High Gain Audio Amplifier Surveillance Circuit - DAA
Built By Pete Zenner - Oct. 2013, Sioux Falls, SD.
I finished the DAA, got it potted into a metal enclosure. Here's are some photos of the final set. The "Atomic Amp" on the end is the coffee can with your suggested smaller enclosure on the back end to hold the mic. I couldn't find a 35mm canister, so a pill bottle had to substitute. The DAA amp is in the center, two jack—for a head set and the attenuated output for a recorder, An 8Q. mono headset. This one was found in a thrift store. I'd suggest that when people who make your amplifiers see low impedance mono headsets, they snap them up. I found three of these, with no make or manufacturer's mark, but they work great after a plug change to 1/8".
The enclosure actually looks nicer than this photo. It's just a black enamel painted gift tin. For some reason all the blemishes show up under a flash. The mic jack is on top—2.5mm Switchcraft. I now use all 2.5mm jacks and plugs for microphones to keep people from plugging headsets into mic jacks and vice versa. The 3.5mm (1/8") headphone jacks are hidden below the knobs. Knobs are a greater pain in the butt than I realized. I have a bunch of different potentiometers and there's whether they have a flat section on the shaft, slotted, 1/4" or 6mm-all take different knobs. Just finding or modifying two that match can be difficult. It's the curse of buying surplus parts. They cost less, but you spend more time making your project look nice.
It is a very powerful amplifier
NOTE: For the details on the "Atomic Amp" - mentioned by Pete, in the text below - Please click into the "Atomic Amp" Link at the bottom of this page.