Electric Guitar Amplifier

So Why was this so hard to build? Well the image shown here with the back cover removed gives a good idea.

Due to the shear number of features I wanted to include, there is a lot of electronics involved. I had to not only design and build circuits for each of the features/pedals I wanted to add, but also build the power electronics to power them. In the case of the vacuum tubes this created a real problem because they require 160V to power their anodes.

Rather than deal with high voltage input, rectifiers etc, I decided to generate this voltage using a boost converter to boost the 18v input up to the 160V required. I could have used an IC to do this but I instead decided to use it as an opportunity to learn more about power electronics and built my own boost converter with a closed loop feedback system from first principles.

Welcome Home(Sanitarium) intro solo:

Chorus/delay circuit:

This is by far my most ambitious hardware project to date due to the time constraint(1.5months), the immense electrical complexity of the amp and the requirement for a robust, good looking enclosure.

The Features:

• Clean and Distortion channels.

• Real tube distortion (3x ecc83 tubes).

• Chorus and Delay pedals (on clean).

• Klon and Tube Screamer 808 pedals (on distortion).

• Line in/out with volume mixer for channels+I/O.

• Brightness and EQ controls on both channels.

This boost converter uses a standard topology with a MOSFET, inductor, capacitor and diode and uses a tl431 negative feedback system with an optocoupler. The variable duty cycle square wave is generated with a comparator and a 555-timer triangle wave generator. This circuit operates at approximately 80% efficiency at 160V while powering the tubes.

Some one-take audio demos (guitar and backing track coming from the amp speakers)

Here are images of all the circuits involved:

The Physical construction/testing: