Aston Microphones Halo Reflection Filter by Arthur Stone
The Halo is a 'high-end' microphone reflection filter designed to improve vocal recording; a felt-foam hemisphere mounted to a mic stand half-surrounds the mic and blocks out unwanted room reflections allowing a clearer recording of the source.
Aston is a newish company, it's team has extensive experience in the pro audio field, and it's stated ethos is to bring new and unique products to a crowded generic market. Aston's main line is microphones: The multi-polar Spirit, reviewed here on Gearslutz, also the fixed-cardioid Origin (reviewed by Dowsed here on Gearslutz)...and the Starlight advanced pencil mic (which Gearslutz will be reviewing soon).
A video overview and with/without comparison:
'Allo Halo: Historically, the word 'halo' commonly referred to the orb of light seen on iconographic paintings of religious figures - a visual aura of pure light; there's also a reference in mathematics and science, to the Halo, as a 'monad.'
The term 'monad' describes the Aston Halo's function and affect well; the monad deals with a set of conditions close to a given point – in this case the mic. The Halo can be seen as forming a protective aural aura (sorry!) between the mic and the source it captures for recording. It achieves this by filtering out the sound of the source that is reflected off walls, floor and ceiling; as these indirect sounds have a slight delay they can cloud/jitter the direct signal. The result is a clearer direct signal from the source with less reflected room sound.
Aside from the first-rate metal components the Halo is constructed by sandwiching 100mm of acoustic foam between two PET shells giving structure and absorption.
The PET material used for the Halo can be thought of simply as recycled plastic water bottles (70%) yet this is used in many high-end and luxury products; the felt material that Aston obtain is patented and it is the perfect material for this application with a great mass/absorption ratio (or 'mass attenuation coefficient') in the vocal range.
Current price (Sept. 2017): approx. £220_$299_240 Euro
As always, worth shopping around for the best prices and dealer bundles.
Leonardo's Tardis: When I first saw the Halo in a photo I wasn't that impressed by the colour or shape but in the flesh it isn't as kitsch as I had imagined; the purple colour is kind of deep and tasteful. I swear Da Vinci could have drawn up the plans for the Aston Halo; it has an organic form and plays with light (and, given mirror points, sound too). There seems to be the Golden Mean in it's form.
Two 'non-slutz' visited the home studio; they thought the Spirit and Halo combo was cool and “cute” (not a word I'd personally use) – cool, yes. Elegant. Organic. Friendly. Encouraging. Yes.
It's like singing into a large sea shell and has a slightly Tardis-like effect of feeling deeper and more spacious than it is; the Halo didn't feel claustrophobic or boxy at all. Like all classics the form has function; in addition to great visual aesthetics, the Halo shape and texture diffuses and direct the sound close to the mic and source.
In use (Home-studio test): First I placed my head in the position where the mic would be inside the Halo – and listened. I could hear attenuation of external noise (traffic, seagulls, owls, neighbourhood sounds); this is quite handy if external noise is an issue. The Halo's attenuation was quite broadband in comparison with other filters I've used. A rough guess 200Hz to 7 kHz.
I used the Aston Spirit multi-polar mic with the Halo reflection filter in a variety of patterns: I liked omni which had a slightly compressed vibe within the semi-confines of the Halo, and cardioid for a more conventional sound. I tested on: vocal; spoken word; acoustic guitar; amp'ed lapsteel, electric guitar and bass guitar; hand drums; and percussion.
On vocal I recorded a signal that was less sibilant and brittle than usual and as there was more detailed source info the recording responded to EQ and compression well. Whilst I thought the Halo worked well for mic'ing guitar amps it was difficult to position it low enough without becoming unstable on a boom – I needed to raise the amp – but I liked the focus on the amp rather than the room. The same was true for most sources recorded: better definition and body. The Halo seemed less influential on higher frequency percussion e.g. shaker, tambourine, bright hand drums, but there was still something subtle affecting the high frequencies and I think this would be more evident with many tracks combined in a mix. On vocals though, the Halo's affect is more easily discernible.
A range of audio files are available at this link for the Gearslutz Aston Spirit review and also on the accompanying video.
I also did a compare-and-contrast with/without the Halo: the mic was in cardioid mode @48/24 WAV and dithered to 16-bit in Reason. The samples are raw and not processed. The first half of each audio file is without the Halo, then with in the second half. The levels are matched by ear.
Voc3 – I'm more confident with the Halo vocal as it sounds more focussed and better balanced. I hear more solidity and body especially in the low-mids; also there is less sibilance. IMO the Halo version will respond better to processing than without.
Although designed for and aimed at vocals the Halo also worked well with instruments, in general tightening the low-mids and bass and cutting room reflections in the vocal range.
AcGtr – This is a generic Chinese Gypsy Jazz acoustic guitar with steel strings. The Halo version sounded darker at first but the harmonics are still there (especially with some EQ) and I definitely hear more of the guitar body and articulation of the lower E and A strings; although the Halo-less version is immediately appealing and full of chaotic harmonics it is also quite brittle and faint and might sound sibilant in the mix. The Halo version is more intimate and plausible IMO.
Egtr - Hagstróm Viking semi-acoustic guitar into an Orange Crush 50 bass amp....mic about 3ft/1m away.
Clean guitar, nothing exciting. I do hear more plumpness in the low-mids on the Halo version, also a bit less scratchy. I think the Halo version would sit more easily in a mix and respond to EQ better – a bit more solid and tangible...warmer!
Bass1 – Squire Mikey Way Mustang bass into the Orange. Same mic position as above. Plumpness. Fatter sound.
Bass2 – I preferred the non-Halo version
In use (with/without Halo): When testing the vocal in the 'Green Room' (larger, longer reverb) I noticed that although the Halo improved the intelligibility of the source I also lost a bit of the room sound (which I wanted); with time and testing I could have possibly found a sweet spot without compromising one thing for another. Initially I could hear the Halo, mainly as colouration (darker tone like tape or saturation); I couldn't really tell until post-recording that the Halo hadn't coloured the sound but had removed a component (reflections) which had previously been colouring the sound. Consequentially I realised the slightly darker sound was the actual sound without reflections emphasizing the high end (and sibilant regions). The transition to accepting this as a norm was very quick; it isn't really apparent while tracking but later, with a couple of dB's boost it becomes obvious that the source is represented in better quality. A mini paradigm shift. Perhaps the reason tape and saturation processing is so popular is that it compensates for the issues caused by room reflections – something the Halo alleviates naturally at source.
My experience is that it takes a little time to get used to what the Halo is doing; the way recorded sounds are perceived is new and different and gear does not need to be used to compensate for the reflected sound.
That said, I think I do hear some character imparted by the Halo and my concern is whether this character might be generic and evident across many recordings. It makes sense that a resonant mass might, in the wrong room conditions and with a particular source, make itself heard – particularly in spaces where the room sound is desired.
Halo Spectrum: Voc1/2/3 were analysed in the fabulous Voxengo Span; I was looking for any visible patterns that confirmed (or not) what I was hearing. The Halo take is the bright green line, and without, the red line. The levels were matched by ear and this comparison isn't scientific or calibrated but I think there's enough to illustrate a couple of points (more graphs are attached below).
In the full bandwidth graph below (which represents the AVG average signal) we see a slight attenuation below 150 Hz and particularly in the subsonic 'rumble' region; also there is some attenuation in the 10-20 kHz region. I hear this as a more tamed bass and treble in the Halo-on samples.
When the graph above has a 1/6 oct smoothing filter applied we see a confirmation of the very slight bass and treble roll-off with the Halo (green line) on. The full bandwidth graphs for Voc1-2 (attached) also show similar characteristics.
The mid-range is the most critical region for the vocal recording; that's where the human voice is centred and where the ear of the listener expects to hear it. We've evolved to be more sensitive to sound in the mid-range; the environment once offered advantages (probably sex and escaping predators!) in that frequency range.
In the graph below the mid-range looks a little more restrained with the Halo on – which is what would expected if the Halo is filtering out reflections in that range. It's likely that the red line peaks are strong frequencies in terms of room sound and standing resonance; without the Halo these reflections would interfere with the direct source creating peaks and nulls and an uneven recording. The Halo recordings all sound more balanced and even to me; I can hear the mids and body of the instruments and vocals more clearly.
Saint or Sinner? In a nutshell, the Halo has a positive affect on the recorded sound; the recording sounds clearer, more defined, and has more body. To me it sounded unusual at first – almost coloured like tape or saturation, but I realised that I was hearing the source and character of the signal chain without the interference of the reflected room sound and there was a lot less treble than I was used to; another outcome of the Halo is that the signal is a couple of dB's quieter as it is not picking up the reflected sound. Once I matched volumes (with a Halo-less take) I could clearly hear an improvement: definition, body, tone, balance.
I debated with Tristan at Aston Mics about the validity of testing the Halo with the mic in omni and figure-of-eight modes: in theory, the Halo is designed to function with a mic in cardioid mode and nothing else. Being a Gearslut I was keen to test the Halo in all modes. There are some interesting tones available: the slightly compressed sound in omni that keeps the mids tight or the high-mid focus of figure-of-eight. This vastly extends the utility of the Halo, and a (multi-pattern) mic in smaller spaces or fixed positions.
Another factor is that if the Halo could only work with cardioid mode mics then it would need to be removed each time the polar pattern is moved out of cardioid, which is a nuisance if it's a fixed installation in home/project studios; in some uses/modes the Halo will adversely affect the source so it will need to be removed and stored. Less of an issue in larger spaces/studios with planned sessions and less need to capture spontaneity. Perhaps a hinged version would solve this issue.
Another point that came up for discussion was the integrity of the join between the metal hardware and the PET material of the main body. I initially saw that as a weak point especially after accidents, falls, bangs BUT – there will be a valuable mic inside the Halo, that could be damaged by a fall too. I realised that the Halo is not, nor designed to be, a rufty-tufty protective device (although ironically, it would actually protect the mic); the Halo is a finely balanced mass with the purpose of attenuating unwanted noise – the more I played around with the joint the more I realised that flexibility helped to 'float' the Halo and add to it's performance; it's a delicate balanced mass to attenuate room sound and care should be taken with it – even so it is robust and stable and likely to last decades.
Still Tristan at Aston Mics insisted I try my best to 'break it' – he would cover any damages personally :D
I did my best; the Halo survived bending designed to approximate a gnarly accident.
So far, the name Halo is deserved.
Sound quality: 5/5 Like any instrument or signal chain gear, some time is needed to learn the Halo and find the sweet spot. It won't compensate for a bad source or gear issues – in fact it may accentuate them in the same way that adding acoustic treatment tiles at mix-position mirror-points reveals previously unheard inaccuracies or flaws (when using the same monitors). Despite noticing some of the Halo's character in the reverberant Green Room, I felt I could work on positioning to find the sweet spot of colouration; the Halo's character was less evident in a dry or acoustically-compromised room and this is it's natural habitat unless used for separating multiple sources in a live session/tracking. One plus point is that the Halo will work with all your mics in cardioid and provide some interesting and unique tones in other polar patterns.
I didn't test the Halo in a noisy environment or tracking multiple sources in a live session; my instinct is that it would help improve source-mic quality and maybe alleviate feedback or crosstalk between sources on a recording.
Ease of use: 4/5 The Halo will likely need to be removed for different polar patterns; not too much of a session killer given the ease of removal. Regarding positioning (mic/Halo-room-source) it's quite straightforward, especially when no room sound is required but I found it took some experimenting to find the sweet spot where the Halo 'disappeared' from the recording in situations where room sound or ambience is required. For most users this will be a 5 stars category but I think 'slutz will appreciate the nuances.
Features: 5/5 The Halo is very well designed – simple but effective - and the hardware is good quality and very stable for a stand-mounted device of this type. The design offers a greater degree of coverage (rear, right/left, above/below) than other reflection filters and consequently more of the unwanted room sound is attenuated. The patented PET felt doesn't feel or look cheap. Photos do not really do it justice. I found the Halo to be instructive/educational too – I realised that I often need to compensate for room reflections by EQ, de-essing, etc. when a filter would alleviate that.
Bang-for-buck: 5/5 The Halo will be of more value to some than others but considering its effectiveness and cost it's a good deal for everyone. If you have a great-sounding room then it will not be as necessary as a terrible room; but, even then, there will be specific applications (especially non-vocal) where it would provide value. I really liked it on guitar amps and acoustic guitar. Even if only used infrequently or for specific problems, the Halo is less that the cost of a good plug-in and it won't need updating!
Paul White “highly-recommended” the Halo in his Sound-On-Sound review and I agree; it's a cost-effective way to improve your recordings at source especially in rooms/studios with below-par acoustics but also in great-sounding rooms e.g. for a more intimate vocal or when an auxiliary reverb is to be used.
Credits and References:
Halo - Aston Microphones
Industry Guru: Aston Microphones
Photos used with permission from Aston Microphones Ltd.
Original Tardis By Babbel1996 - selbst fotografiert CC BY 2.5
Leonardo da Vinci - Leonardo Da Vinci - This image is the work of Luc Viatour used with permission and under Public Domain.
Wall_of_MOOG.jpg: guiltysin CC BY 2.0
Moog Liberation Werbebroschüre Copyright holder allows free use and modification.
Museumsinsulaner Synthi VCS3 (1973): https://commons.wikimedia.org/wiki/F...ynthesizer.jpg
Creative Commons Attribution-Share Alike 4.0 International license.: Fredandres The Original: https://commons.wikimedia.org/wiki/File:GCB95.MAIN.jpg
Dicklyon - Own work using: Inkscape, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3730979
Additional photos by Arthur Stone