Mini-ALTO – Dr Badphil

Audio Gear

ORTF in a Mini-ALTO part 2: testing

May 11, 2025

Introduction

Following on from part 1, where the design of fitting an ORTF pair into the diminutive Mini-ALTO was covered (using a pair of Sennheiser MKH 8040 mics with modified MZL connectors), this second part of the blog post concerns testing the compact rig. There are two main aspects that I wanted to test to see if such an ORTF rig is usable: transparency (i.e. how much does the windshield colour the sound) and wind protection.

Composite view of ORTF in a Radius Windshields Mini-ALTO showing the position of the mics with two 90mm pods.

Composite view of ORTF in a Radius Windshields Mini-ALTO showing the position of the mics with two 136mm pods.

Transparency

My main concern with colouration was not just the basket structure in general, but the thicker plastic rings that mark the join of the end caps to the cylindrical part of the windshield basket. The impact of such rings can be quite discernible with set ups in some windshields: others have noted the impact of the large rear plastic ring in the Rycote ORTF windshield, and I have noted and measured the impact of the still chunkier ring in the Rycote Cyclone on the sideward-facing lobes of the fig 8 mic when used for mid-side recording. The rings in the Mini-ALTO are much less substantial than in these examples, but, given the 80mm diameter of the basket, they are closer to the mics, so the key questions are: i) is the impact measurable?; ii) is there a difference between the impact in the two different pod sizes? and, iii) if there is a measurable impact, does this matter – i.e. does it translate to noticeable issues when making field recordings?

Without an anechoic chamber it is difficult to get an exact read on the transparency of any windshield, but, as I did with my original Mini-ALTO 115 test, for a reasonable quick and dirty test I placed a bare mic on the windshield ORTF shock-mount in front of a speaker (in my treated studio) playing pink noise, then carefully added the windshield pods without moving the mic for a second recording. I did this with the ORTF bar oriented square-on to the speaker (0 degrees), at 45 degrees and side-on to the speaker (90 degrees). I repeated the exercise for both the 90mm and 136mm pod sizes. The results for each pair of recording were compared using a spectrum analyzer and overlaid as follows:

Pink noise test with Mini-ALTO with ORTF bar square-on to the speaker (0 degrees), using one of the two mics only: green is the bare mic on the shock-mount and the red overlay is the recording with the 90mm basket pods added.

In these tests with the ORTF bar square-on to the speaker the sound is arriving at the cardioid mic about 63 degrees off-axis. In the case of the 90mm pods the plastic ring for the end caps is directly between source and capsule, whereas with the longer 136mm pods the ring sits beyond the direct line. Given this, it is not surprising to see a greater impact when the 90mm pods are used, in addition to some generally increasing attenuation of high frequencies, although the significant colouration only kicks in at 15.2kHz and above.

Pink noise test with Mini-ALTO with ORTF bar at 45 degrees to the speaker, using one of the two mics only: green is the bare mic on the shock-mount and the red overlay is the recording with the 90mm basket pods added.

In these tests with the ORTF bar at 45 degrees to the speaker the sound is arriving at the cardioid mic about 16 degrees off-axis. In the case of the 90mm pods the direct line between source and capsule is through the end cap of the windshield, whereas with the longer 136mm pods the direct line is through the cylindrical part of the basket and near to the end cap ring. It is interesting to see that, despite the seeming greater significance of the plastic ring to the 136mm pods at this angle, the colouration arising from the basket is a little less than with the 90mm pods.

Pink noise test with Mini-ALTO with ORTF bar at 90 degrees to the speaker, using one of the two mics only: green is the bare mic on the shock-mount and the red overlay is the recording with the 90mm basket pods added.

In these tests with the ORTF bar at 90 degrees to the speaker the sound is arriving at the cardioid mic at 35 degrees off-axis. In the case of both the 90mm and 136mm pods the direct line between source and capsule is along the longitudinal axis of the windshield and, thus, through the centre of the end cap of the windshield: in short, the mic position relative to the sound source, apart from being angled, is very much in accordance with a mono directional mic in the windshield as per the original design intention. As a result, the impact of the basket is minimal (and comparable to my previous tests of the Mini-ALTO 115 with a supercardioid mic), although a couple of troughs at high frequencies – at 15.2kHz and 17kHz – are visible with the 90mm pods.

For the purposes of comparison, here is my previous test of an MKH 8030 with the Min-ALTO basket turned side-on to the speaker source so that the fig 8 mic is on axis to the sound source:

Pink noise test with Mini-ALTO 115 with MKH8030 fig 8 mic aimed at speaker: green is the bare mic on the shock-mount and the red overlay is the recording with the basket added.

This is useful, since it shows that – within the limitations of this testing methodology – that the ORTF pair in the Mini-ALTO with 90mm and 136mm pods is less affected by the basket than the fig 8 mic in the Mini-ALTO 115. And for another comparison, here is the same fig 8 test repeated with a Rycote Cyclone.

Pink noise test with Cyclone (small) with MKH8030 fig 8 mic aimed at speaker: green is the bare mic on the shock-mount and the red overlay is the recording with the basket added.

The more significant impact of the Cyclone basket is doubtless largely due to the substantial plastic ring for its end cap.

The pink noise testing evidently shows some impact of the Mini-ALTO basket on the ORTF set up, much of which is a general and modest loss of high frequencies, with a few more obvious anomalies over 15kHz. The colouration, however, looks better than feared, not radically different between the two pod sizes, and, above all, less significant than that with a fig 8 in the Mini-ALTO 115 and far less than with a fig 8 in a Rycote Cyclone.

As I noted when I tested the Mini-ALTO 115, there is one thing demonstrating differences with this pink noise test or, indeed, more exhaustive and expert tests in an anechoic chamber, but how does the colouration actually sound? It is hard to come up with a perfect test, especially with limited resources, but I have settled on an approach that some at least may find informative. Eschewing the variability of successive live recordings, I placed the ORTF rig in front of a pair of speaker (Vivid S12s) in my studio and played back a short section of a recent recording of mine of a singer-guitarist (Luke Chapman), angling the ORTF bar square-on to the speaker, and with the mic aligned to the speaker so that it was 55 degrees off-axis. This positioning ensured that the plastic ring for the end cap was exactly on the line between the speaker and the mic with the 90mm pod, so very much the worse case positioning. Here are the resulting mono sound files:

If really keen, you can download the files and set them up in a DAW and flip between short repeated sections of each pair, which is what I have done. In both the recordings with the windshield you can hear the expected slight change to the high frequencies when the basket is added, as anticipated following the pink noise tests, but I would suggest that it is subtle and, therefore, unlikely to be of great significance to the majority of those making sound recordings in the field. Perhaps more importantly, there seems little practical reason to favour the longer 136mm pods over the more compact 90mm pods in terms of transparency: of course, there may be differences in wind protection, which is what we will explore next.

Wind protection

The laws of physics dictate that the small 80mm diameter of the Mini-ALTO cannot offer the wind protection of larger basket designs, and that was never the intention behind its compact design. That said, the small windshield performs reasonably well outdoors, and I was surprised in my original tests in breezy conditions to note that it outperformed the Rycote Nano Shield, which, although another smaller basket windshield design, has a larger cross-section (measuring internally 86mm high and, with its elliptical form, 107mm wide), although testing confirmed that larger windshields did provide better wind reduction. The questions I have for ORTF in a Mini-ALTO, therefore, are not how it compares to the same in much larger baskets, but the following: i) is there a noticeable difference in the wind reduction performance between the two different (i.e. 90mm and 136mm) pod sizes; and ii) how does the wind protection for an ORTF pair compare to that afforded to other rigs in a Mini-ALTO? With the last, I was particularly interested to see how the ORTF pair compares to a mid-side pair in a Mini-ALTO: if performance was similar to the last, then, given that I have been happy to use MS pairs in the Mini-ALTO where wind conditions allow and where compactness is paramount, this would mean that the ORTF design is similarly viable from a functional point of view.

First off, the matching front and rear pods provided by Radius Windshields for this whole experiment mean that the two Mini-ALTOs are non-standard lengths, so a couple of bespoke furs had to be made by the sewing department in Stroud. These are of the same, longer pile, grey fur that Radius provides as an option for the existing Mini-ALTOs and I have matching ones for my Mini-ALTO 115s. It might seem trivial or obvious, but it is important to have identical furs when testing the wind performance of the different rigs and pod sizes. Wind tests in the real world, where wind is turbulent and not laminar, are never quite as easy as you might think: simultaneous recordings are essential, of course, but the windshields have to be placed a bit apart to avoid one protecting or otherwise affecting the other, so wind gusts can vary a bit in terms of impact and timing. The other difficulty is matching mics: despite my growing mic locker I don’t have a stash of multiple MKH 8040 mics, but just one pair. My solution to this problem has been to record a single channel in each of the two Mini-ALTO ORTF rigs, which is fine: we are after a comparison of the wind performance of the two different sized pods not making beautiful stereo recordings, and this serves the purpose just as effectively. And for the comparison between ORTF and mid-side, where single-channel recording could be a bit misleading (i.e. comparing one channel of ORTF to, say, just the side mic of an MS pair seems like apples to oranges), I used the pair of MKH 8040s in ORTF in one of the test Mini-ALTOs and a MS pair of MKH 8030 and MKH 8090 in the Mini-ALTO 115 I use for MS: I’ve noted very little difference in wind performance with the wide cardioid vs the cardioid mics in MS.

Starting off with the windshields with no fur, here is an excerpt of a windy gust on a pretty breezy day, with the ORTF rig using 90mm pods compared to the Mini-ALTO 115 with an MS pair (MKH 8090 and MKH 8030).

And then compared using a spectrum analyzer and overlaid as follows:

Wind gust test with Mini-ALTO 115 with MS pair (MKH 8090 and MKH 8030) in green, with Mini-ALTO 90+90mm ORTF (MKH 8040) in red.

Both listening to the sound file and viewing the spectrum analyzer show that the ORTF pair in a Mini-ALTO with 90mm pods more than holds its own against the MS pair in the Mini-ALTO 115, each with the bare basket. But it is equally clear from the audio that the the differences are not constant. Moreover, we need to think about the impact of wind direction on performance, given that the two stereo pairs sit at 90 degrees to each other in relation to their windshields: in this example both mic pairs were side on to the wind direction, so that the ORTF windshield presented its small end-on form to the wind while the MS pair’s windshield presented its side to the wind. Changing this around by rotating the mic stand 90 degrees, here is a second set of recordings with the mics facing directly into the wind, so that the windshield housing the MS pair was end-on and the windshield housing the ORTF pair was side on.

The impact of wind on the MS pair is less in this second test compared to that on the ORTF pair. What we can draw from these comparisons, however, is that overall the ORTF pair in the 90mm pods seems to hold its own compared to the the Mini-ALTO 115 with an MS pair, with both baskets being bare.

Moving onto tests with furs added, which, of course, reflects more typical usage of the Mini-ALTOs outdoors, here we have a pair of ORTF and MS recordings with the wind coming from the side:

And then with the mic stand rotated 90 degree so that the two pairs are aimed into the wind, albeit with the ORTF pair’s windshield side-on to the wind and the MS pair’s windshield end-on to the wind:

So, the fur (while, of course, reducing wind noise) does not change the situation: the broadside offered by the windshield when an ORTF pair faces into it and the broadside of the windshield offered when an MS pair faces at 90 degrees to the wind are what creates the most windnoise. With this caveat, which has implications for usage (in any given situation one array may outperform the other: equally it could be argued that wind direction and sound source direction – if not negotiable by moving the mic position – might influence choice of mic array), there is no obvious difference in the overall wind performance and, to some extent, this is predictable given the mic capsule locations and orientations in the two arrays.

So now we should turn to the matter of the two pod sizes for the prototype ORTF rig: does the increased volume of the 136mm pod windshield offer an advantage in wind reduction over its shorter counterpart with the 90mm pods? For this, of course, I was able to orient the two windshields identically, and recorded a single cardioid in the ORTF rig in each simultaneously.

First up we have the 90mm pods (with fur) facing so that the wind direction was end-on to windshield:

And then the simultaneous recording using a Mini-ALTO with 136mm pods (with fur):

And then the mic stand was rotated 90 degrees so that wind direction was side-on to the windshields:

There is again some gust to gust variability between the two windshields, doubtless reflecting the highly localized differences in the turbulent wind you get in the real world, but there is nothing in these short clips (or, indeed, the much longer recordings I made) to suggest that the longer version of the ORTF Mini-ALTO with its 136mm-long pods outperforms the shorter 90mm version. This applies in both orientations into and at 90 degrees to the wind.

Conclusions

So what’s the verdict? Is an ORTF pair viable in the diminutive Mini-ALTO? If so, is a short symmetrical Mini-ALTO with two 90mm pods as effective as a longer version? My short answer is, yes, an ORTF pair is viable in a Mini-ALTO and that the advantages of pods longer than 90mm are so small as to be insignificant: so you might as well use the more compact 90mm pod version. Moreover, I would suggest that an ORTF pair is just as viable in a Mini-ALTO as a mid-side pair, although the number of cardioid mics that are short enough to make use of the 80mm diameter windshield for ORTF are few and far between: so far I have identified the MKH 8040 used here, the Schoeps CMC1 KV + Mk4, the Nevaton MC59S(C) and the upcoming DPA MMP-GS with the existing 4011 capsule as suitable candidates, and, in a third blog post, will be testing at least some of these. And there well be other mics that would fit without resulting in capsules close to the windshield basket. There are other caveats to add to this, but these are very much the same as with the Mini-ALTO for use with a mono directional mic: above all, a small diameter windshield will – all other things being equal – perform less well at reducing wind noise than a larger windshield; and, second, the structure of a basket, especially with significantly chunky plastic components, will provide colouration of sound above and beyond the curtailing of high-frequencies that is inherent to any fabric covering of a mic. So, of course, a Cinela Albert is a better bet for ORTF in terms of acoustic transparency and wind performance (as, indeed, is my own TIG-welded Mega-Blimp), but that’s not really the point: the Mini-ALTO is designed – above all – to be compact, to offer modest wind protection, and to allow rapid changing between bare mics and full basket. Now the latter, which is so relevant to production sound recording with a supercardioid or shotgun mic, may not be quite so relevant to an ORTF pair, but compactness is relevant to many recording in the field. Many people do seem to love dinky little recording rigs with miniscule recorders and lightweight stands (if a stand at all). For them, moving from a pair of furry slip-on covers for an ORTF pair on a stereo bar to a Mini-ALTO containing an ORTF pair would offer better wind performance and a more practical, transportable and robust form for the setup. For those already using ORTF in larger blimps, then a Mini-ALTO ORTF rig offers more compactness for those times when (small) size really matters, just as is the case for using the Mini-ALTO instead of larger windshields for MS or even DMS. Given that many windshields – I am thinking especially of traditional cylinder types such as the Rode, Rycote Modular and Rycote ORTF windshields – don’t have noticeably less colouration than a Mini-ALTO, for many it just comes down to size vs wind reduction: just as it would for a mono supercardioid or shotgun mic. So, yes, ORTF in a Mini-ALTO is usable and will appeal to many. Whether or not that translates to commercial viability is beyond me, not least given the small number of mics that are short enough: that is one for Simon Davies and the team at Radius Windshields to ponder. If the two blog posts on this experiment have piqued your interest, do get in touch with them (they are eminently approachable and responsive) and let them know as feedback will doubtless influence where they go with this!

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Audio Gear DIY Projects

ORTF in a Mini-ALTO? Part 1: design

April 28, 2025

Introduction

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.

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!

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Audio Gear

Radius Mini-ALTO windshield

January 21, 2025

Introduction

Radius Windshields have only been around since February 2023, but, of course, the team embodies years of experience from former Rycote days, so the development of the first full basket windshield from the company has generated a lot of interest. This interest has been stimulated by the refreshingly open approach to development of their products, especially via social media, with plenty of behind-the-scenes photos and videos, not least showing the novel use of ultrasonic welding to fix the fabric to the basket. The long development of the first basket windshield – the Mini-ALTO – saw pre-production models being packed up on Christmas Eve, to be sent off to UK field testers, and I received mine a few days later. In his covering letter, Simon Davies asked for ‘no filters on your opinion please’ and has no qualms about these opinions being public, so here goes!

First off, it is important to stress that the Mini-ALTO is just that: mini. The pre-production model I have been sent (the baby of the range: the 115) is the smallest full basket windshield that I have used, and so, of course, there are limits to what size mics can fit in it (obviously longer mics can fit in the 180 and 210 models, and the planned 260 model). Equally there are limits as to what such a small basket can offer in terms of wind reduction, and Radius are clear about this: their planned larger models, the ALTO and the CIRRUS will offer better wind reduction. Now Radius will have their own view on the market place for such a dinky windshield, but here I will be testing it from my own perspective, comparing it to realistic alternatives: above all, this will include the small Rycote Nano Shield NS1-BA, which is what I have used previously when I need an ultra-compact windshield, and which has long left my Rycote Baby Ball Gags largely redundant. Others may wish to compare it to the Cinela COSI models, and let’s hope so: I don’t have one to hand! Anyway, enough of a preamble: let’s get stuck in…

Design, construction and operation

Above all, the Mini-ALTO has been designed with ‘speed of transition between interior and exterior set up’. To achieve this, the basket follows the pattern of the Rycote Cyclone and Nano Shield in using magnets to hold the two halves together, except here the magnets are much stronger and do not need the assistance of physical latches: a couple of silicone safety straps on the sides can be used if required, but these seem entirely superfluous to any use I can imagine and can be removed (and lost!) easily. In fact the magnets are so strong that I had to refer to the instructions when opening the basket the first time: I didn’t want to break the windshield within the first five minutes. Once you know that the magnets are all that hold the Mini-ALTO together, opening is a breeze. What is also nice is that the magnets are properly embedded, and cannot be pulled out: I have had several come out on my Nano Shields over the years.

Mini-ALTO 115 with the front pod removed, showing the magnets that hold the two halves together, the slot into which the pods slide, and the cable gland. The mic clips are the RAD 19/20mm clips, which – amongst other options (inc. DIY) – can be swapped with the universal clips supplied.

Inside the basket the Mini-ALTO utilizes the RAD-2 mount, released in 2023, which will be familiar to many. This doesn’t connect to the basket directly, but does so via an adapter, which Radius call the ‘Smiley Face’. Perhaps I need to drink more cider to see the piece of plastic in that light, but it is well made and, more to the point, its wide channel accepts the two halves of the basket really easily: the basket halves slide into place smoothly and with a positive clunk. That’s a refreshing and distinct difference from the frequent fumbling with the Nano Shield basket, and by far the easiest (dis)assembly of a windshield basket I have come across. When the adapter is not in place (i.e. when the basket isn’t in use) it can be replaced with the supplied small ‘windshield stowage holder’: this has a carabiner attached so you can dangle the basket off your body or bag until you need to pop it back on. The adapter has two other functions beyond holding the basket to the shock-mount: it provides an exit point for the cable and holds the shock-mount hoops (Radius’s equivalents to Rycote’s lyres and Cinela’s elliptical isolators). Looking at the cable exit first, the test model is provided with a rubbery gland to fit thin cables, but there is no other cable management inside the basket: the user is urged to utilize the straps on the mic clips or the short cable straps supplied to run the cable along the mic. I’m no fan of clunky and unshielded conn boxes in windshields, but I quite like the neat little clip on the rear of the rail of a Nano Shield. Of course, the cable cleats and the XLR holder on the RAD-2 mount should mean that cable-borne noise isn’t an issue. Turning to the shock-mount hoops, for me, and I suspect others, these are one of the small but most useful features of the Radius Windshields approach: their modular nature (whereby hoops and mic clips are screwed together and can be changed) is a significant departure from the Rycote lyres, where the mic clips are integrated. Above all, this means that the hoops and, by extension, the Mini-ALTO can be adapted for a mid-side (MS) pair. Radius have an MS clip in development for release shortly, with which I have had some input, but in the meantime I am using my own similar 3d-printed clips. It is such a pleasure to get away from clunky back-to-back clips and to be able to get the two mics closely spaced. I have posted previously about how the hoops lend themselves to such customization, and here’s a couple of examples of how this now translates to the diminutive Mini-ALTO:

That flexibility of the Radius hoops, which allows MS clips to fit the shock-mounts directly (no more back-to-back clips!), is now carried over to the Mini-ALTO.

This might be taking it too far, but with some MKH 8000 mics and MZL connectors, the Mini-ALTO 115 can even house a double mid-side (DMS) rig: those Radius hoops are just so adaptable!

Turning to the design of the basket, the fabric looks reassuringly transparent compared to, say, the thicker 3d tex material of the Cyclone and Nano Shield. The basket itself, though, looks less transparent on purely visual grounds: there is something of a price to pay for the slick assembly/disassembly in the resultant 21mm-wide plastic ring formed when the two half-baskets are fitted (the slight chunkiness is necessary to house the magnets securely). And each end cap joins the cylindrical part of the basket with another ring: 9.5mm wide externally, but 12.5mm wide internally. Such H-rings for end caps are a feature of most cylindrical windshields, although not, of course, in the case of the Nano Shield. I am probably a bit more focused than most on the potential impact of plastic rings around windshields given my preference for MS pairs in the field, and the potential for impact on the sideways facing lobes of the fig 8 mic in particular, but at least in this case the fig 8 mic capsule naturally sits between the central ring and that of the front end cap. The mesh of the Mini-ALTO basket is formed by plastic 3.3mm wide, with mesh cells a lot smaller than the more open Nano Shield or Cyclone, but much larger than more traditional windshields such as the Rycote Modular. We will have to see, or hear, how the design of the basket affects sound (see below), but there is no denying that it is well engineered, robust and, above all, very easy to disassemble and assemble.

Turning to the size of the Mini-ALTO 115, the numerical suffix of the model derives from the 115mm length of the cylindrical section, with the end caps giving it an overall length of 198mm. This compares to the overall length of 225mm for the Nano Shield NS1-BA. The Mini-ALTO 115 weighs almost the same as this Nano Shield model: using the same cable for both, I weighed them in at 275g and 267g respectively.

The Mini-ALTO 115 (bottom in both photos) and the Nano Shield NS1-BA (top in both photos: don’t be confused that it too is wearing a Radius fur!).

Interestingly, Radius have a choice of furs for their new windshield. The initial plan, I understand from Simon Davies, was to sell the Mini-ALTO with the black fur, likely – given it being an interior to exterior system – the most popular choice for those in production sound. But Radius now plan to sell the Mini-ALTO with the grey fur option too: the longer grey fur offers slightly better wind-noise reduction (suggested as much as 5dB) and it is certainly the fur I prefer (not just on the Mini-ALTO: I have also chosen this for the various Radius furs that I have acquired for other windshields – from Cinela and Rycote and for my DIY blimps). To give me the complete set, Radius also sent me a brown fur, which is very similar to the black fur in terms of performance and feel. I’m not entirely sure whether it would help anyone recording nature sounds blend into the background!

Three colours of fur: the grey one is more matte and, with a longer pile, has slightly better wind-reduction performance.

Handling noise

Back in September 2023 I tested the RAD-1 and RAD-2 shock-mounts and was impressed by them. The question arising for me, therefore, is how the addition of the Mini-ALTO affects things, if at all? And having found the Nano Shield lyres better performing than the older Rycote standard lyres, how does handling noise differ between the two diminutive windshields. Time to whip out the boom-pole and a short stereo bar for some simultaneous testing, this time using the new Radius 55D hoops, and a matched pair of Rycote CA-08 mics.

First up, here are the spectrum analyzer visualizations of a static hold with the boom-pole extended, so that my muscles were shaking (a long boom, two mics and windshields and puny arms!):

Static extended boom-pole hold of Mini-ALTO 115 with 55D-shore hoops.

Static extended boom-pole hold of Nano Shield NS1-BA with 55D-shore lyres.

There is little in this, with the Mini-ALTO showing a slightly higher peak, but with a smaller frequency range and both are effectively removed by even a 40Hz high-pass filter (which would be a minimum for even the most static use of a handheld boom-pole). Giving the boom-pole some thumps again produces similar results:

Thumping of the boom-pole test: Mini-ALTO with 55D-shore hoops.

Thumping of the boom-pole test: Nano Shield NS1-BA with 55D-shore lyres.

And finally, here we have some deliberate shaking of the two windshields on the end of the boom-pole:

Shaking of the boom-pole test: Mini-ALTO with 55D-shore hoops.

Shaking of the boom-pole test: Nano Shield NS1-BA with 55D-shore lyres.

In short, I haven’t found there to be any significant difference from the shock-mounts when tested previously sans windshield baskets, and handling noise in both the Mini-ALTO and Nano Shield was well controlled, with resultant noise from normal use easily removed at source by use of a high-pass filter in the 40Hz to 80Hz range. Obviously different mics and more energetic boom-pole use might produce different results, but there is little doubt that the Mini-ALTO is competent in this regard.

Wind reduction

The internal diameter of the Mini-ALTO is, at 81mm, smaller than most basket windshields (with many designs, such as the Rycote Modular, being 100mm diameter). Even the Rycote Nano Shield has a larger cross-section, measuring internally 86mm high and, with its elliptical form, 107mm wide. It is for that reason that Radius Windshields have emphasized that this is a windshield designed for limited outside use and, of course, why they have larger models in the pipeline. Taking a larger windshield outside is not normally a concern for me, but there are occasions when a very compact rig is desirable and I was keen to test the Mini-ALTO against the Nano Shield (itself no slouch with wind reduction). Here are two clips recorded simultaneously on a very breezy day with both windshields rigged with matched MS pairs (each with a Rycote BD10 and CA08). When I say breezy, the wind speed was around 25 mph, gusting near 40 mph, so pretty tough conditions. No high-pass filtering was used when recording or in post, whereas, in this sort of wind some filtering would be used with most windshields.

As you can hear, and, to be honest, against expectations, the Mini-ALTO 115 does a slightly better job of wind reduction: for the test, I was using the initially supplied black fur with the Mini-ALTO, and the longer-pile grey fur, which I received subsequently, should improve things further. Of course, with an MS recording it is not immediately clear whether that reflects better side, front or all-round performance, so it is useful to look at what is happening with the fig 8 and cardioid mics separately, using a spectrum analyzer:

Mini-ALTO 115 with cardioid (CA-08) mic.

Nano Shield NS1-BA with cardioid (CA-08) mic.

Nano Shield NS1-BA with fig 8 (BD-10) mic.

The difference in performance between the two small windshields evidently applies to both mics (and, thus, both forwards and sidewards). I was particularly surprised to see that the Nano Shield, with its greater width, did not show any advantage over the Mini-ALTO with the sidewards-facing lobes of the fig 8 mic. Of course, much of the significant difference seen in these spectrum analyzer visualizations would be removed by judicious use of a high-pass filter (the scale used here going right down to 1Hz), but, nonetheless, it is evident that there are significant differences in the crucial area between, say, 50Hz and 200Hz. How much of a difference any sound recordist will find between the two small windshields in use will depend on the mics used and the high-pass filtering (if any) applied, but there is a discernible difference between the two and, certainly, the wind-reduction performance in a blustery outdoor wind is better with the Mini-ALTO.

And for anyone who wonders how a small windshield such as the Mini-ALTO copes with wind compares to a rather larger windshield, here are two test recordings – one with the Mini-ALTO (sporting its grey fur) and one with the Cyclone Stereo MS kit 5 – on another very windy day, again using matched MS pairs (each with a Rycote BD10 and CA08):

As expected, the larger Cyclone performs better with wind reduction in such brisk conditions, although, of course, a high-pass filter (not applied in this test recording) would improve matters for the Mini-ALTO. And, as mentioned, larger windshields in the pipeline from Radius will be better able to handle such use.

Composite view showing how the Sennheiser MKH 8030 sits within the basket of the Mini-ALTO 115: the capsule of the fig 8 mic is positioned forward of the double ring where the two pods join, but to the rear of the ring that marks the junction of the front end cap.

Transparency

When thinking about windshield performance many give little thought to transparency, but it is a key part of the equation and something that I have become more and more conscious of over the years, especially when using windshields with fig 8, omni and wide cardioid mics, where the polar patterns mean that baskets need to offer low colouration of sound beyond the front end of the windshield. Without an anechoic chamber it is difficult to get an exact read on the transparency of any windshield, but for a reasonable quick and dirty test I placed a bare mic on the windshield shock-mounts in front of a speaker (in my treated studio) playing pinknoise, then carefully added the basket without moving the mic for a second recording. I did this with a supercardioid mic (Sennheiser MKH 8050) head on, and then with a fig 8 mic (MKH 8030) side on to get a sense of how the two windshields compared at both angles. The results for each pair of recording were compared using a spectrum analyzer and overlaid as follows:

Pinknoise test with Nano Shield NS1-BA with MKH8050 supercardioid mic aimed at speaker: green is the bare mic on the shock-mount and the red overlay is the recording with the basket added.

Pinknoise test with Mini-ALTO 115 with MKH8050 supercardioid mic aimed at speaker: green is the bare mic on the shock-mount and the red overlay is the recording with the basket added.

With the supercardioid mic and the sound source on axis there is little colouration other, as would be expected, than some high-frequency attenuation: both windshields perform well in this test, which, of course, represents the primary intended function (i.e. a single directional mic for film, ENG, outside broadcast etc. ).

Moving onto a fig 8 mic with the windshields side on to the sound source, the results were as follows:

Pinknoise test with Nano Shield NS1-BA with MKH8030 fig 8 mic aimed at speaker: green is the bare mic on the shock-mount and the red overlay is the recording with the basket added.

Here the results differ: the Nano Shield shows similar (i.e. minimal) colouration as with its end-on test, while the Mini-ALTO shows more variation between the bare mic and the recording with its basket added: this is both above 4kHz and below around 150Hz. The latter represents some consistent bass attenuation, while the high-frequency colouration is more varied and potentially problematic. But before we get too concerned, it is perhaps worth including the results of the same test for the Rycote Cyclone (small):

With the Cyclone, the colouration of the higher frequencies is more significant and extends much lower (to just over 2kHz, compared with over 4kHz for the Mini-ALTO). In both the Cyclone and Mini-ALTO designs there can be little doubt that the colouration of the sideward facing lobes of the fig 8 mic is a consequence of the plastic rings around the windshields (less substantial in the Mini-ALTO, although much closer to the mic), which, in both cases, are not problematic for sounds on axis to the windshield.

There is one thing demonstrating differences with this pinknoise test or, indeed, more exhaustive and expert tests in an anechoic chamber, but how does the colouration actually sound? It is hard to come up with a perfect test, especially with limited resources, but I have settled on an approach that some at least may find informative. Eschewing the variability of successive live recordings, I placed an omni mic in front of a single speaker in my studio and played back a short section of a recent recording of mine of a singer-guitarist (Luke Chapman): the mic was angled successively at 0 degrees, 45 degrees and 90 degrees, in each position with the mic in the bare shock-mount of the Mini-ALTO and then, without moving the mic, each time carefully adding the windshield. I then repeated the exercise with the Nano Shield for comparison. Obviously each set up will vary fractionally, but not for each pair of recordings (i.e. a given windshield at a given angle, with and without the windshield basket) and it is comparing each such pair where any value in the exercise comes. I left off the furs as a) the focus here is on the effect of the basket design and b) maintaining the exact position of a windshield while adding the fur is so difficult. Anyway, for better or worse, here are the resulting sound files:

If really keen, you can download the files and set them up in a DAW and flip between short repeated sections of each pair, which is what I have done. In all the recordings with the windshield you can hear the expected slight change to the high frequencies when the basket is added, and, as anticipated following the pinknoise tests, the Mini-ALTO 115 shows the most discernible difference at 90 degrees. I was pleased to note that such colouration isn’t obvious at 45 degrees.

I have heard (rather than just measured) similar colouration with the Cyclone with side-on sound sources. Although the Cyclone windshield is now sold with mid-side and double mid-side configurations, the basket was not designed for such use, and the primary purpose of the Mini-ALTO to house a single end-address microphone is even more evident. For that purpose the Mini-ALTO offers very good transparency. Whether or not colouration from the sides actually matters for those who wish to use the windshield will depend partly on whether planned use is for a miniscule mid-side rig or, perhaps, a pair of the windshields for spaced omni mics. And, of course, it will depend on the direction of the principal sound source(s), how transparent the recording needs to be, and whether the small size and convenience of a Mini-ALTO outweigh any such concerns. Many, perhaps without consciously considering transparency, make a similar compromise with the Cyclone for MS/DMS vs, say, the more transparent Cinela models (for a comparison of the Cinela Zephyx and Pianissimo models and the Rycote Cyclone for MS use see my tests and write up), or, indeed, using a pair of Baby Ball Gags for spaced omni mics. Needless to say, there are plenty of windshields with plastic rings in places that will colour the sound for certain polar patterns and arrays, and I should stress that the Mini-ALTO is not at all unusual in this regard. Aaargh: am I just getting obsessed with transparency?!

Conclusions

What then of the Mini-ALTO? There is no doubt that it is well-engineered and, as such, builds on the Rycote experience of the team: most of the design is more robust, and much more positive and quicker to put together and take apart than the Rycote counterparts, most notably the Mini-ALTO’s closest competitor – the Nano Shield. That its wind-noise reduction capability holds up to outdoor use in moderate conditions and, moreover, exceeds the Nano Shield (at least in my tests!) was unexpected, given the smaller cross-section, and for many this will be reassuring. As the saying goes, however, there is no such thing as a free lunch, and, just as I have seen when comparing the Cyclone to the less user-friendly Cinelas, the convenience and robustness come with the price of less transparency of the windshield off-axis. As with the Cyclone, this is almost certainly a consequence of the plastic rings that encircle the basket, and, of course, such rings are to be found on most cylindrical windshield baskets, including Rycote Modular models and the Rode blimp, and, equally, are found in the spherical Baby Ball Gags. So there is nothing new here and for most users – with single shotgun, supercardioid, hypercardioid and cardioid mics – this will simply not be an issue. And for many users with omni mics, wide cardioids or, indeed, mid-side or even double mid-side, a bit of colouration from the sides will either be unnoticeable or a price worth paying for size, robustness and ease of use. For some the Cinela COSI models may well be a better compact option, but until (unless?) the release of the prototyped MS COSI version that was shown with the MKH 8030 at its announcement in September 2023, the restriction of the COSI windshields to single mics makes them not quite so appealing to me personally.

It is clear that the Mini-ALTO isn’t a panacea for all problems for mics involving wind, but it was never intended to be so. What is evident is that it is an excellent compact tool for outside broadcast, ENG, some narrative recording purposes, and, some field and FX recording, above all for those who need to switch from a bare mic to moderate wind protection at the drop of a hat. It has been fascinating watching the Radius Windshield journey thus far to the point of production of their first full basket windshield, and it will be interesting to see the larger ALTO and, particularly, the CIRRUS in due course.

And a final note: do please remember that I have been field-testing a pre-production model, as have others (who will doubtless offer other insights: e.g. from experienced production sound or outside broadcast perspectives), and that there may be the odd minor tweak before the production run starts!

Pricing and availability

For many the price of different windshields will come into play when making choices, so it was interesting to hear from Simon Davies how the Mini-ALTO compares with the Nano Shield on this too. The latter is priced at £525 ex VAT for the kit (including fur and cable), while the Mini-ALTO 115, 180 & 210 kits (again with fur and cable) come in at £360 ex VAT. Without the cable, the kits are £320 ex VAT, and if you already have a RAD-2 shock-mount then the upgrade kit (without cable) is £270 ex VAT.

In terms of availability, the latest update from Simon Davies (22.1.2025) is: ‘We’ve set a formal launch date of 1^st March for v1.1, however we’ll be releasing some units during February as they become available.’

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