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Do It Yourself audio: Jecklin/Schneider disc!

11 Jan

First of all, happy new year for everyone! Hope everything’s going fine for you. It has been hectic back in Spain for holidays those last weeks, seeing friends and enjoying time as much as I could but also working my ass off to prepare University assignments for the next 2 weeks. I guess it’s time to get to it…

One of the things that I had left for when I was back home was recording my fellow friends and bandmembers of Sweet Q playing in our rehearsal room. And not recording them in the usual way, but in Surround! I’ll have to bring that tracks back to Salford University’s studios and produce a 5.1 mix where I can recreate the room so a listener can feel like he or she is just there listening them play. More technical details on the recording process and technique will come in the next post, in a few days.

While I was doodling about which microphone technique to use for the surround recording, I came to remember something that I always wanted to try and do myself: construct a Jecklin disc with my own materials! Let’s go to the first stop: what’s a Jecklin disc?

As it name says, it is just a disc that is placed between two separated microphones to recreate a natural stereo image that is convincing both when listening in headphones and in loudspeakers. It does so because it is a baffle, made of acoustically absorbent material that creates a shadow area at high frequencies between those microphones, such in a way that recreates more or less accurately the amplitude, time-difference and frequency response between the ears. Low frequencies don’t represent an obstacle to the disc due to their large wavelengths so they reach both microphones more or less at the same time. Difference comes with high frequencies: the disc is an obstacle to them, so that the sound source becomes directional at that point and one of the pair of microphones will capture it before the sound wave arrives to the other one, giving us the idea of localization of the source. Continue reading

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Compromises in audio (I): Microphones

3 Nov

Since I started my engineering degree, I started to acknowledge (assuming it was way harder) that everything in life is a compromise between a great solution with a high cost and a “just OK” solution that’s much more convenient. Or as his Satanic Majesties The Rolling Stones very wisely said: “You can’t always get what you want/ but if you try, sometimes/ you get what you need“. Pop lyrics are sometimes more than great. Try to express it better and simpler, Yeats!

As I was saying before digressing, there is no perfect solution that covers all of the issues that we might face with no drawbacks at any point. The audio and acoustic world is one of the best exponents of compromises being made to achieve the best possible solution, which is far from perfect but is the best we can get with the technology or knowledge that we have at the present moment.

If we start by the first link in the chain from acoustic source to storage medium, we have the transducer, this is, microphones. And microphones are one of the biggest examples of a compromise solution if we have a look at them. Let’s take the difference between condenser and dynamic mics to start with. Simply put:

  • Condenser mics: Good (fast) time response able to capture accurately transients due to the diaphragm’s low mass, which means great high frequency response… they directivity might be switchable from omnidirectional to cardoid or figure of 8. The drawback? They’re mechanically very delicate and they need a constant voltage between the diaphragm and its backplate (48 V Phantom power or prepolarized electret).

A condenser microphone (Photo by Bill Selak, under CC BY-ND 2.0)

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Aeolus exposition

30 Oct

A short and simple post!

I spent this beautiful Sunday morning in an Audio Suite at the University of Salford building in MediaCityUK, doing a bit of work for the Digital Sound Production module.

And, while there, I had the occasion to spend some time in the amazing Aeolus exhibition by artist Luke Jerram that has been there since last week, but this time explained by acousticians and volunteers to a small crowd of families and passer-bys on this sunny day. This Aeolus is an acoustic sculpture, made by steel pipes of different longitude that connect in the center of the sculpture.

Aeolus acoustic sculpture at MediaCity UK

It’s really cool how it operates, not only producing sound by making resonate its pipes, but also by amplifying some of them using strings inside them who help the tubes’ own resonating modes. I also love how the light changes during the day according to the different position of the Sun in the sky. Continue reading