This is an attempt to try to get more signal out of dynamic microphones, as I literally have to max out the gain on my Presonus AudioBox iTwo to barely get a usable signal level, and that is with me speaking right on top of the microphone. This design is based on Project 66 by Eliott Sound Products , with some minor modifications, mostly me just playing around to see what are the effects of changing stuff around....
So here’s the situation, I accidentally ordered the parts for the Inline Microphone Preamp Project … to Malaysia. One month and a trip to Portugal later, I finally got the chance to use the electronics lab here in Cambridge for the first time to asesemble this thing (thanks Elena for bringing the stuff over for me!), and in good old DIY analog electronics fashion, it didn’t work first time. Turns out, the SOT-89 footprint in KiCad has it’s pins in the opposite order from those in the NXP datasheet for the PBSS4540X and PBSS5540X transistors I was using....
I recently picked up a Behringer BA85A (yes, yet another Behringer clone…) dynamic microphone, and have thoroughly enjoyed the sound that comes out of it. However, it does require me to crank the gain on my PreSonus AudioBox iTwo audio interface all the way to the maximum, and even then, I either have to speak quite loudly or be right on top of the microphone to get a signal that I don’t have to apply any post amplification, which is kinda annoying because I use it quite a lot for video calls, and sometimes adjusting the levels for ASIO devices can be tricky....
This is my attempt to try building this power amplifier from Elliott Sound Products , which was specifically designed to be a practice amplifier, in the sense that it allows electronics enthusiasts like us to practice our building and bug-tracking skills, and also to try modifying the circuit to learn some analog electronics. I had a lot of fun building this amplifier and attempting to do some measurements on it, and I hope you will enjoy this slightly more lab-notes style post....
Being on a little analog synth nerd-out lately, I chose to kick things off by designing the sawtooth generator that will ultimately determine the switching frequency of the boost converter. The sawtooth wave generated is used to derive the PWM signal that drives the gate of the FET. By connecting it and a control voltage to a comparator, a PWM signal with a duty cycle directly proportional to the control voltage will be generated....