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Omni mic pair in a single blimp

January 8, 2021

I’m a fan of omni SDC pairs for outside recording. For music I will often use these in Rycote Baby Ball Gags mounted on a stereo bar, itself on a substantial stand (usually the Manfrotto 1004BAC). But where I want something more portable and more windproof, I mount the two omni mics end-to-end inside a single windshield – the Rode blimp Mk1. Joining the two mics end-to-end is easy with a rewired and drilled female-to-female xlr coupler (well, actually, the female-to-female XLR connector is actually not off-the-peg, but made up of three items: two Neutrik NM3FXI and one Neutrik KM. Neutrik’s own female-to-female XLR connector doesn’t unscrew). This places the mics  (a pair of Rode NT55 mics with the excellent NT45-O omni capsules) at a 360mm spacing, which renders a good stereo image and is exactly the ideal length for the Rode blimp (i.e. the same length as the straight part of the blimp). Being pure pressure omni mics there is, of course, no phase issue arising from the fact that they are pointing different directions.

So the end result: a simple robust set up, less fiddly and more portable than common field-recording set-ups for ORTF pairs etc. and – being all enclosed – more windproof. It’s not something I have seen or read about, but I imagine – or hope – others are doing the same.

And here’s a detail of the easily modified connector: just drill a couple of holes for the cables.

Audio Gear Audio Projects

Something (not so) nasty in the woodshed: fun with figure of eights

January 7, 2021

It has been a drawn-out project, what with Covid-19 lockdowns and restrictions, but currently I’m midway through recording an acoustic album for Norfolk singer-songwriter Luke Chapman. It’s a long way from some of Luke’s other musical pursuits, such as the stoner grunge rock Rolodex of Gods. After an initial session at Oulton Chapel (lovely acoustics), we have since been using the woodstore part of his workshop on the edge of the Barningham Hall estate: by day Luke is a woodcarver.

With a sitting position and songs with a huge dynamic range, Luke’s voice and guitar playing need the mics to give as much separation as possible between the tracks. Early tests included using a ribbon mic on his vocals (a NoHype Audio LRM-V), but I have since been using three Rode NT2a mics, all in figure-of-eight pattern so that the nulls are used to great effect to cut out spill as much as possible: the guitar mics – a stereo pair – are parallel at 300mm spacing, one aimed around the 12th fret and one towards the bridge. The results are sounding good (to our ears): the Rode NT2a is often underrated, but the HF1 capsule (also used in the Rode K2 tube mic) is quite different from the harsher capsule of the Rode NT1a and is a pretty neutral beast. And so quiet (7dBA) that you can hear the rats running around in the roof as we record. The three mics are fed through to the ‘control room’ (the main workshop) to a Sound Devices MixPre-3: simple, but effective.

I’ll post more – with some audio – as the project continues.

Audio Gear DIY Projects

Windshield for LDC mics

January 7, 2021

TIG welded cage

Sometimes, however impractical it seems, it is useful or at least tempting to get a low-noise large-diaphragm condenser (LDC) microphone pair outside. Various set-ups have been tried over the years by nature recordists, often taking advantage of a pair of the affordable and low-noise Rode NT1a mics. I have been particularly impressed by Magnús Bergsson’s recordings with NT1a mics, not least as he often runs these in parallel to Sennheiser MKH20, 30, 40, 8020 and 8040 mics: see his website at HLJODMYND – SOUNDIMAGE.

For use when I need lower self-noise than provided by my usual small-diaphragm condenser (SDC) options, I wanted a mid-side pair of LDC mics (i.e. a coincident stereo pair comprising a figure-of-8 mic for the sides and, in this case, a forward facing cardioid mic), so having a Rode NT1 (the more neutral successor to the NT1a: 4dBA) and a Rode NT2a (7dBA) to hand I have put together an oversize windshield or blimp for a vertical mid-side set up.

For better stiffness than the usual plastic, I have gone for TIG-welded stainless-steel wire (2mm diameter), with the blimp cage incorporating (isolated) spigots to fit a Manfrotto 154 stereo bar. The blimp disassembles into two halves, but, in reality, I just leave it assembled and insert the mics through the spaces in the cage. For the covering, I have gone for Rycote’s red lining cloth and Rycote long fur (all supplied by the metre direct from Rycote: amazingly helpful people there), with the usual elasticated drawstring tightly closing the side opening. The cage was built to my design by a friend of mine, who works with stainless steel wire for rolling-ball sculptures – all for a few pints of beer – and the fur covering was made by another friend with professional sewing skills.

Blimp with fur

Initial testing met expectations, not least with the better windnoise attenuation resulting from a larger diameter windshield than those usually designed with necessary compromises for boom-pole use: it’s the distance from the sound generating surface (the outer side of the blimp) that matters, with the inverse-square law applying.

Needless to say, I am by no means claiming this as a sensible/feasible option for most usage (and I have much more practical alternatives for most projects): it is heavy and I wouldn’t want to carry it and its stand (I use a Manfrotto 1004BAC) more than half a mile or so. There are, of course, many lighter, more robust and less humidity-sensitive microphone solutions that will be preferable for most projects (e.g. a Sennheiser MKH 30/40 pair).

However, this DIY approach might be of interest to anyone else was thinking along similar lines with LDCs (and there is no need to be afraid of getting large studio mics outdoors): LDC mid-side arrays are feasible for such use and it makes good sense to consider (affordable) purpose-built windshields as alternatives to shoe-horning LDC mics into undersized windshields or adaptation of less than ideal items from the local DIY store!

In action, recording musicians in the grounds of Mannington Hall

And for anyone really keen, here’s my design