Sound Blaster 2000

*Note: An adapter tray is required to hold a smartphone in place. An example starter tray can be found here.

I am testing and researching sound propagation at various frequencies from 10khz to 20khz. The Sound Blaster 2000 redirects the bottom speaker sound, from a smartphone, in a forward direction to match the top (ear) speaker.

On iOS an app like this can be used for frequency generation: 

https://apps.apple.com/us/app/audio-function-generator-pro/id895074703

This app has a number of functions for frequency generation, but what is really handy is the in-app volume adjustment. That way you don't need to remove the smartphone for volume adjustment. There are also functions for cycling/looping frequencies between limits.

The Sound Blaster 2000 ‘chassis’ accepts customizable ‘trays’ that adapt the stock chassis to whatever smartphone you have (with or without case). A default starter tray, designed for an iPhone 15 Pro Max with faux leather case, can be found here. Feel free to customize the adapter tray. Note that the adapter tray has a series of friction ‘snubbers’ to secure the phone to the tray. Since there are hundreds of variations in phone sizes with/without protective cases I'm leaving it to the user to create a custom adapter. Note that the tray drops into the chassis and has 2 small retaining posts to prevent the tray from sliding out of the chassis.

I included a frequency spectrogram showing without/with a 15khz sound spike. Note that some smartphones may not generate signals > 16khz using default speakers. Or, it could be the microphone on the iPad used for testing does not accurately record signals > 16khz. The spectrogram test was done at half volume from appx 25' away.

I printed the SB2k using PLA on an OPXL2h with input shaper at .32 speed. In the SB2k project .3mf you'll see that I used a support enforcer for the chassis slot face (print so text upside down.) No other supports are required. For the tray adapter Remix, print it speaker side down with supports (also enforced.) I'm thinking PLA may be better than PETG as it is more firm/hard in structure and might reflect audio better.