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Roland

Audio Gear DIY Projects

Mid-side with AKG CK94

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

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

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

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

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

I was expecting something much noisier.

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

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

Music video with Lucy Grubb

April 27, 2021
Filming by the side of the Bridewell in Norwich

With things easing from lockdown on 12 April, it has been good to hear of musical life picking up a bit and, in that spirit, I was glad to be asked by Lucy Grubb to film a music video for a single (You Don’t Do Anything) from her upcoming next EP release. Lucy is a Norfolk-based country and Americana singer/songwriter, who has been carving out a name for herself and her band, not least at various music festivals.

In this case the music was pre-recorded in the studio, so it was the usual case of miming to the track. When I say usual, I think I’ve only done one like this before, so it was a fun exercise for me, from planning through to editing. The idea (which fitted the theme of the song) was to have Lucy moving forwards continually throughout the video, passing through or past the band members (Kevin Burton, Piers Hunt, Richard Poynton, Richard Ward and Paul Weston), with locations – all around Norwich – changing fairly frequently.

So it was a lot of backward-tracking camerawork. I tested out the old wheelchair as dolly idea (think of Jean-Luc Godard’s Breathless), but, while doubtless fine for smooth-floored interiors, it was clear it wouldn’t be one for pavements or, even, cobbled streets, so I stopped being lazy and used a gimbal (a Zhiyun Crane v2). Eschewing my Meike T2 cinema lens-based rig with follow-focus, I went for the lighter Leica Lumix 12-60mm on my Lumix G9, using autofocus just to lock on focus for each shot (but not to track focus) and avoided any wafer-thin depth-of-field shots. I’m not sure what the serious pros use for playback of the audio track, but we managed fine with a linked pair of Bluetooth speakers: one by the camera and Lucy, and one by the band. Loud enough, especially for early on a Sunday morning (dodging the post-lockdown shopping throngs). Despite my rust, all went well on the shoot last weekend, not least thanks to two helpers (good to have band members old enough to have teenage offspring), and with the weather settling down to the hoped-for grey sky with enough wind to give (guitarist) Richard Poynton’s long Covid hair sufficient movement… I edited in Vegas, giving it a fairly heavy grade tied into the muted colours of the band and, indeed, the locations (see pics).

You can play the song on Spotify and here’s the finished video:

And filming at Elm Hill

Camera Gear DIY Projects

This camera is not for turning…

March 25, 2021
Compact follow-focus rig with an anti-twist Arca-type plate.

The best ideas for inventions are those that turn out to have already been thought of and produced. OK, that means you can’t make your fortune, but odds are you wouldn’t make the leap from an idea hatched in the shower to a production line anyway: and, anyway, you can go out and buy the thing with none of the hassle of being the next James Dyson. This happened to me with my genius solution to feeling all tangled up and constrained by sleeping bags when camping: just imagine if the sleeping bag had separate legs and arms? Well, as you probably know but I didn’t, you can buy these already…

To the case in hand, I’ve long been frustrated how stills cameras rotate all too easily on tripods, fixed (in the loosest sense of the word) by a single 1/4″ screw and lacking the additional pin hole found on camcorders. With stills cameras then moving into video and, for cinematic focusing, then needing follow focuses, the need for anti-rotation got all the more compelling. While camera companies vie about 4k and 8k, or 10-bit and raw on mirrorless cameras, nobody seems remotely bothered to drill a hole in the base to allow a second pin to stop rotation. An L-bracket or a cage can sometimes solve the problem, but, unless you need one, they are clunky additions, making access to controls and connections much harder and losing the carefully designed ergonomics of the camera. Also, many L-brackets and cages are just not rigid enough or not fixed to the camera well enough. With my compact – and cageless – follow-focus rig for my Lumix G9 I’ve found the old problem rearing its head, with the camera sometimes gradually rotating away from the follow focus to the point that, eventually, the gear disengages. So my genius ‘invention’? Well, simply a small Arca-style plate with a ridge at the front, forming a snug fit against the front of the camera: with the G9’s flip screen there is no value in a ridge or lip at the rear. Visions of finding someone who could mill one for me proved unnecessary since, as you will have guessed, the idea has already been thought of. Oddly, though, I haven’t simply missed something common, as such plates are incredibly obscure. Arca themselves sell an anti-twist plate (the blandly named ‘Kameraplatte 40mm’) as do Really Right Stuff (the equally unrevealingly named ‘B9 Multi-use bidirectional plate’), but both are extremely pricey for a small bit of metal with a lip (€63 and $49 respectively), need an allen key to tighten, and are hard to find in the UK. And then I came across the plates made by the Colorado Tripod Company in the USA: a perfectly sized 40mm plate (they do 60mm and 85mm-long versions too) with a bolted-on lip, and, unbelievably (since their well-made kit isn’t generally cheap), available for $10 (in my case £9 on Amazon UK). It turned up today, and is a supremely well-engineered plate, and even includes miniature bubble levels: you can tighten it with fingers or a coin. I might not have made my fortune with a new invention, but it hasn’t cost me a fortune either: I just wish I’d realized, and hunted for, the solution to camera twisting before.

UPDATE 18.6.2021. Well, sadly my optimism about the off-the-peg anti-twist plate wasn’t entirely merited: after a month or so in use I found the plate still undoing from time to time: not as badly as before, but enough to be frustrating. The reason for this is evidently the slot (instead of a hole) for the screw, also common to the more expensive offerings from Arca and Really Right Stuff, which, while designed to allow fitting of the plate to different cameras, allows the screw to loosen when used with a follow-focus. Doubtless, the designers didn’t have that in mind. What is needed, evidently, is a plate with a hole rather than a slot for the screw, which, of course, means a plate designed perfectly for the camera body. So, after all, it was necessary to DIY something: I simply added an aluminium bar at exactly the right point (with some very careful sub-millimetre measurements) to an existing Arca plate and – voilà – at last I have got there: in use it has proved reliably rigid.

Colorado Tripod Company anti-twist Arca-type quick-release plate with lip at the front or rear. The detachable front/rear part with the lip (and bubble levels) is bolted on from below and further aligned by two pins that slide into the main part of the plate. Sadly, like any such lipped plate with slot for the screw (which allows it to fit many different cameras), it will still loosen under the duress of a follow-focus.
My modified Arca-style plate with the screw through a hole and an aluminium bar bolted on so as to perfectly abut the front of a Lumix G9. Not pretty, perhaps, but at last rock solid with a follow-focus.
And here’s the DIY-modified plate on the camera. I’ll probably paint the aluminium addition black in due course, but, meanwhile, it is clearer for these photos.
Audio Projects Film Projects

Experimenting with moving or POV stereo ambiences…

March 6, 2021
Setting off in the cause of research…or seeking ridicule?

I think Lockdown III must be getting to me: I’ve been pondering over stereo ambiences for film lately, wondering if they ever are or should be recorded while moving to match the POV (point of view) of the camera?

This was stimulated by thinking about sound for an upcoming project with drone footage, where the drone will follow the course of a small local river from source to sea – flying fairly low and slowly. I want the sound to match the view – along the bubbling stream, the passing over of weirs, cows and sheep being flown past etc. Obviously bunging a couple of mics on the drone isn’t an option given the noise of the motors and rotors, so any ambiences will need to be recorded quite separately. Initially I thought of helium balloons: I calculated that seven normal-sized party balloons would lift a pair of Rode Wireless GO II transmitters into the air, but, the more I have thought about this the more complex it seems: a totally windless day seems essential and, even then, trying to stop the mics spinning or, harder, trying to get the balloons in the right place seem fraught with difficulties. And then, more fundamentally, what does a moving stereo recording actually sound like? In other words, would it even be worthwhile trying to do this?

Recording to the miniscule MixPre-3

Drawing a blank through internet searches (the nearest thing being people trying to record the sounds of – say – a bike travelling, rather than just the ambience without evidence of the mode of transport), and not knowing how the soundtrack of any film with apparent moving stereo ambiences was actually made, it seemed easiest to experiment. A bicycle appeared to be the best bet for near-silent travel, as long as fast speed or free-wheeling was avoided. After initial less than satisfactory attempts with semi-binaural set-ups of lav mics by my ears and either side of a rucksack (both getting far too much bike noise, and, also, showing up the inadequacies of furry wind-protection for these mics), I rigged up a boom pool to a sheet of ply, cut to the shape of a rucksack, to mount the mics well above me (so further from the bike and road noise) and to prevent unwanted rotation. The mics were omni SDCs mounted end-to-end in a single blimp to minimize windnoise (see my post here on using mics in this way). Extending the boom pole very far got unwieldly, so it was only partly extended. Sound was recorded to a Sound Devices MixPre-3 on a light harness. The results were in a different league to the lav mic experiments, but the bike was still very evident and, above all, I’m not at all convinced that the sense of movement is very strong. This last point is critical. In short, I have no doubt that a better result could be achieved by recording general ambiences and specific sound effects from static positions and amalgamating them into the soundtrack to give the illusion of moving through space: doubtless this is what sound designers know and do, anyway, but it is good to experiment and find that, sometimes, the seemingly logical approach doesn’t work. And if, in doing so, I’ve gained an eccentric reputation in the village (yes, cycling with a blimp on a vertical boom pole does look extremely silly), then so be it…

For anyone interested, here is a recording of one of my tests with the SDC spaced pair in blimp, including the reaction of a passing neighbour.

Audio Gear

Testing the new Rode Wireless GO II

February 27, 2021
Rode Wireless GO II recording into an Android phone

Putting your equipment through its paces is part of getting to understand it properly. Given its newness (only released this week), my tests on the Rode Wireless GO II might be of wider interest: so here’s a post about them.

First, a quick bit of background. I’m not normally in a rush to adopt new technology, but this week – following the death of an old handheld recorder (my Sony M10) and while planning a couple of projects – I was looking at lav mic self-recording back-up options, and Rode’s new offering seemed on the nail and very timely. I know the first version was nothing like a professional wireless mic set up (not least for its dropouts when out of line-of-sight), but I’d found it eminently usable for the particular and less exacting uses I bought it for: in particular, the sound quality stood up compared to the same lav mic hard-wired. So, rather than wait for anyone to get round to a thorough test – as opposed to the numerous unboxing and product review vlogs that will doubtless flood YouTube – I ordered one from CVP.

Overall audio quality

There are different aspects to the audio quality of such a system, including its on-board mics vs external lavs, its on-board recorder vs transmitted audio, and both the recorder and the transmitted audio vs a better system.

Using a Sound Devices MixPre-3 to provide a decent sound source into the Rode Wireless Go II transmitters

Most interesting to me was to take the on-board and external lav mics (both of which have relatively high self-noise due to their small diaphragms) out of the equation, and test the recorder and wifi alone. For this, I fed the two transmitters with a stereo signal of a simple acoustic guitar recording (recorded with a spaced pair of 7dBA Rode NT2a mics in fig 8 mode) via my Sound Devices MixPre-3 (feeding a signal from the stereo out at -6dB to give a reasonable level at the transmitters, comparable to that of the mics above). I recorded the transmitted signal via the USB out of the receiver. Here are the clips, with no processing added:

Original MixPre-3 recording:

Rode Wireless GO II on-board recorders in uncompressed/broadcast mode:

Rode Wireless GO II on-board recorders using the compressed/standard mode:

Rode Wireless GO II transmitted recording:

The verdict? Well, see what your ears say. The most obvious positive is that the Rode Wireless GO II on-board and transmitted audio show remarkably low self-noise: there is effectively no hiss in the short lead-in. The most obvious negative is the lack of bass response: OK the datasheet shows a frequency response graph with a sharp fall-off below 100Hz, but this appears to relate to the mic. Needless to say, you can boost the bass response in post, and here is a quick EQ’d version (I looked at the bass fall-off in the Rode Wireless GO II using pink noise, though my resultant EQ might be a bit too heavy – but it makes the point):

And, of course, what is effectively a high-pass filter isn’t a significant problem with intended use (speech) and will aid reduction of wind noise and other unwanted low frequencies.

So my overall view on the audio quality of the electronics? Well, the transmitted and on-board recordings sound surprisingly good: OK not up to the level of a Sound Devices MixPre-3 and not ideal for music recording, but easily good enough for use with the on-board lav mics or external lav mics (or other PIP mics such as Micbooster’s Clippy mics) for speech or ambience/nature recording, and perhaps usable – in the way that you might use a small handheld recorder – for music recording where, for whatever reason, a better and more conventional set-up wouldn’t work. Also, the compressed on-board recordings don’t sound too bad at all, despite my natural dislike of lossy compressed formats!

On-board mics

Given the mic in the original Rode Wireless GO, I was reasonably optimistic about it and, also, conscious that a) different people like different lav mics and b) I don’t own any of the more expensive lav mics (such as those made by DPA). But, for what it is worth, here’s a simple comparison of Rode’s lav mic (that’s their more expensive one – at c.£160 – and perfectly usable) vs the on-board mic recording a voice (apologies for the performance!), and recorded via the Rode Wireless GO II’s receiver (both digital out, into an Android phone running USB Audio Recorder Pro, and via the 3.5mm output into a Sound Devices MixPre-3).

Rode Wireless GO II on-board mic via digital out on the receiver:

Rode Wireless GO II on-board mic via 3.5mm analogue out:

Rode lavalier mic plugged into Rode Wireless GO II via digital out on receiver:

Rode lavalier mic plugged into Rode Wireless GO II via 3.5mm analogue out:

The verdict? The on-board lav mic is quite usable if – and this is the key – you don’t mind the transmitter being visible too. The much more secure furry windshields of the new model at least make this more feasible. And as for the difference between digital and 3.5mm output, there is little in it. Well at least with a decent sound recorder: of course, the difference will be greater if choosing between USB into a phone and analogue into a camera with poor audio.

Range and dropouts

As I said, I found the original Rode Wireless GO usable for my purposes, but I can’t deny that a more robust wifi signal wouldn’t be useful. Indeed, for many, it would be essential. The 200m line-of-sight spec for the new version (vs 70m for the original version) shows an improved wifi capability, and this is borne out even in initial, simple, testing. For example, whereas the original Rode Wireless GO – under my test conditions (a rural Norfolk village) – experiences dropouts from around 20m when worn on the rear of the subject (or ‘talent’) – i.e. blocked by the wearer’s body – the new version worn in the same way is good for about 35-40m. Obviously, different locations will produce different results, but this suggests much more suitability for, say, wedding videographers, where, of course, the recorder provides a back-up anyway. For professional sound recordists’ use (e.g. television and film) the improved signal strength is probably immaterial as the units lack the range, features, robustness and ease of control of professional wireless systems such as those produced by Audio Ltd. and Lectrosonics.

Field-recording (an update of 15.3.2020)

Rode Wireless GO II TX units in action for stereo ambience recording…

Having had the Wireless GO II for a few weeks, I’ve had a chance to use it for different scenarios, one of which is as a remote field recorder. Here the ability to use the two TX units as a remote spaced-pair of omni mics opens up all sorts of possibilities, not least recording sounds of nature (such as timid birds) from afar. Of course, if the tests above suggest that the on-board mics or the electronics aren’t are not high enough quality, you can simply use the system for monitoring: for example, running SDC mics into a Sound Devices recorder, and plugging the TX units into the recorder’s stereo out so you can hear what is being recorded from afar. Taking the Sound Devices example you could, of course, use the wireless remote control (Wingman) for the recorder too, though I haven’t tried that combination or, indeed, tested the Bluetooth range. Anyway, what I have tried out is simply recording remotely with the on-board mics, both within a Rode blimp and with their supplied fluffy windshields: of course, the former, while restricted to 35cm spacing, provides more wind protection, but the Wireless GO windshields on their own were surprisingly good and allow any spacing (in my tests this happened to be 46cm). And the fluffy windshields of the new TX units fit much more securely than those of the original Rode Wireless GO. So here are a couple of examples, one in very high wind (we had gales at the weekend) and one in slightly less windy conditions. Both just with the TX units alone and their own fluffy windshields, and simply placed in a holly tree in the garden (near the road), as in the photo above. The recordings are from the RX unit’s USB output.

Stereo ambience recording (garden in high wind):

Stereo ambience recording (garden in moderate wind):