MC59-8 fig 8, in which set up, of course, it can also function as a DMS rig, with all the choices made in post: and, as we have seen before, this is still a very compact pairing, capable of use in the field in a small windshield such as the Mini-ALTO.