PaRfM – Task 3: Write Up
The third task making up Production and Recording for Musicians involved choosing three tuned instruments and making three stereo recordings for each, exploring different microphone placement techniques. The task required a lot of experimentation, close listening and fine adjustment for each of the nine recordings we made in total. I chose to record a mandolin, guitar and harmonica as I felt this gave me a variety of timbres to work with. While one may assume that a mandolin is very similar to a guitar there are many subtle differences which made recording each of them very different, for example the fact that all the mandolins strings are doubled, naturally causing a chorus like effect. I will, however, discuss these differences further later on.
The first recordings I made where using the AB pair technique for each of the instruments, starting with the mandolin. This involves two omni-directional microphones in parallel to each other, roughly 30cm apart. I tried a number of different positions for the microphones around the room and decided that slightly underneath the instrument pointing upward at it produced a very full sound, enhancing in particular the lower tones. This was very interesting as generally the mandolin’s sound has a very subtle bottom end and this mic technique and placement seemed to even the sound out.
However, this recording made me want to capture the sound of the mandolin as it usually is, i.e. with heavier top end. I decided rather than move the microphones themselves, I would simply try switching to figure of 8 and cardioids to see the effect this had on the sound. I found that the cardioids instantly gave me the sound I wanted and so although an AB pair is never usually used with such microphones, in this instance the ends justified the means.
I then switched back to omni-directional mics and began experimenting with the placement for guitar. I found that the mics needed to be on the same level as the guitar otherwise the signal became either too predominantly high or low end. I also experimented with placing the mics behind the instrument but the recording wasn’t as crisp and dry as before. However, with the AB pair directly in front of the instrument the recording became too dry and thin and seemed to lack body. To remedy this I tried offsetting the distances of the microphones from the instrument so that one was roughly 20cms further away. This instantly produced a very subtle chorus, probably due to the slight time difference for the sound to travel to the two mics.
Given the experimentation I had already done with mic positions within the room I decided that for the harmonica, placing the mics very high up would bring out the top end, which is essentially all the harmonica sound is. This instantly produced a very full sound with a lot of presence and so I used that for my AB pair recording of the harmonica.
The next technique I was keen to try out was the Decca Tree (due to it’s musically historic name), and needing only one more mandolin recording I decided to use it for that. It gave a very full sound indeed as this technique involves a third microphone (omni-directional) sitting in between and slightly in front of the other two, 90cm apart. However, this technique probably ending up being the least successful of the three mandolins as the stereo pair pointing outwards picked up almost only top end giving the sound as a whole a very tinny quality. Within the context of a whole band mix this may have worked very well as the abundance of high frequencies may have set it apart from the rest of the mix, for a solo recording however, there was just too much.
I decided to next try another three mic technique for a second guitar recording and so set up an OCT layout. However I found this produced a similar level of high frequencies to the Decca Tree and so I began to tweak the positioning of the mics to form my own variation. This helped in creating a more balanced sound but still didn’t seem to work quite as well as my variation of the AB pair.
For the final guitar recording I wanted to try the XY pair given the success of my AB pair previously. The XY pair is a coincidental technique as the microphones (both cardioids) occupy almost exactly the same space but are set up perpendicular to each other forming a right angle. I figured this may give the same subtle chorus effect that the AB pair did as they would both be picking up different reflections of the sound from the two sides of the room. This was primarily the result, although the mics also picked up a lot more top end than I had expected. In this case though, this did not compromise the sound, as it still sounded very full and vibrant.
This very rich, yet top heavy sound seemed perfect for use with the harmonica and so I did another XY pair recording for that. As I had expected, the sound fit perfectly and seemed far brighter than the AB pair I had used previously.
This thought then lead me to think about using the NOS technique for my final recording as it is almost an amalgamation of the XY and AB techniques. The NOS involves two cardioids at right angles to each other, 30cm apart. The sound this technique produced was by far the warmest and fullest of the three harmonica recordings I had done. I also produced a very wide stereo image in comparison to the other techniques, probably because the mics are separated not only by distance between them, but also by the angles they are pointing at. For this recording I also placed the microphone as close to the back wall as possible to minimise the sound bouncing around the room before hitting them. This may have also helped in producing such a clear recording.
I feel overall the my slight variation on the AB pair for guitar was the most successful recording and given the need to record guitar in the future I will know exactly what to do!
