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DIY Projects The Mega-Blimp Project

The Mega-Blimp Project

January 31, 2025

Introduction

It’s a funny thing, sound-recording equipment. The products out there are often designed with very particular types of recordists in mind and may not be optimal for all users: and yet many of us use such gear for quite unintended purposes either unthinkingly or because we have no alternatives. Nowhere, perhaps with the exception of sound bags, is this more obvious than with windshields. As Philippe Chenevez of windshield-maker Cinela put it ‘commercialized units are always compromises with hard choices’ (Chenevez 2009, 1). When buying commercial windshields sound recordists have very little control over those unavoidable compromises, other than selecting from the available models one that offers, for them, the best balance between price, size, weight, ruggedness, ease of use, flexibility, acoustic transparency, effectiveness at reducing handling noise, and wind-noise reduction.

Most of the fundamental aspects of windshield design (which lead to the compromises) have been long established, and there are a good number of research papers stretching back over 60 years that cover the physics and that demonstrate, through tests, how different aspects of design affect performance: I list the research papers I have found most useful at the bottom of this post. Of all the aspects of design, there is no doubt that the most important is that size is the key factor in basket windshield performance: bigger really is better. Many have failed to grasp this fundamental point and desire the smallest windshields as if, somehow, the laws of physics can be miniaturized!

Practicalities come into play, of course: any sound recordist is going to struggle with a massive windshield on the end of an 18ft-long boom-pole. He or she won’t be able to hold the boom-pole, will struggle to aim or cue the mic, and won’t be able to make rapid adjustments. So, of course, common sense dictates that windshields for such use tend to be elongated (if not cylindrical), of manageable size and of lightweight material – invariably plastic. Over the many years of developing such windshields, refinements have been made by manufacturers to reduce handling noise, not just via improvements to mic shock-mounts, but also in the form of independent basket suspensions, as pioneered by Cinela with the Zephyx (in 2005). While there remains scope for improvement, the compromises involved in making a windshield for production sound are well understood by the experienced designers, and today there are a range of good tools available from the likes of Cinela, Rycote, Rode, and, most recently, Radius Windshields. I’ve been lucky enough to have used, tested and compared many of these windshields: indeed, looking around the room where I am typing this at all the windshields and their furs, the uninitiated might think I am starting a wig shop!

But what has begun to interest me more lately is what about windshields for those who don’t have the specific requirements of production sound, outside broadcast or, even, those involved in some more unusual aspects of sound recording for film and TV where they too don’t have the same needs? Above all, how different could a windshield be if liberated from the considerable constraint of being designed to go on the end of a boom-pole? The point came more sharply into focus recently when I finally got around to testing my massive DIY blimp made several years ago, alongside commercially made windshields, with the same mics. The old DIY blimp is a behemoth: I designed it to house a mid-side pair of LDC mics, end-to-end, and, as it has a bespoke TIG-welded basket and was going to be cumbersome anyway, I thought I might was well give it a healthy volume to improve performance: that unavoidable physics again. I used it from time to time when LDC mics were of value to me outdoors, but increasingly it has gathered dust as my SDC mic collection has improved. Fishing it out recently – initially because it was big enough to fit a B-format Nimbus-Halliday array of SDC mics inside – I wondered how it would stack up against a top-end commercially-produced windshield. The better wind reduction from the behemoth blimp was entirely expected, given its size, but what was less expected was the audible difference in transparency. So when I came to do my pseudo-anechoic chamber transparency tests of the Rycote Cyclone, Cinela Pianissimo and Cinela Zephyx models, I included the huge blimp too. As expected this time, it performed rather better than the commercial offerings. Although having not thought about its transparency before, it doesn’t take a genius to work out why it should colour the sound less: the sparse array of 3mm-round stainless-steel rods that make up the basket offer little obstacle to sound waves compared to the larger and/or more closely-spaced plastic elements of the other windshields. Now, the difference was hardly going to be enough to get me lugging this huge blimp and its necessarily bulky stand into the field regularly, but what, I wondered, about making a shorter TIG-welded blimp, more suited to SDC mics that I could use easily for stand-mounted field recording? And what if, at the same time, it could tackle some of the other frustrating aspects of windshields I have noted over the years? Now there was an idea: nothing if not ambitious! And that is how this DIY project was born. Well, I say ‘DIY’ project: as you will see below, it has involved a couple of other very skilled people, even if the designs – for better or for worse – are very much my own!

The two sizes of Mega-Blimp on the workbench.

The design

Using and, more recently testing, all sorts of windshields, plus the experience of my old LDC TIG-welded behemoth, gave me the basis of the main design requirements. The SDC blimp for field recording needed to maintain a large diameter, but should be much shorter than the old LDC behemoth, and able to fit in a backpack, and without being crazily heavy; it needed to be easy to use in the field, especially for accessing the mics; it needed to be rugged, but with a skeletonal structure to be as transparent as possible; the internal structure to support the microphones should be minimized, again to help with transparency; it needed to be stable and able to handle wind and structure-borne vibrations; and it needed to be adaptable, to be able to accommodate a range of mic arrays and to allow easy swapping between them. What follows is a description of how I have tackled each of these design requirements.

Over-sized maybe, but the Mega-Blimp large can still fit in a normal backpack, such as my old North Face Borealis, with room for cables, headphones and a sound recorder. OK the tripod will need to be strapped on too, but that’s nothing new.

Size: While the diameter remains large – indeed it has increased slightly from the old LDC blimp from 231mm to 242mm – the new version is much shorter. At the design stage I played around with various lengths for the central section, balancing the need to keep the blimp manageable versus its ability to comfortably accommodate a range of set ups, including ORTF. In the end, I designed two sizes, which I am calling, with breathtaking originality, the Mega-Blimp ‘standard’ and the Mega-Blimp ‘large’. Both have much of their length formed by the hemispherical end caps, so seem vastly smaller than my old LDC blimp. For the ‘standard’ version the central cylindrical element was reduced from the old LDC blimp’s 421mm to 60mm, and for the ‘large’ version the central section is 140mm long: their respective overall lengths are 302mm and 382mm. Both sizes are able to fit in a backpack.

Some size comparisons of windshield baskets: the Mega-Blimp standard compared to the much longer previous DIY blimp for LDC mics from some years ago, along with the Rycote Cyclone small (MS kit), and the two Cinela MS windshields tested recently.
The same windshields for size comparison, but this time with furs added.

Ease of access: One of the constants of basket-type full windshields is the need to take them apart to fit, adjust or remove mics. This introduces functional issues (i.e. the faff often involved) and performance issues: the need to have windshields come apart often results in thick bits of plastic often where you don’t want them (e.g. where unscrewable end-caps join windshield bodies) – as we have seen very clearly with the massive ring around a Cyclone and its consequences for an MS pair. Unthinkingly, I took the need to take apart the windshield into the design of the old LDC behemoth blimp a few years ago, and the elements that relate to that are the most substantial parts of its basket. But with a sparse frame I found myself inserting and removing LDC mics and their shock-mounts without dismantling the windshield at all. With SDC mics this is even easier, so this time the two Mega-Blimps do not come apart, and, at one fell swoop, one of the biggest hassles of windshields, and the source of many of the lack of transparency issues is removed!

Tough, but skeletonal structure: As before, the Mega-Blimps are TIG-welded stainless-steel, to give maximum strength, durability and (though I suspect this won’t be needed) repairability, whilst minimizing the acoustic impact of the structure. I did consider other materials and even spent some time playing around with thin carbon-fibre rods (including testing them to destruction, which was unpleasant), but stainless steel won out easily. I wasn’t worried about weight since a) the Mega-Blimps aren’t for use on a boom-pole; b) a little bit more mass helps stability; and c) the weight is still fairly modest: for example, the basket (inc. baseplate) for the shorter ‘standard’ version weighs 510g, 710g with the fur, and around 960g with the large Arca plate, cable, mic shock-mount etc. (vs 744g for the small Cyclone Stereo Kit 5). Besides, when carrying the blimp it is nothing like the weight of a tripod or, even, my 788T field recorder. Now some of you may be thinking that steel will ring: well, of course, it resonates a bit if you ping the open basket with your fingernail (or a hammer!), but there is no use for a naked windshield basket, and the covering of fur completely dampens it. I was aware of this beforehand from the experience of the earlier LDC version. The open structure of the baskets ensures the transparency (and access), but might be seen as likely to cause flapping of the covering: again, from the previous experience, I knew that this was not an issue, and this has been further confirmed in my latest tests. This time around the stainless-steel rod is mainly 3mm diameter again except for the two main rings, which are beefed up to 4mm, and the two 6mm diameter rods to which the baseplate is welded: these slightly thicker elements have minimal acoustic effect, but strengthen the blimp hugely. And the longer central section (the ‘hamster wheel’) in the larger version also uses 4mm-diameter rod to maintain strength. Both sizes of the Mega-Blimp are, as a result, sparse but extremely tough: if they have no other attributes, they are at least far stronger than any commercially-produced windshields and will age much better than plastic!

Close-up showing the 3d-printed skirt on top of the baseplate (to reduce any reflections), through which the 15mm rod rises to the mic mount. You can also see how the XLR connector is mounted to the baseplate: it is easily swappable, of course (needless to say without soldering!).

Basket stability and shock-mounts: I have been intrigued by the independent basket suspensions pioneered by Cinela, and then followed, in quite different form, in the Rycote Cyclone. In his 2009 paper on the basket suspension, Philippe Chenevez (Cinela), describes how the ‘external skin [of the basket-type windshield] behaves as a drum excited by the vibrations of the support (boom or stand)’, but it is clear from his discussion and, indeed, from my own use of windshields (not least that of the earlier LDC DIY blimp), that the problem is predominantly one related to booming. It is one thing using a windshield on the end of a boom-pole or even a pistol-grip that is always moving (either unintentionally – through transmitted shaking of the muscles, or handling – or deliberately whilst cueing) and quite another using a windshield statically on a stand – as is the intention with the Mega-Blimp. The approach here, therefore, is to welcome mass (within reason) and anything that could hold the basket steady and reduce vibrations reaching the windshield: so goodbye to a tiny 3/8″ connector and wobbly repurposed mini light stands, and hello to a larger connector in the form of the quick-release Arca plate, popular with photographers, to be coupled to a sturdy camera tripod (itself much better for rough terrain than a lighting stand). With a fixing point at the bottom of the basket only, even if quite large, I was concerned about wobbliness, which is the main reason why the two main rings are made of 4mm instead of 3mm stainless steel: this does the job perfectly, so that if you apply increasing pressure to the top of the blimp ultimately you tip the basket and the tripod on which it is mounted as if one rigid body, rather than simply flex the windshield. This was the part of the design that most concerned me before building, and I was relieved that it worked out so well, and that there was no need to resort to clunky internal bracing or, say, seriously chunky main rings. With a stable basket and static use the windshield needs to protect the mics inside from structure-borne vibration coming from three main sources: vibration of the basket itself due to wind buffeting; vibration of the tripod due to wind; and vibration of the tripod transmitted from the ground. Aside from extreme winds or particularly shaking ground, these are much less problematic than handling noise from a boom-pole or pistol-grip, so, in this case, the Mega-Blimps rely on the mic shock-mount. I designed them to take both Rycote lyres and Radius Windshields hoops, though the latter are much more useful due to their modular design: they allow the use of integrated MS clips, doing away with back-to-back clips (apart from with my larger-diameter SDCs – the MKH 30 and MKH 50 MS pair). The support for the shock-mounts and, indeed, the form of the shock-mount bases has been minimized to keep the acoustic impact down: the amount of plastic internal structure in many a windshield is a real issue that I wanted to avoid. The laser-cut stainless-steel baseplate, at 74mm x 93mm, to which the Arca plate is bolted, obviously offers some scope for reflections, although it is some distance below the mics: nonetheless, I have mitigated any such effect by addition of a 3d-printed curvy cover or skirt.

Underside of the Mega-Blimp large showing the stainless-steel baseplate welded to two 6mm rods for strength (which in turn span between the main hoops), and with the (modified) Arca quick-release plate and XLR plug attached.

Adaptability: The size and lack of internal structure make the two Mega-Blimps highly adaptable, so there was little extra to think about in this regard, beyond a central 3/8″ mount that could take a variety of off-the-peg or 3d-printed shock-mounts, and a simple cabling solution. Here, I eschewed the (puzzlingly always unshielded) conn boxes that manufacturers use on many higher-end models, but which then get the user stuck to particular numbers of mics (typically one, two or three). Rather I have gone for an easily removable XLR cable that fits, via the unscrewable end of the plug, firmly to the base. It is the same approach I (and manufacturers such as Ambient) have taken to mounting XLRs at the top of boom-poles. Simple, swappable and effective.

For the mounting of mics, the two Mega-Blimps each have a 3/8″ threaded bolt projecting upwards from the baseplate. This can be fitted with, say, a Rycote InVision 6 or 7 shock-mount, although my preferred solution is to use a length of 15mm rod with 3/8″ threads, as shown here, in turn supporting a small Field Edition mount by Radius Windshields or my various 3d-printed mounts. There is no need for pivot mounts (as found in the InVision 6 or 7) since angling of the mics is normally preferable by angling the whole windshield (i.e. at the tripod head), and the more minimalist approach clearly is to the acoustic benefit. Here are the current configurations I am using, although other mounts could be designed easily (for example, I haven’t yet made an XY mount as I almost never use such a pair):

ORTF

ORTF (for anyone unfamiliar, an acronym for the Office de Radiodiffusion Télévision Française, where this stereo technique was developed about 65 years ago) is popular for field recording despite its requirement (if conditions go beyond what slip-on or Baby Ball Gag type wind protection offer) for larger windshields and, often, very short mics (such as Sennheiser MKH 8000 mics with MZL connectors or Schoeps CCMs). And even then, the mic diaphragms can end up nearer the basket edge than ideal (i.e. with loss of wind-reduction). So having sufficient space for ORTF in the Mega-Blimp was important and the 242mm diameter means that it is easy to set the mic capsules on the centre-line of the windshield without the rear of the mics or their XLRs getting near the basket. In fact, there is enough room for a wide range of SDC mics, so short mics like the Sennheisers and Schoeps are not essential. Obviously longer SDCs used for ORTF have the problem of the rear of the mics or their XLRs clashing, so, as with XY pairs, they are offset vertically – one above the other. Whilst I have MKH 8040 cardioids with MZL cables – i.e. short enough not to need such offsetting – my Rycote CA-08 cardioids are just long enough that their XLRs do clash when set as an ORTF pair, so I have given them a vertical offset: there are different ways to do this, and I have chosen the simple route of keeping the ORTF mount untouched but using different length clips (3d-printed) in the Radius hoops. The length of the Mega-Blimp large is particularly suited to ORTF, with the mic capsules projecting just past the two main rings of the basket. The Mega-Blimp standard works fine with ORTF, although the capsules do project further into the end cap/hemispheres (which, of course, are very roomy anyway).

ORTF pair (110° angle, 170mm spacing between diaphragm centres), here shown in the Mega-Blimp large: the greater length of the blimp works well with such a wide pair.
The ORTF pair and blimp rotated so that the pair can be seen as if from above. The 3d-printed mount is a development of the one I produced previously, for non-windshield use, so that the mic capsules sit on the centre line. In this case the MKH 8040s would benefit from MZLs to reduce length.
Single-hoop mounting of an ORTF pair means that a smaller 3d-printed ORTF bar can be used and that the mics are clearer of any shock-mount structure (and any acoustic effect that has). Here a pair of MKH 8040s are shown with MZL cables in the Mega-Blimp standard. With this shorter windshield they project further into the end hemispheres: I think in reality that the Mega-Blimp large works better for ORTF whether or not the double or single-hoop ORTF bar is used.
And just to show one solution (i.e. clips of different lengths within the Radius hoops) to vertically offset longer mics for ORTF, here even using full-sized XLR connectors. With low-profile XLR connectors the maximum length of mics used for ORTF – assuming that the capsule is still on the centre line of the windshield – is about 130mm. The Rycote CA-08 cardioids shown here are only 80mm long, and, even with low-profile XLR connectors, are just about long enough to need a vertical offset. Obviously slightly longer mics than 130mm could be used, but the diaphragms would need to advance from the centre line: not a major issue given the 242mm diameter of the basket.

MID-SIDE (MS)

Mid-side recording is, as readers of this blog will know, perhaps my favourite approach to stereo, using a range of mid mic polar patterns that include omni, wide-cardioid, cardioid, super-cardioid and fig 8. Indeed, I am probably unusual in having more fig 8 SDC mics (essential for the side mic in an MS pair, of course) than any other polar pattern. Although smaller fig 8s (especially the new Sennheiser MKH 8030 and Rycote BD-10) feature heavily in my posts, it is nice at last to have a windshield that has plenty of room for my MKH 30 and MKH 50 MS pair: they sit particularly well in the Mega-Blimp large.

The Mega-Blimp large works well with a larger mid-side pair, such as the classic Sennheiser MKH 30 and MKH 50 pair shown here. Given that the current Radius Windshield hoops don’t work with mics of such larger diameter, the mics are rigged on a Rycote InVision 7 shock-mount and with Rycote universal back-to-back clips.
By contrast, the shorter Mega-Blimp standard works well with a smaller mid-side pair, such as the MKH 8030 and MKH 8040 pair shown here. In this case they are mounted in Radius Windshields hoops on their small field edition mount: the lack of a pivot on this mount is useful as it ensures the mics are not angled up or down in relation to the basket. The MS clips are my 3d-printed design, but it won’t be long now before Radius produce their injection-moulded versions. The daisy-chained MS cable (for want of a better term) is a new idea from ETK Cables: Ed was inspired by my MS clips, which was nice to hear!

DOUBLE MID-SIDE (DMS)

I’m not a heavy user of double mid-side arrays, but occasionally use them: most recently I was required to use the technique for a surround-sound recording of the sea, to feature as the introduction to an organ music SACD (an unusual intro, I know). There are different ways to rig DMS, of which the most satisfactory is using side-address cardioid mics oriented vertically, above and below the horizontally-set fig 8 mic. The downside with this is that there are few side-address SDC cardioids, with the Schoeps Mk4V and CCM4V being the obvious examples. Cinela used to produce a DMS mount for the CCM4V and CCM8 (the X-SET-DMS-CCM), but that appears to have been discontinued (it is not on their website). Schoeps and Rycote also used to make the WRS DMS LU mount for such a DMS array, although this too has been discontinued, and if you go to the Schoeps website today you will see they show DMS rigs in Rycote and Cinela windshields with end-address mics. With end-address cardioids these can either be set above and below the fig 8, so that all are coincident on the horizontal plane, or set in a close triangle with the cardioids side by side (obviously facing different directions) and the pair above or below the fig 8. The latter arrangement is more compact, but, evidently, the three mics are not perfectly coincident on the horizontal plane. And, although I am not as concerned by mic shadowing as many (often from a largely theoretical stance), both configurations of the mics and the gubbins needed to support them do seem rather clunky and in the way of each other more than seems desirable and, indeed, much more than if using side-address cardioids. Lacking the latter (at least at present), I have simply used the DMS mount I created for Radius hoops (and, indeed, for the Mini-ALTO), using MZL connectors to minimize the bulk of the mics as much as possible. In due course (if I acquire the necessary Schoeps mics), I will develop a DMS mount for side-address cardioids along the lines of my native B-format mount below: I’m pretty confident that this would have less acoustic impact than the discontinued WRS DMS LU mount.

The close spacing of a double mid-side array suits the Mega-Blimp standard, and the 3d-printed mount is shown here using Radius Windshield hoops fitted to a Rycote InVision 7 mount.
Another view of the double mid-side array, which uses an MKH 8030 and two MKH 8040 mics with MZL cables, showing the mount in more detail.

NIMBUS-HALLIDAY NATIVE B-FORMAT

I mentioned above the (sadly less popular) version of DMS with vertically oriented cardioids, and, of course, this looks strikingly like a Nimbus-Halliday native B-format array (the difference being that the latter has two vertical fig 8s above and below a horizontal omni mic). Particularly avid readers of this blog (are there any?!) may recall that I wrote about this array when using it to record a pipe band (and those that aren’t familiar with the technique can read about it – and download WAV files for a play – here), to give me a variety of options in post. Since then, I have reduced the size of the array by using MKH 8000 mics with MZLs, and worked hard to minimize the size of the mount and, while still using shock-mounts, avoid too much in the way of gubbins close to the mic capsules, to produce a compact version that fits in the Mega-Blimp, and does so with the windshield being oriented horizontally (I didn’t want to turn it vertically, as then the baseplate would have had some impact on the rearward sound capture). I must confess of all the rigs that I have made for the Mega-Blimps, the 3d-printed Nimbus-Halliday mount has been the most satisfying so far, and the design evidently has relevance to an improved approach to DMS rigging in windshields.

Getting a bit more esoteric perhaps, but here is my design of a 3d-printed shock-mount, again using Radius hoops, for a Nimbus-Halliday native B-format array, comfortably sitting within the standard Mega-Blimp.
An angled view of the Nimbus-Halliday native B-format array. The use of single hoops helps keep the area around the convergent mic capsules unimpeded.
And an end-on view of the Nimbus-Halliday native B-format array, showing the omni mic in the middle, with the fig 8 mics above and below.

This is a pretty clean (i.e. low acoustic impact) shock-mount configuration for a native B-format array (or DMS with the mics swapped out), but, as always with such three-mic arrays, there are some elements that still lie within the polar patterns of the different mics. The tall vertical element is less than ideal: there is some inevitable impact in native B-format behind the omni middle mic, and if used for DMS behind what would be the rear-facing (side-address) cardioid top mic. The hoop and mic clip of the middle mic also get a bit in the way for both set ups. Fussy, I know! Sky-hooks would be one solution, but in the absence of mythical devices, I realized (belatedly) that the top mic could hang from the top of the Mega-Blimp basket (for once a windshield is an advantage other than for reducing wind!), doing away with the vertical element. And then, a more minor refinement, to get rid of the effect of the hoop and clip around the middle mic, perhaps the hoops could be dropped so that the mic sits on top of them…yes, not the design intention of Radius Windshields, but it works OK! Hoops and mic clips for the middle mic are then both placed neatly out of the way into the null of the bottom mic in either native b-format or DMS. And with the middle hoop out of the way, I thought I might as well revert to double hoops for each mic: this gives a little more stability and the mics stay in place more readily without such careful cable dressing as in the first Nimbus-Halliday native B-format rig. So there you have it: almost nothing in the way of the relevant polar patterns of the mics (note: for DMS the bottom mic would be the forward-facing cardioid, and the top mic the rearward-facing cardioid). If I can get some side-address cardioids (a pair of Schoeps CCM 4V mics would be ideal), then I’ll add a photo of the DMS version. Crumbs, I am enjoying the combination of a 3d-printer, Radius Windshield hoops and the Mega-Blimp!

A variation of the Nimbus-Halliday native B-format rig (equally applicable to DMS, given side-address cardioids such as the Schoeps CCM 4V). In this case the shock-mount for the top mic is fixed to the top of the windshield basket, and the middle mic sits on top of two Radius hoops, all leading to a still more transparent version of the rig.

These are but a few examples of the configurations of mics possible in the Mega-Blimps, but the scope is considerable – as intended. Funnily enough, while building the blimps I was asked whether a single LDC mic would fit. My first reaction was doubt, as, of course, the Mega-Blimp was very much designed as a much shorter version of the original LDC blimp from years ago, specifically for SDC mics, and I wasn’t quite certain how an LDC mic would sit within the basket, but nothing ventured, nothing gained. I only had the Mega-Blimp standard at that point, and this encouraged me to think more about the Mega-Blimp large (at the CAD design stage, the length of the central section – the ‘hamster wheel’ – changed on an almost daily basis), which has turned out rather better for ORTF pairs. But, anyway, here is the result of the LDC test:

Not at all the original intention, but here’s an LDC mic inside the Mega-Blimp large. The mic sits in a Rycote InVision USM-L (Rycote 044903), which bolts directly to the baseplate of the blimp via the lighting-stand stud.

Obviously the size of the basket would prevent close spacing of a pair of LDCs for, say, ORTF, but a NOS pair would work fine, or, indeed, any of the large surround or ambience arrays such as Hamasaki square.

The master of bending and TIG-welding stainless-steel rod, Rob Moore, here at work on his current rolling-ball sculpture (The Brain), which is a little more involved than a Mega-Blimp!

The construction

There’s not a great deal additional that needs to be said about the construction as, by now, it should be pretty clear to the reader. The TIG-welding was again undertaken by my good friend Rob Moore, who lives in a nearby village. His normal work is building highly elaborate rolling-ball sculptures, and he has years of experience of bending and TIG-welding stainless-steel rod in complex geometries. Most of his sculptures are done freehand, but, for the blimps, he constructed some simple jigs to help achieve a regular appearance. Of course there is no acoustic benefit from things being absolutely perfectly regular (perhaps the reverse), and the Mega-Blimps are unashamedly hand-crafted. The welding leaves the stainless steel rather discoloured, and normally Rob takes his large sculptures to a specialist firm in Birmingham for electro-polishing. In this case, however, he just cleaned the baskets with a wire brush bit in a drill – a fiddly, messy and time-consuming business. Rob let me do one, I suspect just so I could experience how little fun it is and to convince me that, if there’s a next time, we go down the electro-polishing route. Powder-coating could be another, cheaper, option, though I much prefer the stainless-steel appearance. The 3mm-thick stainless-steel baseplates were welded to the baskets and, as mentioned above, during construction of the different versions (Rob made five in the end!), we moved from laboriously hand cutting and drilling to having a small batch of 10 plates laser-cut. The Arca quick-release plates that are fixed to the bottom of the baseplates are the Manfrotto MSQ6PL: I chose these for the wider than usual top part to the plate, which extends further across the width of the baseplate above and, thus, gives more rigidity. The Arca plates were drilled to allow stainless-steel M5 bolt fixings to the baseplate, with the nylock nuts on the upper face accommodated in the 3d-printed skirt designed to remove any possible sound reflections from the baseplate. The skirts have a few different designs to fit the two models and the different heights of the 15mm aluminium rods that hold the mic shock-mounts. The 15mm rods have 3/8″ male and female threads either end, and I found a supplier that makes sets of three with lengths of 1″, 2″ and 3″ (I do love mixed imperial and metric dimensions: it’s like buying 4.8m of 4″ x 2″ timber!), which have proved ideal. The various mic mounts for different arrays, which combine elements from Radius Windshields, Rycote and my own 3d-printed designs, I have covered and illustrated above. Doubtless, I will come up with more: I use Onshape for 3d modelling and output on a Bambu Labs printer. Last, but not least, the two sizes of lined fur were specially made by Radius Windshields: Donna, Kim and Megan, at their Stroud sewing workshop, have, I suspect, unrivalled experience of making windshield furs. Radius make plenty of replacement furs for other manufacturer’s windshields and are happy to make one-offs and small runs, which is good news for DIYers. As originally conceived, the Mega-Blimp was not intended to have any fabric covering to the basket below the fur, and that is how I am happily using it at present. However, I am exploring options for a stretchy fabric – which would need to be easily and quickly removable (as well as acoustically transparent) – to be used instead of the fur in very gentle conditions (to reduce the unavoidable high-frequency attenuation from fur) or in conjunction with the fur in extreme conditions: one might as well reap the full benefit of the large diameter of the Mega-Blimp in such high wind. More on that anon perhaps.

Bespoke furs from Radius Windshields: the unfitted one on the left is for the Mega-Blimp large, and you can see the lining, single popper at the rear and the drawstring; and that fitted on the right is on the Mega-Blimp standard. Both fit easily and closely, and tighten up very snugly around the baseplate and Arca plate. It was worth having an expert on the case!

Conclusions

The two Mega-Blimps I have designed will not make my (unhealthily large) collection of commercial windshields redundant: like any sane sound recordist, I understand that these expertly designed and engineered plastic windshields are often the best tools for the job. But when that job doesn’t require booming or otherwise has weight and size as practical constraints, the Mega-Blimps will be a key tool for me: the robustness, ease of use and, above all, the transparency and adaptability for all sorts of arrays (including some hitherto not to my knowledge achieved in a windshield) they offer will be a real boon to recording sound effects, ambiences and music outdoors. Yes, they are a bit larger to carry, but as they fit in a small backpack that makes little difference for much of my usage. And they are far more resilient in transit, which rather compensates for size, even without considering the performance gains. I’m rather pleased at the end results and interested to see which of the two sizes of Mega-Blimps I find myself using more: time will tell. I also suspect that this won’t be the end of my dalliance with windshields. Not least, I have already begun to ponder the design of more specialized baskets for more complex arrays of SDC mics: there is little doubt that TIG-welded stainless-steel construction is unusually well suited to large, robust and transparent bespoke windshield designs. We will see. And in the meantime, I hope this account inspires readers to think more about windshield design, performance and the various compromises that are inevitable in any design; and, perhaps, even engage in their own elaborate projects to create something bespoke for their particular type of sound recording.

Further reading

Anyone really keen to understand windshield design and performance may find the following articles of interest: I certainly have. You may well have to join the AES to access them, as I did, but there’s not a lot I can do about that!

Bleazey, J.C., ‘Experimental Determination of the Effectiveness of Microphone Wind Screens’, Journal of the Audio Engineering Society (Jan 1961, vol. 9, no. 1), 48-54.

Brixen, E. B., ‘Microphones, High Wind and Rain’, Audio Engineering Society 119th convention paper 6624 (2005), 1-8.

Chenevez, P., ‘Handling noise analysis in large cavity microphone windshields. Improved solution,’ Audio Engineering Society 126th convention paper 7774 (2009), 1-7.

Wuttke, J., ‘Microphones and Wind’, Journal of the Audio Engineering Society (Oct 1992, vol. 40, no. 10), 809-17.

DIY Projects

ORTF: working towards a minimalist approach

November 15, 2024

The near-coincident ORTF stereo pair has a huge following that extends way beyond the remit of the body for which it was invented – the Office de Radiodiffusion-Télévision Française – and long after its demise in 1975. The required 110 degrees angling of the mics and diaphragm centres at 170mm spacing can be set up with any stereo bar. Or you can always use the Schoeps MSTC 74 ORTF mic (or its predecessor, the MSTC 64), where the spacing and angles are built in. And if you don’t have nearly £3k to spare, there’s the similarly designed Superlux S502 at around £100. But, evidently, there are many that find setting the angles and spacings on a stereo bar too fiddly by far (it’s certainly harder to eyeball 110 degrees than a right-angle); many who don’t want to splash out on a dedicated (but inflexible) Schoeps solution; and many who want something of higher quality than the Superlux. As a result there are many dedicated ORTF mounts available for SDC mics. These include offerings by major mic companies, such as DPA’s CXO4000 (which can also mount an XY pair) and, more recently, commercially available 3d-printed options. Ostensibly neat solutions, these dedicated mounts hold the mics directly, and can then be fixed directly to a mic stand: attempts to introduce shock-mounts then become clumsy, typically using Rycote lyres for the whole rig (fixed on a stem protruding from the bottom of the ORTF mic holder, and at 90 degrees to the intended use: a real shot in the foot). Come to think of it, an effective shock-mount or suspension for the Schoeps MSTC 64/74 or Superlux S502 isn’t immediately obvious: a Shure donut perhaps?

ORTF using a standard stereo bar (the small K&M 23550) and the smallest lyre/hoop mounts that I know: the Radius Windshields RAD field edition mounts. Rycote InVision INV 6s would be a larger alternative. The red hoops are a test run of softer 55D shore ones, and will go into production soon in a more subtle dark green. This is a fairly minimalistic ORTF rig with properly set up shock-mounts, but there is no denying that setting angles and spacing is a bit fiddly.

With a 3d-printer to hand, I wondered about a neater solution, using mics mounted correctly in suspensions (as if, for example, using a pair of Rycote InVision INV 6s or, smaller, Radius Windshields RAD field edition mounts on a standard stereo bar), which would then be fixed to a dedicated ORTF bar: the best of both worlds. First off, I designed a simple mount with size slots to fit both Rycote lyres and Radius Windshield hoops. The latter can fit Rycote mounts, but not vice versa. The three slots to each channel allow a bit of flexibility in the placement of the lyres/hoops for different mic models. I added a cable grip at the rear to help isolate the mics from cable-borne vibrations and, for my personal usage, designed this to perfectly grip a Sennheiser MZL cable: in my usage the ORTF mount will be used for MKH 8040 mics with MZLs. Taking a more minimalist route with MZLs made me think a bit more about the suspensions and clips, so I ordered a pair of 19/20mm clips from Radius (much more minimal than their chunky universal clips) and a pair of their 8mm clips (designed to hold the rear of a Sennheiser MZL or a Schoeps Lemo connector). This works fine although there is a mildly disconcerting slope to the mics as a result of the centres of the two clips being slightly different (they didn’t originate as such a pair), but the ORTF mount can be angled freely anyway: for this the bar makes use of a Gravity Quick-Tilt Microphone Adapter (MS QT 1 B).

With the same hoops mounted on the 3d-printed ORTF bar.
And angled a bit to show the construction of the ORTF bar more clearly.

So far so good, but when talking to Simon Davies at Radius about the different centres of the clips, he suggested that I try the two clips individually: that is, use one hoop only (the curved profile giving the new hoops more stability when used singly than the flat lyres from his Rycote days), and suggested I try the 8mm clip only. That was food for thought, so with the ORTF mount I tested the following:

8mm clip with single RAD-2 (21b) hoop x 2 (the control)

8mm clip with single hoop 21b vs two 21b hoops with 19/20mm + 8mm clips

8mm clip with single hoop 21b vs 19/20mm clip with single hoop 21b

8mm clip with single hoop 21b vs 8mm clip with single RAD-1 (21a) hoop

8mm clip with single hoop 21b vs single Rycote lyre 72 shore

8mm clip with single hoop 21b vs no shock-mount (another sort of control!)

With structure-borne noise transmitted from a suspended floor via the stand, the 8mm clip with a single hoop 21b sounded the best: in my test it offers less transmission of the lower frequencies than the 19/20mm hoop (or the latter with two hoops and an 8mm clip in the rear hoop), which I suspect is due to the fact that the 8mm clip is holding the rubber element at the rear of the MZL rather than the mic body direct. I couldn’t really hear/see any difference between the RAD-2 (21b) and RAD-1 (21a) hoops with the single 8mm clip. The single Rycote lyre worked OK on its own with such a light mic, but, connecting to the mic body, again transmitted much more than the 8mm clip. The absence of any shock-mount was definitely much worse than any of the clip/hoop/lyre combinations, as one would expect! So the conclusion is that the single-hoop and 8mm clip is an excellent idea for an ORTF mount for static mics with MZLs (sans windshield: or, indeed, inside a large windshield).

So with these useful tests in mind, I quickly modeled and printed a shorter version of the ORTF mount, this time with just with two slots – for one hoop for each mic. With the RAD hoops set with the concave side forward (orientation of the hoops is irrelevant as long as opposing if in a pair), the MKH 8040 sits nicely forward of any suspension or mount that could have an acoustic effect, and the whole arrangement has a certain minimalistic elegance (though I say it as shouldn’t, as my great grandmother would say).

Here’s the 3d model of the mini ORTF mount/bar.
A view of the single-hoop ORTF mount, this time with the 62D-shore hoops.
The view from the rear: the cable grips are important to both stop transmission of vibrations along the cables, and also to set the angle of the mics. I was a little sceptical that the cable clips would do both, but testing very much shows they do. Obviously differently sized cables than the Sennheiser MZLs used here would need different cable clips in the 3d-printed mount, but that’s part of the beauty of 3d-printing: you can design something that works for you!

It was only yesterday, after having modeled and printed these different ORTF mounts, that I received the 55D test hoops from Radius Windshields, in their ‘Evil Red’ colour. I had suggested the idea to Simon Davies as with Rycote lyres I felt that many end up using too stiff a suspension for a lightweight static mic with no windshields – be that for indoor effects or for music recording. Both Rycote and Radius are primarily geared to production sound markets, and those using mics statically often forget this and that there is a substantial difference between the needs of a mic that is moving – often quite quickly – on a boom-pole or in a pistol grip (think of the momentum involved) and a mic that is completely static, and where the aim of the suspension is to reduce the impact of structure-borne noise transmitted from, or through, the floor and then through the stand. So today I tested the 55D shore hoops on the mini ORTF bar, and they reduced low-frequency transmitted sound significantly, which can be useful on those occasions where you do not want to roll-off the low end of the mic. The MKH 8040 mics with MZLs mounted in 55D hoops (in the eventual production colour of dark green) and the mini ORTF bar (which I will now 3d print in black) will make a very minimalistic, discreet and well-suspended pair that are quick to set to the ORTF configuration on those occasions when I steer away from my favoured MS pairs. Sorted, as they say!

Just for completeness, here’s my comparison of the effectiveness of the 55D hoops vs the 62D hoops:a useful reduction in low-frequency structure-borne noise for those occasions (particularly when recording music: think of organ recordings, or even a standard piano where the lowest note is 27.5Hz) where you don’t want to use a high-pass filter.

Obviously the ORTF mounts shown here are very much tailored to my use, with MKH 8040 mics with MZL cables, but just in case anybody else wants to 3d-print these ORTF bars (free of course!), here is a link to the larger version for two Radius hoops/Rycote lyres per mic and here is the link for the more minimal one for a single Radius hoop. For others with very different mics and different cables, perhaps this DIY project will give a bit of inspiration!

DIY Projects

3d printing clips for the Radius Windshield hoops

October 27, 2024
At last, mid-side clips integrated into a shock-mount, yet easily swappable with clips for a single mic.

Mid-side clip for 19mm Ø mics

When Radius Windshields launched and produced their RAD shock-mounts one of the unique features was that the mic clips could be unscrewed from the hoops and switched to something different. A radical difference from, say, the Rycote Invision series shock-mounts, where the mic clips and lyres are all one moulding. This has provided scope for Radius to produce dedicated clips for the older MKH 50 etc. mics and, ultimately, to produce dedicated MS clips, doing away with the need to use clips to fix a mic to the shock-mount then a pair of back-to-back clips to attach the second mic to the first. A fiddly faff and also bedeviled by the lack of back-to-back clips with a close spacing, which is preferable for mid-side recording. I have been encouraging Simon Davies at Radius to produce MS clips, and this is now in train using some of the ideas I have proposed. While their nice injection-moulded version is awaited, here is my version for a MS clip to fit their RAD-1 and RAD-2 hoops, and designed for 19mm Ø mics such as the MKH 8000 series and the Rycote SDC series. I should add that Simon Davies at Radius Windshields has supported me in putting this design out into the public domain, which follows similar release of their first prototype for others to 3d print (their initial design was rather different to mine, and their upcoming production version, with a central bolt and a consequently wider spacing as this is tightened). The approach I have taken with this clip is very much a product of many discussions with Simon – via email – on MS clips and other Radius items in development, but also reflective of the company’s refreshingly open engagement with sound recordists.

One of the nice things about the Radius Windshields hoops is that they fit to Rycote shock-mounts such as the InVision INV 7 here, so you can make good use of existing hardware.
CAD drawing, created using Onshape, for the MS clip.

In designing this MS clip I have gone for a spacing of 2.5mm between the mics, which is nice and close but still provides just enough room to allow two MKH 8030 mics to be inserted for a Blumlein pair of two fig 8 mics(the MKH 8030 having a wider front part to the mic). The mics are given enough grip by the springiness of the clips, and this took quite a bit of work to get right: in particular, the internal seemingly circular clips are made up of several different radii so that they hold the 19mm Ø mics properly as the necessarily undersized opening is enlarged by insertion of the mic to give sufficient grip. I have printed them in both PLA and PETG filament (with solid infill) so nothing fancy is required: the PETG filament gives a bit more flexibility and is what I have been using for them mainly. If you are determined you can break them, but, of course, that applies to many a commercial-produced back-to-back clip!

There are two bits of metal hardware that you will need for each clip, which comprise an M3 thin square nut (standard size 5.5mm x 1.8mm), and one of the same M3 socket head button flange screws that Radius use, in this case 12mm long. Of course, you can just use the existing screws that come with your RAD-1 and RAD-2 shock-mounts, so strictly the only extra part you need is the square nut. Stainless steel A2 is best. I got both the nuts and some of the extra screws from Westfield Fasteners (in the UK).

You can go to the file here in Onshape and export in STL, STEP, 3mf etc. file format as required. Note that the clip looks a little skewed or angled when printed: this is deliberate since loading it with two mics opens up the two clips elements a little and consequently, with this built-in angling of the lower circle, the MS clip sits properly square and central (i.e. with the mic centres exactly one above the other) when in use.

MS clip showing vertical alignment when loaded with a pair of mics: a bit of a fiddle to compensate for the skewing effect when the clips are expanded to take the mics, but worth get right.

And, yes, with the MS pair nicely in the Radius Windshield hoops, you can not only retrofit them to InVision shock-mounts or, say, a Rycote Modular windshield, but even, with a bit of ingenuity, get them into a Rycote Nano Shield: with the rather high-set mount for the lyres in the Nano Shield there is not a lot of height to play with (which makes back-to-back clips a very imperfect solution: the top mic ends up right by the basket), so a 3d-printed mounting bar (here’s a link to this too) and mounting the Radius hoops on the underside gives a good workable solution.

While I am at it, here’s another view of the MS clips in Radius hoops being used in a Nano Shield: a pretty dinky MS set up!
Yes you can fit three mics into a RAD-1 and RAD-2 shock-mount!

Triple mic clip for 19mm Ø mics

For something a little more esoteric, I have also created a triple-mic mount to fit the Radius RAD-1 and RAD-2 hoops. Such a triple configuration of mics is something I have used from time to time for MMS (i.e. mid-side but with two different mid mics with different polar patterns – say omni and supercardioid – facing forward so that the polar pattern of the mid mic can be chosen in post) or side-by-side Blumlein with, say, a single supercardioid for recording a singing guitarist, as I demonstrated recently here. Previously I have had to use two pairs of back-to-back clips to connect three mics, which is a fiddle. As I said, a bit esoteric, but that’s the fun with 3d printing: making the commercially unviable possible.

In terms of design, this drew on the mid-side clip, but the loading of the three mics had an impact on the form of the different near circular forms, so even more complex curves were necessary to ensure a snug fit for each mic. I also chose to beef up the thickness of the clip a little, to 3mm, due to fear of the additional forces involved getting three mics into a single clip; and then angled the top interface/mating part by 3 degrees to allow for the change in angle arising from the necessary expansion of the individual clips due to inserting all three mics. In all, nine iterations were required, and doubtless there is room for improvement still: things like best thickness vary a little with filament used. I used a slightly different approach to the fillets, but that is a subtle change. The solid modelling takes a few minutes only, but the printing at finest quality takes an age! The interface, or mating, with the Radius hoops is the same as for the mid-slide clip, so the same size nut and screw are needed. I suspect not many will want to print this model – it is largely presented as showing the potential for very specific mic clips (inc. DIY) offered by the interchangeable design of the Radius hoops – but if you do want to use it, then you can download it (again freely) here from Onshape and choose which file format suits you for export.

And here are the triple clips as 3d printed.

EDIT (6.1.2025) More triple mic clips: double mid side (DMS)

I’ve also spent some time playing around with mic clips for double mid side (DMS), and, spurred on by receiving a Mini-ALTO 115 from Radius Windshields for field testing, I revisited this. DMS always feels a bit clunky (it’s that rearward-facing mid mic out front that seems so odd) and, though I’m never overly concerned about it, shadowing does seem more obvious than in, say, side-by-side Blumlein of MS. But using MKH 8000 mics with MZL connectors at least goes some way to reducing the bulk of the mics. With the size of the Radius hoops there is no scope for three mics in a vertical line so, as with, say, the Rycote Cyclone DMS kits, I have gone for the two mid mics set side-by-side (although facing opposite directions, of course) with the fig 8 centrally above. The wider front part of the MKH 8030 means that this needs to be taken into account by the front clip that holds it too: the fig 8 provides the only common mic spanning between the two mic clips, and there isn’t much to grab onto at the front, so I decided – like many a DMS rig – to include a couple of metal rods (these are chopped down ones, 2mm in diameter, that were redundant from a Rycote MS stereo Cyclone kit 5 – where they are superfluous and, indeed, prevent better rigging). Anyway, here are a few images of the model (you can download the front and rear clips from Onshape) and the resultant rig.

Rear clip for DMS, showing holes for 2mm connecting rods.
Front clip for DMS.
The 3d-printed clips with connecting rods in place.
And the DMS rig set up in Radius hoops (the mount looks a little different since this includes the ‘smiley face’ adapter that allows the RAD-2 shock-mount to be used with the Mini-ALTO windshield).
Audio Gear DIY Projects

If only boom poles could grow legs…

February 17, 2023
Options for mic supports outside: camera tripods, lighting stands and a boom pole.

Field recording can mean mics on a pistol grip for a quick grab of a sound, on a boom pole for something equally quick but harder to reach, or clipped to a bag or hat for some stealthy ambience recording. But much recording outside – and that includes music – requires something more stable and static in the way of support so the mics can stay steady and the recordist can step right way to monitor from afar – not least to avoid capture of rustling, breathing and stomach gurgles from the recordist. Strapping mics to either side of a tree (‘tree ears’) can work, but, of course, there may not be a suitable tree to hand in the right place, so, mostly, it’s a case of taking a stand with you. The trouble with that, of course, is that there are no commercially available stands that have been purpose-built for field recording: so it’s a case of making do with what’s out there. In this post, I’m going to look at the conventional options I have been using in different situations, plus one additional option that I have put together recently and which others may want to try.

Mic stands

Conventional mic stands have little value outside unless in the tamest of environments (think streets, pavements, patios and lawns), being heavy and, with their circular or short fixed tripod bases, have no adaptability to uneven terrain. Not to be sniffed at if you have nothing else – and a short mic stand (the sort you might use for miking a kick drum or a guitar amp) could work fine for recording out in nature with mics near the ground – but not something I’ve found an attractive option.

Lighting stands

Lighting stands are great alternatives to mic stands indoors, not least for getting mics up high for, say, recording an organ, choir or orchestra: obviously they aren’t so good when you want a small footprint, or a short boom arm. They are also useful outdoors, and with a wide range of sizes, can cover a range of uses. When hiking/travelling light I often take a Manfrotto 5002 Nano Plus stand, which folds down to 52cm (it can fit in a rucksack with a blimp), yet extends to 1.97m. It has one slightly extendable foot so has a bit of adaptability to uneven terrain, though nothing very dramatic. It’s the beefiest of the Manfrotto Nano stands (taking a 4kg payload), but I can’t pretend it is rock solid: out in the wind anything above its shortest length is a bit hairy. I tried out the slightly lighter Manfrotto Nano Pole stand in the local camera shop, since it is lauded by some field recordists and looked good on-line, but it was not for me: it was so much flimsier than the 5002 Nano Plus stand and the removable centre column can hardly pass muster as a boom pole. At the taller end of the spectrum, I have a Manfrotto 1004BAC: this is my go to stand for recording acoustic music indoors when not close miking, and I’ve used it outdoors too many a time. It is in a different league than the little Nano Plus stand, rising to 3.66m and carrying up to 9kg (but still only weighing 3kg): it can happily support my chunky stereo bar and, even, my massive windshield for two LDC mics. Outside, though, it has the downside of lighting stands: the legs are designed for a flat surface and the tripod legs only rise a short way up the central pole or column, so it is prone to wobbliness and vibrations especially when extended.

Camera tripods

Many field recordists use camera tripods, and with good reason: the better engineering and, above all, the stability of legs rising much higher take away most of the wobbles and vibrations; many models can collapse far smaller than even the diminutive Nano lighting stands; many models can get mics close to the ground, unlike lighting stands; the legs are adjustable for length and angle, so the tripods can be used pretty much anywhere, even in water; and, of course, they can be used for their primary purpose too (less to carry, say, when hiking to the recording location). Obviously, adaptation is needed to connect mic clips/suspensions, or a stereo bar to the camera head (or remove that), but this is basic stuff: and use of quick-release plates means that you can swap from an audio to camera set up in seconds. There are a few downsides of varying significance: above all, camera tripods lack height, naturally enough being limited to average eye level or a little above; at full height the footprint of the tripod can be a bit large (not really an issue if, say, recording natural ambiences); with no full-height pole/column element, cable routing can be a bit fiddlier; and some tripods can take longer to set up than, say, a Nano Plus stand.

Options for mic support outside, left to right: Gitzo GB3560 carbon-fibre boom pole, Manfrotto 1004 BAC lighting stand, Manfrotto 5002 Nano Plus stand, Manfrotto 055 Pro camera tripod, and, then, the same at two different heights with a boom pole clamped to it (and, no, I don’t have three identical boom poles and three identical 055 tripods…!).

Boom pole with camera tripod

Advocates of the little Manfrotto Nano Pole stand often cite the removable centre column for use as a boom pole as a key attraction, although, as I said above, it’s a very poor substitute for a real boom pole and the stand itself is flimsy too. But the idea has merit: it is so handy having a boom pole in the field (great not just for any dialogue, but also for those hard to reach sounds – once you use a boom pole you will come to appreciate how many such sounds can be recorded, or better recorded, with the reach and the distance from you it provides – or when moving around, sans stand, catching quick close-up sounds) and it’s annoying carrying bits of kit that have very similar – and duplicated – elements to them. So it’s a pity that no manufacturer has scaled up the Nano Pole idea to produce a more stable stand, perhaps with leg geometry more like a camera tripod, with a decent-sized carbon-fibre boom pole at its core (or, better, the ability to incorporate a range of different boom poles from different manufacturers). I’ve looked for tripod legs that could be used to cobble together something with my boom pole, but with no joy. Then I had the idea (doubtless not the first or the last to do so) of mounting the boom pole to a camera tripod head with the bottom of the pole resting on the ground (crucial for giving stability), essentially making a four-legged stand. Looking around, the nearest thing I found to this out there is a tripod pole bracket made by Hague Camera Supports for attaching an aerial camera mast to a camera or video tripod: rather too massive and laborious for the sort of slick set up I had in mind, but it was reassuring to find someone thinking on similar lines. So to my rather smaller and quicker to use solution: a quick-release 30mm rod clamp (made by Camvate) fixed by two 1/4″ screws (i.e. ensuring no rotation) to an Arca-style quick-release plate. Both the plate and the clamp can be fixed to the tripod and the boom pole in seconds, and the pole can be set vertically or at an angle, with its bottom end firmly planted on the ground. It can be used with any of my Arca-fitted tripods – from the reasonably substantially Manfrotto 055 pro with large ball head, down to my little Benro travel tripod. And the advantage? Well I can use the tripod alone for mic support when convenient; I can use the boom pole alone when useful; and I can combine the two in seconds to get a far more stable tall stand than my current most substantial light stand (indeed, at 4m long, taller than my Manfrotto 1004BAC) with completely adjustable legs. It was a very blowy day today, so I was able to confirm stability in fairly extreme conditions (using Rycote Nano Shields with fur as windshields): at the 1.97m height of the Manfrotto 5002 Nano Plus stand it was completely stable, while the Manfrotto 1004BAC had a significant wobble, and the Nano Plus stand was worse still (both given extra stability by a heavy camera bag hung off them); and at the full 3.66m height of the 1004BAC the boom pole set up did wobble a bit, but less so than the lighting stand and, crucially, vibrations/wobbles calmed down much more quickly. Obviously, as would be expected, the advantage afforded by the taller legs of a camera tripod vs those of a lighting stand diminishes as the boom pole gets towards its maximum of 4m and also as the boom pole sections reduce, but it was interesting to see that the lighting stand didn’t out perform it at such height. For £30 for the rod clamp (and others may find/need different and better solutions for their boom pole), I have another flexible set-up to add to the choices when I take my sound gear out into the wilds, especially when I know the terrain won’t suit a lighting stand.

Top left, Camvate 30mm rod clamp; bottom left, the rod clamp (given a little internal lining to be gentler on my carbon-fibre boom pole) screwed to an Arca-style quick-release plate; and right, the boom pole then attached via these to the ball head of a camera tripod.
And outside in high wind with the boom pole fully extended (about 4m). If setting up for longer in such wind I’d have hung my sound bag off the tripod for a bit more low-down weight.

Audio Gear DIY Projects

Mid-side with AKG CK94

May 25, 2021
AKG CK94 (top) and CK93 (bottom) in Rode Mk1 blimp suspension

I’ve had one of the AKG Blueline mics for years. This has the CK93 capsule, which is an excellent mid-price hypercardioid SDC mic that has proved great for booming indoor (and, on occasion, outdoor) dialogue. I have also used it for music recording where I needed a narrower polar pattern than cardioid. It is leagues above my Oktava MK012 hypercardioid – so beloved by indie filmmakers – in terms of build quality, handling noise, and features (having low-cut and attenuation switches).

From time to time I’ve wondered about the other interchangeable capsules in the Blueline range and, above all, about the CK94 – the figure of eight capsule. Of course LDC multi-pattern mics include a fig 8 polar pattern and, paired with another mic, this allows mid-side recording, which I have done many a time. And, as I have posted, with a massive DIY blimp I have even got such an LDC pair outside for field recording. That said, it would be useful and, for most uses, more practical to have a compact SDC mid-side pair. The standard for field-recording pros is the Sennheiser MKH30, which, while excellent and with the advantage of humidity-beating RF technology, has the distinct disadvantage of cost: it has a street price of around £1500, and even used ones seem rare below £1000. Add another Sennheiser MKH mic (say an MKH40) and wind protection to fit and you will need to spend £3000 or more. Unlike other polar patterns, SDC fig 8s are rare, and there are few more affordable ones: ignoring the clunky pseudo fig 8s made by Oktava and Kortwich (made using two cardioids mounted back-to-back, giving a T-shaped mic), the only affordable true single -diaphragm fig 8 other than the AKG CK94 is the Ambient ATE208 Emesser. The latter, however, has a lot of bass roll-off due to it being tailored to match the off-axis response of a shotgun mic (its intended partner). Recently, boutique Taiwanese mic-maker B9Audio has produced the CM180, but it is only available direct from the maker: so this means significant shipping and duty costs need to be added to the US$749 price. Reviews are also thin on the ground to say the least.

So, with all this in mind, the AKG CK94 remains the most viable affordable SDC fig 8 for general usage (i.e. music as well as film sound). Although now out of production (AKG/Harman/Samsung appear to be phasing out the whole Blueline family and the CK94 was the first to be discontinued), at the time of writing it is just possible to find one or two new examples for sale: with the SE 300B amplifier/mic body, street price is around £600. But I’ve been keeping my eye on the used market, and was please to spot one on the Saturn Sound website (where there is a list for a grand closing down sale of mics – with some very rare examples), and – together with the SE300B amplifier/mic body – the other day I became the owner of a very good condition example: indeed, during a pre-sales check, Ashley Styles of Saturn Sound thought the capsule a bit noisy and replaced it with one he still had. All this, plus delivery in person (he has retired not so far away), for a remarkably affordable £200.

I had no concerns about the CK94 for music or louder effects recording, but, with 22dBA self-noise (a long way from the MKH30’s 13dBA) my hopes were low for recording quieter ambiences. So I was surprised how good it sounded during an initial test recording the ambient noise in the garden (in a village in rural Norfolk). You can have listen here:

I was expecting something much noisier.

In terms of rigging it up for field recording, I purchased a couple of the older style (i.e. lower profile) back-to-back clips made by Rycote (ref. no. 048460), which, unlike the new fit-any-mic clips Rycote make for MS pairs, neatly fit into a Rode Mk1 blimp and have lugs to attach to the suspension bands: the mics sit centrally and with a healthy blimp diameter of 100mm there is still plenty of air space around both mics. The CK94 has to project further forward given the location of its capsule (the centres of the two capsules should align, of course). I’ve added a DIY conn box equivalent (a clamp for the two thin cables – Sommer Cicada – that go from the mics to the DIY boompole-top XLR holder) to avoid the two heavier cables entering the blimp, so I’m there with a very nice sounding SDC mid-side rig for a very modest outlay. And, of course, I can use the AKG CK94 with mid-mics other than the hypercardioid CK93: for example, my Rode NT55 mics give me cardioid and omni mid-mic options. I’ll post other recordings – including music – with the CK94-based mid-side rig in due course.

With blimp on, and showing the double XLR holder at the top of the boompole
And a close-up of the DIY double XLR holder at the top of the boompole