Chladni Plates

Mojo Goro

Ernst Chladni  was a German physicist and musician, most known for the Chladni Plates – an experiment which still looks intriguing to most of the people. This experiment is a good and beautiful way of visualizing the nodes and antinodes on a vibrating surface. Originally this experiment was obtained with a metal plate with some sand on it that is driven into various resonant states with the use of a violin bow. The plate itself like everything in the physical world would have a certain resonant frequency, and when the frequency of the vibrations matches or is proportional the resonant one, these interesting shapes as in the picture below would be formed by the sand.

Chladni Plates patterns for different frequencies

You can actually watch a modern recreation of the original experiment on youtube:

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Acoustic Music Production – Part II – Recording acoustic live sessions

Some musicians prefer to record themselves with other musicians in the same room. With this, some technical difficulties in recording each signal may appear. For example, we don’t want the sound of the drummer appearing in the microphone of the lead singer. To avoid this undesired interference, the choice of the microphones is, again and always, essential.

Microphones can be classified according to their pattern and according to their transducer type.

The pattern indicates from where in the space the microphone can recognize the signal. The figure below shows the most common type of polar patterns:

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The figure below shows the microphones according to their transducer:

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The condenser microphone is more sensitive to the variations in the sound pressure and, due to this, it can capture a more detailed signal. However, on stage this can be a problem, since the noise from the audience, for example, can appear too much in the recording. In the case of recording in studios, the dynamic microfone is more indicated to record both instruments and voices.

The combo of dynamic + cardioid is the most used pattern for recording voices at live sessions (studio or stage) because this pattern has good rejection from the things that are not in front of the microphone. So, in the video below, we chose to record the voice with the classic Shure SM58. The guitar had the mid-side technique on it (which was talked about in the previous post) and a direct injection as well. Enjoy!

 

Acoustic Music Production – Part I – Recording in stereo with the mid-side technique

Recording acoustic music seems to be way much easier than recording an entire band. In fact, if we have less instruments to be recorded, the recording process will be easier. The differences between the two patterns will be seen in the mixing process. Last month I entered in the studios to record three acoustic songs. The format of the recording was very simple: two acoustic guitars and voice. For the people that doesn’t understand, if asked, they would say that we just have to put a microphone for the voice and plug the guitars directly on the hardware. However, this can be a mistake.

For recording processes with microphones, there are loads of ways of placing the microphones. Most of the techniques used with microphones are the so called stereo techniques. When we record a signal from a source, the signal will be stored in the computer as a mono signal, which means that, in general, the sense of ambience will be lost, since the signal will be reproduced in both left and right ears with the same characteristics.

Broadly and technically speaking, a stereo signal is a two channel signal. If we want to record an acoustic guitar, for example, in order to avoid the loss of ambience, at least two microphones would be needed. The technique that I used in the recordings of last month was the mid-side technique.

To do this, you need two microphones, one with the figure-of-eight pattern, and another with a cardioid pattern. The microphones are placed very close to each other, in order to avoid phase cancelation. The representation is shown in the figure below:

 

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Figure 01 a) – Mid-Side technique diagram

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Figure 01 b) – Mid-Side technique demonstration

Then, after the recording, we will have two signals, each one from each microphone. We then duplicate the signal from the figure-of-eight microphone (by this point you should have three tracks in your DAW software). The duplicated signal will have its phase inverted and panned 100% to the right (or left); the original signal of the figure-of-eight must be panned 100% to the opposite side of the inverted signal (right if the inverted is for left and vice-versa); the signal of the cardioid must be centered in the sound field image. With this, we will have a stereo recording without losing ambience.

In the next part we will talk about mixing acoustic recordings. See you!

 

 

This week we started the releasing of new videos of mine. The idea behind this project is to show the audio production in the studios of the University of Salford, and also to gather attention to the release of my EP, which will be on in August. To take a look on them, press play!

 

Filming Augusto’s Music

Recording with Davide this afternoon!

Davide Desimone

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Today I am filming my Brazilian friends in the Newton Studios at the University of Salford. So I have just been to Media City UK to pick up a camera.

I will be using two cameras to record the videos. One is the Sony Ex-3 and then my own personal GoPro Hero 3+. We are planning to film and record 3-5 songs in an 4 hour session.

I have been excited about this session, ever since it was organised last week. Both Augusto and Lucas are brilliant musicians and I hope to work with them more in the future.

Thanks for reading!

Davide Desimone

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New Song – “Boa Hora”

“Boa Hora” (“Good Time”, in English), was the first song that was released for my brand new work, called “Mini-Acústico Augusto”. Produced by me and Lucas Pitangueira, the video was released in early December of 2013, and has more than 3000 views. Ingrid Knochenhauer helped us by singing (as an angel, indeed!) with me.

It seems quite unusual to record more than one musician in the same room by using condenser microphones. We tried to use them in order capture the best details of Ingrid’s voice and also mine. The microphones used for this work were:

2x Neumann 87ai (vocals), 1x Rode NT-2A (spot), 2x Neumann KM184 (percussion), 1x MXL 990 and 1 MXL991 (both for the acoustic guitar).

The mixing was made by Lucas Pitangueira. To view the lyrics in English, don’t forget to activate the subtitles!