Magazine Archive

Home -> Magazines -> Issues -> Articles in this issue -> View

Are All Those Microphones Necessary?

Hi-Fi Supplement


This article by Mike Skeet suggests that simple techniques using just a few microphones can produce fine results even in the "pop" field, the most likely place to find "the mic for every instrument situation". His specialisation in 'Dummy Head Binaural' is well known in the Hi-Fi world and this introduction should give some ideas for making lower budget recordings.

Having begun my own small record label three years ago with the main objective of issuing material recorded with more simple microphone techniques (which generally means less microphones) than other studios, I was attracted to try binaural recording with a Dummy Head. The results proved that here was a low cost means to assist in launching recordings of new composers and performers in modern and classical music. Moreover, using binaural techniques retained significantly the original atmosphere of the location, from churches, concert halls to clubs and pubs.

Mic Placement



It does of course depend on what is being recorded, i.e. the instrumental line up. For this article I have in mind the "pop" music line up of lead, rhythm, bass, drums, vocals and possibly keyboards.

My drawing in Figure 1 shows a likely Multimic layout and Figure 2 shows the proposed set-up using fewer mics based on the use of a couple of crossed directional pairs with additional "spot" mics for bass, drum and vocals.

Figure 1. Multimic layout.


Figure 2. Crossed pair layout.


In case it is necessary to cover the point I must define Multimic and Multitrack. The latter implies the use of the former of course, but where the individual mic outputs are kept separate for later mix down to pan-potted 'stereo' or by 'simulsync' overdub of individual musicians. For both Figure 1 and 2 I am assuming a direct mix into two track stereo of the "live" performance. As far as multitracking with microphones is concerned, I feel that 16 track is a minimum (not forgetting that many studios exist as 24 or 46 track) and that 8 track is too restricting, with 4 track not worth considering.

Crossed Pairs



Figure 3. Crossed 'coincident' pairs. Shown above is AKG C414 Capacitor (switched to Cardioid or Hypercardioid or even 'figure of eight')

Cardioid or Hyper Cardioid pick-up pattern mics are required as the stereo information is directly achieved by the intensity differences produced by their polar patterns, provided that the diaphragms are as coincident as possible. The best that can be obtained is to mount them one above the other at around 110° as shown in Figure 3. Crossed figure of eight mics are also possible and here 90° crossing is the norm - care must be taken to keep in the 90° quadrant as out of phase signals are produced outside this, although it only becomes a real worry if analogue disc cutting is finally envisaged.

Calrec CM652 Cardioid Capacitor pair


Why Dummy Heads?



Being a bit of a fan of headphone listening is the main reason. It is probably not all that well known that a couple of omni microphones spaced around 140mm apart and separated from each other by a baffle of approximately 190mm diameter (see Figure 4) can produce surprising "out of head" or binaural effects when listened to on headphones and also a very effective "stereo" on loudspeakers.

Figure 4. Omni mics baffled from each other for 'dummy head' binaural. Sennheiser MKE203 Electret Capacitor (left) and AKG C414 Capacitor set to omni.


The Means!



Now I'm not going to suggest that one takes any old pair of mics and a portable cassette recorder and straightaway you are the new recording vogue of the 80s! The minimum one needs is around five low impedance mics, a mixer with at least that number of channels, a couple of reel to reel recorders (to allow copy overdubbing), suitable mic stands and booms, long enough mic leads to reach a separate room for monitoring, a means of monitoring on site, preferably with decent loudspeakers and amplifiers. Then there is "talk-back" to instruct the performers and even "foldback" of what is being recorded on headphones. This latter can however often be done by the band themselves — preferably on phones as foldback loudspeakers can "colour" the sound in the "studio".

Figure 5. A really effective low cost dummy head using Omni tie clip (RS components 249-463) element mics in chipboard/foam/windshield construction.

On quality aspects, each link in the chain will need a pedigree at least up to the standards expected. Notwithstanding that however, there's nothing like gaining experience with what one has got around you. I've found that good results can be obtained using just two omni mics (in a dummy head) and a stereo cassette recorder, provided that instruments have been carefully positioned, along the lines of Figure 2, and the control levels of each instrument have been suitably adjusted.

How is Balance Obtained?



Straightaway it must be stated that BALANCE is the operative word. One is trying to achieve a balance of the relative levels and perspectives of the instruments against each other and in the case of crossed pairs or dummy heads, also against the acoustics of the room being used. With the multi-mic approach, the closeness of the mics (usually themselves directional) means that the room acoustics recede in the pickup. The resultant pan-potted stereo presentation produces, for me, the abhorant leaping out of 'unrelated to each other' sounds. My favouring simpler mic techniques is not just on possible economic grounds - it's more to feel on playback that the sound stage is a unified whole and not a fragmented jigsaw of close-up sounds.

So to balancing when crossed pairs or dummy head pairs are in use. The separate miking of the drums and vocals allows conventional "mixer" level control. The instrumentation grouped around the main mic has to be balanced by the performers, although basically with a layout like that in Figure 2 they need to be at a high enough level relative to the drum kit, to prevent the main mic acquiring too much drum sound. With directional crossed pairs one could place the drum kit behind the main mic and take advantage of the 20dB or so back rejection available. However, in small rooms this is only partially achieved due to reflections (the whole room becomes a sound box) and also, if omni mics are used in a dummy head, one has not got any directional effect in terms of pick-up level.

Figure 6. Even low budget recordings can amass some gear! Used fora Whitetower session with 'The Crew' band.


Giving the performers "control" of the balance can be the death knell of the good intentions! Each musician will in turn, after every subsequent playback, try and get his or her instrument loudest! While I certainly favour the band having their say about the balance, there has to be a discipline about how it is done. Initially I get them to play at a normal practice level or moderate "gig" level and balance, record it and judge the changes needed on playback. Then leaving the bass alone, if satisfactory relative to the drums, I appropriately make adjustments to the other instruments. It's a good idea to get players to note their level settings. They soon learn that an otherwise good take can be ruined by an accidental change in someone's level and the engineer can do nothing but wish possibly that he had multi-miked the whole affair!

Remember also that in crossed pair or dummy head main mic situations, moving an instrument's cabinet position can also be used to "adjust" its level, provided the change in perspective is acceptable.

Finally, some kindred aspects. Some amplifying systems produce annoying hiss, or worse, hum levels. In my experience this can often be due to inappropriate settings on "pre" and "main" amps. Also I like the cabinets to be raised off the floor to avoid honking. The aim is to get the high frequency output "firing" straight at the main mic.

Should any reader want to sample the ideas described, there are several sampler cassettes available on Mike Skeet's own Whitetower record label. Problems normally encountered with high speed cassette duplication (both sides at once) are avoided by copying in 'real time'. The quality and variety of examples should convince you of the merits of binaural techniques. Listening on headphones can give a very strong sensation of sounds all around you. Mike has kindly offered his 'This is Binaural' cassette to readers at the special price of £3.75 including VAT, post and packing. Send your cheque made out to 'Whitetower Records' (E&MM Offer), to (Contact Details). It contains 40 minutes of music and sound effects, with church, classical, pipe band, jazz, pop pieces recorded at different locations that impose their own special atmosphere through these techniques, and trains, cars, planes, speech and fireworks showing the realistic sound fields created.


More with this topic


Browse by Topic:

Microphones



Previous Article in this issue

Hi-Fi

Next article in this issue

Education


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Aug 1981

Topic:

Microphones


Feature by Mike Skeet

Previous article in this issue:

> Hi-Fi

Next article in this issue:

> Education


Help Support The Things You Love

mu:zines is the result of thousands of hours of effort, and will require many thousands more going forward to reach our goals of getting all this content online.

If you value this resource, you can support this project - it really helps!

Donations for January 2022
Issues donated this month: 3

New issues that have been donated or scanned for us this month.

Funds donated this month: £141.00

All donations and support are gratefully appreciated - thank you.


Magazines Needed - Can You Help?

Do you have any of these magazine issues?

> See all issues we need

If so, and you can donate, lend or scan them to help complete our archive, please get in touch via the Contribute page - thanks!

Please Contribute to mu:zines by supplying magazines, scanning or donating funds. Thanks!

Monetary donations go towards site running costs, and the occasional coffee for me if there's anything left over!
muzines_logo_02

Small Print

Terms of usePrivacy