Keritech "Litle Red Devil" EL84SE - A custom-made amp with a Bluetooth interface and remote control
Channel: Keri Szafir
Date: 2023-01-01

Presenting the Keritech Electronics 84SE-LJ "Little Red Devil" stereo single-ended EL84 amplifier... with a twist that makes this amp unlike any others I built before. It has some very old-school and modern tech inside, working together. All handmade with love by yours truly, none of that machine and artificial intelligence rubbish. They ain't takin' amp builders' work away!

My customer's wish was to have a lovely little and cheap amp with a possibility of enhancing it with a Bluetooth interface and a remotely controlled volume pot sometime in the future. Here I come - doing the project on a budget tighter than Ethel Granger's laces, with a small enclosure I had to put it in, and a bunch of design obstacles to work around. I think I overdelivered. Ha.

0:00 Intro
1:48 Amp Overview
3:45 Little Red Devil? 
4:50 Back Panel
5:48 Signal Flow
11:10 Plate Voltage Filter (and Stupid Schematic Shenanigans)
13:18 Control Circuits and Bluetooth Interface
18:02 Power Supply
21:05 Correcting Again!
22:33 The Nerdiest Amp?
24:00 Recombobulation
27:35 Tubes and Final Words


The initial phase of wiring this amp appeared in one of my livestreams: https://www.youtube.com/watch?v=6bq5-hr4i0k - and the listening test 

The story of how I made it and what I had to overcome: https://www.youtube.com/watch?v=DFhWSQ70SNI
Problems with remote control: https://www.youtube.com/watch?v=t_BGBVj8iq0

Little Red Devil on Hackaday: https://hackaday.io/project/188931-keritech-little-red-devil-single-ended-el84-amp

Support me on my Patreon page at https://www.patreon.com/KeritechElectronics
Instagram - https://www.instagram.com/KeriSzafir
Hackaday - https://hackaday.io/keritech