Speaker System with Vacuum Tube Amplifier
This week’s goal is to figure out the dynamics from audio inputs to amplifier and output from the speaker.
This is the vacuum tube that I am using for amplifying audio signals.
We used oscilioscope at N51's MAD studio to test the electric signals in my LED matrix. The matrix uses MAX7291 chip driver, and has 5 pins: VCC, GND, Data in, Chip Select, Clock. I kept my 2048 game's matrix layout, and used one extra wire to retrieve the signal from end pins.
First, Xdd writes code to set all LED on every frame and test Data In pin, which showed a low/high signal. The cycle length is around 35 - 40 μs, which indicates the data update frequency is around 25 - 30 kHz. However, it is unsure what this cycle does, since to update the whole board of LED, 16 * 8 * 2 data will be sent (16 matrices, 8 bytes address + 8 bytes data for each board).
Meawhile, the clock pin showed a cycle of 2μs, which suggest a clock frequency of 50kHz.
The Chip Select pin showed a cycle of 625μs, suggesting a data reading frequency of 1600Hz.
The Chip Select signal cycle should directly reflects how frequent LED data updates. Therefore, I modified the code to update LED once every second. Indeed, Chip Select pin showed an 1Hz signal.
What we did not understand at all was both VCC and GND pins showed a wave of nearly 1V at 60Hz. We connected VCC to Arduino board's 5V out, and the board is powered by my MacBook without external power, which means we shouldn't get alternating current.
This week’s goal is to figure out the dynamics from audio inputs to amplifier and output from the speaker.
This is the vacuum tube that I am using for amplifying audio signals.
Ideally, it can be combined with multiple amplifiers to make the sound louder and also multiple controllers in between the systems
The first scheme of the idea was to get audio inputs from USB-C or Bluetooth and combine three vacuum tube amplifiers in a row, with a sound control bar attached to the speaker at the bottom.
In order to make this I began with Autodesk Fusion for the first time. However, I couldn’t find the components in the library and could not really make it from scratch within a short time
This is the prototype that I "manually" drew by Rhino. It only has one vacuum tube and one output mixer connected to the speaker as the output.
Although the system's sizes might not be correct, having this visual sketch as the first version of my electronic design was helpful. For next week's production, I will try to move forward while optimizing the design.
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