I have been wanting to build an amplifier like this but I have no time to build it so I thought I can just share this design and let you readers build it. The design is pretty much similar to Elliott’s Amplifier design with very minor tweaks. As usual I always simulate my design with simetrix to validate that my circuit is working correctly.
About the Circuit
The circuit is based on Elliott’s design with very minor tweaks. These tweaks are very minimal and you can play on the simulation circuit which can be downloaded on the download page. the download link is on the bottom of this page.
D3 and D4 are being replaced with a LED on the final design but this will work also in case you don’t want to replace it with LED. D3 and D4 together with R16, R9 and Q7 are used to provide constant current for the differential amp Q9 and Q6.
D1 and D2 can be removed, they are only used in case Q5/VR1 fails. You can also opt to remove VR1 and Q5 instead and leave D1 and D2. But keep in mind that this will increase the idle/standby current of the amplifier.
R13 only represent the speaker and not an actual component of the amplifier. It is only there to act as an “speaker load” on the simulation.
Simulation
Simulation is done with simetrix, a free simulation software for hobbyist with some circuit size limitations.
AC Response:
PCB Design
The PCB design isn’t well made because I am too busy to make it better. The sizing of the components are only assumed so if you want to build this project better buy first the component and measure its dimension versus the one on the PCB, you can download the PCB file on the download page so you can edit it for your own preference.
You should take note that the instances of the components are not the same on the simulation model I made(i.e. R1 on the simulation circuit is not the labeled R1 on the PCB). I am just too lazy to edit it. The circuit is not too complicated to see which is which on the simulation and on the PCB.
Downloads:
You can download the simulation and eagle files on our download page.
[Download Page]