This might be one of my shortest blog posts ever, but that’s doubtless a refreshing change from some of my very long ones, especially if you read them on your phone! Anyway, I was just putting together the gear for a recording tomorrow morning and while grabbing a stereo bar, I thought it perhaps worth highlighting, first, how over the years I have found the Manfrotto 154b to be a great option and, second, how easy it is to modify.
Like many others, I have found the 154b to be an eminently affordable stereo bar, a decent length (spigot centres up to 620mm), really adaptable, quick to set up and adjust, keeps the mics as set, strong, and robust. And if you have a few, like I do, you can add more of the connection clamps that hold each mic when you want, say, four mics on the bar: and it is much cheaper doing that than ordering additional clamps (part R154,01). But, over the years I have noticed that some dismiss it, especially for field recording, for two features: it has an aluminium tube construction that can resonate (not often an issue) and it has two holes near the ends that, if the movable spigots are not over them, can catch the wind when used outdoors. For many uses I deploy the 154b as sold with no issue, but often I don’t want such a long bar so I have a modified version that is 520mm long: this fits neatly in a rucksack I often use when field recording, and is no longer than the (folded) tripods and stands I pack with it. Obviously cutting an aluminium tube to length is no great deal and needs no special gear (care and a junior hacksaw would suffice if you don’t have much of a workshop) and, as long as you cut both ends off, then the two offending holes will be removed. The plastic end caps can then be knocked out easily from inside, so no need to scuff them by prising them off. And, finally, you can do as I did and stuff the inside to damp any resonance: I just used a bit of Rockwool insulation I had spare, but I am sure anything similar would do the trick. So, 10 mins work and, voila, a slightly more compact stereo bar fit for anything in the wilds.
All very obvious, I know, but it might just help someone view the 154b a bit differently!
Like many, I have used double mid-side (DMS) from time to time and, doubtless less typically, I have used horizontal native B-format arrays too: I have written a couple of blog posts on the latter already. Given that DMS can be converted to horizontal B-format and vice versa, I have wondered why DMS is much more widely used and, more specifically, about the practicalities of mounting both arrays: in short, are the two advantages of DMS in use that a) it requires one fig 8 mic only (vs the two for native B-format) and b) that it lends itself better to compact mounting that fits more easily in a windshield? And if DMS is often achieved using this compact mounting – with the three horizontal mics clustered together – would it be better if implemented more spaciously, and with less difficulty in terms of mounting the rearward-facing cardioid, along the lines of a horizontal B-format array?
Now, fear not, this isn’t a blog post about the theoretical side of DMS (or, indeed, native/horizontal B-format) nor, for that matter, about why anyone should use it in preference to affordable ambisonic mic options (and there are compelling reasons): for that, you are much better in the care of Dr Helmut Wittke (CEO of Schoeps) and his colleagues in publications such as this: Wittek, H., Haut, C., and Keinath, D., Double M/S – a Surround recording technique put to test (Schoeps paper, 10.03.2010).
Rather, this post is about some of my dabbling with practical implementations of DMS rigs both generally and in the context – or constraints – of windshields, and with reference to the analogous horizontal B-format rigs. I include some examples of commercially available DMS mounts (past and present) along with some of my own solutions. I hope it isn’t too much of an idiosyncratic ramble, and that it may chime with or, even, be useful for others.
NB having drafted much this blog post I found it rather long and, also, dividing into a few key sections, so I have divided into three separate blog-posts. This one, (part one), is concerned purely with the rigging options: my take on the options for how to mount mics for DMS. It is concerned with SDC mics and, also, doesn’t go into DMS with shotgun mics: it is primarily focused on rigs suitable for taking into the field (i.e. in windshields). Part 2 concerns practical comparison of the different rigs, not least exploring the reality of shadowing effects caused by mics sitting close to other mics. Part 3, to follow very soon, explores the practical differences between DMS and horizontal B-format set ups: there is so much in common – and conversion from one to the other is simple mathematically – but what are the practical pros and cons? Parts 2 and 3 include sound samples that you can download and play with.
Different mic mounting options for DMS
When using small-diaphragm condensers (SDCs) there are three main ways you can configure the three mics needed for DMS:
1) end-address mid mics combined with a side-address fig 8, so that all three horizontally-oriented mics are aligned vertically (typically the central mic is the fig 8, but not always so);
2) end-address mid mics combined with a side-address fig 8, so that all three horizontally-oriented are clustered more closely than in option 1, forming a tightly spaced triangle, but with the two mid mics horizontally offset from the centre of the array (the fig 8 can be above or below the mid mics); and
3) side-address mid mics oriented vertically, flanking, from above and below a horizontally-oriented fig 8.
These three configurations are shown with unmounted mics in the image below:
The three fundamental mic configurations for DMS, for clarity shown here without the complexity of mic support. In all three photos the view is as if from the side of the array and front is to the left.
The composite image above shows that, with the end-address mics (options 1 and 2), the forward-facing mic and fig 8 are easy to mount in the manner of a simple mid-side pair, with the complexity coming from the addition of a rearward-facing cardioid, the body of which projects awkwardly away from the front of the other two mics. In a studio context this can be supported by a separate mount and stand, but this still requires fiddly alignment and is a real pain when adjusting the location of the array to the best position. Obviously, mounting the three mics together is more practical and, indeed, is essential for use in the field in a windshield.
Option 1– end-address cardioids, all aligned
This option with the three mics aligned vertically, is perhaps harder to rig, but with shorter mics (such as Sennheiser MKH 8000 mics with MZLs, and Schoeps CCM mics) it is more feasible. Cinela, for one, has effective windshield mounting solutions shown below, where in each example the rearward-facing mic is supported by pairs of thin struts to reduce acoustic impact. In both these designs the central mic has a long plastic holder to extend the mic to the quite widely-spaced OSIX isolators, necessary to counteract the mass of the three mics at the front.
Cinela Pianissimo with DMS rig, with the mics (Sennheiser MKH 8030 + 2 x MKH 8040) aligned vertically: photo courtesy of Cinela.In this variation from Cinela, for Schoeps mics, the three mics are again aligned vertically, but the fig 8 mic (CCM8) is at the top: photo courtesy of Cinela.
Of course, where DMS rigs involve a shotgun for the forward mic, then the fig 8 and the rearward facing cardioid can be clipped above and below the long body of the shotgun: this is a not entirely satisfactory use of DMS given the polar pattern of a shotgun mic and the irregular response off-axis arising from its interference tube. With a little bit of head scratching and some 3d printing, similar options can DIY’d, although any shock-mount needs to be able to counter the front-heavy loading.
My 3d-printed DMS rig with the MKH 8030 and 8040 mics aligned vertically and in a Rycote InVision shock-mount. The mics are fairly unimpeded (even the cable – from ETK Cables with custom MZLs – for the top cardioid is routed through the clip and along the null of the fig 8), but, obviously, the rig is rather front-heavy and too tall for most windshields.
Option 2– end-address cardioids, side-by-side
This mounting option, where the two end-address cardioid mics are positioned side-by-side, has become a common approach. As with the vertical configuration (above), mic length can quickly make things unwieldy: even the modest 78mm length of the Rycote CA-08 cardioid, plus a low-profile XLR connector, makes for a rather long projection of the front (rear-facing) mic, as shown here:
DMS with Rycote mics, showing the significant forward projection of the rear-facing cardioid despite its fairly short (78mm length).
The more diminutive Sennheiser MKH 8000 mics with MZL connectors instead of XLR modules are, of course, the intended mics for my Rycote Cyclone DMS Kit 1, and show rather better the more compact end-result of the side-by-side cardioids in this option :
The Rycote Cyclone DMS Kit 1 with half of the basket shell in place, and with the basket and supporting arm fully removed. MKH 8030 and 8040 mics.
The constraints of the hoop size (which precludes vertical alignment) meant I also adopted this approach with my DMS mount for MKH 8000 mics in the diminutive Radius Windshields Mini-ALTO 115. As with the Rycote Cyclone DMS Kit 1, this uses thin stainless-steel bars to keep the clips aligned, but also uses the small front ring of the MKH 8030 fig 8 as a fixing point for a clip: it is workable if you need an extremely compact DMS array in a windshield, but is a bit fiddly to set up. Moreover, unlike MS pairs in the Mini-ALTO, DMS rigs in this windshield – or at least my attempts! – end up with the fig 8 mic between the hoops, so that the sideward-facing lobes of the mic are aimed directly at the rather chunky plastic ring where the two windshield pods join: obviously not ideal.
Another rig with DMS using the compact side-by-side cardioid approach: in this case my initial 3d-printed design for the Radius Mini-ALTO. MKH 8030 and 8040 mics, with a triple MZL cable by ETK Cables.A more recent – simplified – variant of the above, which is much easier to use (no fiddly rods). Again, MKH 8030 and 8040 mics, with a triple (customized) MZL cable by ETK Cables.
While this configuration for DMS is arguably easier to mount and is certainly more compact, there are two obvious downsides. First, the coincidence of the mics in the horizontal plane is lost, with both cardioid mics horizontally offset from the centre of the array. Given how much care is usually taken with MS rigs to ensure that the capsules of the two mics are aligned vertically, to ensure coincident time of arrival (and phase coherence) of sounds from the (usually predominant) horizontal plane at the two mics, this might seem problematic for higher frequencies (depending on spacing, but typically above c.10kHz). Such concerns are often over emphasized by the theorecticians, however, and in practical use – even recording, say, classical music – the effects of even side-by-side MS pairs are not always evident: one to bear in mind and check for your usage and ears, perhaps. The second downside, is that the mics are more obviously shadowing each other than when positioned exactly vertically above each other. The physics are undeniable, but, again, whether it matters or not will come down to how critical the recording is and the nature of the sound source. I will explore this – with sound samples – in Part 2 of my DMS blog-post series. And, of course, mic size comes into play: for example an MKH 30 + 2 x MKH 40 MS rig is quite a different beast to the MKH 8030 + 2 x MKH 8040 rig, especially if the latter uses MZL connectors as in the photos above. And you can take the miniaturization of the cardioid further: below is a photo of my Nevaton DMS rig using their new diminutive MC59uS/C2 cardioid mic, which is only 23.5mm long, with their MC59/8 fig 8. In this case the mics are too wide (22mm diameter) to fit in a Radius hoops (and are here shown on a Rycote Nanoshield shock-mount, although would work in any Rycote or similar windshield), but the difference in size between the fig 8, with its XLR connection, and the tiny cardioids makes mounting a bit easier and, of course, any shadowing effect is reduced to some extent by the shortness of the cardioids. On the downside, the MC59/8 has no front part to be used for support as in my MKH 8030-based DMS rigs above.
DMS rig with MC59uS/C2 cardioid mics and MC59/8 fig 8, using a Rycote Nanoshield shock-mount. This is a fairly clean (in the sense of minimizing shadowing from mics and mount parts) version of the side-by-side cardioid option, although the ‘lollipop’ design of the fig 8 means supporting that rear-facing cardioid out front is a tad trickier. Now if someone would make a fig 8 mic with fixings on the front/top (say a couple of M3 threaded holes) that would make life so much easier for DMS rigging!DMS rig with MC59uS/C2 cardioid mics and MC59/8 fig 8: head-on view. The cardioids use magnetic mounts.
Option 3 – using side-address cardioids
This mounting option, using side-address cardioids, used to have two commercially-produced options in the form of the Cinela Z-DMS-CCM (for the Cinela Zephyx, launched in 2005) and the Schoeps/Rycote WSR DMS LU (introduced by 2005), which were both designed for the Schoeps CCM8 + two CCM4V combination. The Schoeps/Rycote mount is certainly discontinued, although I understand that the Cinela mount, although no longer on their website, is still produced occasionally as a special item: make certain you ask nicely! The Schoeps option was used to illustrate Wittek et al’s paper on DMS and appears to have been Schoeps’s preferred implementation of DMS for some time, but currently the DMS options on their website use end-address mid mics either in Rycote Cyclone or Cinela Pianissomo windshields. The Schoeps/Rycote and Cinela methods of rigging the DMS setups with side-address cardioids are quite different as you can see from the photos below:
Schoeps/Rycote WSR DMS LU, with Schoeps CCM8 + two CCM4V: photo courtesy of Schoeps.Cinela Z-DMS-CCM shock-mount for the Cinela Zephyx, again for the Schoeps CCM8 + two CCM4V combination: photo courtesy of Cinela.
I came across both these mounts for DMS with the side-address Schoeps CCM4V only more recently when wondering if my thoughts on adapting the approach taken for horizontal B-format rig to DMS had any precedents: evidently, there is nothing new under the sun! Of course, both the Cinela and Schoeps/Rycote mounts could be used for horizontal B-format too, but I have no idea if that has ever been done: you would hope so.
The two different configurations of horizontal B-format figs I have been using (the revised version having the omni mic rigged vertically, so that its polar pattern is more consistent at high frequencies in the horizontal plane): the similarity to DMS with side-address cardioids is evident.
Coming at my own attempts for DMS with the side-address Schoeps CCM4V (and I am grateful to Schoeps for loan of the mics to test this) was, of course, from the perspective of using horizontal B-format either without any windshield (e.g. for location music recording, as with my bagpipe recordings last year) or within one of my Mega-Blimps. The latter, being much larger than windshields used with the commercially produced mounts, mean that a) the windshield basket can be oriented as designed and b) there is scope to reduce the proximity of structural supports around the mics. If the advantage of using side-address cardioids is that one can avoid the cluster of mics and consequence colouration arising from using end-address mics for the most demanding and critical applications, then it seems worth keeping the mics as free as possible of other sources of colouration, be that the windshield basket structure or the supports for the mics. Anyway, that is the rationale behind my DMS mount for the Mega-Blimp, albeit with a balance struck between transparency and isolation from structure-borne noise: i.e. the mics need shock-mounts (in this case mainly Radius Windshield hoops, but also using Rycote lyres where this reduces obstructions in front of the mics). The result does look similar to the horizontal B-format mount, although there are some significant tweaks to the geometry of the design to better fit the three Schoeps mics than the MKH 8000 mics.
Mount for DMS with Schoeps CCM4V side-address cardioids and CCM8 fig 8 for indoor recording. The hoops and clips, plus the vertical arm to hold the top mic are the main residual items affecting the sound pickup, but the effects are limited to the rear-facing cardioid (the top mic).
Of course, such mounts that aim to minimize colouration are quite large, especially the revised version with its deeper rearward projection, but they fit happily in even my standard-sized Mega-Blimp, which, of course, minimizes additional colouration with its sparse and thin (mostly 3mm diameter) basket structure.
DMS mount (first version) in the shorter, standard, Mega-Blimp.
As with the horizontal B-format mic, such a rig presents challenges for the rear-facing upper mic, which here, as with the Schoeps/Rycote WSR DMS LU, has some on axis obstacles, in this case being the hoop and mic clip of the central mic, quite close to the cardioid, and beyond that the 18mm-wide vertical element of the mount. Looking at this more closely, it is, of course, possible to remove the hoop and mic clip by swapping to a Rycote lyre, which supports the fig 8 mic from underneath (and I have made provision in the mount for use of a rear lyre with a 9.5mm mount for the Lemo connector). And the impact of the 18mm-wide rear bar can be addressed by making this much thinner – in this case a slim 8mm (I tried 6mm, but that seemed too flimsy) – and also by moving this further still from the mic. There’s no such thing as a free lunch, however, with the downside of this version being less lateral stiffness for the arm to the upper mic (so not one to use if the mount is being subjected to much vibration). This revised version can be seen below.
Revised mount for DMS with Schoeps CCM4V side-address cardioids and CCM8 fig 8 for indoor recording, with the design modified to reduce the residual impact of structural elements on the rear-facing capsule. I could do with building in some cable clips to this design as with the previous version!And the same rig in a windshield.
For windshield use only, of course, it is possible to remove the need for an arm extending upwards to the top mic by adopting the approach previously used for one of my horizontal B-format rigs, which removes obstacles in front of the topmost (i.e. rear-facing cardioid) mic without the penalty of introducing more wobbliness to it.
The most transparent solution – well, that I can come up with! – for DMS in the Mega-Blimp, with separate mountings for the bottom and centre mics, and the top mic.A detail showing the largely unencumbered rear-facing (topmost) cardioid, which is a contrast to the situation in most DMS rigs.
So here we have it: an exploration of the three configurations used for DMS with SDC mics. Commercially available solutions exist for the first two options (with end-address cardioids), but are thin on the ground, to say the least, for the third option (with side-address cardioids). In all three cases there is significant scope for DIY solutions: indeed, for any particular mics this might well be essential. Hopefully some of my ramblings – or at least the photos – might inspire others to their own DMS solutions. Meanwhile, stay tuned for the practical comparisons in Part 2 and Part 3.
During my recent experiments to see whether you could fit an ORTF pair into the diminutive Mini-ALTO windshields from Radius Windshields, I began to wonder whether any of the four mics I found that worked for that purpose would allow other stereo configurations in the windshields, including XY. Of the mics I used for the ORTF experiment, the DPA 4011 capsule with the MMP-GS preamp was the only one short enough, having an overall length of 33mm; but the mic pair was on loan only and had a little too much self-noise for my liking (OK, 18dBA isn’t that bad!). You can imagine, then, that I was delighted to receive a pair of an upcoming smaller version of the Nevaton MC59 cardioid. The standard MC59S + 59/C sounds excellent and has low self-noise (8.6dBA), and is already a short mic at 47mm: rather incredibly, and largely due to the miniaturization of the preamp (just 5.5mm long), the MC59uS + 59/C2 combination halves that to give a length of just 23.5mm, and, with a side-exit cable, its effective length is less than half that of its sibling. I will be looking at the mics in more detail in different posts, but suffice it to say here that the idea with the MC59uS + 59/C2 has been to keep the same acoustic and electrical specs as the larger standard version.
Anyway, with such small mics in hand there was scope to have a play with the idea of XY in a Mini-ALTO. First up was the challenge of mounting the mics, and here I took advantage of the MC59uS having magnets in its base (goodness knows how they were squeezed in!), so I used some powerful Neodymium magnets (Simon Davies at Radius kindly sent me some of the ones they use in the windshields) and incorporated these into a mount: the rebated form of the magnets means it is really easy to keep them secure and not popping out.
3d-printed mount sans microphones, showing the magnet pairs (above the M3 brass insert fixings that fix these mounts to the overall XY mount). The mount has two halves, which are bolted together to form a 19mm diameter cylinder that is held by the Radius hoops. With the mics popped on the mounts: I do like the magnetic mounts – super slick!And some head-on views with and without one of the Mini-ALTO pods, along with a rear view.
So there you go: another fun test with a bit of 3d-modelling and printing for another type of stereo in a Mini-ALTO. As with my mid-side pairs, this fits comfortably in the smallest model – the Mini-ALTO 115. I’m very much aware that the MC59uS + 59/C2 mic is not yet in production (first batches are planned in October-November) and will be fairly expensive (more than the standard MC59/C models) and, therefore, won’t be a choice for every recordist. But, as I said in the Mini-ALTO ORTF post, if DIYers are wanting a much more affordable ultra-short cardioid, but still with decent specs and sound, then the Primo EM200 (which is what I believe is used in the well-respected Line Audio CM4) could easily be housed in an equally short, if not shorter, body: in fact, I’m rather puzzled that none of the many small businesses making Primo-capsuled mics haven’t done so already. Perhaps there are other mics that might fit. Whatever the case, I hope this small project might inspire others to have a play: the modularity of Radius hoops is a call to inventiveness!
The long-awaited Mini-ALTO windshields are rolling off the production line as fast as Radius Windshield’s small team can manage and are evidently going down a storm. As readers of this blog know, I’ve been playing with the Radius hoops since introduced and, more latterly, the pre-production Mini-ALTO 115 windshield (which I tested here). With the latter, my first thought was to stick a mid-side (MS) pair inside it and then, for a bit of fun, a double mid-side array. Well, the slightly mad schemes – at the opposite end of the spectrum size-wise from my DIY Mega-Blimp project – continue. In this case, the project began when John and Simon at Radius asked if I could squeeze an ORTF rig into a Mini-ALTO: not as a commercial commission, I must hasten to add, but just knowing I like a challenge and am always up for esoteric mic-mounting solutions. My first reaction was no, but thinking on it more – and having been rather immersed in ORTF lately (or, rather, an eight-mic ORTF-3D rig using Nevaton mics) – I decided to have a go.
The design problems
Straight off the bat there seemed two main issues. First, there was the common problem for anybody trying to fit ORTF pairs in a windshield: mic length means the capsules end up too near the basket edge for effective wind protection. Not for nothing did Rycote make a larger diameter windshield specifically for ORTF, and a much larger diameter for ORTF was one of the reasons behind my Mega-Blimp. With the diminutive 80mm diameter of the Mini-ALTO the problem is even greater than with a more standard 100mm diameter windshield. Second, the Mini-ALTOs have small rear pods and various – all longer – front pods, none of which are swappable from front to rear due to the polarity of the magnets that hold them in place: what would be needed is a longer rear pod and, ideally, matching pods front and rear. A third, more minor issue, is that the Mini-ALTOs are designed to be aimed at the subject on the longitudinal axis, so the base pivots the wrong way.
The design solutions
The solution to the small diameter of the Mini-ALTO – insofar as there could be one – was to use short mics and to offset the mic mounts from the centre-line of the windshield as far as possible. Most of the familiar small SDC mics are still too long, not least as connectors and, even when hard wired, projecting cables come into play: even the small Schoeps CCM4s seem too long once cables (and, for the popular Lemo version, connectors) are factored in, although the diminutive Schoeps CMC 1 KV preamp (with its side-exit cable) and an MK 4 capsule should fit. The Sennheiser MKH 8040, of which I own a pair, also seemed feasible, if only the short MZL connector (which can be used instead of the XLR module) didn’t have such a long rubber boot (itself over a long brass nipple) and then a cable projecting from this. Realizing I didn’t know what was inside an MZL, I worked out how to open one (OK, I just crudely levered the innards out with a penknife: but, no, it wasn’t one my precious Sennheiser MZL 8003 remote cables that I butchered!), and saw that there was scope to have a side-exit. A quick slice with a Dremel blade removed the brass nipple, and it was equally easy to drill a hole in the brass casing: 10 minutes and I had my proof of concept. I wasn’t convinced about my skills to take apart an MZL properly or to wire them up, so, in exchange for doing the slicing and drilling of a batch of forty (that was a fun lunchtime activity!), Ed Kelland at ETK Cables made up some cables for me: I suspect his right-angled custom MZLs might sell like proverbial hot cakes, if I don’t grab them all myself (the super-short MKH 8000 mics that result are really useful for all sorts of other arrays, not just ORTF)!
My working through to the shorter MZL solution, with the mics in an early iteration of the ORTF mount.And here’s the cable I am actually using, kindly put together for me by experienced wireman Ed Kelland at ETK Cables.
With mic length sorted – or minimized as far as I could achieve using a mic commonly used for field recording and production sound – it was time to move on to the second problem. The key to mounting the mics was, of course, to keep the hoops where they normally sit in a Mini-ALTO, but have them hold a bar to which the mics are clipped. I had been doing the same for the ORTF-3D rig, so it was an obvious choice. Then it was just a matter of making various iterations of the design (thanks to the 3d-printer) until I got the right balance between keeping the capsules away from the basket edge on one side, and the keeping the back of the mics (or the customized MZLs) away from the other side. It was really satisfying that by the time I got to the sixth version (there were other changes along the way) I got the centre of the diaphragms on the centre-line of the windshield: there’s nothing magical about that (getting it back from the centre-line would have been better in such a small windshield), but at least it doesn’t feel as if the design leaves the mic capsules right up close to the basket. And clearance at the rear is enough that the mics don’t knock against the basket in normal use: I assumed that an ORTF-equipped windshield would not be handheld by a circus acrobat recording themselves in action…
The model of the bar and clips shown with the mics, giving main dimensions.The finished design, 3d printed and tilted sideways so I could photograph it.Rear view: you can see the ball joint I am using instead of the standard base.Front view.End view.End view with pod attached: the rear of mic clearance is actually better than this photo suggests, partly due to perspective, and partly because the basket narrows very slightly at the central plastic ring (which isn’t near the mics).
As for the short rear pod and unequal length of pods, Radius sorted that by getting a couple of pairs of symmetrical pods made up for these tests. That was easy – at least for me. The reason I wanted a couple of pairs is that I was concerned about the impact of the plastic ring that marks the division between the end-cap and cylindrical body of the basket. The large thick plastic ring (bigger at one end) of the dedicated Rycote ORTF windshield has an impact on the sound, and I have been concerned with the impact of large plastic elements in other designs when using mid-side pairs: for example, the chunky ring on a Cyclone has a measurable impact on the sideways-facing fig 8 mic (which may or may not matter for a recording). The Mini-ALTO end-cap rings are nothing like as chunky and such plastic elements don’t worry many a recordist, but I think it will be instructive to test the difference between a pair of shorter 90mm pods (where the end-cap rings sit inside the 110 degree angle between the mics) and longer 136mm pods (where the end-cap rings sit outside the 110 degree angle between the mics). I will cover these tests and, also, some field recording tests in part 2 of this blog post (by which time, I hope, Radius may have made a fur to fit the new windshield lengths: it will be good to compare how it performs in wind against, say, an MS pair in a Mini-ALTO 115).
Mini-ALTO baskets, top to bottom: 136mm symmetrical pair; 90mm symmetrical pair; and, bottom, my standard 115 model (the smallest) with its unequal front and rear pods.
And, finally, to the problem of the mic base pivot being oriented 90 degrees from what would suit ORTF. Well, for that I just 3d-printed a new base for the Mini-ALTO that has a 3/8″ thread and fitted it to a Gravity MS QT 1 BQuick-Tilt Microphone Adapter. A slightly clunky and chunky solution for now, but I know that Simon and Tim at Radius have been working on a small ball-joint mount anyway that will work with the Mini-ALTOs.
What is less certain is whether they will take my ORTF design and refine it into an actual injection-moulded product. I guess that will depend partly on the testing (do come back for part 2 of this blog post) and partly on practicalities and whether they think there is a market. But, even if not, just as with the other parts I have designed to fit Radius hoops (e.g. the MS clips), I will make the parts shown freely available for 3d printing: of course, this would be rather dependent on the matching pods becoming available!
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.
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. The Arca plate – and indeed the use of a stable camera tripod – is a core part of the Mega-Blimp approach and not some interchangeable alternative to a simple 3/8″ fixing.
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.
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.
