SoundBar VU Meter Laminated Wooden Speaker

I felt that the battery powered Bluetooth speaker I made could be improved with more colour! Taking a leaf from the VU meters on amplifiers of the 80s, I decided it would be neat to sandwich clear acrylic between the plywood layers, each with an integrated LED that would form a full body amplitude meter.

Having a look around, I found a IC made by Texas instruments that did the VU meter job for me: the LM3915. Below is a photo series showing the construction and completed unit. I designed this version as a soundbar to sit below my monitors at work, so it doesn’t have a battery or Bluetooth, making the wiring easier inside and a slimmer unit. For this one I also used an Oak stain rather than a clear stain on the ply and filled the text with black acrylic, which looks much better I think.

Ambient Noise Level Indicator

As part of my work at MACH Acoustics – understanding how internal ambient noise levels affect different environments – I was inspired to create an indicator that shows when noise becomes higher than the base level. Some solutions already exist but they are pricey (because they used calibrated sound level meters), and not very engaging. I wanted something that could sit in a classroom and be a friendly indicator for the teachers and students, bringing the noise back down and perhaps learning something in the process!

The solution is a simple RGB led connected to the PWM outputs of an Arduino and uses Processing with the Minim Library to perform a FFT on the mic input – similar to a couple of other projects.

The operation is best described by the video below and commented code. I’ve added a handy GUI that allows the user to do a number of things:

  • View the mic reading, background sample, instantaneous sample, current colour and sample difference.
  • Change the threshold between colours and benchmark colour.
  • Set continuous sampling, direct LED/mic feedback
  • Resample the background
  • Set the frequency band that is used for the amplitude average – this is useful to demonstrate that it is working and also to ignore low frequency to only show speech for example; screechy children in a classroom!
The control panel when the Java applet is running.
The control panel when the Java applet is running.

Its only a prototype concept at the moment. I’d like to design an enclosure that would suit the particular environment, such as a glowing star or dragon for a classroom.

Continue reading Ambient Noise Level Indicator

Musical Rainbows in the Van

I always intended on creating my own driver for the LED lights in my van but with the thieving skum pointlessly taking the remote for the included unit, I was spurred into action. Having installed a sound system, a musical light system was a given, to enable the van to live up to the Bang Bus name it has acquired (of certain definition!).
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