Ben Anderson’s Uniblog

This task was all about experimenting with different stereo miking techniques used on three different instruments and analysing the results. I recorded a total of nine different recordings using three of the same techniques on each of the three instruments. The instruments I recorded were Saxophone, Clarinet and Piano.

   My reasons for choosing these instruments were mainly due to the fact that I know people who play them, but also because of the rich sounds that they produce. Saxophone’s produce naturally low and loud frequencies therefore I felt it would be interesting to experiment with different mic techniques to achieve the best recordings. The clarinet is produces a nice broad frequency range and unlike the saxophone it is not quite as loud and harsh. The piano is also a very challenging instrument to record because it has such a wide frequency range larger than that of either the saxophone or the clarinet.

The room from which I recorded in was Helmore 041. Acoustically this was not an ideal room to record in as it is very lively, and produced a lot of reverberation and resonance. There are several reasons for this, firstly the room is not ideally shaped and was too square. Secondly there was no acoustic treatment of any kind. There was also an awful lot of flutter echo as well, so any recording that was made was being treated by the acoustics of the room. However the room across the other side Helmore 044 was a little better for recording in as it did have some acoustic treatment such as acoustic pads which cut down the amount of reflected sound. This meant it was far less reverberate and more acoustically dead.

Stereo Technique 1: AB

This particular technique comprises of using two omnidirectional condenser microphones spaced evenly apart around 40-60cm as stated in the microphone university website. This i felt achieved a deeper tonal response especially for the saxophone and clarinet. For this technique I opted to use the Octavia condenser microphones as I felt they sounded more lively than the SE Electronics Z3300a condensers.

Saxophone recordng

 For this recording I wanted to pick up as much of the overall range of frequencies of the instrument as possible. I didn’t however want to pick up too much room ambience as I didn’t feel that the room had particularly good acoustic qualities. Therefore I ensured that the microphones were placed roughly around the same distance as the length of the instrument. Also because the saxophone is fairly loud instrument, the microphone needed to be a little further away to avoid clipping on the recording. This achieved a very rich recording of the entire range of frequencies. The distance between the two microphones was fairly wide as I felt this achieved some very nice deep tonal qualities. The microphones were angled so that they pointed at the bell of the saxophone.  I wanted to pick up the breaths and key noises and I felt that this was a more natural sounding recording.

Clarinet

The miking of the clarinet was very similar to that of the saxophone. The microphones were positioned slightly closer to the clarinet at around 3 feet away, as it isn’t such a harsh instrument, but still enough distance to pick up the full body of the clarinet and some of the natural ambience.  The microphones were placed exactly the same distance apart as the saxophone recording at 40cm. I opted to angle the microphone away from the bell as the better range of frequencies comes from above the instrument towards the mouthpiece. This delivered a bright recording and a very deep tonal sound.

Piano

Piano miking always provides a challenge when trying to get the purest recording of the frequencies and dynamic range. Unfortunately due to the room resonating a lot, I was unable to get a perfect recording so I simply had to work with what I had. If I were looking to make a clean and professional recording of a piano then firstly the room would have to be better acoustically and bigger such as a hall. Also I would require more than one stereo mic set up, possibly a further four microphones. Anyway I decided that the sound was richer when the microphone was pointed directly at the strings. This required me to remove the lid and position the microphones down at the hammer and strings. As mentioned in sound on sound, it is suggested that the microphones should be placed four metres back from the front of the piano and around two to three metres up positioned on an imaginary line across the axis of the open lid. This would be an ideal positioning, but there just wasn’t sufficient room for this, therefore I positioned the microphones as high as possible and around a metre away from the piano, and around half a metre above, pointing at the inside of the strings. This appeared to give me a more natural sound and picked up some very rich tonal qualities which any other positioning did not achieve. There are many theories on how to mike a piano, but I simply went by the judgement of my ears.

Stereo Mic Technique 2 - XY

This technique requires both microphone capsules to be practically touching each other, positioned 90 degrees apart and the centre line at 0 degrees is where the instrument will face. The microphones used were again octavia condensers using a cardioid polar response setting. As described in the DPA microphones guide, the stereo image is produced by the off axis attenuation of the cardioid microphones. This technique in contrast to AB is a a difference in level stereo as opposed to a difference in time stereo.

Saxophone

For this technique I moved the microphones closer to the saxophone as the capsules were facing away from the bell, meaning that it wouldn’t clip as easily. The microphone was around half the length of the saxophone away from the bell and directed the microphone lower down to the floor just under the bell. This resulted in a much fuller recording than the previous technique.

Clarinet

 For this technique I placed the microphones roughly at the same distance of around three foot same as that of the AB technique, directing the microphones upwards towards the mouthpiece. The stereo image wasn’t as noticeable as that of the AB technique, but I found that this technique gave a fuller frequency recording.

Piano

For this technique I decided to place the microphone in the same spot as the last recording achieved a nice full frequency response. As this technique means that the mics are very close together, it does not achieve such a large stereo image, and I had problems with phase cancellation. However after a bit of trial and error I eventually positioned the microphones about 2-4 feet away at the end of the piano and about 3 foot above the top of the piano pointing across the top of the strings for a richer sound.

Stereo Mic Technique 3 - ORTF

This technique uses two cardioid condensers spaced 17cm apart from the diaphragms and at 110 degree angle from the capsules. This technique is good for reproducing a stereo image similar to the perception of the human ear. The spacing of these microphones mimics the distance between the human ears offering a wide stereo image.

Saxophone

With this technique I began by positioning the microphones further back than with the other techniques, but soon found that I had a lot of low end loss so ended up moving the microphone closer to gain a fuller recording. The microphones were around 3 foot away from the bell, and about a foot off the floor picking up a much wider spectrum of frequencies.

Clarinet

Similar to the saxophone the microphones were positioned about 3 foot away pointing upwards towards the mouthpiece and this picked up a more natural overall sound of the clarinet.

Piano

This technique I put the microphone around a foot above the piano facing downwards towards the strings and the capsule was roughly 3 feet away. This provided a very full recording however I felt it sounded less natural than the other techniques, and slightly harsher. However it did pick up a very nice stereo image of the piano hence the full sound.

Conclusion

Having completed and experimented with these techniques, I feel that the results could have been further improved by having a better acoustic environment. Especially for the piano recordings as the room was far too resonant and the sounds reflected off the walls too much to get a natural sound. The Helmore 044 drum room was slightly better for recording as it had acoustic padding to reduce the reflections but it was still not ideal. However I simply made the most of what I had and feel that I still achieved some good results with the various techniques and gained knowledge of what worked and what didn’t work so well. It would have been interesting to try out a wider range of miking techniques and perhaps improvised with some of my own techniques, in order to test them against the three other techniques.

Anyway I will now look at the saxophone recording and assess what I believe to be the most effective technique.

The AB technique yielded some very nice results. I felt it achieved a warm sound on the saxophone perhaps not as harsh as the other techniques, and picked up a nice wide stereo field. The way in which the microphones were positioned I feel helped gain the richness of frequencies and it picked up the bottom end very nicely.

The XY technique was my least favoured technique of the three. You can definitely hear that the stereo field is much narrower and the recording sounds quite flat in comparison to the AB. This is due to the microphones being much closer together, therefore it sounds much more mono than the AB technique.

The ORTF technique was my favourite technique of the three. It produced a nice wide stereo image due to the capsules being spaced widely apart from one another. I also felt that this technique picked up a nice room ambience and a very full range of frequencies. I felt that the technique yielded some lovely tonal qualities and this would definitely be my preferred choice over AB and XY techniques.

For the clarinet I felt AB technique had a really nice and well rounded sound. It picked up the dynamics of the clarinet perfectly and had a very natural frequency range, very full and rich tonally. This one was definitely my favourite of the three techniques with this instrument. The ORTF sounded way too harsh and the frequency pick up was not as well rounded, and the same goes for XY which sounded a little thin in my opinion.

Finally onto the piano and this was a difficult one as the room was not the most practical for recording piano due to unwanted early reflections and sound resonance’s. However the most successful technique after much debate and thought I have decided to be AB. This technique had the most natural sound and wasn’t affected too much by the rooms acoustics and maintained a perfect stereo image throughout. The frequency range was so full and precise compared to the other two which I felt to be rather flat in comparison. It appeared to pick up much more of the higher end range and sounded more vibrant.  

This entry was posted on Saturday, May 17th, 2008 @ 7:07 pm on the category Production and Recording for Musicians and . You can follow any responses to this entry through the RSS 2.0 You can leave a response, or trackback from your own site.